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. Mon, 06 Feb 2012 16:52:14 +0100 http://www.medworm.com/index.php?rid=5657491&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%3D22298423%26dopt%3DAbstract Authors: Berens TJ, Toczyski DP Abstract When DNA is damaged, or DNA replication goes awry, cells activate checkpoints to allow time for damage to be repaired and replication to complete. In Saccharomyces cerevisiae, the DNA damage checkpoint, which responds to lesions such as double-strand breaks, is activated when the lesion promotes the association of the sensor kinase Mec1 and its targeting subunit Ddc2 with its activators Ddc1 (a member of the 9-1-1 complex) and Dpb11. It has been more difficult to determine what role these Mec1 activators play in the replication checkpoint, which recognizes stalled replication forks, since Dpb11 has a separate role in DNA replication itself. Therefore, we constructed an in vivo replication-checkpoint mimic, which recapitulates Mec1-dependent ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5657491 Wed, 01 Feb 2012 05:00:00 +0100 5657491 http://www.medworm.com/index.php?rid=5657490&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%3D22298424%26dopt%3DAbstract Authors: Izawa T, Nagai H, Endo T, Nishikawa SI Abstract The endoplasmic reticulum (ER) has an elaborate quality control system, which retains misfolded proteins and targets them to ER-associated protein degradation (ERAD). To analyze sorting between ER retention and ER exit to the secretory pathway, we constructed fusion proteins containing both folded carboxypeptidase Y (CPY) and misfolded mutant CPY (CPY*) units. While the luminal Hsp70 chaperone BiP interacts with the fusion proteins containing CPY* with similar efficiency, a lectin-like ERAD factor Yos9p binds to them with different efficiency. Correlation between efficiency of Yos9p interactions and ERAD of these fusion proteins indicates that Yos9p but not BiP functions in the retention of misfolded proteins for ERAD. Yos9p ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5657490 Wed, 01 Feb 2012 05:00:00 +0100 5657490 http://www.medworm.com/index.php?rid=5657489&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%3D22298425%26dopt%3DAbstract Authors: Murata D, Nomura KH, Dejima K, Mizuguchi S, Kawasaki N, Matsuishi-Nakajima Y, Ito S, Gengyo-Ando K, Kage-Nakadai E, Mitani S, Nomura K Abstract Glycosylphosphatidylinositol (GPI)-anchor attachment is one of the most common post-translational protein modifications. Using the nematode Caenorhabditis elegans, we determined that GPI-anchored proteins are present in germline cells and distal tip cells (DTCs), which are essential for the maintenance of the germline stem cell niche. We identified 24 C. elegans genes involved in GPI-anchor synthesis. Inhibition of various steps of GPI-anchor synthesis by RNAi or gene knockout resulted in abnormal development of oocytes and early embryos, and both lethal and sterile phenotypes were observed. The piga-1 gene (ortholog of human PIGA)... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5657489 Wed, 01 Feb 2012 05:00:00 +0100 5657489 http://www.medworm.com/index.php?rid=5657488&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%3D22298426%26dopt%3DAbstract In this study we investigated the functional interaction between Cdo and Stim1 in myogenic differentiation. Overexpression and depletion of Stim1 enhanced or decreased myotube formation, respectively. Interestingly Stim1 protein levels were decreased in Cdo-deficient perinatal hindlimb muscles or primary myoblasts; this correlates with defective NFATc3 activation in Cdo(-/-) myoblasts upon differentiation. Forced activation of NFATc3 by overexpression of Calcineurin restored differentiation of Cdo-depleted C2C12 myoblasts. Furthermore, Cdo and Stim1 formed a complex in 293T cells or in differentiating C2C12 myoblasts. The netrin-2-mediated NFATc3 activation was coincident with robust interactions between Cdo and Stim1 in myoblasts and the ERK-mediated Stim1 phosphorylation at serine 575. T... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5657488 Wed, 01 Feb 2012 05:00:00 +0100 5657488 http://www.medworm.com/index.php?rid=5657487&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%3D22298427%26dopt%3DAbstract Authors: Ye Y, Lee IJ, Runge KW, Wu JQ Abstract Cytokinesis is crucial for integrating genome inheritance and cell functions. In multicellular organisms, Rho-GEFs and Rho GTPases are key regulators of division-plane specification and contractile-ring formation during cytokinesis, but how they regulate early steps of cytokinesis in fission yeast remains largely unknown. Here we show that putative Rho-GEF Gef2 and Polo kinase Plo1 coordinate to control the medial cortical localization and function of anillin-related protein Mid1. The division-site positioning defects of gef2 plo1-ts18 double mutant can be partially rescued by increasing Mid1 levels. We find that Gef2 physically interacts with the Mid1 N-terminus and modulates Mid1 cortical binding. Gef2 localization to cortical nodes... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5657487 Wed, 01 Feb 2012 05:00:00 +0100 5657487 http://www.medworm.com/index.php?rid=5657486&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%3D22298428%26dopt%3DAbstract Authors: Tanno H, Yamaguchi T, Goto E, Ishido S, Komada M Abstract The mechanism of ubiquitin-dependent endocytosis of cell surface proteins is not completely understood. Here, we examined the role of the ankyrin repeat domain (Ankrd) 13A, 13B, and 13D proteins, which constitute a functionally unknown family of ubiquitin-interacting motif (UIM)-bearing proteins, in the process. Stimulation of human HeLa cells with epidermal growth factor (EGF) rapidly induced direct binding of Ankrd 13 proteins to ubiquitinated EGF receptor (EGFR) via the UIMs. The binding was inhibited when the Ankrd 13 proteins underwent UIM-dependent monoubiquitination, suggesting that their activity is regulated by ubiquitination of themselves. Ankrd 13 proteins bound specifically to Lys63-linked ubiquitin chai... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5657486 Wed, 01 Feb 2012 05:00:00 +0100 5657486 http://www.medworm.com/index.php?rid=5657485&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%3D22298429%26dopt%3DAbstract Authors: Wan X, Cimini D, Cameron LA, Salmon ED Abstract Kinetochores bound to kinetochore microtubules (kMTs) exhibit directional instability in mammalian and other mitotic vertebrate cells, oscillating between poleward (P) and away from the pole (AP) movements. These oscillations are coupled to changes in length of kMTs in a way that maintains a net stretch of the centromere. To understand how sister kinetochore directional instability and kMT plus-end dynamic instability are coupled to oscillations in centromere stretch, we tracked at high resolution the positions of fluorescent kinetochores and their poles for oscillating chromosomes within spindles of metaphase PtK1 cells. We found that the kinetics of P and AP movement are non-linear and different. By subtracting contribution... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5657485 Wed, 01 Feb 2012 05:00:00 +0100 5657485 http://www.medworm.com/index.php?rid=5657484&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%3D22298430%26dopt%3DAbstract Authors: Urbé S, Liu H, Hayes SD, Heride C, Rigden DJ, Clague MJ Abstract Ubiquitination is a reversible modification that influences a broad range of physiological processes. There are approximately 90 DUBs encoded in the human genome, of which 79 are predicted to have catalytic activity. We have tagged 66 DUBs with GFP and systematically surveyed their sub-cellular distribution, identifying enzymes specific to the nucleus, plasma membrane, secretory and endocytic pathways. USP21 is unique in showing clear association with both centrosomes and microtubules. Using an in vitro assay, we show that microtubule binding is direct and identify a novel microtubule binding motif, encompassed within amino acids 59-75 of the N-terminus of USP21. Our functional studies indicate a key role fo... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5657484 Wed, 01 Feb 2012 05:00:00 +0100 5657484 http://www.medworm.com/index.php?rid=5637772&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%3D22278742%26dopt%3DAbstract Authors: Wang R, Zhu J, Dong X, Shi M, Lu C, Springer TA Abstract GARP associates with latent TGFβ (proTGFβ) on the surface of T regulatory cells and platelets; however, whether GARP functions in latent TGFβ activation, and the structural basis of co-association remain unknown. We find that Cys192 and Cys331 of GARP disulfide link to the TGFβ1 prodomain, and that GARP with C192A and C331A mutations can also noncovalently associate with proTGFβ1. Noncovalent association is sufficiently strong for GARP to outcompete latent TGFβ binding protein (LTBP) for binding to proTGFβ1. Association between GARP and proTGFβ1 prevents the secretion of TGFβ1. Integrin α(V)β(6) and to a lesser extent α(V)β(8) are able to activate TGFβ from the GARP-proTGFβ1 complex. Activation require... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5637772 Wed, 25 Jan 2012 05:00:00 +0100 5637772 http://www.medworm.com/index.php?rid=5637771&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%3D22278743%26dopt%3DAbstract Midbody Assembly and its Regulation during Cytokinesis. Mol Biol Cell. 2012 Jan 25; Authors: Hu CK, Coughlin M, Mitchison TJ Abstract The midbody is a transient structure that connects two daughter cells at the end of cytokinesis, with the principle function to localize the site of abscission, which physically separates two daughter cells. Despite its importance, our understanding of midbody assembly and its regulation is still limited. Here we describe how the structural composition of the midbody changes during progression throughout cytokinesis, and explore the functional implications of these changes. Deriving from midzones, midbodies are organized by a set of microtubule interacting proteins that colocalize to a zone of microtubule overlap in the center. We found that ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5637771 Wed, 25 Jan 2012 05:00:00 +0100 5637771 http://www.medworm.com/index.php?rid=5637770&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%3D22278744%26dopt%3DAbstract We examined the hypothesis that cAMP/PKA stimulation regulates CFTR biogenesis post-translationally, based on predicted 14-3-3 binding motifs within CFTR and forskolin-induced CFTR expression. 14-3-3beta, gamma and epsilon isoforms were expressed in airway cells and interacted with CFTR in co-immunoprecipitation assays. Forskolin stimulation (15 min) increased 14-3-3beta and epsilon binding to immature and mature CFTR (bands B and C), and 14-3-3 over-expression increased CFTR bands B and C and cell surface band C. In pulse-chase experiments, 14-3-3beta increased the synthesis of immature CFTR, reduced its degradation rate, and increased conversion of immature to mature CFTR. Conversely, 14-3-3beta knockdown decreased CFTR B and C bands (70 and 55%), and elicited parallel reductions in cell... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5637770 Wed, 25 Jan 2012 05:00:00 +0100 5637770 http://www.medworm.com/index.php?rid=5619490&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%3D22262454%26dopt%3DAbstract Authors: Vinogradova T, Paul R, Grimaldi AD, Loncarek J, Miller PM, Yampolsky D, Magidson V, Khodjakov A, Mogilner A, Kaverina I Abstract Assembly of an integral Golgi complex is driven by microtubule-dependent transport. Conversely, the Golgi itself functions as an unconventional microtubule-organizing center (MTOC). This raises a question of whether Golgi assembly requires centrosomal microtubules, or the Golgi can be self-organized relying on it's own MTOC activity. The computational model presented here predicts that each microtubule population is capable of gathering Golgi stacks, but not of establishing Golgi complex integrity or polarity. In contrast, the concerted effort of two microtubule populations would assemble an integral polarized Golgi complex. Indeed, while laser a... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5619490 Thu, 19 Jan 2012 05:00:00 +0100 5619490 http://www.medworm.com/index.php?rid=5619489&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%3D22262455%26dopt%3DAbstract Authors: Tyra HM, Spitz DR, Rutkowski DT Abstract The unfolded protein response (UPR) signals protein misfolding in the endoplasmic reticulum (ER) to effect gene expression changes and restore ER homeostasis. While many UPR-regulated genes encode ER protein processing factors, others such as those encoding lipid catabolism enzymes seem unrelated to ER function. It is not known whether UPR-mediated inhibition of fatty acid oxidation influences ER function, and if so, by what mechanism. Here, we demonstrate that pharmacological or genetic inhibition of fatty acid oxidation renders liver cells partially resistant to ER stress-induced UPR activation both in vitro and in vivo. Reduced stress sensitivity appeared to be a consequence of increased cellular redox potential as judged by an e... