MedWorm.com provides a medical RSS filtering service. Over 6000 RSS medical sources are combined and output via different filters. This feed contains the latest items from the 'Mol Biol Cell' source. Sat, 13 Mar 2010 16:09:18 +0100 http://www.medworm.com/index.php?rid=3336160&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20200222%26dopt%3DAbstract Authors: Sasarman F, Brunel-Guitton C, Antonicka H, Wai T, Shoubridge EA, Consortium L Monitoring Editor: Thomas D. Fox Mutations in LRPPRC are responsible for the French Canadian variant of Leigh syndrome (LSFC), a neurodegenerative disorder caused by a tissue-specific deficiency in cytochrome c oxidase (COX). To investigate the pathogenic mechanism of disease we studied LRPPRC function in LSFC and control fibroblasts. The level of mutated LRPPRC is reduced in LSFC cells, and this results in decreased steady-state levels of most mitochondrial mRNAs, but not rRNAs or tRNAs, a phenotype that can be reproduced by siRNA-mediated knockdown of LRPPRC in control cells. Processing of the primary transcripts appears normal. The resultant defect in mitochondrial protein synthesis in LSFC cells ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3336160 Wed, 03 Mar 2010 00:00:00 +0100 3336160 http://www.medworm.com/index.php?rid=3336159&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20200223%26dopt%3DAbstract Authors: de Thonel A, Ferraris SE, Pallari HM, Imanishi SY, Kochin V, Hosokawa T, Hisanga SI, Sahlgren C, Eriksson JE Monitoring Editor: M. Bishr Omary Atypical protein kinase Czeta (PKCzeta) is emerging as a mediator of differentiation. Here, we describe a novel role for PKCzeta in in myogenic differentiation, demonstrating that PKCzeta activity is indispensable for differentiation of both C2C12 and mouse primary myoblasts. PKCzeta was found to be associated with and to regulate the Cdk5/p35 signaling complex, an essential factor for both neuronal and myogenic differentiation. Inhibition of PKCzeta activity prevented both myotube formation and simultaneous reorganization of the nestin intermediate filament cytoskeleton, which is known to be regulated by Cdk5 during myogenesis. p35, th... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3336159 Wed, 03 Mar 2010 00:00:00 +0100 3336159 http://www.medworm.com/index.php?rid=3336158&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20200224%26dopt%3DAbstract Authors: Shindiapina P, Barlowe C Monitoring Editor: Benjamin S. Glick Secretory proteins are exported from the ER at specialized regions known as the transitional ER (tER). COPII proteins are enriched at tER sites although the mechanisms underlying tER site assembly and maintenance are not understood. Here we investigated the dynamic properties of tER sites in Saccharomyces cerevisiae and probed protein and lipid requirements for tER site structure and function. Thermosensitive sec12 and sec16 mutations caused a collapse of tER sites in a manner that depended on nascent secretory cargo. Continual fatty acid synthesis was required for ER export and for normal tER site structure, whereas inhibition of sterol and ceramide synthesis produced minor effects. An in vitro assay to monitor ass... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3336158 Wed, 03 Mar 2010 00:00:00 +0100 3336158 http://www.medworm.com/index.php?rid=3336157&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20200225%26dopt%3DAbstract Authors: Dieckmann R, von Heyden Y, Kistler C, Gopaldass N, Hausherr S, Crawley SW, Schwarz EC, Diensthuber RP, Côté GP, Tsiavaliaris G, Soldati T Monitoring Editor: Carole Parent Actin dynamics and myosin contractile forces are necessary for formation and closure of the phagocytic cup. In Dictyostelium, the actin-binding protein Abp1 and myosinIK are enriched in the closing cup and especially at an actin-dense constriction furrow formed around the neck of engulfed budded yeasts. This phagocytic furrow consists of concentric overlapping rings of MyoK, Abp1, Arp3, coronin and myosin II, following an order strikingly reminiscent of the overall organization of the lamellipodium of migrating cells. Mutation analyses of MyoK revealed that both a C-terminal farnesylation membrane a... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3336157 Wed, 03 Mar 2010 00:00:00 +0100 3336157 http://www.medworm.com/index.php?rid=3336156&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20200288%26dopt%3DAbstract In conclusion, longitudinal genotyping of C. dubliniensis isolates from HIV-infected patients reveals that isolates from the same patient are generally closely related and may undergo microevolution. In addition, isolates may acquire itraconazole resistance, even in the absence of prior azole therapy. PMID: 20200288 [PubMed - as supplied by publisher] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3336156 Wed, 03 Mar 2010 00:00:00 +0100 3336156 http://www.medworm.com/index.php?rid=3328116&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20195709%26dopt%3DAbstract Authors: Sabourin J, Cognard C, Constantin B Recent studies proposed a pivotal role of TRPC channels, in particular TRPC1, in the striated muscle tissue and in the development of calcium mishandling observed in dystrophin-deficient skeletal and cardiac muscle cells (Vandebrouck et al. in J Cell Biol 158:1089-1096, 2002; Williams and Allen in Am J Physiol Heart Circ Physiol 292:H846-H855, 2007; Stiber et al. in Mol Cell Biol 28:2637-2647, 2008). In skeletal muscle, TRPCs are proposed to function in a costameric macromolecular complex (Vandebrouck et al. in FASEB J 21:608-617, 2007; Gervasio et al. in J Cell Sci 121:2246-2255, 2008) in which scaffolding proteins and dystrophin are central components maintaining normal calcium entry (Stiber et al. in Mol Cell Biol 28:2637-2647, 2008; Sabo... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3328116 Tue, 02 Mar 2010 00:00:00 +0100 3328116 http://www.medworm.com/index.php?rid=3316302&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20185770%26dopt%3DAbstract Authors: Ferrara N Vascular endothelial growth factor (VEGF, VEGF-A) is a major regulator of physiological and pathological angiogenesis. One feature of VEGF is the existence of multiple isoforms arising from alternative exon splicing. Our initial biochemical and biological studies indicated that such isoforms are uniquely suited to generate angiogenic gradients by virtue of their differential ability to interact with the extracellular matrix (ECM). Although ECM-bound VEGF was bioactive, processing by physiologically relevant proteases such as plasmin was identified as a key mechanism to convert ECM-bound VEGF into freely diffusible forms. This retrospective article examines the early studies and also emphasizes the subsequent progress in our understanding of these processes in health ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3316302 Sun, 28 Feb 2010 17:50:10 +0100 3316302 http://www.medworm.com/index.php?rid=3316301&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20185771%26dopt%3DAbstract Authors: PMID: 20185771 [PubMed - in process] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3316301 Sun, 28 Feb 2010 17:50:05 +0100 3316301 http://www.medworm.com/index.php?rid=3316309&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20181825%26dopt%3DAbstract Authors: Hernández MV, Wehrendt DP, Arregui CO Monitoring Editor: Vivek Malhotra PTP1B bound to mature N-cadherin promotes the association of beta-catenin into the complex, the stable expression of the complex at cell surface, and cadherin-mediated adhesion. Here we show that PTP1B is also required for N-cadherin precursor trafficking through early stages of the secretory pathway. This function does not require association of PTP1B with the precursor. In PTP1B null cells, the N-cadherin precursor showed higher sensitivity to endoglycosidase H than in cells reconstituted with the wild type enzyme. It also showed slower kinetics of ER to Golgi translocation and processing. Trafficking of the viral stomatitis vesicular glycoprotein, VSV-G, however, revealed no differences between PTP... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3316309 Wed, 24 Feb 2010 00:00:00 +0100 3316309 http://www.medworm.com/index.php?rid=3316308&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20181826%26dopt%3DAbstract Authors: Shinoda T, Ito H, Sudo K, Iwamoto I, Morishita R, Nagata KI Monitoring Editor: Josephine C. Adams Septins are a family of conserved GTP/GDP-binding proteins implicated in a variety of cellular functions such as cell cycle control and cytokinesis. Although several members of septin family, including Septin 14 (Sept14), are abundantly expressed in nervous tissues, little is known about their physiological functions, especially in neuronal development. Here we report that Sept14 is strongly expressed in the cortical plate of developing cerebral cortex. Knockdown experiments by using the method of in utero electroporation showed that reduction of Sept14 caused inhibition of cortical neuronal migration. Whereas cDNA encoding RNAi-resistant Sept14 rescued the migration defect, the C... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3316308 Wed, 24 Feb 2010 00:00:00 +0100 3316308 http://www.medworm.com/index.php?rid=3316307&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20181827%26dopt%3DAbstract Authors: Saha S, Mundia MM, Zhang F, Demers RW, Korobova F, Svitkina T, Perieteanu AA, Dawson JF, Kashina A Monitoring Editor: David G. Drubin Actin arginylation regulates lamella formation in motile fibroblasts, but the underlying molecular mechanisms are unknown. To understand how arginylation affects the actin cytoskeleton, we investigated the biochemical properties and the structural organization of actin filaments in wild type and arginyltransferase (Ate1) knockout cells. We found that Ate1 knockout results in a dramatic reduction of the actin polymer levels in vivo accompanied by a corresponding increase in the monomer level. Purified nonarginylated actin has altered polymerization properties, and actin filaments from Ate1 knockout cells show altered interactions with several ass... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3316307 Wed, 24 Feb 2010 00:00:00 +0100 3316307 http://www.medworm.com/index.php?rid=3316306&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20181828%26dopt%3DAbstract Authors: Kong DK, Georgescu SP, Cano C, Aronovitz MJ, Iovanna JL, Patten RD, Kyriakis JM, Goruppi S Monitoring Editor: Jonathan Chernoff Autophagy is a cytoprotective pathway used to degrade and recycle cytoplasmic content. Dysfunctional autophagy has been linked to both cancer and cardiomyopathies. Here we show a role for the transcriptional regulator p8 in autophagy. P8 RNAi increases basal autophagy markers in primary cardiomyocytes, in H9C2 and U2OS cells, and decreases cellular viability after autophagy induction. This autophagy is associated with caspase activation, and is blocked by atg5 silencing and by pharmacological inhibitors. FoxO3 transcription factor was reported to activate autophagy by enhancing the expression of autophagy-related genes. P8 expression represses FoxO3 t... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3316306 Wed, 24 Feb 2010 00:00:00 +0100 3316306 http://www.medworm.com/index.php?rid=3316305&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20181829%26dopt%3DAbstract Authors: Xiong W, Jordens I, Gonzalez E, McGraw TE Monitoring Editor: Sandra Lemmon Insulin stimulates glucose transport by recruiting the GLUT4 glucose transporter to the plasma membrane. Here we use total internal reflection fluorescence microscopy to show that two trafficking motifs of GLUT4, a FQQI motif and a TELE-based motif, target GLUT4 to specialized vesicles that accumulate adjacent to the plasma membrane of unstimulated adipocytes. Mutations of these motifs redistributed GLUT4 to transferrin-containing recycling vesicles adjacent to the plasma membrane, and the degree of redistribution correlated with the increases of the GLUT4 mutants in the plasma membrane of basal adipocytes. These results establish that GLUT4 defaults to recycling endosomes when trafficking to specialize... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3316305 Wed, 24 Feb 2010 00:00:00 +0100 3316305 http://www.medworm.com/index.php?rid=3316304&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20181830%26dopt%3DAbstract Authors: Weber M, Chernov K, Turakainen H, Wohlfahrt G, Pajunen M, Savilahti H, Jäntti J Monitoring Editor: Thomas F.J. Martin Sec1p/Munc18 (SM) family proteins regulate SNARE complex function in membrane fusion through their interactions with syntaxins. In addition to syntaxins, only a few SM protein interacting proteins are known and typically, their binding modes with SM proteins are poorly characterized. We previously identified Mso1p as a Sec1p binding protein and showed that it is involved in membrane fusion regulation. Here we demonstrate that Mso1p and Sec1p interact at sites of exocytosis and that the Mso1p-Sec1p interaction site depends on a functional rab GTPase Sec4p and its GEF Sec2p. Random and targeted mutagenesis of Sec1p, followed by analysis of protein interactio... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3316304 Wed, 24 Feb 2010 00:00:00 +0100 3316304 http://www.medworm.com/index.php?rid=3316303&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20181831%26dopt%3DAbstract Authors: Appel S, Allen PG, Vetterkind S, Jin JP, Morgan KG Monitoring Editor: Josephine C. Adams Migration of fibroblasts is important in wound healing. Here, we demonstrate a role and a mechanism for h3/acidic calponin (aCaP, CNN3) in REF52.2 cell motility, a fibroblast line rich in actin filaments. We show that the actin binding protein, h3/acidic calponin, associates with stress fibers in the absence of stimulation but is targeted to the cell cortex and podosome-like structures after stimulation with a phorbol ester, PDBu. By coimmunoprecipitation and colocalization, we show that ERK1/2 and PKCalpha constitutively associate with h3/acidic calponin and are cotargeted with h3/acidic calponin in the presence of PDBu. This targeting can be blocked by a PKC inhibitor, but does not requi... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3316303 Wed, 24 Feb 2010 00:00:00 +0100 3316303 http://www.medworm.com/index.php?rid=3291367&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20164256%26dopt%3DAbstract Authors: Wang H, Kazanietz MG Monitoring Editor: J. Silvio Gutkind The C1 domains in PKC isozymes and other signaling molecules are responsible for binding the lipid second messenger diacylglycerol and phorbol esters, and mediate translocation to membranes. Previous studies revealed that the C1 domain in alpha- and beta-chimaerins, diacylglycerol-regulated Rac-GAPs, interacts with the ER/Golgi protein p23/Tmp21. Here we found that p23/Tmp21 acts as a C1 domain-docking protein that mediates perinuclear translocation of beta2-chimaerin. Glu227 and Leu248 in the beta2-chimaerin C1 domain are crucial for binding p23/Tmp21 and perinuclear targeting. Interestingly, isolated C1 domains from individual PKC isozymes differentially interact with p23/Tmp21. In the case of PKCepsilon, it interacts... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3291367 Wed, 17 Feb 2010 00:00:00 +0100 3291367 http://www.medworm.com/index.php?rid=3291366&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20164257%26dopt%3DAbstract Authors: Raleigh DR, Marchiando AM, Zhang Y, Shen L, Sasaki H, Wang Y, Long M, Turner JR Monitoring Editor: M. Bishr Omary In vitro studies have demonstrated that occludin and tricellulin are important for tight junction barrier function, but in vivo data suggest that loss of these proteins can be overcome. The presence of a heretofore unknown, yet related, protein could explain these observations. Here, we report marvelD3, a novel tight junction protein that, like occludin and tricellulin, contains a conserved four-transmembrane MARVEL (MAL and related proteins for vesicle trafficking and membrane link) domain. Phylogenetic tree reconstruction; analysis of RNA and protein tissue distribution; immunofluorescent and electron microscopic examination of subcellular localization; character... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3291366 Wed, 17 Feb 2010 00:00:00 +0100 3291366 http://www.medworm.com/index.php?rid=3269921&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20147447%26dopt%3DAbstract Authors: Todd LR, Damin MN, Gomathinayagam R, Horn SR, Means AR, Sankar U Monitoring Editor: Donald D. Newmeyer The relationship of mitochondrial dynamics and function to pluripotency are rather poorly understood aspects of stem cell biology. Here we show that growth factor erv1-like (Gfer) is involved in preserving mouse embryonic stem cell (ESC) mitochondrial morphology and function. Knock-down (KD) of Gfer in ESCs leads to decreased pluripotency marker expression, embryoid body (EB) formation, cell survival, and loss of mitochondrial function. Mitochondria in Gfer-KD ESCs undergo excessive fragmentation and mitophagy while those in ESCs overexpressing Gfer appear elongated. Levels of the mitochondrial fission GTPase dynamin-related protein 1 (Drp1) are highly elevated in Gfer-KD ESC... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3269921 Wed, 10 Feb 2010 00:00:00 +0100 3269921 http://www.medworm.com/index.php?rid=3269920&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20147448%26dopt%3DAbstract Authors: Gao L, Liu W, Bretscher A Monitoring Editor: Charles Boone Formins are conserved eukaryotic proteins that direct the nucleation and elongation of unbranched actin filaments. The yeast formins, Bni1p and Bnr1p, assemble actin cables from the bud cortex and bud neck, respectively, to guide overall cell polarity. Here we examine the regions of Bnr1p responsible for bud neck localization. We define two nonoverlapping regions, Bnr1p-L1 (1-466) and Bnr1p-L2 (466-733) that can each localize to the bud neck independently of endogenous Bnr1p. Bnr1p-L1 and Bnr1p-L2 localize with septins at the bud neck, but show slightly differently spatial and temporal localization, reflecting the localization (Bnr1p-L1) or cell cycle timing (Bnr1p-L2) of full length Bnr1p. Bnr1p is known to be very st... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3269920 Wed, 10 Feb 2010 00:00:00 +0100 3269920 http://www.medworm.com/index.php?rid=3269919&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20147449%26dopt%3DAbstract Authors: Yamamoto T, Mochida J, Kadota J, Takeda M, Bi E, Tanaka K Monitoring Editor: Fred Chang The assembly of filamentous actin is essential for polarized bud growth in budding yeast. Actin cables, which are assembled by the formins Bni1p and Bnr1p, are thought to be the only actin structures that are essential for budding. However, we found that formin or tropomyosin mutants, which lack actin cables, are still able to form a small bud. Additional mutations in components for cortical actin patches, which are assembled by the Arp2/3 complex to play a pivotal role in endocytic vesicle formation, inhibited this budding. Genes involved in endocytic recycling were also required for small-bud formation in actin cable-less mutants. These results suggest that budding yeast possesses a mecha... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3269919 Wed, 10 Feb 2010 00:00:00 +0100 3269919 http://www.medworm.com/index.php?rid=3244798&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20130081%26dopt%3DAbstract Authors: Mukhopadhyay S, Bachert C, Smith DR, Linstedt AD Monitoring Editor: Keith E. Mostov Manganese is an essential element that is also neurotoxic at elevated exposure. However, mechanisms regulating Mn homeostasis in mammalian cells are largely unknown. As increases in cytosolic Mn induce rapid changes in the localization of proteins involved in regulating intracellular Mn concentrations in yeast, we were intrigued to discover that low concentrations of extracellular Mn induced rapid redistribution of the mammalian cis Golgi glycoprotein GPP130 to multivesicular bodies. GPP130 was subsequently degraded in lysosomes. The Mn-induced trafficking of GPP130 occurred from the Golgi via a Rab-7 dependent pathway and did not require its transit through the plasma membrane or early endosom... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3244798 Wed, 03 Feb 2010 00:00:00 +0100 3244798 http://www.medworm.com/index.php?rid=3244797&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20130082%26dopt%3DAbstract Authors: Kurasawa Y, Yu-Lee LY Monitoring Editor: Yixian Zheng To maintain genomic stability, chromosome architecture needs to be tightly regulated as chromosomes undergo condensation during prophase and separation during anaphase, but the mechanisms remain poorly understood. Here we show that the Plk1-binding protein PICH and Plk1 kinase coordinately maintain chromosome architecture during prometaphase. PICH knockdown results in a loss of Plk1 from the chromosome arm and an increase in highly-disorganized "wavy" chromosomes that exhibit an "open" or "X-shaped" configuration, consistent with a loss of chromosome arm cohesion. Such chromosome disorganization occurs with essentially no change in the localization of condensin or cohesin on chromosomes. Interestingly, the chromosome disorg... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3244797 Wed, 03 Feb 2010 00:00:00 +0100 3244797 http://www.medworm.com/index.php?rid=3244796&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20130083%26dopt%3DAbstract Authors: Wang S, Ng DT Monitoring Editor: Jeffrey L. Brodsky In the endoplasmic reticulum (ER), most newly synthesized proteins are retained by quality control mechanisms until folded. Misfolded molecules are sorted to ER-associated degradation (ERAD) pathways for disposal. Reports of mutant proteins degraded in the vacuole/lysosome suggested an independent Golgi-based mechanism also at work. Although little is understood of the post-ER pathway, the growing number of variants using it suggests a major role in quality control. Why seemingly redundant mechanisms in sequential compartments are needed is unclear. To understand their physiological relationship, the identification of endogenous pathway-specific substrates is a prerequisite. With ERAD substrates already well characterized, th... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3244796 Wed, 03 Feb 2010 00:00:00 +0100 3244796 http://www.medworm.com/index.php?rid=3244795&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20130084%26dopt%3DAbstract Authors: Yang HJ, Neiman AM Monitoring Editor: David G. Drubin Spore morphogenesis in yeast is driven by the formation of membrane compartments that initiate growth at the spindle poles during Meiosis II and grow to encapsulate daughter nuclei. Vesicle docking complexes, called Meiosis II Outer Plaques (MOPs), form on each Meiosis II spindle pole body (SPB) and serve as sites of membrane nucleation. How the MOP stimulates membrane assembly is not known. Here, we report that SpSpo13, a component of the MOP in S. pombe, shares homology with the guanine nucleotide exchange factor (GEF) domain of the S. cerevisiae Sec2 protein. ScSec2 acts as a GEF for the small Rab GTPase ScSec4, which regulates vesicle trafficking from the late-Golgi to the plasma membrane. A chimeric protein in which th... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3244795 Wed, 03 Feb 2010 00:00:00 +0100 3244795 http://www.medworm.com/index.php?rid=3244794&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20130085%26dopt%3DAbstract Authors: Moore P, Bernardi KM, Tsai B Monitoring Editor: Ramanujan S. Hegde Cholera toxin (CT) is transported from the plasma membrane of host cells to the endoplasmic reticulum (ER) where the catalytic CTA1 subunit retro-translocates to the cytosol to induce toxicity. Our previous analyses demonstrated that the ER oxidoreductase protein disulfide isomerase (PDI) acts as a redox-dependent chaperone to unfold CTA1, a reaction postulated to initiate toxin retro-translocation. In its reduced state, PDI binds and unfolds CTA1; subsequent oxidation of PDI by Ero1alpha enables toxin release. Whether this in vitro model describes events in cells that control CTA1 retro-translocation is unknown. Here we show that down-regulation of Ero1alpha decreases retro-translocation of CTA1 by increasing ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3244794 Wed, 03 Feb 2010 00:00:00 +0100 3244794 http://www.medworm.com/index.php?rid=3244793&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20130086%26dopt%3DAbstract This study underscores the emerging role of the endosomal recycling system in apical surface development and identifies NHE6 as a novel regulatory protein in this process. PMID: 20130086 [PubMed - as supplied by publisher] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3244793 Wed, 03 Feb 2010 00:00:00 +0100 3244793 http://www.medworm.com/index.php?rid=3244792&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20130087%26dopt%3DAbstract Authors: Vetterkind S, Lee E, Sundberg E, Poythress RH, Tao TC, Preuss U, Morgan KG Monitoring Editor: Mark H. Ginsberg Myosin phosphatase (MP) is a key regulator of myosin light chain (LC20) phosphorylation, a process essential for motility, apoptosis and smooth muscle contractility. While MP inhibition is well studied, little is known about MP activation. We have recently demonstrated that prostate apoptosis response-4 (Par-4) modulates vascular smooth muscle contractility. Here, we test the hypothesis that Par-4 regulates MP activity directly. We show, by proximity ligation assays, surface plasmon resonance and coimmunoprecipitation, that Par-4 interacts with the targeting subunit of MP, MYPT1. Binding is mediated by the leucine zippers of MYPT1 and Par-4, and reduced by Par-4 phosp... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3244792 Wed, 03 Feb 2010 00:00:00 +0100 3244792 http://www.medworm.com/index.php?rid=3244791&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20130088%26dopt%3DAbstract Authors: Marconett CN, Sundar SN, Poindexter KM, Stueve TR, Bjeldanes LF, Firestone GL Monitoring Editor: Jonathan Chernoff ERalpha is a critical target of therapeutic strategies to control the proliferation of hormone dependent breast cancers. Preferred clinical options have significant adverse side effects that can lead to treatment resistance due to the persistence of active estrogen receptors. We have established the cellular mechanism by which indole-3-Carbinol (I3C), a promising anti-cancer phytochemical from Bassica genius vegetables, ablates ERalpha expression, and have uncovered a critical role for the GATA3 transcription factor in this indole-regulated cascade. I3C dependent activation of the aryl hydrocarbon receptor (AhR) initiates Rbx-1 E3 ligase-mediated ubiquitination an... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3244791 Wed, 03 Feb 2010 00:00:00 +0100 3244791 http://www.medworm.com/index.php?rid=3244790&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20130089%26dopt%3DAbstract In this study, we characterized a pex7 missense mutation, pex7-2, that disrupts both PEX7 cargo binding and PEX7-PEX5 interactions in yeast, as well as PEX7 protein accumulation in plants. We examined localization of peroxisomally targeted GFP derivatives in light-grown pex7 mutants and observed not only the expected defects in PTS2 protein import, but also defects in PTS1 import. These PTS1 import defects were accompanied by reduced PEX5 accumulation in light-grown pex7 seedlings. Our data suggest that PEX5 and PTS1 import depend on the PTS2 receptor PEX7 in Arabidopsis and that the environment may influence this dependence. These data advance our understanding of the biogenesis of these essential organelles and provide a possible rationale for the retention of the PTS2 pathway in some or... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3244790 Wed, 03 Feb 2010 00:00:00 +0100 3244790 http://www.medworm.com/index.php?rid=3244789&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20130090%26dopt%3DAbstract Authors: Cheng J, Cebotaru V, Cebotaru L, Guggino WB Monitoring Editor: Adam Linstedt The PDZ domain-containing protein CAL mediates lysosomal trafficking and degradation of CFTR. Here we demonstrate the involvement of a CAL-binding SNARE protein syntaxin 6 (STX6) in this process. Overexpression of STX6, which colocalizes and coimmunoprecipitates with CAL, dramatically reduces the steady-state level and stability of CFTR. Conversely, overexpression of a STX6 dominant-negative mutant increases CFTR. Silencing endogenous STX6 increases CFTR but has no effect on DeltaTRL-CFTR which cannot bind to CAL. Silencing CAL eliminates the effect of STX6 on CFTR. Both results suggest a dependence of CAL on STX6 function. Consistent with its Golgi localization, STX6 does not bind to ER-localized Del... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3244789 Wed, 03 Feb 2010 00:00:00 +0100 3244789 http://www.medworm.com/index.php?rid=3244799&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20124007%26dopt%3DAbstract Authors: Senger DR Vascular endothelial growth factor (VEGF) is best known as a cytokine essential for embryonic vasculogenesis and for the angiogenesis associated with various pathologies including cancer. However, VEGF also serves other functions that are less widely recognized. An early study (Berse et al., 1992) revealed widespread expression of VEGF transcripts in adult tissues devoid of ongoing neovascularization, thereby predicting additional VEGF functions distinct from angiogenesis. More recent studies have confirmed that VEGF does indeed serve multiple additional functions, including normal maintenance of endothelial and neural cell compartments. These findings have important implications for the use of VEGF antagonists and VEGF receptor antagonists in patients for which inhi... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3244799 Mon, 01 Feb 2010 00:00:00 +0100 3244799 http://www.medworm.com/index.php?rid=3224822&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20110345%26dopt%3DAbstract Authors: Lee J, Dunphy WG Monitoring Editor: Daniel J. Lew Rad17 is critical for the ATR-dependent activation of Chk1 during checkpoint responses. It is known that Rad17 loads the Rad9-Hus1-Rad1 (9-1-1) complex onto DNA. We show that Rad17 also mediates the interaction of 9-1-1 with the ATR-activating protein TopBP1 in Xenopus egg extracts. Studies with Rad17 mutants indicate that binding of ATP to Rad17 is essential for the association of 9-1-1 and TopBP1. Furthermore, hydrolysis of ATP by Rad17 is necessary for the loading of 9-1-1 onto DNA and the elevated, checkpoint-dependent accumulation of TopBP1 on chromatin. Significantly, a mutant 9-1-1 complex that cannot bind TopBP1 has a normal capacity to promote elevated accumulation of TopBP1 on chromatin. Taken together, we propose the... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3224822 Thu, 28 Jan 2010 00:00:00 +0100 3224822 http://www.medworm.com/index.php?rid=3224821&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20110346%26dopt%3DAbstract Authors: Buck TM, Kolb AR, Boyd CR, Kleyman TR, Brodsky JL Monitoring Editor: Reid Gilmore The epithelial sodium channel, ENaC, is composed of a single copy of an alpha, beta, and gamma subunit and plays an essential role in water and salt balance. Because ENaC assembles inefficiently after its insertion into the ER, a substantial percentage of each subunit is targeted for ER associated degradation (ERAD). To define how the ENaC subunits are selected for degradation, we developed novel yeast expression systems for each ENaC subunit. Data from this analysis suggested that ENaC subunits display folding defects in more than one compartment and that subunit turn-over might require a unique group of factors. Consistent with this hypothesis, yeast lacking the lumenal Hsp40s, Jem1 and Scj1, e... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3224821 Thu, 28 Jan 2010 00:00:00 +0100 3224821 http://www.medworm.com/index.php?rid=3224820&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20110347%26dopt%3DAbstract Authors: Stark BC, Sladewski TE, Pollard LW, Lord M Monitoring Editor: Rong Li Myosin-II (Myo2p) and tropomyosin are essential for contractile ring formation and cytokinesis in fission yeast. Here we used a combination of in vivo and in vitro approaches to understand how these proteins function at contractile rings. We find that ring assembly is delayed in Myo2p motor and tropomyosin mutants, but occurs prematurely in cells engineered to express two copies of myo2. Thus, the timing of ring assembly responds to changes in Myo2p cellular levels and motor activity, and the emergence of tropomyosin-bound actin filaments. Doubling Myo2p levels suppresses defects in ring assembly associated with a tropomyosin mutant, suggesting a role for tropomyosin in maximizing Myo2p function. Correspondi... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3224820 Thu, 28 Jan 2010 00:00:00 +0100 3224820 http://www.medworm.com/index.php?rid=3224819&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20110348%26dopt%3DAbstract In this study, we detected a robust interaction between FOXO3a and PP2A. We further demonstrate that 14-3-3, while not impeding the interaction between PP2A and FOXO3a, restrains its activity toward AKT phosphorylation sites, T32/S253. Disruption of PP2A function revealed that following AKT inhibition, PP2A-mediated dephosphorylation of T32/S253 is required for dissociation of 14-3-3, nuclear translocation, and transcriptional activation of FOXO3a. Our findings reveal that distinct phosphatases dephosphorylate conserved AKT motifs within the FOXO family and that PP2A is entwined in a dynamic interplay with AKT and 14-3-3 to directly regulate FOXO3a subcellular localization and transcriptional activation. PMID: 20110348 [PubMed - as supplied by publisher] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3224819 Thu, 28 Jan 2010 00:00:00 +0100 3224819 http://www.medworm.com/index.php?rid=3224818&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20110349%26dopt%3DAbstract Authors: Titus LC, Dawson TR, Rexer DJ, Ryan KJ, Wente SR Monitoring Editor: Yixian Zheng The assembly, distribution and functional integrity of nuclear pore complexes (NPC) in the nuclear envelope (NE) are key determinants in the nuclear periphery architecture. However, the mechanisms controlling proper NPC and NE structure are not fully defined. We used two different genetic screening approaches to identify S. cerevisiae mutants with defects in NPC localization. The first approach examined GFP-Nic96 in 531 strains from the yeast Tet-promoters Hughes Collection with individual essential genes expressed from a doxycycline-regulated promoter (TetO7-orf). Under repressive conditions, depletion of the protein encoded by 44 TetO7-orf strains resulted in mislocalized GFP-Nic96. These includ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3224818 Thu, 28 Jan 2010 00:00:00 +0100 3224818 http://www.medworm.com/index.php?rid=3224817&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20110350%26dopt%3DAbstract Authors: Ma N, Tulu US, Ferenz NP, Fagerstrom C, Wilde A, Wadsworth P Monitoring Editor: Yixian Zheng TPX2 is a Ran-regulated spindle assembly factor that is required for kinetochore fiber formation and activation of the mitotic kinase Aurora A. TPX2 is enriched near spindle poles, and is required near kinetochores, suggesting that it undergoes dynamic relocalization throughout mitosis. Using photoactivation, we measured the movement of PA-GFP-TPX2 in the mitotic spindle. TPX2 moves poleward in the half-spindle and is static in the interzone and near spindle poles. Poleward transport of TPX2 is sensitive to inhibition of dynein or Eg5, and to suppression of microtubule flux with nocodazole or antibodies to Kif2a. Poleward transport requires the C-terminus of TPX2, a domain that interac... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3224817 Thu, 28 Jan 2010 00:00:00 +0100 3224817 http://www.medworm.com/index.php?rid=3224816&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20110351%26dopt%3DAbstract In this study we present a systematic in vivo analysis of the Vps4 interaction network. The data demonstrated a high degree of redundancy in the network. While no single interaction was found to be essential for the localization or activity of Vps4, certain interactions proved more important than others. The most significant among these were the binding of Vps4 to Vta1 and to the ESCRT-III subunits Vps2 and Snf7. In our model we propose the formation of a recruitment complex in the cytoplasm that is composed of Did2-Ist1-Vps4, which upon binding to ESCRT-III recruits Vta1. Vta1 in turn is prediceted to cause a rearrangement of the Vps4 interactions that initiates the assembly of the active Vps4 oligomer. PMID: 20110351 [PubMed - as supplied by publisher] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3224816 Thu, 28 Jan 2010 00:00:00 +0100 3224816 http://www.medworm.com/index.php?rid=3201095&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20089829%26dopt%3DAbstract We report here that Vav3 is expressed at high levels in Purkinje and granule cells, suggesting additional roles for this protein in the cerebellum. Consistent with this hypothesis, we demonstrate using Vav3-deficient mice that this protein contributes to Purkinje cell dendritogenesis, the survival of granule cells of the internal granular layer, the timely migration of granule cells of the external granular layer, and to the formation of the cerebellar intercrural fissure. With the exception of the latter defect, the dysfunctions found in Vav3(--/--) mice only occur at well-defined postnatal developmental stages and disappear, or become ameliorated, in older animals. Vav2-deficient mice do not show any of those defects. Using primary neuronal cultures, we show that Vav3 is important for de... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3201095 Wed, 20 Jan 2010 00:00:00 +0100 3201095 http://www.medworm.com/index.php?rid=3201094&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20089830%26dopt%3DAbstract Authors: Zallen JA, Yap AS Monitoring Editor: Doug Kellogg Understanding morphogenesis is the ultimate multidisciplinary (ad)venture. Three-dimensional tissues are generated from the actions of genes, biochemical pathways, and cells that form multicellular networks and interact with their biomechanical environment. A comprehensive explanation of morphogenetic processes must encompass these different levels of analysis. A recent meeting in Kyoto on "Building the Body Plan: How Cell Adhesion, Signaling, and Cytoskeletal Regulation Shape Morphogenesis" highlighted recent advances in tackling this challenging problem. PMID: 20089830 [PubMed - as supplied by publisher] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3201094 Wed, 20 Jan 2010 00:00:00 +0100 3201094 http://www.medworm.com/index.php?rid=3201093&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20089831%26dopt%3DAbstract Authors: Koulov AV, Lapointe P, Lu B, Razvi A, Coppinger J, Dong MQ, Matteson J, Laister R, Arrowsmith C, Yates JR, Balch WE Monitoring Editor: Jeffrey L. Brodsky The accelerator of Hsp90 ATPase 1 (Aha1) has been shown to participate in the Hsp90 chaperone cycle by stimulating the low intrinsic ATPase activity of Hsp90. To elucidate the structural basis for ATPase stimulation of human Hsp90 by human Aha1 we have developed novel mass-spectrometry approaches that demonstrate that the N- and C-terminal domains of Aha1 cooperatively bind across the dimer interface of Hsp90 to modulate the ATP-hydrolysis cycle and client activity in vivo. Mutations in both the N- and C-terminal domains of Aha1 impair its ability to bind Hsp90 and stimulate its ATPase activity in vitro, and impair in vivo th... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3201093 Wed, 20 Jan 2010 00:00:00 +0100 3201093 http://www.medworm.com/index.php?rid=3201092&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20089832%26dopt%3DAbstract Authors: Ohe M, Kawamura Y, Ueno H, Inoue D, Kanemori Y, Senoo C, Isoda M, Nakajo N, Sagata N Monitoring Editor: Mark J. Solomon Emi2 (also called Erp1) inhibits the anaphase-promoting complex/cyclosome (APC/C) and thereby causes metaphase II arrest in vertebrate eggs. Both the D-box and the zinc-binding region (ZBR) of Emi2 have been implicated in APC/C inhibition. However, it is not well known how Emi2 interacts with and hence inhibits the APC/C. Here we show that Emi2 binds the APC/C via the C-terminal tail, termed here the RL tail. When expressed in Xenopus oocytes and egg extracts, Emi2 lacking the RL tail fails to interact with and inhibit the APC/C. The RL tail itself can directly bind to the APC/C, and, when added to egg extracts, either an excess of RL tail peptides or anti-RL... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3201092 Wed, 20 Jan 2010 00:00:00 +0100 3201092 http://www.medworm.com/index.php?rid=3201091&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20089833%26dopt%3DAbstract Authors: Bentley M, Nycz DC, Joglekar A, Fertschai I, Malli R, Graier WF, Hay JC Monitoring Editor: Adam Linstedt The significance and extent of Ca(2+) regulation of the biosynthetic secretory pathway has been difficult to establish, and our knowledge of regulatory relationships integrating Ca(2+) with vesicle coats and function is rudimentary. Here we investigated potential roles and mechanisms of luminal Ca(2+) in the early secretory pathway. Specific depletion of luminal Ca(2+) in living NRK cells using cyclopiazonic acid (CPA) resulted in the extreme expansion of vesicular tubular cluster (VTC) elements. Consistent with this, a suppressive role for vesicle-associated Ca(2+) in COPII vesicle homotypic fusion was demonstrated in vitro using Ca(2+) chelators. The EF-hand-containing pr... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3201091 Wed, 20 Jan 2010 00:00:00 +0100 3201091 http://www.medworm.com/index.php?rid=3201090&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20089834%26dopt%3DAbstract Authors: Robbins JA, Cross FR Monitoring Editor: Daniel J. Lew APC-Cdh1 targets multiple mitotic proteins for degradation upon exit from mitosis into G1; inhibitory phosphorylation of Cdh1 by CDK and Polo kinase has been proposed to prevent the premature degradation of substrates in the ensuing cell cycle. Here we demonstrate essentiality of CDK phosphorylation of Cdh1 in S. cerevisiae by exact endogenous gene replacement of CDH1 with CDK-unphosphorylatable CDH1-m11; in contrast, neither Cdh1 polo kinase sites nor polo interaction motifs are required. CDH1-m11 cells arrest in the first cycle with replicated DNA and sustained polarized growth; most cells have monopolar spindles. Blocking proteolysis of the Cin8 kinesin in CDH1-m11 cells does not promote spindle pole body (SPB) separatio... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3201090 Wed, 20 Jan 2010 00:00:00 +0100 3201090 http://www.medworm.com/index.php?rid=3201089&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20089835%26dopt%3DAbstract Authors: Pusapati GV, Krndija D, Armacki M, von Wichert G, von Blume J, Malhotra V, Adler G, Seufferlein T Monitoring Editor: Benjamin S. Glick Protein Kinase D (PKD) isoenzymes regulate the formation of transport carriers from the trans-Golgi network (TGN) that are en route to the plasma membrane. The PKD C1a domain is required for the localization of PKDs at the TGN. However, the precise mechanism how PKDs are recruited to the TGN is still elusive. Here we report that ADP-ribosylation factor1 (ARF1), a small GTPase of the Ras superfamily and a key regulator of secretory traffic, specifically interacts with PKD isoenzymes. ARF1, but not ARF6, binds directly to the second cysteine-rich domain (C1b) of PKD2 and precisely to Pro275 within this domain. Pro275 in PKD2 is not only crucial f... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3201089 Wed, 20 Jan 2010 00:00:00 +0100 3201089 http://www.medworm.com/index.php?rid=3201088&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20089836%26dopt%3DAbstract This study provides new compelling information on the mechanism by which TGFbeta1 gives rise to fibrosis in skeletal muscle, opening new perspectives for its pharmacological treatment. Moreover it highlights the pleiotropic role of SK/S1P axis in skeletal myoblasts which, depending on the expressed S1PR pattern, appears capable of eliciting multiple, even contrasting biological responses. PMID: 20089836 [PubMed - as supplied by publisher] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3201088 Wed, 20 Jan 2010 00:00:00 +0100 3201088 http://www.medworm.com/index.php?rid=3201087&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20089837%26dopt%3DAbstract Authors: Nickerson DP, West M, Henry R, Odorizzi G Monitoring Editor: Jean E. Gruenberg Recruitment of endosomal sorting complexes required for transport (ESCRTs) to the cytosolic face of endosomes regulates selective inclusion of transmembrane proteins into the lumenal vesicles of multivesicular bodies (MVBs). ESCRT-0, -I, and -II bind directly to ubiquitinated transmembrane cargoes of the MVB pathway, while polymerization of ESCRT-III at endosomes is thought to bend the membrane and/or provide the energetic force that drives membrane scission and detachment of vesicles into the endosome lumen. Disassembly of the ESCRT-III polymer and dissociation of its subunits from endosomes requires the Vps4 ATPase, the activity of which is controlled in vivo by regulatory proteins. We identify di... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3201087 Wed, 20 Jan 2010 00:00:00 +0100 3201087 http://www.medworm.com/index.php?rid=3201086&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20089838%26dopt%3DAbstract We examined the involvement of endocytic soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) in xenophagosome/lysosome fusion. Confocal microscopic analysis showed that SNAREs, including VAMP7, VAMP8, and Vti1b, colocalized with GFP-LC3 in xenophagosomes. Knockdown of Vti1b and VAMP8 with siRNAs disturbed the colocalization of LC3 with LAMP1. The invasive efficiency of GAS into cells was not altered by knockdown of VAMP8 or Vti1b, whereas cellular bactericidal efficiency was significantly diminished, indicating that antimicrobial autophagy was functionally impaired. Knockdown of Vti1b and VAMP8 also disturbed colocalization of LC3 with LAMP1 in canonical autophagy, in which LC3-II proteins were negligibly degraded. In contrast, knockdown of Syntaxin 7 and Syntax... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3201086 Wed, 20 Jan 2010 00:00:00 +0100 3201086 http://www.medworm.com/index.php?rid=3201085&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20089839%26dopt%3DAbstract Authors: Zubovych IO, Straud S, Roth MG Monitoring Editor: Donald D. Newmeyer In a previous genetic screen for C. elegans mutants that survive in the presence of an antimitotic drug, hemiasterlin, we identified 8 strong mutants. Two of these were found to be resistant to multiple toxins, and in one of these we identified a missense mutation in phb-2, which encodes the mitochondrial protein prohibitin 2. Here we identify two additional mutations that confer drug resistance, spg-7 and har-1, also in genes encoding mitochondrial proteins. Other mitochondrial mutants, isp-1, eat-3 and clk-1, were also found to be drug-resistant. Respiratory complex inhibitors, FCCP and oligomycin, and a producer of reactive oxygen species (ROS), paraquat, all rescued wild type worms from hemiasterlin toxic... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3201085 Wed, 20 Jan 2010 00:00:00 +0100 3201085 http://www.medworm.com/index.php?rid=3201084&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20089840%26dopt%3DAbstract In this study, we demonstrate that phosphodiesterase type 3A (PDE3A) physically and functionally interacts with cystic fibrosis transmembrane conductance regulator (CFTR) channel. PDE3A inhibition generates compartmentalized cyclic adenosine 3',5'-monophosphate (cAMP) which further clusters PDE3A and CFTR into microdomains at the plasma membrane and potentiates CFTR channel function. Actin skeleton disruption reduces PDE3A-CFTR interaction; segregates PDE3A from its interacting partners thus compromises the integrity of the CFTR-PDE3A-containing macromolecular complex. Consequently, compartmentalized cAMP signaling is lost. PDE3A inhibition no longer activates CFTR channel function in a compartmentalized manner. The physiological relevance of PDE3A-CFTR interaction was investigated using p... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3201084 Wed, 20 Jan 2010 00:00:00 +0100 3201084 http://www.medworm.com/index.php?rid=3201083&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20089841%26dopt%3DAbstract Authors: Benesh AE, Nambiar R, McConnell RE, Mao S, Tabb DL, Tyska MJ Monitoring Editor: Thomas Pollard Epithelial cells lining the intestinal tract build an apical array of microvilli known as the brush border. Each microvillus is a cylindrical membrane protrusion that is linked to a supporting actin bundle by myosin-1a (Myo1a). Mice lacking Myo1a demonstrate no overt physiological symptoms, suggesting that other myosins may compensate for the loss of Myo1a in these animals (Tyska et al., 2005). To investigate changes in the microvillar myosin population that may limit the Myo1a KO phenotype, we performed proteomic analysis on WT and Myo1a KO brush borders. These studies revealed that WT brush borders also contain the short-tailed class I myosin, myosin-1d (Myo1d). Myo1d localizes to ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3201083 Wed, 20 Jan 2010 00:00:00 +0100 3201083 http://www.medworm.com/index.php?rid=3201082&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20089842%26dopt%3DAbstract Authors: Torres JZ, Ban KH, Jackson PK Monitoring Editor: Fred Chang In early mitosis, the END (Emi1/NuMA/Dynein-dynactin) network anchors the Anaphase Promoting Complex/Cyclosome (APC/C) to the mitotic spindle and poles. Spindle anchoring restricts APC/C activity, thereby limiting the destruction of spindle-associated cyclin B and ensuring maintenance of spindle integrity. Emi1 binds directly to hypo-phosphorylated APC/C, linking the APC/C to the spindle via NuMA. However, whether the phosphorylation state of the APC/C is important for its association with the spindle and what kinases and phosphatases are necessary for regulating this event remain unknown. Here, we describe the regulation of APC/C-mitotic spindle pole association by phosphorylation. We find that only hypo-phosphorylat... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3201082 Wed, 20 Jan 2010 00:00:00 +0100 3201082 http://www.medworm.com/index.php?rid=3201081&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20089843%26dopt%3DAbstract Authors: Tsapara A, Luthert P, Greenwood J, Hill CS, Matter K, Balda MS Monitoring Editor: Keith E. Mostov Maintenance of the epithelial phenotype is crucial for tissue homeostasis. In the retina, dedifferentiation and loss of integrity of the retinal pigment epithelium (RPE) leads to retinal dysfunction and fibrosis. TGF-beta critically contributes to RPE dedifferentiation and induces various responses including increased Rho signaling, upregulation of alpha-smooth muscle actin (alpha-SMA), cell migration and dedifferentiation. Cellular TGF-beta responses are stimulated by different signal transduction pathways: some are Smad-dependent and others -independent. Alterations in Rho signaling are crucial to both types of TGF-beta signaling, but how TGF-beta-stimulates Rho signaling is poo... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3201081 Wed, 20 Jan 2010 00:00:00 +0100 3201081 http://www.medworm.com/index.php?rid=3201080&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20089844%26dopt%3DAbstract Authors: Taboubi S, Garrouste F, Parat F, Pommier G, Faure E, Monferran S, Kovacic H, Lehmann M Monitoring Editor: J. Silvio Gutkind Insulin-like growth factor-I (IGF-I) activation of phosphoinositide 3-kinase (PI3K) is an essential pathway for keratinocyte migration which is required for epidermis wound healing. We have previously reported that activation of Galpha(q/11)-coupled-P2Y2 purinergic receptors by extracellular nucleotides delays keratinocyte wound closure. Here, we report that activation of P2Y2 receptors by extracellular UTP inhibits the IGF-I-induced p110alpha-PI3K activation. Using siRNA and pharmacological inhibitors, we demonstrate that the UTP antagonistic effects on PI3K pathway are mediated by Galpha(q/11)- and not G(i/o)- independently of phospholipase Cbeta. Purin... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3201080 Wed, 20 Jan 2010 00:00:00 +0100 3201080 http://www.medworm.com/index.php?rid=3201079&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20089845%26dopt%3DAbstract Authors: Fiaschi T, Tedesco FS, Giannoni E, Diaz-Manera J, Parri M, Cossu G, Chiarugi P Monitoring Editor: Carl-Henrik Heldin Mesoangioblasts are progenitor endowed with multipotent mesoderm differentiation ability. Despite the promising results obtained with mesoangioblast transplantation in muscle dystrophy, an improvement of their efficient engrafting and survival within damaged muscles, as well as their ex-vivo activation/expansion and commitment toward myogenic lineage, is highly needed and should greatly increase their therapeutic potential. We show that globular adiponectin, an adipokine endowed with metabolic and differentiating functions for muscles, regulates vital cues of mesoangioblast cell biology. The adipokine drives mesoangioblasts to entry cell cycle and strongly count... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3201079 Wed, 20 Jan 2010 00:00:00 +0100 3201079 http://www.medworm.com/index.php?rid=3201078&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20089846%26dopt%3DAbstract In this study we demonstrate that overexpression of GbpD in pi3k1/2-null cells does not induce the adhesion and cell morphology phenotype. Furthermore we show that Rap1 directly binds to the Ras binding domain of PI3K, and overexpression of GbpD leads to strongly enhanced PIP3 levels. Consistently, upon overexpression of the PIP3 degradating enzyme PTEN in GbpD-overexpressing cells, the strong adhesion and cell morphology phenotype is largely lost. These results indicate that a GbpD/Rap/PI3K pathway helps control pseudopod formation and cell polarity. Like in Rap regulated pseudopod formation in Dictyostelium, mammalian Rap and PI3K are essential for determining neuronal polarity, suggesting that the Rap/PI3K pathway is a conserved module regulating the establishment of cell polarity. ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3201078 Wed, 20 Jan 2010 00:00:00 +0100 3201078 http://www.medworm.com/index.php?rid=3179110&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20071466%26dopt%3DAbstract Authors: Tang L, Machacek T, Mamnun YM, Penkner A, Gloggnitzer J, Wegrostek C, Konrat R, Jantsch M, Loidl J, Jantsch V Monitoring Editor: Orna Cohen-Fix From a screen for meiotic mutants based on high incidence of males, we identified a novel gene, him-19, with multiple functions in prophase of meiosis I. Mutant him-19(jf6) animals show a reduction in pairing of homologous chromosomes and subsequent bivalent formation. Consistently, synaptonemal complex formation is spatially restricted and possibly involves nonhomologous chromosomes. Also, foci of the recombination protein RAD-51 occur delayed or cease altogether. Ultimately, mutation of him-19 leads to chromosome mis-segregation and reduced offspring viability. The observed defects suggest that HIM-19 is important for both, homology ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3179110 Wed, 13 Jan 2010 00:00:00 +0100 3179110 http://www.medworm.com/index.php?rid=3179109&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20071467%26dopt%3DAbstract Authors: Müller L, Diaz de Escauriaza M, Lajoie P, Theis M, Jung M, Müller A, Burgard C, Greiner M, Snapp EL, Dudek J, Zimmermann R Monitoring Editor: Ramanujan S. Hegde Due to similarity to their yeast orthologues, the two membrane proteins of the human endoplasmic reticulum (ER) Sec62 and Sec63 are expected to play a role in protein biogenesis in the ER. We characterized interactions between these two proteins as well as the putative interaction of Sec62 with ribosomes. These data provide further evidence for evolutionary conservation of Sec62/Sec63 interaction. In addition, they indicate that in the course of evolution Sec62 of vertebrates has gained an additional function, the ability to interact with the ribosomal tunnel exit and, therefore, to support cotranslational me... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3179109 Wed, 13 Jan 2010 00:00:00 +0100 3179109 http://www.medworm.com/index.php?rid=3179108&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20071468%26dopt%3DAbstract Authors: Yoshiki S, Udagawa R, Aoki K, Kamioka Y, Kiyokawa E, Matsuda M Monitoring Editor: J. Silvio Gutkind Situated downstream of Ras is a key signaling molecule, Raf1. Increase in Ca(2+) concentration has been shown to modulate the Ras-dependent activation of Raf1; however, the mechanism underlying this effect remains elusive. Here, to characterize the role of Ca(2+) in Ras signaling to Raf1, we used a synthetic guanine nucleotide exchange factor (GEF) for Ras, eGRF. In HeLa cells expressing eGRF, Ras was activated by the cAMP analogue 007 as efficiently as by epidermal growth factor (EGF), whereas the activation of Raf1, MEK, and ERK by 007 was about half of that by EGF. Using a biosensor based on fluorescence resonance energy transfer, it was found that activation of Raf1 at the p... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3179108 Wed, 13 Jan 2010 00:00:00 +0100 3179108 http://www.medworm.com/index.php?rid=3153974&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20053675%26dopt%3DAbstract Authors: López-Marqués RL, Poulsen LR, Hanisch S, Meffert K, Buch-Pedersen MJ, Jakobsen MK, Pomorski TG, Palmgren MG Monitoring Editor: Reid Gilmore Members of the P4 subfamily of P-type ATPases are believed to catalyze flipping of phospholipids across cellular membranes, in this way contributing to vesicle biogenesis in the secretory and endocytic pathways. P4-ATPases form heteromeric complexes with Cdc50-like proteins and it has been suggested that these act as beta-subunits in the P4-ATPase transport machinery. In this work, we investigated the role of Cdc50-like beta-subunits of P4-ATPases for targeting and function of P4-ATPase catalytic alpha-subunits. We show that the Arabidopsis P4-ATPases ALA2 and ALA3 gain functionality when coexpressed with any of three different A... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3153974 Wed, 06 Jan 2010 00:00:00 +0100 3153974 http://www.medworm.com/index.php?rid=3153973&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20053676%26dopt%3DAbstract Authors: Stone MC, Nguyen MM, Tao J, Allender DL, Rolls MM Monitoring Editor: Stephen Doxsey Axon regeneration is crucial for recovery after trauma to the nervous system. For neurons to recover from complete axon removal they must respecify a dendrite into an axon- a complete reversal of polarity. We show that Drosophila neurons in vivo can convert a dendrite to a regenerating axon, and that this process involves rebuilding the entire neuronal microtubule cytoskeleton. Two major microtubule rearrangements are specifically induced by axon, and not dendrite, removal: 1. 10-fold upregulation of the number of growing microtubules and 2. microtubule polarity reversal. After one dendrite reverses its microtubules, it initiates tip growth and takes on morphological and molecular characteristi... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3153973 Wed, 06 Jan 2010 00:00:00 +0100 3153973 http://www.medworm.com/index.php?rid=3153972&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20053677%26dopt%3DAbstract In this study we conducted a structure-function analysis to identify the determinants of Sanpodo targeting in vivo. We identified an NPAF motif in the amino terminal cytoplasmic tail of Sanpodo, which is conserved among insect Sanpodo homologues. The Sanpodo NPAF motif is predicted to bind directly to the Numb phosphotyrosine-binding domain and is critical for Numb binding in vitro. Deletion or mutation of the NPAF motif results in accumulation of Sanpodo at the plasma membrane in Numb-positive cells in vivo. Genetic analysis of Sanpodo NPAF mutants shows that Numb-dependent Sanpodo endocytic targeting can be uncoupled from Notch signaling regulation. Our findings demonstrate that Sanpodo contains an evolutionarily conserved motif that has been linked to Numb-dependent regulation in verteb... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3153972 Wed, 06 Jan 2010 00:00:00 +0100 3153972 http://www.medworm.com/index.php?rid=3153971&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20053678%26dopt%3DAbstract Authors: Hajeri VA, Little BA, Ladage ML, Padilla PA Monitoring Editor: Mark J. Solomon Oxygen, an essential nutrient, is sensed by a multiple of cellular pathways that facilitate the responses to and survival of oxygen deprivation. The Caenorhabditis elegans embryo exposed to severe oxygen deprivation (anoxia) enters a state of suspended animation in which cell cycle progression reversibly arrests at specific stages. The mechanisms regulating interphase, prophase, or metaphase arrest in response to anoxia are not completely understood. Characteristics of arrested prophase blastomeres and oocytes are the alignment of condensed chromosomes at the nuclear periphery and an arrest of nuclear envelope breakdown. Notably, anoxia-induced prophase arrest is suppressed in mutant embryos lacking... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3153971 Wed, 06 Jan 2010 00:00:00 +0100 3153971 http://www.medworm.com/index.php?rid=3153970&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20053679%26dopt%3DAbstract Authors: Flinn RJ, Yan Y, Goswami S, Parker PJ, Backer JM Monitoring Editor: Benjamin Margolis The multi-subunit mTORC1 complex integrates signals from growth factors and nutrients to regulate protein synthesis, cell growth, and autophagy. To examine how endocytic trafficking might be involved in nutrient regulation of mTORC1, we perturbed specific endocytic trafficking pathways and measured mTORC1 activity using S6K1 as a readout. When early/late endosomal conversion was blocked by either overexpression of constitutively active Rab5 (Rab5CA) or knockdown of the Rab7 GEF hVps39, insulin and amino acid stimulated mTORC1/S6K1 activation were inhibited and mTOR localized to hybrid early/late endosomes. Inhibition of other stages of endocytic trafficking had no effect on mTORC1. Overexpres... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3153970 Wed, 06 Jan 2010 00:00:00 +0100 3153970 http://www.medworm.com/index.php?rid=3153969&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20053680%26dopt%3DAbstract Authors: Ciraolo E, Morello F, Hobbs RM, Wolf F, Marone R, Iezzi M, Lu X, Mengozzi G, Altruda F, Sorba G, Guan K, Pandolfi PP, Wymann MP, Hirsch E Monitoring Editor: J. Silvio Gutkind Phosphoinositide 3-kinases (PI3K) are key molecular players in male fertility. However, the specific roles of different p110 PI3K catalytic subunits within the spermatogenic lineage have not been characterized so far. Herein, we report that male mice expressing a catalytically inactive p110beta develop testicular hypotrophy and impaired spermatogenesis, leading to a phenotype of oligo-azoospermia and defective fertility. The examination of testes from p110beta-defective tubules demonstrates a widespread loss in spermatogenic cells, due to defective proliferation and survival of pre and post-meiotic cells.... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3153969 Wed, 06 Jan 2010 00:00:00 +0100 3153969 http://www.medworm.com/index.php?rid=3153968&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20053681%26dopt%3DAbstract Authors: Gagou ME, Zuazua-Villar P, Meuth M Monitoring Editor: Jonathan Chernoff H2AX phosphorylation at serine 139 (gammaH2AX) is a sensitive indicator of both DNA damage and DNA replication stress. Here we show that gammaH2AX formation is greatly enhanced in response to replication inhibitors but not ionizing radiation (IR) in HCT116 or SW480 cells depleted of Chk1. While H2AX phosphorylation precedes the induction of apoptosis in such cells, our results suggest that cells containing gammaH2AX are not committed to death. gammaH2AX foci in these cells largely colocalize with RPA foci and their formation is dependent upon the essential replication helicase cofactor Cdc45, suggesting that H2AX phosphorylation occurs at sites of stalled forks. However Chk1-depleted cells released from re... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3153968 Wed, 06 Jan 2010 00:00:00 +0100 3153968 http://www.medworm.com/index.php?rid=3153967&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20053682%26dopt%3DAbstract Authors: Lang C, Grava S, Finlayson M, Trimble R, Philippsen P, Jaspersen SL Monitoring Editor: Kerry S. Bloom In the multinucleate fungus Ashbya gossypii, cytoplasmic microtubules (cMTs) emerge from the spindle pole body outer plaque (OP) in perpendicular and tangential directions. To elucidate the role of cMTs in forward/backward movements (oscillations) and bypassing of nuclei, we constructed mutants potentially affecting cMT nucleation or stability. Hyphae lacking the OP components AgSpc72, AgNud1, AgCnm67 or the MT-stabilizing factor AgStu2 grew like wild-type but showed substantial alterations in the number, length and/or nucleation sites of cMTs. These mutants differently influenced nuclear oscillation and bypassing. In Agspc72Delta only long cMTs were observed, which emanate ta... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3153967 Wed, 06 Jan 2010 00:00:00 +0100 3153967 http://www.medworm.com/index.php?rid=3153966&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20053683%26dopt%3DAbstract Authors: Xu YZ, Thuraisingam T, Morais DA, Rola-Pleszczynski M, Radzioch D Monitoring Editor: Marvin Wickens Studies have shown that nuclear translocation of actin occurs under certain conditions of cellular stress; however, the functional significance of actin import remains unclear. Here, we demonstrate that during the phorbol 12-myristate 13-acetate (PMA)-induced differentiation of HL-60 cells toward macrophages, beta-actin translocates from the cytoplasm to the nucleus and this process is dramatically inhibited by pretreatment with p38 MAPK inhibitors. Using Chromatin Immunoprecipitation (ChIP)-on-chip assays, the genome-wide maps of beta-actin binding to gene promoters in response to PMA treatment is analyzed in HL-60 cells. A gene ontology-based analysis shows that the identified... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3153966 Wed, 06 Jan 2010 00:00:00 +0100 3153966 http://www.medworm.com/index.php?rid=3153965&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20053684%26dopt%3DAbstract Authors: Wang S, Hu C, Zhu J Monitoring Editor: Yixian Zheng hTERT, the human telomerase reverse transcriptase, is highly expressed in stem cells and embryonic tissues but undetectable in most adult somatic cells. To understand its repression mechanisms in somatic cells, we investigated the endogenous hTERT gene regulation during differentiation of human leukemic HL60 cells. Our study revealed that silencing of the hTERT promoter was a biphasic process. Within 24 h after initiation of differentiation, hTERT mRNA expression decreased dramatically, accompanied by increased expression of Mad1 gene and disappearance of a nucleosome-free region at the hTERT core promoter. Subsequent to this early repression, nucleosomal remodeling continued at the promoter and downstream region for several ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3153965 Wed, 06 Jan 2010 00:00:00 +0100 3153965 http://www.medworm.com/index.php?rid=3153964&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20053685%26dopt%3DAbstract Authors: Segref A, Cabello J, Clucas C, Schnabel R, Johnstone IL Monitoring Editor: Marcos Gonzalez-Gaitan Coordination between cell fate specification and cell cycle control in multicellular organisms is essential to regulate cell numbers in tissues and organs during development and its failure may lead to oncogenesis. In mammalian cells, as part of a general cell cycle checkpoint mechanism, the F-box protein beta-TrCP and the SCF complex controls the periodic cell cycle fluctuations in abundance of the CDC25A and B phosphatases. Here we find that the C. elegans beta-TrCP orthologue LIN-23 regulates a progressive decline of CDC-25.1 abundance over several embryonic cell-cycles and specifies cell number of one tissue, the embryonic intestine. The negative regulation of CDC-25.1 abundan... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3153964 Wed, 06 Jan 2010 00:00:00 +0100 3153964 http://www.medworm.com/index.php?rid=3153963&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20053686%26dopt%3DAbstract Authors: Sharma A, Takata H, Shibahara KI, Bubulya A, Bubulya PA Monitoring Editor: A. Gregory Matera Subnuclear organization and spatiotemporal regulation of pre-mRNA processing factors is essential for the production of mature protein-coding mRNAs. We have discovered that a large protein called Son has a novel role in maintaining proper nuclear organization of pre-mRNA processing factors in nuclear speckles. The primary sequence of Son contains a concentrated region of multiple unique tandem repeat motifs that may support a role for Son as a scaffolding protein for RNA processing factors in nuclear speckles. We used RNAi approaches and high-resolution microscopy techniques to study the functions of Son in the context of intact cells. While Son precisely colocalizes with pre-mRNA spli... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3153963 Wed, 06 Jan 2010 00:00:00 +0100 3153963 http://www.medworm.com/index.php?rid=3153962&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20053687%26dopt%3DAbstract Authors: Hortsch R, Lee E, Erathodiyil N, Hebbar S, Steinert S, Lee JY, Chua DS, Kraut R Monitoring Editor: Marcos Gonzalez-Gaitan In lipid storage diseases, the intracellular trafficking of sphingolipids is altered by conditions of aberrant cholesterol accumulation. Drosophila has been used recently to model lipid storage diseases, but the effects of sterol accumulation on sphingolipid trafficking are not known in the fly, and the trafficking of sphingolipids in general has not been studied in this model organism. Here, we examined the uptake and intracellular distribution of a fluorescent glycolipid analog, BODIPY-lactosyl-ceramide, in Drosophila neurons. The uptake mechanism and intracellular trafficking route of this simple glycolipid are largely conserved. Our principle finding is... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3153962 Wed, 06 Jan 2010 00:00:00 +0100 3153962 http://www.medworm.com/index.php?rid=3146794&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20048254%26dopt%3DAbstract Authors: Drubin DG PMID: 20048254 [PubMed - in process] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3146794 Fri, 01 Jan 2010 00:00:00 +0100 3146794 http://www.medworm.com/index.php?rid=3146793&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20048255%26dopt%3DAbstract Authors: Botstein D Three articles from the early years of Molecular Biology of the Cell (MBoC) have had remarkably many citations in the literature since their publication approximately 10 years ago. As a coauthor of these articles and the former editor of MBoC, I was asked for possible explanations. I believe the answer lies in the unusual nature of these articles: each presents and summarizes gene expression data for nearly every gene in the yeast or human genomes. Continuing interest in the data themselves by cell biologists, rather than results or conclusions drawn by the authors, best accounts for the citation history. The flatness of the numbers of citations over time, the continuing high rate of accesses to individual Web sites set up to allow searching and display of the under... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3146793 Fri, 01 Jan 2010 00:00:00 +0100 3146793 http://www.medworm.com/index.php?rid=3146792&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20048256%26dopt%3DAbstract Authors: Yamashita YM Loving science and nature and being a scientist can be very different, yet the two are so intertwined in a scientist's life that you will certainly experience both aspects. This essay presents my perspective on how, as one who loves science and nature, I came to fall in love with centrosome behavior in stem cells and how I came to run a lab as a scientist. When I started, there was a big gap between my love for science and my experience as a scientist. I filled this gap by learning a "laid-back confidence." PMID: 20048256 [PubMed - in process] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3146792 Fri, 01 Jan 2010 00:00:00 +0100 3146792 http://www.medworm.com/index.php?rid=3146791&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20048257%26dopt%3DAbstract Authors: Rossant J A career in science is a journey of wonder and discovery. To succeed in science requires curiosity, perseverance, a good dose of luck, and wise guidance from those who have taken the journey ahead of you. We also need to use our science skills to contribute to public debate on complex issues of the day. PMID: 20048257 [PubMed - in process] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3146791 Fri, 01 Jan 2010 00:00:00 +0100 3146791 http://www.medworm.com/index.php?rid=3146790&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20048258%26dopt%3DAbstract Authors: Vale RD Many years of training are required to obtain a job as an academic scientist. Is this investment of time and effort worthwhile? My answer is a resounding "yes." Academic scientists enjoy tremendous freedom in choosing their research and career path, experience unusual camaraderie in their lab, school, and international community, and can contribute to and enjoy being part of this historical era of biological discovery. In this essay, I further elaborate by listing my top ten reasons why an academic job is a desirable career for young people who are interested in the life sciences. PMID: 20048258 [PubMed - in process] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3146790 Fri, 01 Jan 2010 00:00:00 +0100 3146790 http://www.medworm.com/index.php?rid=3146789&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20048259%26dopt%3DAbstract Authors: Walter P Deciphering of the molecular mechanism of the "unfolded protein response" (UPR) provides a wonderful example of how serendipity can shape scientific discovery. Secretory and membrane proteins begin their journey to the cell surface in the endoplasmic reticulum (ER). Before leaving the organelle, proteins are quality-controlled, and only properly folded proteins are transported onwards. The UPR detects an insufficiency in the protein-folding capacity in the ER and in the ways of a finely tuned homeostat adjusts organelle abundance according to need. If the protein-folding defect in the ER cannot be corrected, the UPR switches from a cell-protective to a cell-destructive mode and activates apoptosis in metazoan cells. Such life or death decisions position the UPR in the... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3146789 Fri, 01 Jan 2010 00:00:00 +0100 3146789 http://www.medworm.com/index.php?rid=3119483&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20032300%26dopt%3DAbstract Authors: Granic A, Padmanabhan J, Norden M, Potter H Monitoring Editor: Yixian Zheng Both sporadic and familial Alzheimer's disease patients exhibit increased chromosome aneuploidy, particularly trisomy 21, in neurons and other cells. Significantly, trisomy 21/Down syndrome patients develop early onset AD pathology. We investigated the mechanism underlying mosaic chromosome aneuploidy in AD and report that FAD mutations in the Alzheimer Amyloid Precursor Protein gene, APP, induce chromosome mis-segregation and aneuploidy in transgenic mice and in transfected cells. Furthermore, adding synthetic Abeta peptide, the pathogenic product of APP, to cultured cells causes rapid and robust chromosome mis-segregation leading to aneuploid, including trisomy 21, daughters, which is prevented by Li... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3119483 Wed, 23 Dec 2009 00:00:00 +0100 3119483 http://www.medworm.com/index.php?rid=3119482&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20032301%26dopt%3DAbstract Authors: Keely S, Glover LE, Weissmueller T, Macmanus CF, Fillon S, Fennimore B, Colgan SP Monitoring Editor: Asma Nusrat Mucosal surfaces, such as the lung and intestine, are lined by a monolayer of epithelia which provides tissue barrier and transport function. It is recently appreciated that a common feature of inflammatory processes within the mucosa is hypoxia (so called inflammatory hypoxia). Given the strong association between bacterial translocation and mucosal inflammatory disease, we hypothesized that intestinal epithelial hypoxia influences bacterial translocation. Initial studies revealed that exposure of cultured intestinal epithelia to hypoxia (pO2 20 torr, 24-48 h) resulted in a increase of up to 40-fold in the translocation of some strains of Gram-positive bacteria, in... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3119482 Wed, 23 Dec 2009 00:00:00 +0100 3119482 http://www.medworm.com/index.php?rid=3119481&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20032302%26dopt%3DAbstract Authors: Takada H, Nishida A, Domae M, Kita A, Yamano Y, Uchida A, Ishiwata S, Fang Y, Zhou X, Masuko T, Kinoshita M, Kakehi K, Sugiura R Monitoring Editor: Daniel J. Lew The highly conserved fission yeast Pmk1 MAPK pathway plays a key role in cell integrity by regulating Atf1, which belongs to the ATF/cAMP-responsive element-binding (CREB) protein family. We identified and characterized ecm33(+), which encodes a glycosyl-phosphatidylinositol (GPI)-anchored cell surface protein as a transcriptional target of Pmk1 and Atf1. We demonstrated that the gene expression of Ecm33 is regulated by two transcription factors Atf1 and a MADS-box-type transcription factor Mbx1. We identified a putative ATF/CREB-binding site and an RLM1-binding site in the ecm33(+) promoter region and monitored the t... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3119481 Wed, 23 Dec 2009 00:00:00 +0100 3119481 http://www.medworm.com/index.php?rid=3119480&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20032303%26dopt%3DAbstract Authors: Haling JR, Wang F, Ginsberg MH Monitoring Editor: Joan Brugge Changes in cellular expression of PEA-15 are linked to insulin resistance, tumor cell invasion, and cellular senescence; these changes alter the activation of the ERK1/2 MAP Kinase pathway. Here we define the mechanism whereby increased PEA-15 expression promotes and sustains ERK1/2 activation. PEA-15 binding prevented ERK1/2 membrane recruitment and threonine phosphorylation of FRS2alpha a key link in FGF receptor activation of ERK1/2. This reduced threonine phosphorylation led to increased FGF-induced tyrosine phosphorylation of FRS2alpha, thereby enhancing downstream signaling. Conversely, shRNA-mediated depletion of endogenous PEA-15 led to reduced FRS2alpha tyrosine phosphorylation. Thus, PEA-15 interrupts a ne... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3119480 Wed, 23 Dec 2009 00:00:00 +0100 3119480 http://www.medworm.com/index.php?rid=3119479&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20032304%26dopt%3DAbstract Authors: Noda K, Zhang J, Fukuhara S, Kunimoto S, Yoshimura M, Mochizuki N Monitoring Editor: Asma Nusrat Vascular endothelial (VE)-cadherin is a cell-cell adhesion molecule involved in endothelial barrier functions. Previously, we have reported that cyclic AMP (cAMP)-Epac-Rap1 signal enhances VE-cadherin-dependent cell adhesion. Here, we further scrutinized how cAMP-Epac-Rap1 pathway promotes stabilization of VE-cadherin at the cell-cell contacts. Forskolin induced circumferential actin bundling and accumulation of VE-cadherin fused with green fluorescence protein (VEC-GFP) on the bundled actin filaments. Fluorescence recovery after photobleaching (FRAP) analyses using VEC-GFP revealed that forskolin stabilizes VE-cadherin at cell-cell contacts. These effects of forskolin were mimicke... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3119479 Wed, 23 Dec 2009 00:00:00 +0100 3119479 http://www.medworm.com/index.php?rid=3119478&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20032305%26dopt%3DAbstract Authors: Murthi A, Shaheen HH, Huang HY, Preston MA, Lai TP, Phizicky EM, Hopper AK Monitoring Editor: Karsten Weis tRNAs in yeast and vertebrate cells move bidirectionally and reversibly between the nucleus and the cytoplasm. We investigated roles of members of the beta-importin family in tRNA subcellular dynamics. Retrograde import of tRNA into the nucleus is dependent, directly or indirectly, upon Mtr10. tRNA nuclear export utilizes at least two members of the beta-importin family. The beta-importins involved in nuclear export have shared and exclusive functions. Los1 functions in both the tRNA primary export and the tRNA reexport processes. Msn5 is unable to export tRNAs in the primary round of export if the tRNAs are encoded by intron-containing genes and for these tRNAs Msn5 func... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3119478 Wed, 23 Dec 2009 00:00:00 +0100 3119478 http://www.medworm.com/index.php?rid=3119477&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20032306%26dopt%3DAbstract Authors: Broggini T, Nitsch R, Savaskan NE Monitoring Editor: Asma Nusrat Members of the Plasticity Related Gene (PRG1-4) family are brain-specific integral membrane proteins and implicated in neuronal plasticity, such as filopodia formation and axon growth after brain lesion. Here we report on the cloning of a novel member of the PRG family named PRG5 with high homologies to PRG3. PRG5 is regulated during brain and spinal cord development and is exclusively distributed within the nervous system. When introduced in neurons, PRG5 is distributed in the plasma membrane and induces filopodia as well as axon elongation and growth. Conversely, siRNA mediated knock down of PRG5 impedes axon growth and disturbs filopodia formation. Here we show that PRG5 induces filopodia growth independently ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3119477 Wed, 23 Dec 2009 00:00:00 +0100 3119477 http://www.medworm.com/index.php?rid=3119476&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20032307%26dopt%3DAbstract Authors: Sillibourne JE, Tack F, Vloemans N, Boeckx A, Thambirajah S, Bonnet P, Ramaekers FC, Bornens M, Grand-Perret T Monitoring Editor: Tim Stearns Centrosome duplication occurs once every cell cycle in a strictly controlled manner. PLK4 is a key regulator of this process whose kinase activity is essential for centriole duplication. Here, we show that PLK4 autophosphorylation of serine S305 is a consequence of kinase activation and enables the active fraction to be identified in the cell. Active PLK4 is detectable on the replicating mother centriole in G1/S, with the proportion of active kinase increasing through interphase to reach a maximum in mitosis. Activation of PLK4 at the replicating daughter centriole is delayed until G2, but a level equivalent to the replicating mother cen... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3119476 Wed, 23 Dec 2009 00:00:00 +0100 3119476 http://www.medworm.com/index.php?rid=3119475&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20032308%26dopt%3DAbstract Authors: Roy G, Chalfin EM, Saxena A, Wang X Monitoring Editor: Jeffrey L. Brodsky Multiple mutations in cystic fibrosis transmembrane conductance regulator (CFTR) impair its exit from the endoplasmic reticulum (ER). We compared two processing mutants: DeltaF508 and the ER exit code mutant DAA. While both have severe kinetic processing defect, DAA but not DeltaF508 has substantial accumulation in its mature form, leading to higher level of processing at the steady state. DAA has much less profound conformational abnormalities. It has lower Hsp70 association and higher post-ER stability than DeltaF508. The ER exit code is necessary for DeltaF508 residual export and rescue. R555K, a mutation that rescues DeltaF508 misprocessing, improves Sec24 association and enhances its post-ER stabili... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3119475 Wed, 23 Dec 2009 00:00:00 +0100 3119475 http://www.medworm.com/index.php?rid=3119474&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D20032309%26dopt%3DAbstract Authors: Hammond JW, Huang CF, Kaech S, Jacobson C, Banker G, Verhey KJ Monitoring Editor: Erika Holzbaur Polarized transport by microtubule-based motors is critical for neuronal development and function. Selective translocation of the Kinesin-1 motor domain is the earliest known marker of axonal identity, occurring before morphological differentiation. Thus, Kinesin-1-mediated transport may contribute to axonal specification. We tested whether post-translational modifications of tubulin influence the ability of Kinesin-1 motors to distinguish microtubule tracks during neuronal development. We detected no difference in microtubule stability between axons and minor neurites in polarized stage 3 hippocampal neurons. In contrast, microtubule modifications were enriched in a subset of neur... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3119474 Wed, 23 Dec 2009 00:00:00 +0100 3119474 http://www.medworm.com/index.php?rid=3097289&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19703297%26dopt%3DAbstract CONCLUSION: Our results provide evidence in favour of the hypothesis of endoplasmic reticulum sheet stabilization by intermembrane tethering. PMID: 19703297 [PubMed - indexed for MEDLINE] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3097289 Fri, 18 Dec 2009 01:42:04 +0100 3097289 http://www.medworm.com/index.php?rid=3057288&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19956936%26dopt%3DAbstract In this report, we address the issue of SAS coding in a wider scope. We suggest a variety of advantages that such coding would have had in exploring a wider sequence space before translation became highly specific. In particular, we confirm that in Achlya klebsiana a single gene might have originally coded for an HSP70 chaperonin (class II aaRS homolog) and an NAD-specific GDH-like enzyme (class I aaRS homolog) via its sense and antisense strands. Thus, in contrast to the conclusions in Williams et al. (Mol Biol Evol 26:445-450, 2009), this could indeed be a "Rosetta stone" gene (Carter and Duax, Mol Cell 10:705-708, 2002) (eroded somewhat, though) for the SAS origin of the two aaRS classes. PMID: 19956936 [PubMed - as supplied by publisher] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3057288 Thu, 03 Dec 2009 00:00:00 +0100 3057288 http://www.medworm.com/index.php?rid=3057295&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19955210%26dopt%3DAbstract Authors: Kida Y, Kume C, Hirano M, Sakaguchi M Monitoring Editor: Reid Gilmore In biogenesis of membrane proteins on the endoplasmic reticulum, a protein-conducting channel called the translocon functions in both the membrane translocation of lumenal domains and the integration of transmembrane segments. Here we analyzed the environments of polypeptide chains during the processes by water-dependent alkylation of N-ethylmaleimide at site-directed Cys residues. Using the technique, the region embedded in the hydrophobic portion of the membrane within a signal-anchor sequence and its shortening by insertion of a Proresidue could be detected. When translocation of the N-terminal domain of the signal-anchor was arrested by trapping an N-terminally fused affinity tag sequence, the signal-anc... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3057295 Wed, 02 Dec 2009 00:00:00 +0100 3057295 http://www.medworm.com/index.php?rid=3057294&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19955211%26dopt%3DAbstract Authors: Karnani N, Taylor CM, Malhotra A, Dutta A Monitoring Editor: Mark J. Solomon DNA replication in metazoans initiates from multiple chromosomal loci called origins. Currently, there are two methods to purify origin-centered nascent strands: lambda exonuclease digestion and anti-bromodeoxyuridine immunoprecipitation. Because both methods have unique strengths and limitations, we purified nascent strands by both methods, hybridized them independently to tiling arrays (1% genome) and compared the data to have an accurate view of genome-wide origin distribution. By this criterion we identified 150 new origins that were reproducible across the methods. Examination of a subset of these origins by ChIP against Origin Recognition Complex subunits 2 and 3 showed 93% of initiation peaks t... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3057294 Wed, 02 Dec 2009 00:00:00 +0100 3057294 http://www.medworm.com/index.php?rid=3057293&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19955212%26dopt%3DAbstract Authors: Meili R, Alonso-Latorre B, Del Álamo JC, Firtel RA, Lasheras JC Monitoring Editor: Carole Parent Amoeboid motility requires spatiotemporal coordination of biochemical pathways regulating force generation and consists of the quasi-periodic repetition of a motility cycle driven by actin polymerization and actomyosin contraction. Using new analytical tools and statistical methods, we provide, for the first time, a statistically-significant quantification of the spatial distribution of the traction forces generated at each phase of the cycle (protrusion-contraction-retraction-relaxation). We show that cells are constantly under tensional stress and that wild-type cells develop two opposing "pole" forces pulling the front and back toward the center whose strength is modulated ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3057293 Wed, 02 Dec 2009 00:00:00 +0100 3057293 http://www.medworm.com/index.php?rid=3057292&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19955213%26dopt%3DAbstract We report that anoikis-apoptosis triggered by loss of extra cellular matrix (ECM) contacts-activates a CD95/Fas-mediated signaling pathway regulated by receptor-interacting protein (RIP), a kinase that shuttles between CD95/Fas-mediated cell death and integrin/FAK-mediated survival pathways. RIP's death domain was critical for RIP and Fas association to mediate anoikis. Fas or RIP attenuation reduced this association and suppressed anoikis, whereas their overexpression had the reverse effect. Overexpressing FAK restored RIP and FAK association and inhibited anoikis. Thus, RIP shuttles between CD95/Fas death- and FAK survival signaling to mediate anoikis. PMID: 19955213 [PubMed - as supplied by publisher] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3057292 Wed, 02 Dec 2009 00:00:00 +0100 3057292 http://www.medworm.com/index.php?rid=3057291&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19955214%26dopt%3DAbstract Authors: Wu H, Turner C, Gardner J, Temple B, Brennwald P Monitoring Editor: Sean Munro The Rho3 and Cdc42 members of the Rho GTPase family are important regulators of exocytosis in yeast. However, the precise mechanism by which they regulate this process is controversial. Here we present evidence that the Exo70 component of the exocyst complex is a direct effector of both Rho3 and Cdc42. We identify gain-of-function mutants in EXO70 that potently suppress mutants in RHO3 and CDC42 defective for exocytic function. We show that Exo70 has the biochemical properties expected of a direct effector for both Rho3 and Cdc42. Surprisingly, we find that C-terminal prenylation of these GTPases both promotes the interaction and influences the sites of binding within Exo70. Finally, we demonstrate ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3057291 Wed, 02 Dec 2009 00:00:00 +0100 3057291 http://www.medworm.com/index.php?rid=3057290&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19955215%26dopt%3DAbstract Authors: Wilmeth LJ, Shrestha S, Montaño G, Rashe J, Shuster CB Monitoring Editor: Yu-Li Wang The spatial and temporal coordination of chromosome segregation with cytokinesis is essential to ensure that each daughter cell receives the correct complement of chromosomal and cytoplasmic material. In yeast, mitotic exit and cytokinesis are coordinated by signaling cascades whose terminal components include a NDR family kinase and a noncatalytic subunit, Mob1. There are five human Mob1 isoforms, all of which display redundant localization patterns at the spindle poles and kinetochores in early mitosis, and the spindle midzone during cytokinesis. Mob1 shares similar localization patterns to Polo-like kinase (Plk1) and the chromosomal passenger complex (CPC), and while depletion of Plk1 ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3057290 Wed, 02 Dec 2009 00:00:00 +0100 3057290 http://www.medworm.com/index.php?rid=3057289&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19955216%26dopt%3DAbstract This study examined the relationships between PI3K and the patterns of Rho-family GTPase signaling during phagosome formation. Inhibition of PI3K resulted in persistently active Cdc42 and Rac1, but not Rac2, in stalled phagocytic cups. Patterns of 3'PIs and Rho-family GTPase activities during phagocytosis of 5 mum and 2 mum diameter microspheres indicated similar underlying mechanisms despite particle size-dependent sensitivities to PI3K inhibition. Expression of constitutively active Cdc42(G12V) increased 3'PI concentrations in plasma membranes and small phagosomes, indicating a role for Cdc42 in PI3K activation. Cdc42(G12V) inhibited phagocytosis at a later stage than inhibition by dominant negative Cdc42(N17). Together, these studies identified a Cdc42 activation cycle organized by PI3K... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3057289 Wed, 02 Dec 2009 00:00:00 +0100 3057289 http://www.medworm.com/index.php?rid=3033655&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19940015%26dopt%3DAbstract Authors: Qiang L, Yu W, Liu M, Solowska JM, Baas PW Monitoring Editor: Paul Forscher The formation of interstitial axonal branches involves the severing of microtubules at sites where new branches form. Here we wished to ascertain whether basic fibroblast growth factor (bFGF) enhances axonal branching through alterations in proteins involved in the severing of microtubules. We found that treatment of cultured hippocampal neurons with bFGF heightens expression of both katanin and spastin, which are proteins that sever microtubules in the axon. In addition, treatment with bFGF enhances phosphorylation of tau at sites expected to cause it to dissociate from microtubules. This is important because tau regulates the access of katanin to the microtubule. In live-cell imaging experiments, axo... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3033655 Wed, 25 Nov 2009 00:00:00 +0100 3033655 http://www.medworm.com/index.php?rid=3033651&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19940016%26dopt%3DAbstract Authors: Needleman DJ, Groen A, Ohi R, Maresca T, Mirny L, Mitchison T Monitoring Editor: Kerry S. Bloom Metaphase spindles are steady-state ensembles of microtubules, which turn over rapidly, and slide poleward in some systems. Because the discovery of dynamic instability in the mid1980s, models for spindle morphogenesis have proposed that microtubules are stabilized by the spindle environment. We used single molecule imaging to measure tubulin turnover in spindles, and nonspindle assemblies, in Xenopus egg extract. We observed many events where tubulin molecules spend only a few seconds in polymer, that are difficult to reconcile with standard models of polymerization dynamics. Our data can be quantitatively explained by a simple, phenomenological model - with only one adjustable par... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3033651 Wed, 25 Nov 2009 00:00:00 +0100 3033651 http://www.medworm.com/index.php?rid=3033650&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19940017%26dopt%3DAbstract Authors: Tribus M, Bauer I, Galehr J, Rieser G, Trojer P, Brosch G, Loidl P, Haas H, Graessle S Monitoring Editor: William P. Tansey Acetylation of the N-terminal tails of core histones is an important regulatory mechanism in eukaryotic organisms. In filamentous fungi, little is known about the enzymes that modify histone tails. However, it is increasingly evident that histone deacetylases and histone acetyltransferases are critical factors for the regulation of genes involved in fungal pathogenicity, stress response, and production of secondary metabolites like antibiotics or fungal toxins. Here we show that depletion of RpdA, an RPD3-type histone deacetylase of Aspergillus nidulans, leads to a pronounced reduction of growth and sporulation of the fungus. We demonstrate, that a so far... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3033650 Wed, 25 Nov 2009 00:00:00 +0100 3033650 http://www.medworm.com/index.php?rid=3033649&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19940018%26dopt%3DAbstract Authors: Zwerger M, Kolb T, Richter K, Karakesisoglou I, Herrmann H Monitoring Editor: M. Bishr Omary Lamin B receptor (LBR) is an inner nuclear membrane protein involved in tethering the nuclear lamina and the underlying chromatin to the nuclear envelope. In addition, LBR exhibits sterol reductase activity. Mutations in the LBR gene cause two different human diseases: Pelger-Huët Anomaly and Greenberg skeletal dysplasia, a severe chrondrodystrophy causing embryonic death. Our study aimed at investigating the effect of five LBR disease mutants on human cultured cells. Three of the tested LBR mutants caused a massive compaction of chromatin coincidental with the formation of a large nucleus-associated vacuole (NAV) in a number of human cultured cell lines. Live cell imaging and ele... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3033649 Wed, 25 Nov 2009 00:00:00 +0100 3033649 http://www.medworm.com/index.php?rid=3033647&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19940019%26dopt%3DAbstract Authors: Li FQ, Mofunanya A, Fischer V, Hall J, Takemaru KI Monitoring Editor: Benjamin Margolis In the canonical Wnt pathway, beta-catenin acts as a key coactivator that stimulates target gene expression through interaction with Tcf/Lef transcription factors. Its nuclear accumulation is the hallmark of active Wnt signaling and is frequently associated with cancers. Chibby (Cby) is an evolutionarily conserved molecule that represses beta-catenin-dependent gene activation. Although Cby, in conjunction with 14-3-3 chaperones, controls beta-catenin distribution, its molecular nature remains largely unclear. Here, we provide compelling evidence that Cby harbors bona fide nuclear localization signal (NLS) and nuclear export signal (NES) motifs, and constitutively shuttles between the nucleu... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3033647 Wed, 25 Nov 2009 00:00:00 +0100 3033647 http://www.medworm.com/index.php?rid=3033646&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19940020%26dopt%3DAbstract Authors: Lee TA, Jorgensen P, Bognar AL, Peyraud C, Thomas D, Tyers M Monitoring Editor: William P. Tansey Met4 is the transcriptional activator of the sulfur metabolic network in S. cerevisiae. Lacking DNA-binding ability, Met4 must interact with proteins called Met4 cofactors to target promoters for transcription. Two types of DNA-binding cofactors (Cbf1 and Met31/Met32) recruit Met4 to promoters and one cofactor (Met28) stabilizes the DNA-bound Met4 complexes. To dissect this combinatorial system, we systematically deleted each category of cofactor(s) and analyzed Met4-activated transcription on a genome-wide scale. We defined a core regulon for Met4, consisting of 45 target genes. Deletion of both Met31 and Met32 eliminated activation of the core regulon, whereas loss of Met28 or C... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3033646 Wed, 25 Nov 2009 00:00:00 +0100 3033646 http://www.medworm.com/index.php?rid=3033645&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19940021%26dopt%3DAbstract Authors: Hezel M, de Groat WC, Galbiati F Monitoring Editor: Carl-Henrik Heldin The molecular mechanisms that regulate the organization and activity of the neuromuscular junction remain to be fully identified. Caveolae are invaginations of the plasma membrane. Caveolin-3 is the structural protein component of caveolae in muscle cells. We show that caveolin-3 is expressed at the neuromuscular junction, associates with the nicotinic acetylcholine receptor (nAChR) and that a lack of caveolin-3 inhibits clustering of the nAChR in myotubes. At the molecular level, we demonstrate that caveolin-3 is a novel muscle specific kinase (MuSK) binding protein and that altered nAChR clustering in caveolin-3-lacking myotubes results from inhibition of agrin-induced phosphorylation/activation of muscle... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3033645 Wed, 25 Nov 2009 00:00:00 +0100 3033645 http://www.medworm.com/index.php?rid=3015771&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19923319%26dopt%3DAbstract Authors: Torres VA, Mielgo A, Barbero S, Hsiao R, Wilkins JA, Stupack DG Monitoring Editor: Joan Brugge Caspase-8 is a key apical sensory protein that governs cell responses to environmental cues, alternatively promoting apoptosis, proliferation and cell migration. The proteins responsible for integration of these pathways, however, have remained elusive. Here, we reveal that Rab5 regulates caspase-8-dependent signaling from integrins. Integrin ligation leads to Rab5 activation, association with integrins and activation of Rac, in a caspase-8 dependent manner. Rab5 activation promotes colocalization and coprecipitation of integrins with caspase-8, concomitant with Rab5 recruitment to integrin-rich regions such as focal adhesions and membrane ruffles. Moreover, caspase-8 expression prom... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3015771 Wed, 18 Nov 2009 00:00:00 +0100 3015771 http://www.medworm.com/index.php?rid=3015770&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19923320%26dopt%3DAbstract Authors: Porter MY, Koelle MR Monitoring Editor: Jonathan Chernoff Regulator of G protein Signaling (RGS) proteins inhibit G protein signaling by activating Galpha GTPase activity, but the mechanisms that regulate RGS activity are not well understood. The mammalian R7 binding protein (R7BP) can interact with all members of the R7 family of RGS proteins and palmitoylation of R7BP can target R7 RGS proteins to the plasma membrane in cultured cells. However, whether endogenous R7 RGS proteins in neurons require R7BP or membrane localization for function remains unclear. We have identified and knocked out the only apparent R7BP homolog in C. elegans, RSBP-1. Genetic studies show that loss of RSBP-1 phenocopies loss of the R7 RGS protein EAT-16, but does not disrupt function of the related ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3015770 Wed, 18 Nov 2009 00:00:00 +0100 3015770 http://www.medworm.com/index.php?rid=3015769&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19923321%26dopt%3DAbstract Authors: Macpherson MR, Molina P, Souchelnytskyi S, Wernstedt C, Martin-Pérez J, Portillo F, Cano A Monitoring Editor: Marianne Bronner-Fraser Snail1 is a major factor for epithelial-mesenchymal transition (EMT), an important event in tumor metastasis and in other pathologies. Snail1 is tightly regulated at transcriptional and post-transcriptional levels. Control of Snail1 protein stability and nuclear export by GSK3beta phosphorylation is important for Snail1 functionality. Stabilization mechanisms independent of GSK3beta have also been reported, including interaction with LOXL2 or regulation of the COP9 signalosome by inflammatory signals. To get further insights into the role of Snail1 phosphorylation we have performed an in-depth analysis of in vivo human Snail1 phosphorylatio... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3015769 Wed, 18 Nov 2009 00:00:00 +0100 3015769 http://www.medworm.com/index.php?rid=3015768&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19923322%26dopt%3DAbstract Authors: Hsu RM, Tsai MH, Hsieh YJ, Lyu PC, Yu JS Monitoring Editor: Jonathan Chernoff The p21-activated kinase (PAK) 2 is known to be involved in numerous biological functions, including the regulation of actin reorganization and cell motility. To better understand the mechanisms underlying this regulation, we herein used a proteomic approach to identify PAK2-interacting proteins in human epidermoid carcinoma A431 cells. We found that MYO18A, an emerging member of the myosin superfamily, is a novel PAK2 binding partner. Using a siRNA knockdown strategy and in vitro binding assay, we discovered that MYO18A binds to PAK2 through the betaPIX/GIT1 complex. Under normal conditions, MYO18A and PAK2 colocalized in lamellipodia and membrane ruffles. Interestingly, knockdown of MYO18A in cells... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3015768 Wed, 18 Nov 2009 00:00:00 +0100 3015768 http://www.medworm.com/index.php?rid=3015767&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19923323%26dopt%3DAbstract Authors: Koch A, Poirier F, Jacob R, Delacour D Monitoring Editor: Benjamin Margolis Galectin-3 is a beta-galactoside binding protein widely expressed in all epithelia where it is involved in tissue homeostasis and cancer progression. We recently reported unique abnormalities in the identity of membrane domains in galectin-3 null mutant mice, suggesting that galectin-3 may participate in epithelial polarity program. We investigated the potential role of galectin-3 on early events in polarization of epithelial renal cells, using three-dimensional cultures of MDCK cells and also galectin-3 null mutant mouse kidneys. We show that depletion in galectin-3 systematically leads to severe perturbations of microtubular network associated with defects in membrane compartimentation, both in vitro... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3015767 Wed, 18 Nov 2009 00:00:00 +0100 3015767 http://www.medworm.com/index.php?rid=3015765&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19923324%26dopt%3DAbstract Authors: Kumfer KT, Cook SJ, Squirrell JM, Eliceiri KW, Peel N, O'Connell KF, White JG Monitoring Editor: Benjamin Margolis The anterior-posterior axis of the C. elegans embryo is elaborated at the one-cell stage by the polarization of the partitioning (PAR) proteins at the cell cortex. Polarization is established under the control of the Rho GTPase RHO-1 and is maintained by the Rho GTPase CDC-42. To understand more clearly the role of the Rho family GTPases in polarization and division of the early embryo, we constructed a fluorescent biosensor to determine the localization of CDC-42 activity in the living embryo. A genetic screen using this biosensor identified one positive (putative GEF) and one negative (putative GAP) regulator of CDC-42 activity: CGEF-1 and CHIN-1. CGEF-1 was req... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3015765 Wed, 18 Nov 2009 00:00:00 +0100 3015765 http://www.medworm.com/index.php?rid=3009172&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19917266%26dopt%3DAbstract Authors: Takasaka K, Iwai M, Umena Y, Kawakami K, Ohmori Y, Ikeuchi M, Takahashi Y, Kamiya N, Shen JR Ycf12 (Psb30) and PsbZ are two low-molecular weight subunits of photosystem II (PSII), with one and two trans-membrane helices, respectively. In order to study the functions of these two subunits from a structural point of view, we constructed deletion mutants lacking either Ycf12 or PsbZ from Thermosynechococcus elongatus, and purified, crystallized and analyzed the structure of PSII dimer from the two mutants. Our results showed that Ycf12 is located in the periphery of PSII, close to PsbK, PsbZ and PsbJ, and corresponded to the unassigned helix X1 reported previously, in agreement with the recent structure at 2.9 A resolution (A. Guskov, J. Kern, A. Gabdulkhakov, M. Broser, A. Zouni... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3009172 Fri, 13 Nov 2009 00:00:00 +0100 3009172 http://www.medworm.com/index.php?rid=3000739&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19910486%26dopt%3DAbstract Authors: Wasserman T, Katsenelson K, Daniliuc S, Hasin T, Choder M, Aronheim A Monitoring Editor: Jonathan Chernoff The c-Jun N-terminal kinase (JNK) is part of a Mitogen-activated protein kinase (MAPK) signaling cascade. Scaffold proteins simultaneously associate with various components of the MAPK signaling pathway and play a role in signal transmission and regulation. Here we describe the identification of a novel scaffold JNK binding protein, WDR62, with no sequence homology to any of the known scaffold proteins. WDR62 is a ubiquitously expressed heat-sensitive 175 kDa protein that specifically associates with JNK but not with ERK and p38. Association between WDR62 and JNKs occurs in the absence and following either transient or persistent stimuli. WDR62 potentiates JNK kinase acti... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3000739 Thu, 12 Nov 2009 00:00:00 +0100 3000739 http://www.medworm.com/index.php?rid=3000738&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19910487%26dopt%3DAbstract Authors: Lang C, Grava S, van den Hoorn T, Trimble R, Philippsen P, Jaspersen SL Monitoring Editor: Kerry S. Bloom We investigated the migration of multiple nuclei in hyphae of the filamentous fungus Ashbya gossypii. Three types of cytoplasmic microtubule (cMT)-dependent nuclear movements were characterized using live cell imaging: short range oscillations (up to 4.5 mum/min), rotations (up to 180 degrees in 30 s) and long-range nuclear bypassing (up to 9 mum/min). These movements were superimposed on a cMT-independent mode of nuclear migration, cotransport with the cytoplasmic stream. This latter mode is sufficient to support wild-type-like hyphal growth speeds. cMT-dependent nuclear movements were led by a nuclear-associated MTOC, the spindle pole body (SPB), which is the sole site o... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3000738 Thu, 12 Nov 2009 00:00:00 +0100 3000738 http://www.medworm.com/index.php?rid=3000737&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19910488%26dopt%3DAbstract We present evidence that Pol III transcribed genes such as tRNA and 5S rRNA genes can localize to centromeres and contribute to a global genome organization. Furthermore, we find that ectopic insertion of Pol III genes into a nonPol III gene locus results in the centromeric localization of the locus. We show that the centromeric localization of Pol III genes is mediated by condensin, which interacts with the Pol III transcription machinery, and that transcription levels of the Pol III genes are negatively correlated with the centromeric localization of Pol III genes. This centromeric localization of Pol III genes initially observed in interphase becomes prominent during mitosis, when chromosomes are condensed. Remarkably, defective mitotic chromosome condensation by a condensin mutation, c... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3000737 Thu, 12 Nov 2009 00:00:00 +0100 3000737 http://www.medworm.com/index.php?rid=3000736&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19910489%26dopt%3DAbstract Authors: Allard JF, Wasteneys GO, Cytrynbaum EN Monitoring Editor: David G. Drubin Microtubules confined to the two-dimensional cortex of elongating plant cells must form a parallel yet dispersed array transverse to the elongation axis for proper cell wall expansion. Some of these microtubules exhibit free minus-ends, leading to migration at the cortex by hybrid treadmilling. Collisions between microtubules can result in plus-end entrainment ("zippering") or rapid depolymerization. Here, we present a computational model of cortical microtubule organization. We find that plus-end entrainment leads to self-organization of microtubules into parallel arrays, while catastrophe-inducing collisions do not. Catastrophe-inducing boundaries (e.g., upper and lower cross-walls) can tune the orient... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3000736 Thu, 12 Nov 2009 00:00:00 +0100 3000736 http://www.medworm.com/index.php?rid=3000735&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19910490%26dopt%3DAbstract Authors: Cortesio CL, Perrin BJ, Bennin DA, Huttenlocher A Monitoring Editor: Josephine C. Adams Growth factor stimulation induces the formation of dynamic actin structures known as dorsal ruffles. Mammalian actin binding protein-1 (mAbp1) is an actin binding protein that has been implicated in regulating clathrin-mediated endocytosis; however, a role for mAbp1 in regulating the dynamics of growth factor-induced actin-based structures has not been defined. Here we show that mAbp1 localizes to dorsal ruffles and is necessary for platelet-derived growth factor (PDGF)-mediated dorsal ruffle formation. Despite their structural similarity, we find that mAbp1 and cortactin have nonredundant functions in the regulation of dorsal ruffle formation. mAbp1, like cortactin, is a calpain 2 substrat... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=3000735 Thu, 12 Nov 2009 00:00:00 +0100 3000735 http://www.medworm.com/index.php?rid=2968154&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19889833%26dopt%3DAbstract Authors: Tsuboi T, Kitaguchi T, Karasawa S, Fukuda M, Miyawaki A Monitoring Editor: Akihiko Nakano Although it is evident that only a few secretory vesicles accumulating in neuroendocrine cells are qualified to fuse with the plasma membrane and release their contents to the extracellular space, the molecular mechanisms that regulate their exocytosis are poorly understood. For example, it has been controversial whether secretory vesicles are exocytosed randomly or preferentially according to their age. Using a newly developed protein-based fluorescent timer, mK-GO, which changes color with a predictable time course, here we show that small GTPase Rab27A effectors regulate age-dependent exocytosis of secretory vesicles in PC12 cells. When the vesicles were labeled with mK-GO-tagged neuro... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2968154 Wed, 04 Nov 2009 00:00:00 +0100 2968154 http://www.medworm.com/index.php?rid=2968153&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19889834%26dopt%3DAbstract Authors: Boer VM, Crutchfield CA, Bradley PH, Botstein D, Rabinowitz JD Monitoring Editor: Charles Boone Microbes tailor their growth rate to nutrient availability. Here we measured, using liquid chromatography-mass spectrometry, more than 100 intracellular metabolites in steady-state cultures of S. cerevisiae growing at five different rates and in each of five different limiting nutrients. In contrast to gene transcripts, where approximately 25% correlated with growth rate irrespective of the nature of the limiting nutrient, metabolite concentrations were highly sensitive to the limiting nutrient's identity. Nitrogen (ammonium) and carbon (glucose) limitation were characterized by low intracellular amino acid and high nucleotide levels, whereas phosphorus (phosphate) limitation result... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2968153 Wed, 04 Nov 2009 00:00:00 +0100 2968153 http://www.medworm.com/index.php?rid=2968152&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19889835%26dopt%3DAbstract Authors: Korobova F, Svitkina T Monitoring Editor: Paul Forscher Excitatory synapses in the brain play key roles in learning and memory. The formation and functions of postsynaptic mushroom-shaped structures, dendritic spines, and possibly of presynaptic terminals, rely on actin cytoskeleton remodeling. However, the cytoskeletal architecture of synapses remains unknown hindering the understanding of synapse morphogenesis. Using platinum replica electron microscopy, we characterized the cytoskeletal organization and molecular composition of dendritic spines, their precursors, dendritic filopodia, and presynaptic boutons. A branched actin filament network containing Arp2/3 complex and capping protein was a dominant feature of spine heads and presynaptic boutons. Surprisingly, the spine n... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2968152 Wed, 04 Nov 2009 00:00:00 +0100 2968152 http://www.medworm.com/index.php?rid=2968151&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19889836%26dopt%3DAbstract Authors: Vives-Bauza C, Magrané J, Andreu AL, Manfredi G Monitoring Editor: Thomas D. Fox In mammals, subunit c of the F1F0-ATP synthase has three isoforms (P1, P2, P3). These isoforms differ by their cleavable mitochondrial targeting peptides, while the mature peptides are identical. To investigate this apparent genetic redundancy we knocked down each of the three subunit c isoform by RNA interference in HeLa cells. Silencing any of the subunit c isoforms individually resulted in an ATP synthesis defect, indicating that these isoforms are not functionally redundant. We found that subunit c knock down impaired the structure and function of the mitochondrial respiratory chain. In particular, P2 silencing caused defective cytochrome oxidase assembly and function. Because the express... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2968151 Wed, 04 Nov 2009 00:00:00 +0100 2968151 http://www.medworm.com/index.php?rid=2968150&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19889837%26dopt%3DAbstract Authors: Andersen NJ, Yeaman C Monitoring Editor: Patrick J. Brennwald The Exocyst is a conserved multi-subunit complex involved in the docking of post-Golgi transport vesicles to sites of membrane remodeling during cellular processes such as polarization, migration and division. In mammalian epithelial cells, Exocyst complexes are recruited to nascent sites of cell-cell contact in response to E-cadherin-mediated adhesive interactions, and this event is an important early step in the assembly of intercellular junctions. Sec3 has been hypothesized to function as a spatial landmark for the development of polarity in budding yeast, but its role in epithelial cells has not been investigated. Here we provide evidence in support of a function for a Sec3-containing Exocyst complex in the asse... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2968150 Wed, 04 Nov 2009 00:00:00 +0100 2968150 http://www.medworm.com/index.php?rid=2968149&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19889838%26dopt%3DAbstract Authors: Tapia H, Morano KA Monitoring Editor: Benjamin S. Glick Hsp90 operates in the context of a multichaperone complex to promote maturation of nuclear and cytoplasmic clients. We have discovered that Hsp90 and the cochaperone Sba1/p23 accumulate in the nucleus of quiescent S. cerevisiae cells. Hsp90 nuclear accumulation was unaffected in sba1Delta cells, demonstrating that Hsp82 translocates independently of Sba1. Translocation of both chaperones was dependent on the alpha/beta importin SRP1/KAP95. Hsp90 nuclear retention was coincident with glucose exhaustion and appears to be a starvation-specific response, as heat shock or 10% ethanol stress failed to elicit translocation. We generated nuclear accumulation-defective HSP82 mutants to probe the nature of this targeting event and ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2968149 Wed, 04 Nov 2009 00:00:00 +0100 2968149 http://www.medworm.com/index.php?rid=2968148&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19889839%26dopt%3DAbstract Authors: Li Y, Yan J, Kim I, Liu C, Huo K, Rao H Monitoring Editor: Jeffrey L. Brodsky The Ub-binding protein Rad23 plays an important role in facilitating the transfer of substrates to the proteasome. However, the mechanism underlying Rad23's function in proteolysis remains unknown. Here, we demonstrate that Rad4, a Rad23-binding protein, also regulates ubiquitylated substrate turnover. Rad4 was previously known only as a key repair factor which directly recognizes DNA damage and initiates DNA repair. Our results, however, reveal a novel function of Rad4. We found that Rad4 and Rad23 share several common substrates. Substrates in rad4Delta cells are ubiquitylated, indicating that Rad4 regulates a postubiquitylation event. Moreover, we found that Rad4 participates in the Rad23-Ufd2 pat... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2968148 Wed, 04 Nov 2009 00:00:00 +0100 2968148 http://www.medworm.com/index.php?rid=2968147&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19889840%26dopt%3DAbstract Authors: Budde MW, Roth MB Monitoring Editor: William P. Tansey Rapid alteration of gene expression in response to environmental changes is essential for normal development and behavior. The transcription factor HIF-1 is well known to respond to alterations in oxygen availability. In nature, low oxygen environments are often found to contain high levels of hydrogen sulfide (H2S). Here we show that C. elegans can have mutually exclusive responses to H2S and hypoxia, both involving HIF-1. Specifically, H2S results in HIF-1 activity throughout the hypodermis while hypoxia causes HIF-1 activity in the gut as judged by a reporter for HIF-1 activity. C. elegans require hif-1 to survive in room air containing trace amounts of H2S. Exposure to H2S results in HIF-1 nuclear localization and tran... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2968147 Wed, 04 Nov 2009 00:00:00 +0100 2968147 http://www.medworm.com/index.php?rid=2968146&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19889841%26dopt%3DAbstract Authors: Favia M, Guerra L, Fanelli T, Cardone RA, Monterisi S, Di Sole F, Castellani S, Chen M, Seidler U, Reshkin SJ, Conese M, Casavola V Monitoring Editor: Keith E. Mostov We have demonstrated that NHERF1 overexpression in CFBE41o- cells induces a significant redistribution of F508del CFTR from the cytoplasm to the apical membrane and rescues CFTR-dependent chloride secretion. Here, we observe that CFBE41o- monolayers displayed substantial disassembly of actin filaments and that overexpression of wt NHERF1 but not NHERF1-DeltaERM increased F-actin assembly and organization. Further, the dominant negative FERM domain of ezrin reversed the wt NHERF1 overexpression-induced increase in both F-actin and CFTR-dependent chloride secretion. wt NHERF1 overexpression enhanced the interaction... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2968146 Wed, 04 Nov 2009 00:00:00 +0100 2968146 http://www.medworm.com/index.php?rid=2968145&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19889842%26dopt%3DAbstract Authors: Lewellyn L, Dumont J, Desai A, Oegema K Monitoring Editor: Yu-Li Wang Signaling by the centrosomal asters and spindle midzone coordinately directs formation of the cytokinetic furrow. Here, we explore the contribution of the asters by analyzing the consequences of altering interaster distance during the first cytokinesis of the C. elegans embryo. Delaying aster separation, using TPXL-1 depletion to shorten the metaphase spindle, leads to a corresponding delay in furrow formation, but results in a single furrow that ingresses at a normal rate. Preventing aster separation, by simultaneously inhibiting TPXL-1 and Galpha signaling-based cortical forces pulling on the asters, delays furrow formation and leads to the formation of multiple furrows that ingress toward the midzone. Dis... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2968145 Wed, 04 Nov 2009 00:00:00 +0100 2968145 http://www.medworm.com/index.php?rid=2944329&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19864455%26dopt%3DAbstract We report here that RPTP-kappa mediates functional integration of EGFR and TGF-beta signaling pathways in human keratinocytes. TGF-beta up-regulates RPTP-kappa mRNA and protein, in a dose and time dependent manner. Induction of RPTP-kappa by TGF-beta significantly decreases basal and EGF-stimulated EGFR tyrosine phosphorylation. shRNA-mediated reduction of TGF-beta-induced RPTP-kappa significantly attenuates the ability of TGF-beta to inhibit proliferation. RPTP-kappa induction is dependent on activation of transcription factors Smad3 and Smad4. Inhibition of TGF-beta receptor kinase completely prevents induction of RPTP-kappa. Chromatin immunoprecipitation assays reveal that TGF-beta stimulates Smad3 and Smad4 binding to RPTP- kappa gene promoter. Smad3/4 binding is localized to a 186 bas... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2944329 Wed, 28 Oct 2009 00:00:00 +0100 2944329 http://www.medworm.com/index.php?rid=2944328&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19864456%26dopt%3DAbstract In this study, we have focused on the negative regulation of lysophosphatidic acid (LPA)-induced migration in glioma cells. Using small-interference RNA and dominant-negative gene strategies in addition to pharmacological tools, we found that isoproterenol (ISO) and sphingosine-1-phosphate (S1P) negatively but differently regulate the LPA-induced migration. ISO-induced suppression of the migration of glioma cells occurs via beta2-adrenergic receptor/cAMP/Epac/Rap1B/inhibition of Rac, whereas S1P has been shown to suppress the migration of the cells through S1P2 receptor/Rho-mediated down-regulation of Rac1. The expression of tumor suppressor phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is required for the inhibitory ISO-induced and Rap1B-mediated actions on the migration,... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2944328 Wed, 28 Oct 2009 00:00:00 +0100 2944328 http://www.medworm.com/index.php?rid=2944327&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19864457%26dopt%3DAbstract Authors: Bernardi KM, Williams JM, Kikkert M, van Voorden S, Wiertz EJ, Ye Y, Tsai B Monitoring Editor: Ramanujan S. Hegde To cause disease, cholera toxin (CT) is transported from the cell surface to the endoplasmic reticulum (ER) lumen where the catalytic CTA1 subunit retro-translocates to the cytosol to induce pathological water secretion. Two retro-translocon components are the Derlins and ER-associated multi-spanning E3 ubiquitin ligases including Hrd1 and gp78. We demonstrated previously that Derlin-1 facilitates CTA1 retro-translocation. However, as CTA1 is neither ubiquitinated on lysines nor at its N-terminus, the role of E3 ligases in toxin retro-translocation is unclear. Here, we show that expression of mutant Hrd1 and gp78, and a mutant E2 conjugating enzyme dedicated to ret... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2944327 Wed, 28 Oct 2009 00:00:00 +0100 2944327 http://www.medworm.com/index.php?rid=2944326&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19864458%26dopt%3DAbstract Authors: Sharma M, Panapakkam Giridharan SS, Rahajeng J, Naslavsky N, Caplan S Monitoring Editor: Sandra L. Schmid Endocytic recycling of receptors and lipids occurs via a complex network of tubular and vesicular membranes. EHD1 is a key regulator of endocytosis and associates with tubular membranes to facilitate recycling. Although EHD proteins tubulate membranes in vitro, EHD1 primarily associates with pre-existing tubules in vivo. How EHD1 is recruited to these tubular endosomes remains unclear. We have determined that the Rab8-interacting protein, MICAL-L1, associates with EHD1, with both proteins colocalizing to long tubular membranes, in vitro and in live cells. MICAL-L1 is a largely uncharacterized member of the MICAL-family of proteins that uniquely contains two asparagine-prol... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2944326 Wed, 28 Oct 2009 00:00:00 +0100 2944326 http://www.medworm.com/index.php?rid=2944325&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19864459%26dopt%3DAbstract Authors: Coffman VC, Nile AH, Lee IJ, Liu H, Wu JQ Monitoring Editor: Daniel J. Lew Two prevailing models have emerged to explain the mechanism of contractile-ring assembly during cytokinesis in the fission yeast Schizosaccharomyces pombe: the spot/leading cable model and the search, capture, pull, and release (SCPR) model. We tested some of the basic assumptions of the two models. Monte Carlo simulations of the SCPR model require that the formin Cdc12p is present in >30 nodes from which actin filaments are nucleated and captured by myosin-II in neighboring nodes. The force produced by myosin motors pulls the nodes together to form a compact contractile ring. Live microscopy of cells expressing Cdc12p fluorescent fusion proteins shows for the first time that Cdc12p localizes to a br... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2944325 Wed, 28 Oct 2009 00:00:00 +0100 2944325 http://www.medworm.com/index.php?rid=2944324&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19864460%26dopt%3DAbstract Authors: Ruepp MD, Aringhieri C, Vivarelli S, Cardinale S, Paro S, Schümperli D, Barabino SM Monitoring Editor: Marvin Wickens Export of mRNA from the nucleus is linked to proper processing and packaging into ribonucleoprotein complexes. Although several observations indicate a coupling between mRNA 3' end formation and export, it is not known how these two processes are mechanistically connected. Here, we show that a subunit of the mammalian pre-mRNA 3' end processing complex, CF Im68, stimulates mRNA export. CF Im68 shuttles between the nucleus and the cytoplasm in a transcription-dependent manner and interacts with the mRNA export receptor NXF1/TAP. Consistent with the idea that CF Im68 may act as a novel adaptor for NXF1/TAP, we show that CF Im68 promotes the export of a repor... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2944324 Wed, 28 Oct 2009 00:00:00 +0100 2944324 http://www.medworm.com/index.php?rid=2944323&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19864461%26dopt%3DAbstract Authors: Steinhauer J, Gijón MA, Riekhof WR, Voelker DR, Murphy RC, Treisman JE Monitoring Editor: Marcos Gonzalez-Gaitan Enzymes of the membrane-bound O-acyltransferase (MBOAT) family add fatty acyl chains to a diverse range of protein and lipid substrates. A chromosomal translocation disrupting human MBOAT1 results in a novel syndrome characterized by male sterility and brachydactyly. We have found that the Drosophila homologues of MBOAT1, Oysgedart (Oys), Nessy (Nes) and Farjavit (Frj), are lysophospholipid acyltransferases. When expressed in yeast, these MBOATs esterify specific lysophospholipids preferentially with unsaturated fatty acids. Generating null mutations for each gene allowed us to identify redundant functions for Oys and Nes in two distinct aspects of Drosophila g... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2944323 Wed, 28 Oct 2009 00:00:00 +0100 2944323 http://www.medworm.com/index.php?rid=2944322&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19864462%26dopt%3DAbstract Authors: Platani M, Santarella-Mellwig R, Posch M, Walczak R, Swedlow JR, Mattaj IW Monitoring Editor: Karsten Weis The human Nup107-160 nucleoporin complex plays a major role in formation of the nuclear pore complex and is localized to kinetochores in mitosis. Here we report that Seh1, a component of the Nup107-160 complex, functions in chromosome alignment and segregation by regulating the centromeric localization of Aurora B and other chromosome passenger complex proteins. Localization of CENP-E is not affected by Seh1 depletion and analysis by electron microscopy showed that microtubule kinetochore attachments are intact. Seh1-depleted cells show impaired Aurora B localization, which results in severe defects in biorientation and organization of the spindle midzone and midbody. Our... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2944322 Wed, 28 Oct 2009 00:00:00 +0100 2944322 http://www.medworm.com/index.php?rid=2944321&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19864463%26dopt%3DAbstract Authors: Fu X, Zang K, Zhou Z, Reichardt LF, Xu B Monitoring Editor: Mark H. Ginsberg Neurotrophins at axonal terminals signal to cell bodies to regulate neuronal development via signaling endosomes containing activated Trk receptor tyrosine kinases and mitogen-activated protein kinases (MAPKs). Requirements for the formation of signaling endosomes remain, however, poorly characterized. Here we show that a novel Trk-interacting protein, NTRAP (neurotrophic factor receptor associated protein), plays a crucial role in this signaling process. NTRAP interacts with the Trk intracellular domain through its C2H2 zinc fingers in a kinase-dependent manner. It is associated with vesicles, some of which contain markers for signaling endosomes. Inhibition of NTRAP function suppresses neurotrophin-... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2944321 Wed, 28 Oct 2009 00:00:00 +0100 2944321 http://www.medworm.com/index.php?rid=2944320&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19864464%26dopt%3DAbstract In conclusion, PI(3,4,5)P3 formation in recycling endosomes is essential for AP-1B function. PMID: 19864464 [PubMed - as supplied by publisher] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2944320 Wed, 28 Oct 2009 00:00:00 +0100 2944320 http://www.medworm.com/index.php?rid=2944319&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19864465%26dopt%3DAbstract Authors: Fujimoto M, Hayashida N, Katoh T, Oshima K, Shinkawa T, Prakasam R, Tan K, Inouye S, Takii R, Nakai A Monitoring Editor: M. Bishr Omary The heat shock response is characterized by the expression of a set of classical heat shock genes, and is regulated by heat shock transcription factor 1 (HSF1) in mammals. However, comprehensive analyses of gene expression have revealed very large numbers of inducible genes in cells exposed to heat shock. It is believed that HSF1 is required for the heat-inducible expression of these genes although HSF2 and HSF4 modulate some of the gene expression. Here, we identified a novel mouse HSF3 (mHSF3) translocated into the nucleus during heat shock. However, mHSF3 did not activate classical heat shock genes such as Hsp70. Remarkably, overexpression ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2944319 Wed, 28 Oct 2009 00:00:00 +0100 2944319 http://www.medworm.com/index.php?rid=2917240&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19846657%26dopt%3DAbstract Authors: Deryusheva S, Gall JG Monitoring Editor: A. Gregory Matera During their biogenesis small nuclear RNAs (snRNAs) undergo multiple covalent modifications that require guide RNAs to direct methylase and pseudouridylase enzymes to the appropriate nucleotides. Because of their localization in the nuclear Cajal body (CB), these guide RNAs are known as small CB-specific RNAs (scaRNAs). Using a fluorescent primer extension technique, we mapped the modified nucleotides in Drosophila U1, U2, U4 and U5 snRNAs. By fluorescent in situ hybridization (FISH) we showed that seven Drosophila scaRNAs are concentrated in easily detectable CBs. We used two assays based on Xenopus oocyte nuclei to demonstrate that three of these Drosophila scaRNAs do, in fact, function as guide RNAs. In flies null f... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2917240 Tue, 20 Oct 2009 23:00:00 +0100 2917240 http://www.medworm.com/index.php?rid=2917239&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19846658%26dopt%3DAbstract Authors: Vanoosthuyse V, Meadows JC, van der Sar SJ, Millar JB, Hardwick KG Monitoring Editor: Daniel J. Lew Although critical for spindle checkpoint signaling, the role kinetochores play in APC inhibition remains unclear. Here we show that spindle checkpoint proteins are severely depleted from unattached kinetochoresin fission yeast cells lacking Bub3p. Surprisingly, a robust mitotic arrest is maintained in the vast majority of bub3Delta cells, yet they die, suggesting that Bub3p is essential for successful checkpoint recovery. During recovery, two defects are observed: 1) cells mis-segregate chromosomes and 2) anaphase onset is significantly delayed. We show that Bub3p is required to activate the APC upon inhibition of Aurora kinase activity in checkpoint-arrested cells, suggesting t... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2917239 Tue, 20 Oct 2009 23:00:00 +0100 2917239 http://www.medworm.com/index.php?rid=2917238&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19846659%26dopt%3DAbstract Authors: McLellan J, O'Neil N, Tarailo S, Stoepel J, Bryan J, Rose A, Hieter P Monitoring Editor: David G. Drubin Somatic mutations causing chromosome instability (CIN) in tumors can be exploited for selective killing of cancer cells by knockdown of second-site genes causing synthetic lethality. We tested and statistically validated synthetic lethal (SL) interactions between mutations in six S. cerevisiae CIN genes orthologous to genes mutated in colon tumors and five unlinked CIN genes. To identify which SL interactions are conserved in higher organisms and represent potential chemotherapeutic targets, we developed an assay system in Caenorhabditis elegans to test genetic interactions causing synthetic proliferation defects in somatic cells. We made use of post-embryonic RNA interfere... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2917238 Tue, 20 Oct 2009 23:00:00 +0100 2917238 http://www.medworm.com/index.php?rid=2917237&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19846660%26dopt%3DAbstract Authors: Ekiel I, Sulea T, Jansen G, Kowalik M, Minailiuc O, Cheng J, Harcus D, Cygler M, Whiteway M, Wu C Monitoring Editor: Charles Boone Activation of the high osmolarity glycerol (HOG) pathway for osmoregulation in the yeast S. cerevisiae involves interaction of the adaptor Ste50p with the cytoplasmic tail of single-transmembrane protein Opy2p. We have determined the solution structure of the Ste50p-RA domain, and it shows an atypical RA fold lacking the beta1 and beta2 strands of the canonical motif. While the core of the RA domain is fully functional in the pheromone response, an additional region is required for the HOG pathway activation. Two peptide motifs within the intrinsically disordered cytoplasmic tail of Opy2p defined by NMR spectroscopy physically interact with the Ste... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2917237 Tue, 20 Oct 2009 23:00:00 +0100 2917237 http://www.medworm.com/index.php?rid=2917234&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19846661%26dopt%3DAbstract Authors: Barneda-Zahonero B, Miñano-Molina A, Badiola N, Fadó R, Xifró X, Saura CA, Rodríguez-Alvarez J Monitoring Editor: Marianne Bronner-Fraser Bone morphogenetic proteins (BMPs) have been implicated in the generation and postnatal differentiation of cerebellar granule cells (CGCs). Here, we examined the eventual role of BMPs on the survival of these neurons. Lack of depolarization causes CGCs death by apoptosis in vivo, a phenomenon that is mimicked in vitro by deprivation of high potassium in cultured CGCs. We have found that BMP-6, but not BMP-7, is able to block low potassium-mediated apoptosis in CGCs. The neuroprotective effect of BMP-6 is not accompanied by an increase of Smad translocation to the nucleus, suggesting that the canonical pathway is not invol... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2917234 Tue, 20 Oct 2009 23:00:00 +0100 2917234 http://www.medworm.com/index.php?rid=2917233&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19846662%26dopt%3DAbstract Authors: Hsu KW, Hsieh RH, Wu CW, Chi CW, Lee YH, Kuo ML, Wu KJ, Yeh TS Monitoring Editor: Richard K. Assoian The c-Myc promoter binding protein 1 (MBP-1) is a transcriptional suppressor of c-myc expression and involved in control of tumorigenesis. Gastric cancer is one of the most frequent neoplasms and lethal malignancies worldwide. So far, the regulatory mechanism of its aggressiveness has not yet been clearly characterized. Here we studied roles of MBP-1 in gastric cancer progression. We found that cell proliferation was inhibited by MBP-1 overexpression in human stomach adenocarcinoma SC-M1 cells. Colony formation, migration, and invasion abilities of SC-M1 cells were suppressed by MBP-1 overexpression, whereas promoted by MBP-1 knockdown. Furthermore, the xenografted tumor growth... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2917233 Tue, 20 Oct 2009 23:00:00 +0100 2917233 http://www.medworm.com/index.php?rid=2917232&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19846663%26dopt%3DAbstract Authors: Homem CC, Peifer M Monitoring Editor: Marcos Gonzalez-Gaitan During migration cell protrusions power cell extension and sample the environment. Different cells produce different protrusions, from keratocytes dominated by lamellipodia, to growth cones combining filopodia and lamellipodia, to dendritic spines. One key challenge is to determine how the toolkit of actin regulators are coordinated to generate these diverse protrusive arrays. Here we use Drosophila leading-edge cells to explore how Diaphanous-related formins and Ena/VASP proteins cooperate in this process. We first dissect the Diaphanous-regulatory region, revealing novel roles for the GTPase-binding and FH3 domains in cortical localization, filopodial initiation, and lengthening. Second, we provide evidence that ac... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2917232 Tue, 20 Oct 2009 23:00:00 +0100 2917232 http://www.medworm.com/index.php?rid=2917231&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19846664%26dopt%3DAbstract Authors: Johnson HW, Schell MJ Monitoring Editor: Paul Forscher The actin microstructure in dendritic spines is involved in synaptic plasticity. Inositol trisphosphate 3-kinase A (ITPKA) terminates Ins(1,4,5)P3 signals emanating from spines and also binds filamentous actin (F-actin) through its amino terminal region (amino acids 1-66, N66). Here we investigated how ITPKA, independent of its kinase activity, regulates dendritic spine F-actin microstructure. We show that the N66 region of the protein mediates F-actin bundling. An N66 fusion protein bundled F-actin in vitro, and the bundling involved N66 dimerization. By mutagenesis we identified a point mutation in a predicted helical region that eliminated both F-actin binding and bundling, rendering the enzyme cytosolic. A fusion prote... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2917231 Tue, 20 Oct 2009 23:00:00 +0100 2917231 http://www.medworm.com/index.php?rid=2917230&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19846665%26dopt%3DAbstract Authors: Shyu LF, Sun J, Chung HM, Huang YC, Deng WM Monitoring Editor: Marcos Gonzalez-Gaitan Temporal and spatial regulation of cell division is critical for proper development of multicellular organisms. An important aspect of this regulation is cell-cycle arrest, which in many cell types is coupled with differentiated status. Here we report that the polar cells-a group of follicle cells differentiated early during Drosophila oogenesis-are arrested at G2 phase and can serve as a model cell type for investigation of developmental regulation of cell-cycle arrest. On examining the effects of String, a mitosis-promoting phosphatase Cdc25 homolog, and Notch signaling in polar cells, we found that misexpression of String can trigger mitosis in existing polar cells to induce extra polar ce... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2917230 Tue, 20 Oct 2009 23:00:00 +0100 2917230 http://www.medworm.com/index.php?rid=2917229&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19846666%26dopt%3DAbstract We report that ATP stimulates TGF-alpha proteolysis with concomitant EGFR activation and that this process requires ADAM17/TACE activity in both murine fibroblasts and CHO cells. ATP-induced TGF-alpha shedding required calcium and was independent of Src family kinases, PKC and MAPK signaling. Moreover, ATP-induced TGF-alpha shedding was completely inhibited by scavengers of ROS, whereas calcium-stimulated shedding was partially inhibited by ROS scavenging. Furthermore, hydrogen peroxide restored TGF-alpha shedding after calcium chelation. Importantly, we also found that ATP-induced shedding was independent of the cytoplasmic NADPH oxidase complex. Instead, mitochondrial ROS production increased in response to ATP and mitochondrial oxidative complex activity was required to activate TACE-de... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2917229 Tue, 20 Oct 2009 23:00:00 +0100 2917229 http://www.medworm.com/index.php?rid=2917228&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19846667%26dopt%3DAbstract Authors: Liang Y, Niederstrasser H, Edwards M, Jackson CE, Cooper JA Monitoring Editor: Yu-Li Wang Molecular mechanisms for cell migration, especially how signaling and cytoskeletal systems are integrated, are not understood well. Here, we examined the role of CARMIL (Capping protein, Arp2/3, and Myosin-I Linker) family proteins in migrating cells. Vertebrates express three conserved genes for CARMIL, and we examined the functions of the two CARMIL genes expressed in migrating human cultured cells. Both isoforms, CARMIL1 and CARMIL2, were necessary for cell migration, but for different reasons. CARMIL1 localized to lamellipodia and macropinosomes, and loss of its function caused loss of lamellipodial actin, along with defects in protrusion, ruffling and macropinocytosis. CARMIL1-knockd... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2917228 Tue, 20 Oct 2009 23:00:00 +0100 2917228 http://www.medworm.com/index.php?rid=2902090&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19828732%26dopt%3DAbstract Authors: Zhang Z, Hui E, Chapman ER, Jackson MB Monitoring Editor: Patrick J. Brennwald The synaptic vesicle protein synaptotagmin I (Syt I) binds phosphatidylserine (PS) in a Ca(2+)-dependent manner. This interaction is thought to play a role in exocytosis, but its precise functions remain unclear. To determine potential roles for Syt I-PS binding we varied the PS content in PC12 cells and liposomes, and studied the effects on the kinetics of exocytosis and Syt I binding in parallel. Raising PS produced a steeply nonlinear, saturating increase in Ca(2+)-triggered fusion, and a graded slowing of the rate of fusion pore dilation. Ca(2+)-Syt I bound liposomes more tightly as PS content was raised, with a steep increase in binding at low PS, and a further gradual increase at higher PS. Th... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2902090 Tue, 13 Oct 2009 23:00:00 +0100 2902090 http://www.medworm.com/index.php?rid=2902089&cid=s_31999_67_f&fid=31999&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D19828733%26dopt%3DAbstract Authors: Toshima JY, Nakanishi JI, Mizuno K, Toshima J, Drubin DG Monitoring Editor: Howard Riezman Endocytic internalization of G protein-coupled receptors (GPCRs) plays a critical role in down-regulation of GPCR signaling. The yeast mating pheromone receptor, Ste2p, has been used as a model to investigate mechanisms of signal transduction, modification, and endocytic internalization of GPCRs. We previously used a fluorescently labeled mating pheromone derivative to reveal unappreciated molecular and spatio-temporal features of GPCR endocytosis in budding yeast. Here we identify recruitment of Ste2p to pre-existing clathrin-coated pits (CCPs) as a key step regulated by receptor phosphorylation and subsequent ubiquitination upon ligand binding. The yeast casein kinase I homologue, Yck2... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=2902089 Tue, 13 Oct 2009 23:00:00 +0100 2902089