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5619489 Thu, 19 Jan 2012 05:00:00 +0100 5619489 http://www.medworm.com/index.php?rid=5619488&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%3D22262456%26dopt%3DAbstract Authors: Mao Y, Finnemann SC Abstract Diurnal phagocytosis of shed photoreceptor outer segment particles by retinal pigment epithelial (RPE) cells belongs to a group of conserved clearance mechanisms employing αv integrins upstream of tyrosine kinases and Rho GTPases. Here, we test the interdependence of tyrosine kinases FAK, MerTK and Rho GTPases during engulfment. RPE cells activated and redistributed Rac1 but not RhoA or Cdc42 during phagocytosis. Toxin B, overexpression of dominant-negative Rac1, or decreasing Rac1 expression prevented particle engulfment. Fluorescence microscopy showed that Rac1 inhibition had no obvious effect on F-actin arrangement in resting RPE but prevented recruitment of F-actin to surface-bound phagocytic particles. Quantification of active GTP-Rac1 in... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5619488 Thu, 19 Jan 2012 05:00:00 +0100 5619488 http://www.medworm.com/index.php?rid=5619487&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%3D22262457%26dopt%3DAbstract We report that Eps8L1a, a member of the Eps8 family, and a novel ezrin-interacting partner, controls microvillus length through its capping activity. Depletion of Eps8L1a leads to the formation of long microvilli whereas its overexpression has the opposite effect. We demonstrate that ezrin differentially modulates the actin capping and bundling activities of Eps8 and Eps8L1a during microvillus assembly. Coexpression of ezrin with Eps8 promotes the formation of membrane ruffles and tufts of microvilli while expression of ezrin and Eps8L1a induces the clustering of actin containing structures at the cell surface. These distinct morphological changes are neither observed when a mutant of ezrin defective in its binding to Eps8/Eps8L1a is coexpressed with Eps8 or Eps8L1a nor when ezrin is expre... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5619487 Thu, 19 Jan 2012 05:00:00 +0100 5619487 http://www.medworm.com/index.php?rid=5619486&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%3D22262458%26dopt%3DAbstract Authors: Bradley Zuchero J, Belin B, Dyche Mullins R Abstract Junction-mediating and regulatory protein (JMY) is a regulator of both transcription and actin filament assembly. In response to DNA damage JMY accumulates in the nucleus and promotes p53-dependent apoptosis. JMY's actin regulatory activity relies on a cluster of three actin-binding WH2 domains that nucleate filaments directly and also promote nucleation activity of the Arp2/3 complex. In addition to these activities, we find that the WH2 cluster overlaps an atypical, bipartite nuclear localization sequence (NLS) and controls JMY's subcellular localization. Actin monomers bound to the WH2 domains block binding of Importins to the NLS and prevent nuclear import of JMY. Mutations that impair actin binding, or cellular pert... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5619486 Thu, 19 Jan 2012 05:00:00 +0100 5619486 http://www.medworm.com/index.php?rid=5619485&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%3D22262459%26dopt%3DAbstract Authors: Fasulo B, Koyama C, Yu KR, Homola EM, Hsieh TS, Campbell SD, Sullivan W Abstract Defects in DNA replication and chromosome condensation are common phenotypes in cancer cells. A link between replication and condensation has been established, but little is known about the role of checkpoints in monitoring chromosome condensation. We investigate this function by live analysis, using the rapid division cycles in the early Drosophila embryo. We find S-phase and topoisomerase inhibitors delay both the initiation and the rate of chromosome condensation. These cell cycle delays are mediated by the cell cycle kinases chk1 and wee1. Inhibitors that cause severe defects in chromosome condensation and congression on the metaphase plate result in delayed anaphase entry. These delays ar... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5619485 Thu, 19 Jan 2012 05:00:00 +0100 5619485 http://www.medworm.com/index.php?rid=5619484&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%3D22262460%26dopt%3DAbstract Authors: Stevens LJ, Page-McCaw A Abstract Matrix metalloproteinases (MMPs) are extracellular proteases highly expressed at wound sites. However, the precise function of MMPs during re-epithelialization in vivo has been elusive in mammalian models because of the high level of redundancy between the 24 mammalian MMPs. For this reason we used Drosophila melanogaster, whose genome encodes only two MMPs, one secreted type (Mmp1) and one membrane-anchored type (Mmp2), to study the function and regulation of the secreted class of MMPs in vivo. In the absence of redundancy, we found that the Drosophila secreted MMP, Mmp1, is required in the epidermis to facilitate re-epithelialization by remodeling the basement membrane, promoting cell elongation and actin cytoskeletal reorganization, and... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5619484 Thu, 19 Jan 2012 05:00:00 +0100 5619484 http://www.medworm.com/index.php?rid=5619483&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%3D22262461%26dopt%3DAbstract Authors: Stiburek L, Cesnekova J, Kostkova O, Fornuskova D, Vinsova K, Wenchich L, Houstek J, Zeman J Abstract Mitochondrial AAA (ATPases associated with diverse cellular activities) proteases are involved in the quality control and processing of inner-membrane proteins. Here, we investigated the cellular activities of YME1L, the human ortholog of the Yme1 subunit of the yeast i-AAA complex, using stable shRNA knockdown and expression experiments. Human YME1L is shown to be an integral membrane protein that exposes its carboxy-terminus to the intermembrane space and exists in several complexes of 600-1100 kDa. The stable knockdown of YME1L in HEK293 cells led to impaired cell proliferation and apoptotic resistance, altered cristae morphology, diminished rotenone-sensitive respirati... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5619483 Thu, 19 Jan 2012 05:00:00 +0100 5619483 http://www.medworm.com/index.php?rid=5619482&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%3D22262462%26dopt%3DAbstract This study demonstrates that the speckled distribution of phosphorylated pre-mRNA processing factors is regulated by the nucleocytoplasmic transport system in mammalian cells, and that it is important for alternative splicing. PMID: 22262462 [PubMed - as supplied by publisher] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5619482 Thu, 19 Jan 2012 05:00:00 +0100 5619482 http://www.medworm.com/index.php?rid=5619481&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%3D22262463%26dopt%3DAbstract Authors: Kim J, Kandror KV Abstract GLUT4 is the major glucose transporter which is regulated by insulin and is alone responsible for the effect of insulin on post-prandial blood glucose clearance. However, the nature of the insulin sensitivity of GLUT4 remains unknown. Here, we have replaced the first luminal loop of cellugyrin, the four-transmembrane protein that does not respond to insulin, with that of GLUT4. The chimera protein is targeted to the intracellular insulin-responsive vesicles and is translocated to the plasma membrane upon insulin stimulation. The faithful targeting of the chimera depends on the expression of the sorting receptor sortilin, that interacts with the unique amino acid residues in the first luminal loop of GLUT4. Thus, the first luminal loop may confer ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5619481 Thu, 19 Jan 2012 05:00:00 +0100 5619481 http://www.medworm.com/index.php?rid=5596879&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%3D22238358%26dopt%3DAbstract Authors: Yoneyama T, Angata K, Bao X, Courtneidge S, Chanda S, Fukuda M Abstract Glycans of α-dystroglycan (α-DG), which is expressed at the epithelial cell-basement membrane (BM) interface, play an essential role in epithelium development and tissue organization. Laminin-binding glycans on α-DG expressed on cancer cells suppress tumor progression by attenuating tumor cell migration from the BM. However, mechanisms controlling laminin-binding glycan expression are not known yet. Here, we used siRNA library screening and identified Fer kinase, a non-receptor type tyrosine kinase, as a key regulator of laminin-binding glycan expression. Fer overexpression decreased laminin-binding glycan expression, while siRNA-mediated down-regulation of Fer kinase increased glycan expression on ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5596879 Wed, 11 Jan 2012 05:00:00 +0100 5596879 http://www.medworm.com/index.php?rid=5596878&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%3D22238359%26dopt%3DAbstract Authors: Michaillat L, Baars TL, Mayer A Abstract Size and copy number of organelles are influenced by an equilibrium of membrane fusion and fission. We studied this equilibrium on vacuoles, the lysosomes of yeast. Vacuole fusion can readily be reconstituted and quantified in vitro but fission of the organelle could not be studied in a similar way so far. Here, we present a cell-free system that reconstitutes fragmentation of purified yeast vacuoles (lysosomes) into smaller vesicles. Fragmentation in vitro reproduces physiological aspects. It requires the dynamin-like GTPase Vps1p, V-ATPase pump activity, cytosolic proteins, and ATP and GTP hydrolysis. We used the in vitro system to uncover that the vacuole-associated TOR complex 1 (TORC1) stimulates vacuole fragmentation but not t... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5596878 Wed, 11 Jan 2012 05:00:00 +0100 5596878 http://www.medworm.com/index.php?rid=5596877&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%3D22238360%26dopt%3DAbstract We report the first description of a genetic disruption of NUP107 in metazoan. Caenorhabditis elegans NUP107/npp-5 mutants display temperature-dependent lethality. Surprisingly, NPP-5 is dispensable for incorporation of most nucleoporins into nuclear pores and for nuclear protein import. In contrast, NPP-5 is essential for proper kinetochore localization of NUP133/NPP-15, another NUP107 complex member, whereas recruitment of NUP96/NPP-10C and ELYS/MEL-28 is NPP-5-independent. We found that kinetochore protein NUF2/HIM-10 and Aurora B/AIR-2 kinase are less abundant on mitotic chromatin upon NPP-5 depletion. npp-5 mutants are hypersensitive to anoxia, suggesting that the spindle assembly checkpoint (SAC) is compromised. Indeed, NPP-5 interacts genetically and physically with SAC protein MAD1... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5596877 Wed, 11 Jan 2012 05:00:00 +0100 5596877 http://www.medworm.com/index.php?rid=5596876&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%3D22238361%26dopt%3DAbstract Authors: Leight JL, Wozniak MA, Chen S, Lynch ML, Chen CS Abstract The transforming growth factor-β (TGF-β) signaling pathway is often misregulated during cancer progression. In early stages of tumorigenesis, TGF-β acts as a tumor suppressor by inhibiting proliferation and inducing apoptosis. However, as the disease progresses, TGF-β switches to promote tumorigenic cell functions, such as epithelial-mesenchymal transition (EMT) and increased cell motility. Dramatic changes in the cellular microenvironment are also correlated with tumor progression, including an increase in tissue stiffness. However, it is unknown if these changes in tissue stiffness can regulate the effects of TGF-β. To this end, we examined NMuMG and MDCK epithelial cells cultured on polyacrylamide gels with ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5596876 Wed, 11 Jan 2012 05:00:00 +0100 5596876 http://www.medworm.com/index.php?rid=5596875&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%3D22238362%26dopt%3DAbstract Authors: Sumigray KD, Lechler T Abstract Maintaining proper cell-cell adhesion in the intestine is essential for tissue homeostasis and barrier function. This is thought to be mediated by cell adhesion structures, including tight junctions, adherens junctions, and desmosomes, that concentrate in the apical junctional region. While clear roles for adherens and tight junctions have been established in simple epithelia, the function of desmosomes has not been addressed. In stratified epithelia, desmosomes impart mechanical strength to tissues by organizing and anchoring the keratin filament network. Here, we report that the essential desmosomal protein desmoplakin is not essential for cell adhesion in the intestinal epithelium. Surprisingly, keratin filament localization is also unper... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5596875 Wed, 11 Jan 2012 05:00:00 +0100 5596875 http://www.medworm.com/index.php?rid=5596874&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%3D22238363%26dopt%3DAbstract Authors: Mundy DI, Li WP, Luby-Phelps K, Anderson RG Abstract Caveolin-1 is an integral membrane protein of plasma membrane caveolae. Here we report that caveolin-1 collects at the cytosolic surface of lysosomal membranes when cells are serum starved. This is due to an elevation of the intra-lysosomal pH since ionophores and proton pump inhibitors that dissipate the lysosomal pH gradient also trapped caveolin-1 on late endosome/lysosomes. Accumulation is both saturable and reversible. At least a portion of the caveolin-1 goes to the plasma membrane upon reversal. Several studies suggest that caveolin-1 is involved in cholesterol transport within the cell. Strikingly, we find that blocking cholesterol export from lysosomes with progesterone or U18666A or treating cells with low conc... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5596874 Wed, 11 Jan 2012 05:00:00 +0100 5596874 http://www.medworm.com/index.php?rid=5596873&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%3D22238364%26dopt%3DAbstract Authors: Suzuki M, Otsuka T, Ohsaki Y, Cheng J, Taniguchi T, Hashimoto H, Taniguchi H, Fujimoto T Abstract Apolipoprotein B-100 (ApoB) is the principal component of very low-density lipoprotein. Poorly lipidated nascent ApoB is extracted from the Sec61 translocon and degraded by proteasomes. ApoB lipidated in the ER lumen is also subjected to proteasomal degradation, but where and how it dislocates to the cytoplasm remains unknown. In the present study, we demonstrated that ApoB after lipidation was dislocated to the cytoplasmic surface of lipid droplets (LDs) and accumulated as ubiquitinated ApoB in Huh7 cells. Depletion of UBXD8, which was almost confined to LDs in this cell type, decreased recruitment of p97 to LDs and caused an increase of both ubiquitinated ApoB on the LD surf... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5596873 Wed, 11 Jan 2012 05:00:00 +0100 5596873 http://www.medworm.com/index.php?rid=5577402&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%3D22218866%26dopt%3DAbstract Authors: Zolghadr K, Rothbauer U, Leonhardt H Abstract Information about protein interactions is crucial for the understanding of cellular processes. Current methods for the investigation of protein-protein interactions (PPIs) require either removal of the proteins from their normal cellular environment, perturbation of the cells or costly instrumentation and advanced technical expertise (Fields and Song, Nature 340:245-246, 1989; Deane et al., Mol Cell Proteomics 1:349-356, 2002; Kerppola, Nat Rev Mol Cell Biol 7:449-456, 2006; Blanchard et al., Mol Cell Proteomics 5:2175-2184, 2006; Miller et al., Mol Cell Proteomics 6:1027-1038, 2007; Miyawaki, Dev Cell 4:295-305, 2003; Parrish et al., Curr Opin Biotechnol 17:387-393, 2006; Sekar and Periasamy, J Cell Biol 160:629-633, 2003). He... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5577402 Tue, 10 Jan 2012 14:09:53 +0100 5577402 http://www.medworm.com/index.php?rid=5577401&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%3D22219373%26dopt%3DAbstract Authors: Froquet R, le Coadic M, Perrin J, Cherix N, Cornillon S, Cosson P Abstract TM9 proteins form a family of conserved proteins with nine transmembrane domains essential for cellular adhesion in many biological systems, but their exact role in this process remains unknown. Here we found that in Dictyostelium amoebae, genetic inactivation of the TM9 protein Phg1A dramatically decreases the surface levels of the SibA adhesion molecule. This is due to a decrease in sibA mRNA levels, in SibA protein stability, and in SibA targeting to the cell surface. A similar phenotype was observed in cells devoid of SadA, a protein that does not belong to the TM9 family but also exhibits 9 transmembrane domains and is essential for cellular adhesion. A csA-SibA chimeric protein comprising only... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5577401 Wed, 04 Jan 2012 05:00:00 +0100 5577401 http://www.medworm.com/index.php?rid=5577400&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%3D22219374%26dopt%3DAbstract Authors: Velikkakath AK, Nishimura T, Oita E, Ishihara N, Mizushima N Abstract Macroautophagy is an intracellular degradation system, by which cytoplasmic materials are enclosed by the autophagosome and delivered to the lysosome. Autophagosome formation is considered to take place on the endoplasmic reticulum and involves functions of autophagy-related (Atg) proteins. Here, we report the identification and characterization of mammalian Atg2 homologs, Atg2A and Atg2B. Simultaneous silencing of Atg2A and Atg2B causes a block in autophagic flux and accumulation of unclosed autophagic structures containing most Atg proteins. Atg2A localizes on the autophagic membrane as well as on the surface of lipid droplets. The Atg2A region containing amino acids 1723-1829, which shows relatively h... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5577400 Wed, 04 Jan 2012 05:00:00 +0100 5577400 http://www.medworm.com/index.php?rid=5577399&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%3D22219375%26dopt%3DAbstract In this study we show direct physiological interactions between the mammalian homologue of Lgl (Lgl1) and the non-muscle myosin II isoform A (NMII-A). We demonstrate that Lgl1 and NMII-A form a complex in vivo and provide data that Lgl1 inhibits NMII-A filament assembly in vitro. Furthermore, depletion of Lgl1 results in the unexpected presence of NMII-A in the cell leading edge, a region that is not usually occupied by this protein, suggesting that Lgl1 regulates the cellular localization of NMII-A. Finally, we show that depletion of Lgl1 affects the size and number of focal adhesions as well as cell polarity, membrane dynamics and the rate of migrating cells. Collectively, these findings indicate that Lgl1 regulates the polarity of migrating cells by controlling the assembly state of NMI... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5577399 Wed, 04 Jan 2012 05:00:00 +0100 5577399 http://www.medworm.com/index.php?rid=5577398&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%3D22219376%26dopt%3DAbstract Authors: Naye F, Voz ML, Detry N, Hammerschmidt M, Peers B, Manfroid I Abstract In vertebrates, pancreas and liver arise from bipotential progenitors located in the embryonic gut endoderm. BMP and FGF signalling pathways have been shown to induce hepatic specification while repressing pancreatic fate. Here, we show that BMP and FGF factors also play crucial function, at slightly later stages, in the specification of the ventral pancreas. By analyzing the pancreatic markers pdx1, ptf1a and hlxb9la in different zebrafish models of BMP loss-of-function, we demonstrate that the BMP pathway is required between 20-24 hpf to specify the ventral pancreatic bud. Knockdown experiments show that bmp2a, expressed in the lateral plate mesoderm at these stages, is essential for ventral pancreas ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5577398 Wed, 04 Jan 2012 05:00:00 +0100 5577398 http://www.medworm.com/index.php?rid=5577397&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%3D22219377%26dopt%3DAbstract Authors: Tatavarty V, Ifrim MF, Levin M, Korza G, Barbarese E, Yu J, Carson JH Abstract Dendritic RNAs are localized and translated in RNA granules. Here we use single molecule imaging to count the number of RNA molecules in each granule and to record translation output from each granule using Venus fluorescent protein as a reporter. For RNAs encoding activity-regulated cytoskeletal-associated protein (ARC) or fragile X mental retardation protein (FMRP) translation events are spatially clustered near individual granules and translational output from individual granules is either sporadic or bursty. The probability of bursty translation is greater for Venus-FMRP RNA than for Venus-ARC RNA and is increased in Fmr1 KO neurons compared to wild type neurons. DHPG increases the rate of s... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5577397 Wed, 04 Jan 2012 05:00:00 +0100 5577397 http://www.medworm.com/index.php?rid=5577396&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%3D22219378%26dopt%3DAbstract Authors: Hokanson DE, Bretscher AP Abstract Cell function requires the integration of cytoskeletal organization and membrane trafficking. Small GTP-binding proteins are key regulators of these processes. We find that EPI64, an apical microvillar protein with a TBC domain that stabilizes active Arf6 and has RabGAP activity, regulates Arf6-dependent membrane trafficking. Expression of EPI64 in HeLa cells induces the accumulation of actin-coated vacuoles, a distinctive phenotype seen in cells expressing constitutively active Arf6. Expression of EPI64 with defective RabGAP activity does not induce vacuole formation. Coexpression of Rab8a suppresses the vacuole phenotype induced by EPI64, and EPI64 expression lowers the level of Rab8-GTP in cells, strongly suggesting that EPI64 has GAP ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5577396 Wed, 04 Jan 2012 05:00:00 +0100 5577396 http://www.medworm.com/index.php?rid=5577395&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%3D22219379%26dopt%3DAbstract Authors: Lajoie P, Moir RD, Willis IM, Snapp EL Abstract Accumulation of misfolded secretory proteins in the endoplasmic reticulum (ER) activates the Unfolded Protein Response (UPR) stress pathway. To enhance secretory protein folding and promote adaptation to stress, the UPR upregulates ER chaperone levels, including BiP. Here, we describe chromosomal tagging of KAR2, the yeast homolog of BiP, with superfolder GFP (sfGFP) to create a multifunctional endogenous reporter of the ER folding environment. Changes in Kar2p-sfGFP fluorescence levels directly correlate with UPR activity and represent a robust reporter for high throughput analysis. A novel second feature of this reporter is that photobleaching microscopy (FRAP) of Kar2p-sfGFP mobility reports on the levels of unfolded secre... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5577395 Wed, 04 Jan 2012 05:00:00 +0100 5577395 http://www.medworm.com/index.php?rid=5577394&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%3D22219380%26dopt%3DAbstract In this study, we have investigated whether the molecular motor myosin II represents such a target, by examining glioma invasion in a series of increasingly complex models that are sensitive to PDGF, EGF, or both. Our results lead to two conclusions. First, malignant glioma cells are stimulated to invade brain through the activation of multiple signaling cascades that are not accounted for in simple in vitro assays. Second, even though there is a high degree of redundancy in pro-migratory signaling cascades in gliomas, blocking tumor invasion by directly targeting myosin II remains effective. Our results thus support our hypothesis that myosin II represents a point of convergence for signal transduction pathways that drive glioma invasion and that its inhibition cannot be overcome by other... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5577394 Wed, 04 Jan 2012 05:00:00 +0100 5577394 http://www.medworm.com/index.php?rid=5577393&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%3D22219381%26dopt%3DAbstract Authors: Lacayo CI, Soneral PA, Zhu J, Tsuchida MA, Footer MJ, Soo FS, Lu Y, Xia Y, Mogilner A, Theriot JA Abstract Networks of polymerizing actin filaments can propel intracellular pathogens and drive movement of artificial particles in reconstituted systems. While biochemical mechanisms activating actin network assembly have been well characterized, it remains unclear how particle geometry and large-scale force balance affect emergent properties of movement. We reconstituted actin-based motility using ellipsoidal beads resembling the geometry of Listeria monocytogenes. Beads coated uniformly with the L. monocytogenes ActA protein migrated equally well in either of two distinct orientations, with their long axes parallel or perpendicular to the direction of motion, while intermedi... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5577393 Wed, 04 Jan 2012 05:00:00 +0100 5577393 http://www.medworm.com/index.php?rid=5577392&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%3D22219382%26dopt%3DAbstract Authors: Yi J, Wu XS, Crites T, Hammer JA Abstract Actin retrograde flow and acto-myosin II contraction have both been implicated in the inward movement of TCR microclusters and immunological synapse formation, but no study has integrated and quantified their relative contributions. Using Jurkat T cells expressing fluorescent myosin IIA heavy chain and F-Tractin, a novel reporter for F-actin, we now provide direct evidence that the dSMAC and pSMAC correspond to lamellipodial (LP) and lamellar (LM) actin networks, respectively, as hypothesized previously. Importantly, our images reveal concentric and contracting acto-myosin II arcs/rings at the LM/pSMAC. Moreover, the speeds of centripetally moving TCR microclusters correspond very closely to the rates of actin retrograde flow in th... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5577392 Wed, 04 Jan 2012 05:00:00 +0100 5577392 http://www.medworm.com/index.php?rid=5577391&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%3D22219383%26dopt%3DAbstract Authors: Chiang WC, Messah C, Lin JH Abstract Endoplasmic reticulum is responsible for folding of secreted and membrane proteins in eukaryotic cells. Disruption of ER protein folding leads to ER stress. Chronic ER stress can cause cell death and is proposed to underlie the pathogenesis of many human diseases. IRE1 directs a key Unfolded Protein Response signaling pathway that controls the fidelity of ER protein folding. IRE1 signaling may be particularly helpful in preventing chronic ER stress and cell injury by alleviating protein misfolding in the ER. To examine this, we used a chemical-genetic approach to selectively activate IRE1 in mammalian cells and tested how artificial IRE1 signaling affected the fate of misfolded P23H rhodopsin linked to photoreceptor cell death. We found... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5577391 Wed, 04 Jan 2012 05:00:00 +0100 5577391 http://www.medworm.com/index.php?rid=5558912&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%3D22210845%26dopt%3DAbstract Authors: Mitchison TJ Abstract Cytotoxic cancer chemotherapy drugs are believed to gain selectivity by targeting cells that proliferate rapidly. However, the proliferation rate is low in many chemosensitive human cancers, and it is not clear how a drug that only kills dividing cells could promote tumor regression. Four potential solutions to this "proliferation rate paradox" are discussed for the microtubule-stabilizing drug paclitaxel: drug retention in tumors, killing of quiescent cells, targeting of noncancer cells in the tumor, and bystander effects. Testing these potential mechanisms of drug action will facilitate rational improvement of antimitotic chemotherapy and perhaps cytotoxic chemotherapy more generally. PMID: 22210845 [PubMed - in process] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5558912 Sun, 01 Jan 2012 05:00:00 +0100 5558912 http://www.medworm.com/index.php?rid=5558911&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%3D22210846%26dopt%3DAbstract Authors: Hehnly H, Doxsey S Abstract Cell polarity is important for a number of processes, from chemotaxis to embryogenesis. Recent studies suggest a new role for polarity in the orchestration of events during the final cell separation step of cell division called abscission. Abscission shares several features with cell polarization, including rearrangement of phosphatidylinositols, reorganization of microtubules, and trafficking of exocyst-associated membranes. Here we focus on how the canonical pathways for cell polarization and cell migration may play a role in spatiotemporal membrane trafficking events required for the final stages of cytokinesis. PMID: 22210846 [PubMed - in process] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5558911 Sun, 01 Jan 2012 05:00:00 +0100 5558911 http://www.medworm.com/index.php?rid=5491746&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%3D22113291%26dopt%3DAbstract Authors: Stalker L, Wynder C Abstract The histone demethylases are a relatively novel family of histone-modifying enzymes. Their gene expression suggests that each of the subfamily members may have a discrete role in cell function. The KDM5 family of H3K4 histone demethylases has four members. Each family member has a distinct cellular role, including KDM5a, which is a tumor suppressor (Christensen et al. Cell 128: 1063-1076, 2007); KDM5b, which is an oncogene (Dey et al. Mol Cell Biol 17: 5312-5327, 2008); and KDM5c (Iwase et al. Cell 128: 1077-1088, 2007), which is expressed in terminally differentiated populations. To properly analyze how these enzymes are regulated, we interrogate their bioactivity in ES cells (ESCs) and during neural differentiation of ESCs. We evaluate the bi... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5491746 Sun, 11 Dec 2011 06:56:16 +0100 5491746 http://www.medworm.com/index.php?rid=5491738&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%3D22130794%26dopt%3DAbstract Authors: Gao X, Chaturvedi D, Patel TB Abstract Ribosomal S6 kinase 1 (RSK1) belongs to a family of proteins with two kinase domains and following activation in the cytoplasm by extracellular signal regulated kinases (ERK1/2) mediates the cell proliferative, cell growth, and survival promoting actions of a number of growth factors and other agonists. These diverse biological actions of RSK1 involve regulation of both cytoplasmic and nuclear events. However, the mechanisms that permit nuclear accumulation of RSK1 remain unknown. Herein, we show that phosphorylation of RSK1 on S221 is important for its dissociation from the type Iα regulatory subunit of protein kinase A (PKA) in the cytoplasm and that RSK1 contains a bipartite nuclear localization sequence that is necessary for its ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5491738 Wed, 30 Nov 2011 05:00:00 +0100 5491738 http://www.medworm.com/index.php?rid=5491737&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%3D22130795%26dopt%3DAbstract Authors: Fukunaga K, Hirano Y, Sugimoto K Abstract Chromosome ends, known as telomeres, have to be distinguished from DNA double-strand breaks (DSBs) that activate DNA damage checkpoint. In budding yeast, the Mre11-Rad50-Xrs2 (MRX) complex associates with DNA ends and promotes checkpoint activation. Rap1 binds to double-stranded telomeric regions and recruits Rif1 and Rif2 to telomeres. Rap1 collaborates with Rif1 and Rif2 and inhibits MRX localization to DNA ends. This Rap1-Rif1-Rif2 function becomes attenuated at shortened telomeres. Here, we show that Rap1 acts together with the subtelomere-binding protein Tbf1 and inhibits MRX localization to DNA ends. The placement of a subtelomeric sequence or TTAGGG repeats together with a short telomeric TG repeat sequence inhibits MRX accu... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5491737 Wed, 30 Nov 2011 05:00:00 +0100 5491737 http://www.medworm.com/index.php?rid=5491736&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%3D22130796%26dopt%3DAbstract In this study, we investigated whether the timing of centrosome separation will affect subsequent mitotic events such as establishment of kinetochore attachment or chromosome segregation. We used a combination of experimental and computational approaches to investigate kinetochore attachment and chromosome segregation in cells with complete vs. incomplete spindle pole separation at NEB. We found that cells with incomplete spindle pole separation exhibit higher rates of kinetochore mis-attachments and chromosome mis-segregation compared to cells that complete centrosome separation before NEB. Moreover, our mathematical model showed that two spindle poles in close proximity do not "search" the entire cellular space, leading to formation of large numbers of syntelic attachments, which can be ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5491736 Wed, 30 Nov 2011 05:00:00 +0100 5491736 http://www.medworm.com/index.php?rid=5491735&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%3D22130797%26dopt%3DAbstract Authors: Kang Q, Pomerening JR Abstract Cyclin B activates cyclin-dependent kinase 1 (CDK1) at mitosis, but conflicting views have emerged on the dynamics of its synthesis during embryonic cycles, ranging from continous translation to rapid synthesis during mitosis. Here we show that a CDK1-mediated negative-feedback loop attenuates cyclin production before mitosis. Cyclin B plateaus before peak CDK1 activation, and proteasome inhibition caused minimal accumulation during mitosis. Inhibiting CDK1 permitted continual cyclin B synthesis, whereas adding non-degradable cyclin stalled it. Cycloheximide treatment before mitosis affected neither cyclin levels nor mitotic entry, corroborating this repression. Attenuated cyclin production collaborates with its destruction, since excess cycl... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5491735 Wed, 30 Nov 2011 05:00:00 +0100 5491735 http://www.medworm.com/index.php?rid=5491745&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%3D22114349%26dopt%3DAbstract Authors: Morgera F, Sallah MR, Dubuke ML, Gandhi P, Brewer DN, Carr CM, Munson M Abstract Trafficking of protein and lipid cargo through the secretory pathway in eukaryotic cells is mediated by membrane-bound vesicles. Secretory vesicle targeting and fusion require a conserved multi-subunit protein complex termed the exocyst, which has been implicated in specific tethering of vesicles to sites of polarized exocytosis. The exocyst is directly involved in regulating SNARE complexes and membrane fusion through interactions between the Sec6 subunit and the plasma membrane SNARE protein, Sec9. Here, we show another facet of Sec6 function-it directly binds Sec1, another SNARE regulator, but of the Sec1/Munc18 family. The Sec6-Sec1 interaction is exclusive of Sec6-Sec9, but compatible wit... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5491745 Wed, 23 Nov 2011 05:00:00 +0100 5491745 http://www.medworm.com/index.php?rid=5491744&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%3D22114350%26dopt%3DAbstract Authors: Shu S, Liu X, Kriebel PW, Daniels MP, Korn ED Abstract Starvation induces Dictyostelium amoebae to secrete cAMP towards which other amoebae stream forming multi-cellular mounds that differentiate and develop into fruiting bodies containing spores. We find that the double deletion of cortexillin (ctx) I and II alters the actin cytoskeleton and substantially inhibits all molecular responses to extracellular cAMP. Synthesis of cAMP-receptor and adenylyl cyclase A (ACA) is inhibited and activation of ACA, RasC and RasG, phosphorylation of ERK2, activation of TORC2 and stimulation of actin polymerization and myosin assembly are greatly reduced. As a consequence, cell streaming and development are completely blocked. Expression of ACA-YFP in the ctxI/ctxII-null cells significant... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5491744 Wed, 23 Nov 2011 05:00:00 +0100 5491744 http://www.medworm.com/index.php?rid=5491743&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%3D22114351%26dopt%3DAbstract Authors: Onyenwoke RU, Forsberg LJ, Liu L, Williams T, Alzate O, Brenman JE Abstract AMP-activated protein kinase (AMPK) is a key energy sensor that regulates metabolism to maintain cellular energy balance. AMPK activation has also been proposed to mimic benefits of caloric restriction and exercise. Therefore, identifying downstream AMPK targets could elucidate new mechanisms for maintaining cellular energy homeostasis. We have identified the phosphotransferase nucleoside diphosphate kinase (NDPK), which maintains pools of nucleotides, as a direct AMPK target through the use of 2-dimensional differential in-gel electrophoresis. Furthermore, we have mapped the AMPK/NDPK phosphorylation site (serine 120) as a functionally potent enzymatic "off switch" both in vivo and in vitro. Becau... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5491743 Wed, 23 Nov 2011 05:00:00 +0100 5491743 http://www.medworm.com/index.php?rid=5491742&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%3D22114352%26dopt%3DAbstract Authors: Revenu C, Ubelmann F, Hurbain I, El-Marjou F, Dingli F, Loew D, Delacour D, Gilet J, Brot-Laroche E, Rivero F, Louvard D, Robine S Abstract Actin bundling proteins are identified as key players in the morphogenesis of thin membrane protrusions. Until now, functional redundancy between the actin bundling proteins villin, espin and plastin-1 has prevented definitive conclusions regarding their role in intestinal microvilli. Here, we report that triple knockout mice lacking these microvillus actin bundling proteins suffer from growth delay but surprisingly still develop microvilli. However, the microvillar actin filaments are sparse and lack the characteristic organisation of bundles. This correlates with a highly inefficient apical retention of enzymes and transporters that ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5491742 Wed, 23 Nov 2011 05:00:00 +0100 5491742 http://www.medworm.com/index.php?rid=5491741&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%3D22114353%26dopt%3DAbstract This study demonstrates that fibrillar collagen I is the physiological inducer of a novel class of invadosomes. PMID: 22114353 [PubMed - as supplied by publisher] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5491741 Wed, 23 Nov 2011 05:00:00 +0100 5491741 http://www.medworm.com/index.php?rid=5491740&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%3D22114354%26dopt%3DAbstract Authors: Alkhaja AK, Jans DC, Nikolov M, Vukotic M, Lytovchenko O, Ludewig F, Schliebs W, Riedel D, Urlaub H, Jakobs S, Deckers M Abstract The inner membrane of mitochondria is especially protein rich and displays a unique morphology characterized by large invaginations, the mitochondrial cristae, and the inner boundary membrane, which is in proximity to the outer membrane. Mitochondrial inner membrane proteins appear to be not evenly distributed in the inner membrane but rather organize into functionally distinct subcompartments. It is currently unknown how the organization of the inner membrane is achieved. We have identified MINOS1/MIO10 (C1orf151/YCL057C-A) a conserved mitochondrial inner membrane protein. mio10 mutant yeast cells are affected in growth on non-fermentable carbo... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5491740 Wed, 23 Nov 2011 05:00:00 +0100 5491740 http://www.medworm.com/index.php?rid=5491739&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%3D22114355%26dopt%3DAbstract Authors: Yu Y, Nomikos M, Theodoridou M, Nounesis G, Lai FA, Swann K Abstract Sperm-specific phospholipase C-zeta (PLCζ) activates embryo development by triggering intracellular Ca(2+) oscillations in mammalian eggs indistinguishable from those at fertilization. Somatic PLC isozymes generate InsP(3)-mediated Ca(2+) release by hydrolysing PI(4,5)P(2) in the plasma membrane. Here we examine the subcellular source of PI(4,5)P(2) targeted by sperm PLCζ in mouse eggs. By monitoring egg plasma membrane PI(4,5)P(2) with a GFP-tagged PH domain, PLCζ was shown to effect minimal loss of PI(4,5)P(2) from the oolemma in contrast to control PLCδ1, despite the much higher potency of PLCζ in eliciting Ca(2+) oscillations. Specific depletion of this PI(4,5)P(2) pool by plasma membrane targeti... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5491739 Wed, 23 Nov 2011 05:00:00 +0100 5491739 http://www.medworm.com/index.php?rid=5491747&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%3D22106867%26dopt%3DAbstract Authors: Yao X, Zhang J, Zhou H, Wang E, Xiang X Abstract Microtubule plus-end tracking proteins accumulate at microtubule plus ends for various cellular functions but their targeting mechanisms are not fully understood (Akhmanova and Steinmetz 2008 Nat Rev Mol Cell Biol 9, 309-322.). Here we tested in the filamentous fungus Aspergillus nidulans the requirement for plus-end localization of dynactin p150, a protein essential for dynein function. Deletion of the N-terminal microtubule(MT)-binding region of p150 significantly diminishes the microtubule plus-end accumulation of both dynein heavy chain and p150, and causes a partial defect in nuclear distribution. Surprisingly, within the MT-binding region, the basic domain is more critical than the CAP-Gly domain for maintaining plus-e... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5491747 Tue, 22 Nov 2011 05:00:00 +0100 5491747 http://www.medworm.com/index.php?rid=5438259&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%3D22090343%26dopt%3DAbstract Authors: Woodruff JB, Drubin DG, Barnes G Abstract Incomplete mitotic spindle disassembly causes lethality in budding yeast. To determine why spindle disassembly is required for cell viability, we used live-cell microscopy to analyze a double mutant strain containing a conditional mutant and a deletion mutant compromised for the Kinesin-8 and anaphase-promoting complex-driven spindle disassembly pathways (td-kip3 and doc1Δ, respectively). Under non-permissive conditions, spindles in td-kip3 doc1Δ cells could break apart but could not disassemble completely. These cells could exit mitosis and undergo cell division. However, the daughter cells could not assemble functional, bipolar spindles in the ensuing mitosis. During the formation of these dysfunctional spindles, centrosome dup... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5438259 Wed, 16 Nov 2011 05:00:00 +0100 5438259 http://www.medworm.com/index.php?rid=5438258&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%3D22090344%26dopt%3DAbstract Authors: Ayciriex S, Le Guédard M, Camougrand N, Velours G, Schoene M, Wattelet-Boyer V, Dupuy JW, Shevchenko A, Schmitter JM, Lessire R, Bessoule JJ, Testet E Abstract For many years, lipid droplets (LD) were considered to be an inert store of lipids. However, recent data showed that LD are dynamic organelles playing an important role in storage and mobilization of neutral lipids. Here, we report the characterization of LOA1 (alias VPS66, alias YPR139c), a yeast member of the glycerolipid acyltransferase family. LOA1 mutants show abnormalities in LD morphology. As previously reported, cells lacking LOA1 contain more LD. Conversely, we showed that overexpression results in fewer LD. Then, we compared the lipidome of loa1Δ mutant and wild-type strains. Steady state metabolic label... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5438258 Wed, 16 Nov 2011 05:00:00 +0100 5438258 http://www.medworm.com/index.php?rid=5438257&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%3D22090345%26dopt%3DAbstract Authors: Senn H, Shapiro RS, Cowen LE Abstract The trimorphic fungus Candida albicans is the leading cause of systemic candidiasis, a disease with poor prognosis affecting immunocompromised individuals. The capacity of C. albicans to transition between morphological states is a key determinant of its ability to cause life-threatening infection. Recently, the molecular chaperone Hsp90 has been implicated as a major regulator of temperature-dependent C. albicans morphogenesis; compromising Hsp90 function induces filamentation and relieves repression of Ras1-PKA signaling, though the mechanism involved remains unknown. Here we demonstrate that filaments generated by compromise of Hsp90 function are neither pseudohyphae nor hyphae but closely resemble filaments formed in response to ce... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5438257 Wed, 16 Nov 2011 05:00:00 +0100 5438257 http://www.medworm.com/index.php?rid=5438256&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%3D22090346%26dopt%3DAbstract Authors: Marnef A, Weil D, Standart N Abstract The evolutionarily-conserved Pat1 proteins are P-body components recently shown to play important roles in cytoplasmic gene expression control. Using human cell lines, we demonstrate here that human Pat1b is a shuttling protein, whose nuclear export is mediated via a consensus NES sequence and Crm1, as evidenced with Leptomycin B (LMB) treatment. However, not all P-body components are nucleocytoplasmic proteins since rck/p54, Dcp1a, Edc3, Ge-1 and Xrn1 are insensitive to LMB, and remain cytoplasmic in its presence. Nuclear Pat1b localises to PML associated-foci and splicing SC35-containing speckles in a transcription-dependent manner, whereas in the absence of RNA synthesis, Pat1b redistributes to crescent-shaped nucleolar caps. Furthe... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5438256 Wed, 16 Nov 2011 05:00:00 +0100 5438256 http://www.medworm.com/index.php?rid=5438255&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%3D22090347%26dopt%3DAbstract Authors: Hoelzle MK, Svitkina T Abstract The actin cytoskeleton and associated proteins play a vital role in cell-cell adhesion. However, the procedure by which cells establish adherens junctions remains unclear. We investigated the dynamics of cell-cell junction formation and the corresponding architecture of the underlying cytoskeleton in cultured HUVECs. We show that the initial interaction between cells is mediated by protruding lamellipodia. Upon their retraction, cells maintain contact through thin bridges formed by filopodia-like protrusions connected by VE-cadherin-rich junctions. Bridges share multiple features with conventional filopodia, such as an internal actin bundle associated with fascin along the length and VASP at the tip. Strikingly, unlike conventional filopodia... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5438255 Wed, 16 Nov 2011 05:00:00 +0100 5438255 http://www.medworm.com/index.php?rid=5438254&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%3D22090348%26dopt%3DAbstract Authors: Krüger A, Batsios P, Baumann O, Luckert E, Schwarz H, Stick R, Meyer I, Gräf R Abstract Lamins build the nuclear lamina and are required for chromatin organization, gene expression, cell cycle progression and mechanical stabilization. Despite these universal functions, lamins have so far been found only in metazoans. We have identified a protein NE81 in Dictyostelium, whose properties justify denomination as a lamin-like protein in a lower eukaryote. This is based on its primary structure, subcellular localization, regulation during mitosis, and the requirement of the C-terminal CaaX box as a post-translational processing signal for proper localization of the protein. Our knock-out and overexpression mutants revealed an important role for NE81 in nuclear integrity, chrom... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5438254 Wed, 16 Nov 2011 05:00:00 +0100 5438254 http://www.medworm.com/index.php?rid=5417474&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%3D22064443%26dopt%3DAbstract Authors: Brault ME, Autexier C Abstract Comment on: Brault ME, et al. Mol Biol Cell 2011; 22:179-88. PMID: 22064443 [PubMed - as supplied by publisher] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5417474 Tue, 15 Nov 2011 05:00:00 +0100 5417474 http://www.medworm.com/index.php?rid=5417473&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%3D22072788%26dopt%3DAbstract Authors: Bohdanowicz M, Balkin DM, De Camilli P, Grinstein S Abstract Sealing of phagosomes is accompanied by the disappearance of phosphatidylinositol (4,5)-bisphosphate (PtdIns(4,5)P(2)) from their cytoplasmic leaflet. Elimination of PtdIns(4,5)P(2), which is required for actin remodeling during phagosome formation, has been attributed to hydrolysis by phospholipase C and phosphorylation by phosphatidylinositol 3-kinase. We found that two inositol 5-phosphatases, OCRL and Inpp5B, become associated with nascent phagosomes. Both phosphatases, which are Rab5 effectors, associate with the adaptor protein APPL1, which is itself recruited to the phagosomes by active Rab5. Knock-down of APPL1 or inhibition of Rab5 impair association of OCRL and Inpp5B with phagosomes and prolong the pre... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5417473 Wed, 09 Nov 2011 05:00:00 +0100 5417473 http://www.medworm.com/index.php?rid=5417472&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%3D22072789%26dopt%3DAbstract Authors: Garre E, Romero-Santacreu L, De Clercq N, Blasco-Angulo N, Sunnerhagen P, Alepuz P Abstract In response to osmotic stress, global translation is inhibited, but the mRNAs encoding stress-protective proteins are selectively translated to allow cell survival. To date, the mechanisms and factors involved in the specific translation of osmostress-responsive genes in Saccharomyces cerevisiae are unknown. We find that the mRNA cap-binding protein Cbc1 is important for yeast survival under osmotic stress. Our results provide new evidence supporting a role of Cbc1 in translation initiation. Cbc1 associates with polysomes, while the deletion of the CBC1 gene causes hypersensitivity to the translation inhibitor cycloheximide and yields synthetic "sickness" in cells with limiting amou... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5417472 Wed, 09 Nov 2011 05:00:00 +0100 5417472 http://www.medworm.com/index.php?rid=5417471&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%3D22072790%26dopt%3DAbstract Authors: Widmann B, Wandrey F, Badertscher L, Wyler E, Pfannstiel J, Zemp I, Kutay U Abstract RIO proteins form a conserved family of atypical protein kinases. Humans possess three distinct RIO kinases, hRio1, hRio2 and hRio3, of which only hRio2 has been characterized with respect to its role in ribosomal biogenesis. Here, we show that both hRio1 and hRio3, like hRio2, are associated with precursors of 40S ribosomal subunits in human cells. Further, we demonstrate that depletion of hRio1 by RNA interference affects the last step of 18S rRNA maturation, and causes defects in the recycling of several trans-acting factors (hEnp1, hRio2, hLtv1, hDim2/PNO1 and hNob1) from pre-40S subunits in the cytoplasm. Although the effects of hRio1 and hRio2 depletion are similar, we show that both... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5417471 Wed, 09 Nov 2011 05:00:00 +0100 5417471 http://www.medworm.com/index.php?rid=5417470&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%3D22072791%26dopt%3DAbstract Authors: Buchsbaum S, Bercovich B, Ciechanover A Abstract FAT10 is a ubiquitin-like protein modifier that is induced in vertebrates following certain inflammatory stimuli. Its functions and the repertoire of its target substrates have remained elusive. In contrast to ubiquitin, its cellular abundance is tightly controled by both transcriptional and post-translational regulation, and it was reported to be rapidly degraded by the proteasome. Here we provide data to indicate that the degradation of FAT10 requires ubiquitination: degradation was inhibited in cells expressing a ubiquitin mutant that cannot be polymerized, and in a mutant cell harboring a thermolabile ubiquitin-activating enzyme, E1. Importantly, FAT10 can serve as a degradation signal for otherwise stable proteins, and ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5417470 Wed, 09 Nov 2011 05:00:00 +0100 5417470 http://www.medworm.com/index.php?rid=5417469&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%3D22072792%26dopt%3DAbstract Authors: Barber CF, Heuser T, Carbajal-Gonzalez BI, Botchkarev VV, Nicastro D Abstract Radial spokes (RSs) play an essential role in the regulation of axonemal dynein activity, and thus of ciliary and flagellar motility. However, few details are known about the complexes involved. Using cryo-electron tomography and sub-tomogram averaging, we visualized the three-dimensional structure of the radial spokes in Chlamydomonas flagella in unprecedented detail. Unlike many other species, Chlamydomonas has only two spokes per axonemal repeat, RS1 and RS2. Our data revealed previously uncharacterized features, including two-pronged spoke bases that facilitate docking to the doublet microtubules, and that inner dyneins connect directly to the spokes. Structures of wild type and the head-less... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5417469 Wed, 09 Nov 2011 05:00:00 +0100 5417469 http://www.medworm.com/index.php?rid=5417468&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%3D22072793%26dopt%3DAbstract Authors: Marat AL, Ioannou MS, McPherson PS Abstract The small GTPase Rab35 regulates endosomal membrane trafficking but also recruits effectors that modulate actin assembly and organization. DENN domain proteins are a newly identified class of Rab guanine-nucleotide exchange factors (GEFs) that are grouped into eight families, each activating a common Rab. The members of one family, connecdenn 1-3/DENND1A-C are all GEFs for Rab35. Why Rab35 requires multiple GEFs is unknown. We demonstrate that connecdenn 3 uses a unique C-terminal motif, a feature not found in connecdenn 1 or 2, to directly bind actin. This interaction couples Rab35 activation to the actin cytoskeleton, resulting in dramatic changes in cell shape, notably the formation of protrusive membrane extensions. These alt... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5417468 Wed, 09 Nov 2011 05:00:00 +0100 5417468 http://www.medworm.com/index.php?rid=5417467&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%3D22072794%26dopt%3DAbstract Authors: Chin CF, Bennett AM, Ma WK, Hall MC, Yeong FM Abstract Cytokinesis, which leads to the physical separation of two dividing cells, is normally restrained until after nuclear division. In Saccharomyces cerevisiae, chitin synthase 2 (Chs2), which lays down the primary septum at the mother-daughter neck, also ensures proper acto-myosin ring constriction during cytokinesis. During the metaphase-to-anaphase transition, phosphorylation of Chs2 by the mitotic cyclin-dependent kinase (Cdk1) retains Chs2 at the ER, thereby preventing its translocation to the neck. Upon Cdk1 inactivation at the end of mitosis, Chs2 is exported from the ER and targeted to the neck. The mechanism for triggering Chs2 ER export thus far is unknown. We show here that Chs2 ER export requires the direct rev... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5417467 Wed, 09 Nov 2011 05:00:00 +0100 5417467 http://www.medworm.com/index.php?rid=5417466&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%3D22072795%26dopt%3DAbstract Authors: Cui YH, Xiao L, Rao JN, Zou T, Liu L, Chen Y, Turner DJ, Gorospe M, Wang JY Abstract microRNAs (miRNAs) and RNA-binding proteins (RBPs) jointly regulate gene expression at the posttranscriptional level and they are involved in many aspects of cellular functions. The RBP CUG-binding protein 1 (CUGBP1) destabilizes and represses the translation of several target mRNAs, but the exact mechanism that regulates CUGBP1 abundance remains elusive. Here, we show that miR-503, computationally predicted to associate with three sites of the CUGBP1 mRNA, represses CUGBP1 expression. Overexpression of a miR-503 precursor (pre-miR-503) reduced the de novo synthesis of CUGBP1 protein, whereas inhibiting miR-503 by using an antisense RNA (antagomir) enhanced CUGBP1 biosynthesis and elevated... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5417466 Wed, 09 Nov 2011 05:00:00 +0100 5417466 http://www.medworm.com/index.php?rid=5417465&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%3D22072796%26dopt%3DAbstract Authors: Chu J, Loughlin EA, Gaur NA, Senbanerjee S, Jacob V, Monson C, Kent B, Oranu A, Ding Y, Ukomadu C, Sadler KC Abstract Ubiquitin-like, containing PHD and RING finger domains 1 (uhrf1) is regulated at the transcriptional level during the cell cycle and in developing zebrafish embryos. We identify phosphorylation as a novel means of regulating UHRF1 and demonstrate that Uhrf1 phosphorylation is required for gastrulation in zebrafish. Human UHRF1 contains a conserved cyclin dependent kinase 2 (CDK2) phosphorylation site at serine 661 that is phosphorylated in vitro by CDK2 partnered with Cyclin A2 (CCNA2), but not Cyclin E. A phosphoserine-661 specific antibody recognizes UHRF1 in both in mammalian cancer cells and in non-transformed zebrafish cells, but not in zebrafish beari... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5417465 Wed, 09 Nov 2011 05:00:00 +0100 5417465 http://www.medworm.com/index.php?rid=5417475&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%3D22060014%26dopt%3DAbstract Conclusions: The complement of sex chromosomes in cells studied in culture has the potential to affect expression of proteins and "mechanistic" signaling pathways. Therefore, editorial policies, consistent with scientific excellence, should require reporting sex of cells used in in vitro experiments. PMID: 22060014 [PubMed - as supplied by publisher] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5417475 Mon, 07 Nov 2011 05:00:00 +0100 5417475 http://www.medworm.com/index.php?rid=5378253&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%3D22049022%26dopt%3DAbstract Authors: Yazaki M, Kashiwagi K, Aritake K, Urade Y, Fujimori K Abstract Cyclooxygenase (COX)-1 and hematopoietic prostaglandin (PG) D synthase (H-PGDS) proteins, both involved in the arachidonate cascade were stable in human megakaryocytic MEG-01 cells. In contrast, once the intracellular calcium level was increased by treatment with a calcium ionophore, both protein levels rapidly decreased with a half-life of less than 30 min and 120 min for COX-1 and H-PGDS, respectively. In the presence of a proteasome inhibitor, COX-1 and H-PGDS proteins accumulated within 10 min and 30 min, respectively, and concurrently appeared as the high molecular mass-ubiquitinated proteins within 30 min and 60 min, respectively, after an increase in the intracellular calcium level. The ubiquitination of... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5378253 Wed, 02 Nov 2011 04:00:00 +0100 5378253 http://www.medworm.com/index.php?rid=5378252&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%3D22049023%26dopt%3DAbstract Authors: Liu J, McConnell K, Dixon M, Calvi BR Abstract Epigenetic regulation exerts a major influence on origins of DNA replication during development. The mechanisms for this regulation, however, are poorly defined. We showed previously that acetylation of nucleosomes regulates the origins that mediate developmental gene amplification during Drosophila oogenesis. Here we show that developmental activation of these origins is associated with acetylation of multiple histone lysines. While these modifications are not unique to origin loci, we find that the level of acetylation is higher at the active origins and quantitatively correlated with the number of times these origins initiate replication. All these acetylation marks were developmentally dynamic, rapidly increasing with orig... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5378252 Wed, 02 Nov 2011 04:00:00 +0100 5378252 http://www.medworm.com/index.php?rid=5378251&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%3D22049024%26dopt%3DAbstract Authors: Johnson RG, Reynhout JK, Tenbroek EM, Quade BJ, Yasumura T, Davidson KG, Sheridan JD, Rash JE Abstract Using an established gap junction (GJ) assembly system with experimentally reaggregated cells, we analyzed "formation plaques" (FPs), apparent sites of GJ assembly. Employing freeze-fracture EM methods, combined with filipin labeling of sterols and immunolabeling for connexin43, we demonstrated that FPs constitute distinct membrane "domains" and that their characteristic 10 nm particles contain connexin43, thus representing precursors (i.e., GJ hemichannels) engaged in assembly. Analysis of FPs in new systems, HeLa and N2A cells, resolved questions surrounding several key, but poorly understood steps in assembly, including: matching of FP membranes in apposed cells; reduc... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5378251 Wed, 02 Nov 2011 04:00:00 +0100 5378251 http://www.medworm.com/index.php?rid=5378250&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%3D22049025%26dopt%3DAbstract Authors: Xiong X, Xu Q, Huang Y, Singh RD, Anderson R, Leof E, Hu J, Ling K Abstract E-cadherin-mediated formation of adherens junctions (AJs) is essential for the morphogenesis of epithelial cells. However, the mechanisms underlying E-cadherin clustering and AJ maturation are not fully understood. Here we report that type Iγ phosphatidylinositol phosphate kinase (PIPKIγ) associates with the exocyst via a direct interaction with Exo70, the exocyst subunit that guides the polarized targeting of exocyst to the plasma membrane. Via this interaction, PIPKIγ mediates the association between E-cadherin and Exo70 and determines the targeting of Exo70 to AJs. Further investigation revealed that Exo70 is necessary for clustering of E-cadherin on the plasma membrane and extension of nasce... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5378250 Wed, 02 Nov 2011 04:00:00 +0100 5378250 http://www.medworm.com/index.php?rid=5378249&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%3D22049026%26dopt%3DAbstract Authors: Andersen KL, Collins K Abstract RNase T2 enzymes are produced by a wide range of organisms and have been implicated to function in diverse cellular processes including stress-induced anticodon loop cleavage of mature tRNAs to generate tRNA halves. Here we describe a family of eight RNase T2 genes (RNT2A-RNT2H) in the ciliate Tetrahymena thermophila. We constructed strains lacking individual or combinations of these RNT2 genes that were viable but had distinct cellular and molecular phenotypes. In strains lacking only one Rnt2 protein or lacking a subfamily of three catalytically inactive Rnt2 proteins, starvation-induced tRNA fragments continued to accumulate with only a minor change in fragment profile in one strain. We therefore generated strains lacking pairwise combina... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5378249 Wed, 02 Nov 2011 04:00:00 +0100 5378249 http://www.medworm.com/index.php?rid=5378264&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%3D22039060%26dopt%3DAbstract Authors: Kellogg DR, Drubin DG PMID: 22039060 [PubMed - in process] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5378264 Tue, 01 Nov 2011 04:00:00 +0100 5378264 http://www.medworm.com/index.php?rid=5378263&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%3D22039061%26dopt%3DAbstract Authors: Nachury MV Abstract How did I get to become a cell biologist? Or, more generally, why do things happen the way they do? The answer provided by the philosopher Democritus and later adopted by Jacques Monod is "everything existing in the universe is the fruit of chance and necessity." While I read Monod's book Chance and Necessity as an undergraduate student, little did I appreciate the accuracy of this citation and how much of my scientific trajectory would be guided by chance. PMID: 22039061 [PubMed - in process] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5378263 Tue, 01 Nov 2011 04:00:00 +0100 5378263 http://www.medworm.com/index.php?rid=5378262&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%3D22039062%26dopt%3DAbstract Authors: Rolls M Abstract "Tell a story," my mother instructs her graduate students as they prepare their talks. I will make use of her advice here, and will tell several short stories. The themes revolve around the practice of science-what motivates us to go into science and how we choose questions once we get there. I also touch on progress in scientific tools, teaching, good mentors, and good colleagues, all of which contribute to making a career in science constantly compelling. PMID: 22039062 [PubMed - in process] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5378262 Tue, 01 Nov 2011 04:00:00 +0100 5378262 http://www.medworm.com/index.php?rid=5378261&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%3D22039063%26dopt%3DAbstract Authors: Wente SR Abstract In cell biology, subcellular locale is critical for the action of signaling molecules, for regulation of gene expression, and for proper cell division. In simple terms, everything must be in the right place at the right time. For my research, I have focused on understanding the role the nuclear pore complex (NPC) plays in maintaining this balance. With eukaryotic transcription in the nucleus and translation in the cytoplasm, highly selective import and export events at the NPC connect these spatially separated processes to allow gene expression. In a similar way, spatial and temporal events have repeatedly impacted my scientific career. In different places and times, interactions with mentors, collaborators, colleagues, and trainees have shaped my researc... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5378261 Tue, 01 Nov 2011 04:00:00 +0100 5378261 http://www.medworm.com/index.php?rid=5378260&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%3D22039064%26dopt%3DAbstract Authors: Guyden JC Abstract I am not big on celebrations, nor do I accept many invitations to receive awards. There is much work to be done, and the reward is in the doing. I learned this lesson early from my parents, Martha and Robert Guyden. However, I am humbled that anyone would even mention my name in association with E. E. Just. I, like he, was born into a segregated America, and somehow we both found biology. I think Just's life story instigates a discussion on diversity in science, as well it should. However, after reading Tyrone Hayes' (2010 E. E. Just Award recipient) essay from last year, "Diversifying the Biological Sciences: Past Efforts and Future Challenges" (Hayes, 2010), I have little to add on the subject. His words gave voice to my thoughts. That being said, I wo... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5378260 Tue, 01 Nov 2011 04:00:00 +0100 5378260 http://www.medworm.com/index.php?rid=5378259&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%3D22039065%26dopt%3DAbstract Authors: Lippincott-Schwartz J Abstract The paradigm that the secretory pathway consists of a stable endoplasmic reticulum and Golgi apparatus, using discrete transport vesicles to exchange their contents, gained important support from groundbreaking biochemical and genetic studies during the 1980s. However, the subsequent development of new imaging technologies with green fluorescent protein introduced data on dynamic processes not fully accounted for by the paradigm. As a result, we may be seeing an example of how a paradigm is evolving to account for the results of new technologies and their new ways of describing cellular processes. PMID: 22039065 [PubMed - in process] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5378259 Tue, 01 Nov 2011 04:00:00 +0100 5378259 http://www.medworm.com/index.php?rid=5378258&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%3D22039066%26dopt%3DAbstract Authors: McIntosh JR Abstract The mechanisms by which cells organize and segregate their chromosomes have been under close scrutiny for years, and significant progress has been made in understanding how mitosis works. Modern cell biology has identified most of the molecules that underlie mitotic spindle function, but the ways in which they are organized and controlled to make an effective and accurate cellular machine are exciting subjects for future study. PMID: 22039066 [PubMed - in process] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5378258 Tue, 01 Nov 2011 04:00:00 +0100 5378258 http://www.medworm.com/index.php?rid=5378257&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%3D22039067%26dopt%3DAbstract Authors: Spudich JA Abstract A mere forty years ago it was unclear what motor molecules exist in cells that could be responsible for the variety of nonmuscle cell movements, including the "saltatory cytoplasmic particle movements" apparent by light microscopy. One wondered whether nonmuscle cells might have a myosin-like molecule, well known to investigators of muscle. Now we know that there are more than a hundred different molecular motors in eukaryotic cells that drive numerous biological processes and organize the cell's dynamic city plan. Furthermore, in vitro motility assays, taken to the single-molecule level using techniques of physics, have allowed detailed characterization of the processes by which motor molecules transduce the chemical energy of ATP hydrolysis into mecha... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5378257 Tue, 01 Nov 2011 04:00:00 +0100 5378257 http://www.medworm.com/index.php?rid=5378256&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%3D22039068%26dopt%3DAbstract Authors: Salmon ED, M Waterman C Abstract Fluorescent speckle microscopy (FSM) is a method for measuring the movements and dynamic assembly of macromolecular assemblies such as cytoskeletal filaments (e.g., microtubules and actin) or focal adhesions within large arrays in living cells or in preparations in vitro. The discovery of the method depended on recognizing the importance of unexpected fluorescence images of microtubules obtained by time-lapse recording of vertebrate epithelial cells in culture. In cells that were injected with fluorescent tubulin at ∼10% of the cytosol pool, microtubules typically appeared as smooth threads with a nearly constant fluorescence intensity. One day, when an unusually low concentration of fluorescent tubulin was injected into cells, the images... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5378256 Tue, 01 Nov 2011 04:00:00 +0100 5378256 http://www.medworm.com/index.php?rid=5378255&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%3D22039069%26dopt%3DAbstract Authors: Goldstein LS Abstract I describe a number of valuable lessons I learned from participating in California's Proposition 71 effort about the role that scientists and rigorous scientific advice can play in a public political process. I describe how scientists can provide valuable information and advice and how they can also gain a great deal from the experience that is valuable to a practicing research scientist. Finally, I argue that in the future, building similar broad coalitions to support biomedical and other areas of scientific research will be essential to protect publicly funded science. Thus, a key lesson from the Proposition 71 experience is that engagement of scientists with diverse nonscientific groups can make a big difference and that scientists must actively en... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5378255 Tue, 01 Nov 2011 04:00:00 +0100 5378255 http://www.medworm.com/index.php?rid=5378254&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%3D22039070%26dopt%3DAbstract Authors: Reverter M, Rentero C, de Muga SV, Alvarez-Guaita A, Mulay V, Cairns R, Wood P, Monastyrskaya K, Pol A, Tebar F, Blasi J, Grewal T, Enrich C Abstract Cholesterol regulates plasma membrane (PM) association and functioning of syntaxin-4 and soluble N-ethylmaleimide-sensitive fusion protein 23 (SNAP23) in the secretory pathway. However, the molecular mechanism and cellular cholesterol pools that determine the localization and assembly of these target membrane SNAP receptors (t-SNAREs) are largely unknown. We recently demonstrated that high levels of annexin A6 (AnxA6) induce accumulation of cholesterol in late endosomes, thereby reducing cholesterol in the Golgi and PM. This leads to an impaired supply of cholesterol needed for cytosolic phospholipase A(2) (cPLA(2)) to drive ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5378254 Tue, 01 Nov 2011 04:00:00 +0100 5378254 http://www.medworm.com/index.php?rid=5359997&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%3D22028782%26dopt%3DAbstract Authors: Lee AW Abstract Colony stimulating factor-1 (CSF-1 or M-CSF) is the major physiological regulator of the proliferation, differentiation and survival of cells of the mononuclear phagocyte lineage. CSF-1 binds to a receptor tyrosine kinase, the CSF-1 receptor (CSF-1R). Multiple pathways are activated downstream of the CSF-1R; however, it is not clear which pathways regulate proliferation and survival. Here, we investigated the role of atypical protein kinase Cs (PKCζ) in a myeloid progenitor cell line that expressed CSF-1R (32D.R) and in primary murine bone marrow derived macrophages (BMMs). In 32D.R cells, CSF-1 induced the phosphorylation of PKCζ and increased its kinase activity. PKC inhibitors and transfections with mutant PKCs showed that optimal CSF-1-dependent Erk a... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5359997 Sun, 30 Oct 2011 23:55:02 +0100 5359997 http://www.medworm.com/index.php?rid=5360010&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%3D21998197%26dopt%3DAbstract Authors: Alfonso Pecchio AR, Cardozo Gizzi AM, Renner ML, Molina-Calavita M, Caputto BL Abstract The onco-protein c-Fos is a well recognized AP-1 transcription factor. In addition, this protein associates with the endoplasmic reticulum (ER) and activates the synthesis of phospholipids. However, the mechanism whereby c-Fos stimulates the synthesis of phospholipids in general and the specific lipid pathways activated are yet unknown. Herein we show that induction of quiescent cells to re-enter growth promotes an increase in the labeling of polyphosphoinositides that is dependent on the expression of c-Fos. We also investigated whether stimulation by c-Fos of the synthesis of phosphatidylinositol and its phosphorylated derivatives (PtdInsP's) is dependent on the activation of enzymes ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5360010 Wed, 26 Oct 2011 04:00:00 +0100 5360010 http://www.medworm.com/index.php?rid=5359996&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%3D22031286%26dopt%3DAbstract This study highlights the mechanisms underlying the inefficient secretion of R345W EFEMP1 and demonstrates that alteration of the proteostasis network may provide a strategy to alleviate or delay the onset of this macular dystrophy. PMID: 22031286 [PubMed - as supplied by publisher] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5359996 Wed, 26 Oct 2011 04:00:00 +0100 5359996 http://www.medworm.com/index.php?rid=5359995&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%3D22031287%26dopt%3DAbstract Authors: Smith AL, Dohn MR, Brown MV, Reynolds AB Abstract The dynamic functional linkage of cadherins with the underlying actin cytoskeleton is tightly regulated to achieve proper cell-cell adhesion. p120-catenin (p120) regulates both cadherin stability and actin dynamics, but the relationship between these two functions remains unclear. Using a novel proteomic approach called ReCLIP, we previously identified a physical interaction between p120 and ROCK1, a major effector of RhoA. Here, we show that a discrete fraction of cellular ROCK1 co-immunoprecipitates with p120 and precisely co-localizes to adherens junctions. Manipulation of the adherens junction using a calcium switch assay and cadherin blocking antibodies suggests direct recruitment of ROCK1 to newly forming junctions. I... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5359995 Wed, 26 Oct 2011 04:00:00 +0100 5359995 http://www.medworm.com/index.php?rid=5359994&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%3D22031288%26dopt%3DAbstract Authors: Haynes J, Srivastava J, Madson N, Wittmann T, Barber DL Abstract Remodeling of actin filaments is necessary for epithelial-mesenchymal transition (EMT); however, understanding of how this is regulated in real time is limited. We used an actin filament reporter and high-resolution live cell imaging to analyze the regulated dynamics of actin filaments during TGF-β-induced EMT of mammary epithelial cells. Progressive changes in cell morphology were accompanied by reorganization of actin filaments from thin cortical bundles in epithelial cells to thick parallel, contractile bundles that disassembled more slowly but remained dynamic in transdifferentiated cells. We show that efficient actin filament remodeling during EMT depends on increased expression of the ERM protein moesi... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5359994 Wed, 26 Oct 2011 04:00:00 +0100 5359994 http://www.medworm.com/index.php?rid=5359993&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%3D22031289%26dopt%3DAbstract Authors: Quail DF, Taylor MJ, Walsh LA, Dieters-Castator D, Das P, Jewer M, Zhang G, Postovit LM Abstract Low oxygen (O(2)) levels characterize the microenvironment of both stem cells and rapidly growing tumors. Moreover, hypoxia is associated with the maintenance of stem cell-like phenotypes, and with increased invasion, angiogenesis and metastasis in cancer patients. Metastatic cancers such as breast cancer and melanoma, aberrantly express the embryonic morphogen, Nodal, and the presence of this protein is correlated with metastatic disease. Here, we demonstrate that hypoxia induces Nodal expression in melanoma and breast cancer cells concomitant with increased cellular invasion and angiogenic phenotypes. Of note, Nodal expression remains up-regulated up to 48 hours following re-... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5359993 Wed, 26 Oct 2011 04:00:00 +0100 5359993 http://www.medworm.com/index.php?rid=5359992&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%3D22031290%26dopt%3DAbstract We examined the roles of LM-511 and LM-332, two structurally different laminin isoforms, in the migration of Madin-Darby canine kidney (MDCK) cells by suppressing expression of their α subunits using siRNA. We determined that knockdown of LM-511 inhibits directional migration and destabilizes cell-cell contacts, in part by disturbing the localization and activity of the polarization machinery. Suppression of integrin α3, a laminin receptor subunit, in cells synthesizing normal amounts of both laminins has a similar effect as knockdown of LM-511. Surprisingly, simultaneous suppression of both laminin α5 and laminin α3 restores directional migration and cell-cell contact stability, suggesting that cells recognize a haptotactic gradient formed by a combination of laminins. PMID: 22031... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5359992 Wed, 26 Oct 2011 04:00:00 +0100 5359992 http://www.medworm.com/index.php?rid=5359991&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%3D22031291%26dopt%3DAbstract Authors: Kuravi VK, Kurischko C, Puri M, Luca FC Abstract Saccharomyces cerevisiae Cbk1 kinase is a LATS/NDR tumor suppressor orthologue and component of the RAM signaling network. Cbk1 was previously implicated in regulating polarized morphogenesis, gene expression and cell integrity. Here, we establish that Cbk1 is critical for heat shock and cell wall stress signaling via Bck2, a protein associated with the Pkc1-Mpk1 cell integrity pathway. We demonstrate that cbk1 and bck2 loss-of-function mutations prevent Mpk1 kinase activation and Mpk1-dependent gene expression, but do not disrupt Mpk1 Thr(190)/Tyr(192) phosphorylation. Bck2 overexpression partially restores Mpk1-dependent Rlm1 transcription factor activity in cbk1 mutants, suggesting that Bck2 functions downstream of Cbk1. ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5359991 Wed, 26 Oct 2011 04:00:00 +0100 5359991 http://www.medworm.com/index.php?rid=5359990&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%3D22031292%26dopt%3DAbstract In this study we analyzed the possibility that cellular prion protein (PrP(C)) could play a role in receptor-mediated apoptotic pathway. We first found that CD95/Fas triggering induced a redistribution of PrP(C) to the mitochondria of T lymphoblastoid CEM cells via a mechanism that bring into play microtubular network integrity and function. In particular, we demonstrated that PrP(C) was redistributed to raft-like microdomains at mitochondrial membrane as well as at endoplasmic reticulum (ER)-mitochondria associated membranes (MAM). Our in vitro experiments also demonstrated that, although PrP(C) had such an effect on mitochondria, it induced the loss of mitochondrial membrane potential and citochrome C release only after a contained raise of calcium concentration. Finally, the involvement... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5359990 Wed, 26 Oct 2011 04:00:00 +0100 5359990 http://www.medworm.com/index.php?rid=5359989&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%3D22031293%26dopt%3DAbstract Authors: Goeres J, Chan PK, Mukopadhyay D, Zhang H, Raught B, Matunis MJ Abstract The association of SUMO-specific isopeptidases (also known as Sentrin-specific proteases, or SENPs) with nuclear pore complexes (NPCs) is conserved in eukaryotic organisms ranging from yeast to mammals. However, the functional significance of this association remains poorly understood, particularly in mammalian cells. Here, we have characterized the molecular basis for interactions between SENP2 and NPCs in human cells. We demonstrate using fluorescence recovery after photobleaching that SENP2, although concentrated at the nuclear basket, is dynamically associated with NPCs. This association is mediated by multiple targeting elements within the N-terminus of SENP2 that function cooperatively to mediat... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5359989 Wed, 26 Oct 2011 04:00:00 +0100 5359989 http://www.medworm.com/index.php?rid=5359988&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%3D22031294%26dopt%3DAbstract Authors: Lafountain JR, Cohan CS, Oldenbourg R Abstract The impact of mechanical forces on kinetochore motility was investigated using laser microsurgery to detach kinetochores with associated chromatin (K-fragment) from meiotic chromosomes in spermatocytes from the crane fly Nephrotoma suturalis. In spermatocytes, elastic tethers connect telomeres of homologues during anaphase A of meiosis I, thus preventing complete disjunction until mid-to-late anaphase A. K-fragments liberated from tethered arms moved at twice the normal velocity towards their connected poles. To assess functional states of detached and control kinetochores, we loaded cells with fluorescently labeled tubulin for fluorescence speckle microscopy on kinetochore microtubules. Control kinetochores added fluorescent ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5359988 Wed, 26 Oct 2011 04:00:00 +0100 5359988 http://www.medworm.com/index.php?rid=5359982&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%3D22031295%26dopt%3DAbstract Authors: Pais JE, Schilke B, Craig EA Abstract The Hsp70-based import motor, associated with the translocon on the matrix side of the mitochondrial inner membrane, drives translocation of proteins via cycles of binding and release. Stimulation of Hsp70's ATPase activity by the translocon-associated J-protein, Pam18 is critical for this process. Pam18 forms a heterodimer with the structurally related protein, Pam16, via their J-type domains. This interaction has been proposed to perform a critical regulatory function, inhibiting the ATPase stimulatory activity of Pam18. Using biochemical and genetic assays, we tested this hypothesis by assessing the in vivo function of Pam18 variants having altered abilities to stimulate Hsp70's ATPase activity. The observed pattern of genetic inter... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5359982 Wed, 26 Oct 2011 04:00:00 +0100 5359982 http://www.medworm.com/index.php?rid=5359971&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%3D22031296%26dopt%3DAbstract Authors: Pedram A, Razandi M, Deschenes RJ, Levin ER Abstract Classical estrogen, progesterone, and androgen receptors (ER, PR, AR) localize outside the nucleus at the plasma membrane of target cells. From the membrane, the receptors signal to activate kinase cascades that are essential for the modulation of transcription and non-genomic functions in many target cells. ER, PR, and AR trafficking to the membrane require receptor palmitoylation by palmitoylacyltransferase (PAT) protein(s). However, the identity of the steroid receptor PAT(s) is unknown. We identified the DHHC-7 and 21 proteins as conserved PATs for the sex steroid receptors. From DHHC-7 and 21 knockdown studies, the PATs are required for endogenous ER, PR, and AR palmitoylation, membrane trafficking, and rapid signal... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5359971 Wed, 26 Oct 2011 04:00:00 +0100 5359971 http://www.medworm.com/index.php?rid=5359966&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%3D22031297%26dopt%3DAbstract Authors: Mese G, Sellitto C, Li L, Wang HZ, Valiunas V, Richard G, Brink PR, White TW Abstract Mutations in the GJB2 gene (Cx26) cause deafness in humans. Most mutations are loss-of-function and cause non-syndromic deafness. Some mutations produce a gain-of-function and cause syndromic deafness associated with skin disorders, like keratitis-ichthyosis-deafness syndrome (KIDS). Cx26-G45E is a lethal mutation linked to KIDS that forms constitutively active connexin hemichannels. The pathomechanism(s) by which mutant Cx26 hemichannels perturb normal epidermal cornification are poorly understood. We created an animal model for KIDS by generating an inducible transgenic mouse expressing Cx26-G45E in keratinocytes. Cx26-G45E mice displayed reduced viability, hyperkeratosis, scaling, skin... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5359966 Wed, 26 Oct 2011 04:00:00 +0100 5359966 http://www.medworm.com/index.php?rid=5360007&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%3D21998200%26dopt%3DAbstract Authors: Furth N, Gertman O, Shiber A, Alfassy OS, Cohen I, Rosenberg M, Kleinberger-Doron N, Friedler A, Ravid T Abstract Proper function of the protein folding quality control network depends on its ability to discern diverse structural perturbations to the native states of its protein substrates. Despite the centrality of the detection of misfolded states to cell homeostasis, very little is known about the exact sequence and structural features that mark a protein as being misfolded. To investigate these features, we studied the requirements for the degradation of the yeast kinetochore protein Ndc10p. Mutant Ndc10p is a substrate of a protein folding quality control pathway mediated by the E3 ubiquitin-ligase Doa10p at the endoplasmic reticulum/nuclear envelope membrane. Analysi... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5360007 Wed, 19 Oct 2011 04:00:00 +0100 5360007 http://www.medworm.com/index.php?rid=5360001&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%3D22013075%26dopt%3DAbstract Authors: Wu J, Misra G, Russell RJ, Ladd AJ, Lele TP, Dickinson RB Abstract In order to determine forces on intracellular microtubules, we measured shape changes of individual microtubules following laser severing. Surprisingly, regions near newly created minus ends increased in curvature following severing, while regions near new microtubule plus ends depolymerized without any observable change in shape. With dynein inhibited, regions near severed minus ends straightened rapidly following severing. These observations suggest that dynein exerts a pulling force on the microtubule which buckles the newly created minus end. Moreover, the lack of any observable straightening suggests that dynein prevents lateral motion of microtubules. To explain these results, we developed a model for... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5360001 Wed, 19 Oct 2011 04:00:00 +0100 5360001 http://www.medworm.com/index.php?rid=5360000&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%3D22013076%26dopt%3DAbstract SEQUESTRATION OF PHOSPHOINOSITIDES BY MUTATED MARCKS EFFECTOR DOMAIN INHIBITS STIMULATED CA2+ MOBILIZATION AND DEGRANULATION IN MAST CELLS. Mol Biol Cell. 2011 Oct 19; Authors: Gadi D, Wagenknecht-Wiesner A, Holowka D, Baird B Abstract Protein kinase C β (PKCβ) participates in antigen-stimulated mast cell degranulation mediated by the high affinity receptor for IgE, FcεRI, but the molecular basis is unclear. We investigated the hypothesis that the polybasic effector domain (ED) of the abundant intracellular substrate for PKC known as MARCKS sequesters phosphoinositides at the inner leaflet of the plasma membrane until MARCKS dissociates after phosphorylation by activated PKC. Real time fluorescence imaging confirms synchronization between stimulated oscillations of intra... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5360000 Wed, 19 Oct 2011 04:00:00 +0100 5360000 http://www.medworm.com/index.php?rid=5359999&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%3D22013077%26dopt%3DAbstract Authors: Choo YY, Boh BK, Lou JJ, Eng J, Leck YC, Anders B, Smith PG, Hagen T Abstract Cullin RING ligases (CRL) are the largest family of cellular E3 ubiquitin ligases and mediate polyubiquitination of numerous cellular substrates. CRLs are activated via the covalent modification of the cullin protein with the ubiquitin like protein Nedd8. This results in a conformational change in the cullin carboxy terminus that facilitates the ubiquitin transfer onto the substrate. CSN mediated cullin deneddylation is essential for CRL activity in vivo. However, the mechanism through which CSN promotes CRL activity in vivo is currently unclear. Here we provide evidence that cullin deneddylation is not intrinsically coupled to substrate polyubiquitination as part of the CRL activation cycle. Fur... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5359999 Wed, 19 Oct 2011 04:00:00 +0100 5359999 http://www.medworm.com/index.php?rid=5359998&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%3D22013078%26dopt%3DAbstract Authors: Hazelett CC, Sheff D, Yeaman C Abstract Tight junctions (TJs) are indispensible structures to epithelial cells, and are responsible for regulation of paracellular diffusion and maintenance of cellular polarity. While many interactions between TJ constituents have been identified, questions remain concerning how specific functions of TJs are established and regulated. Here, we have investigated roles of Ral GTPases and their common effector Exocyst complex in formation of nascent TJs. Unexpectedly, RNAi-mediated suppression of RalA or RalB caused opposing changes in TJ development. RalA reduction increased paracellular permeability and decreased incorporation of components into TJs, whereas RalB reduction decreased paracellular permeability and increased incorporation of co... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5359998 Wed, 19 Oct 2011 04:00:00 +0100 5359998 http://www.medworm.com/index.php?rid=5360014&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%3D21998193%26dopt%3DAbstract In this study, the ER luminal integration profiles of TM1 and TM2 were determined using the ER glycosylation machinery and the effects of the CF-causing mutations G85E and G91R thereon were assessed. The mutations either destabilize the integrated conformation or alter the TM1 ER integration profile. G85E misfolding is based in TM1 destabilization by glutamic acid and loss of glycine, and correlates with the temperature insensitive ER accumulation of immature full length CFTR harboring the mutation. By contrast, temperature-dependent misfolding owing to the G91R mutation depends on the introduction of the basic side chain rather than the loss of the glycine. This work demonstrates that CF-causing mutations predicted to have similar effects on CFTR structure actually result in disparate mol... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5360014 Wed, 12 Oct 2011 04:00:00 +0100 5360014 http://www.medworm.com/index.php?rid=5360013&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%3D21998194%26dopt%3DAbstract In this study, we first define the domains of the α pheromone receptor, Ste2, necessary for signaling in white and opaque forms. Both cell states require the intracellular loop 3 (IC3) and the C-terminal tail of Ste2 for the cellular response, whereas the first intracellular loop (IC1) of Ste2 is dispensable for signaling. To also address pheromone-receptor interactions in related species, including apparently asexual Candida species, Ste2 orthologs were heterologously expressed in C. albicans. Ste2 receptors from multiple Candida clade species were functional when expressed in C. albicans, whereas the Ste2 receptor of Candida lusitaniae was non-functional. Significantly, however, expression of a chimeric C. lusitaniae Ste2 receptor containing the C-terminal tail of C. albicans Ste2 gener... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5360013 Wed, 12 Oct 2011 04:00:00 +0100 5360013 http://www.medworm.com/index.php?rid=5360012&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%3D21998195%26dopt%3DAbstract Authors: Dipetrillo CG, Smith EF Abstract Generating the complex waveforms characteristic of beating cilia requires the coordinate activity of multiple dynein isoforms anchored to the axoneme. We previously identified a complex associated with the C1d projection of the central apparatus that includes Pcdp1 (primary ciliary dyskinesia protein 1). Reduced expression of complex members results in severe motility defects, indicating that C1d is essential for wild-type ciliary beating. To define a mechanism for Pcdp1 / C1d regulation of motility, we took a functional and structural approach combined with mutants lacking C1d and distinct subsets of dynein arms. Unlike mutants completely lacking the central apparatus, dynein-driven microtubule sliding velocities are WT in C1d- defective m... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5360012 Wed, 12 Oct 2011 04:00:00 +0100 5360012 http://www.medworm.com/index.php?rid=5360011&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%3D21998196%26dopt%3DAbstract Authors: Ramabhadran V, Korobova F, Rahme GJ, Higgs HN Abstract INF2 is a unique formin which can both polymerize and depolymerize actin filaments. Mutations in INF2 cause the kidney disease focal and segmental glomerulosclerosis. INF2 can be expressed as two C-terminal splice variants: CAAX and nonCAAX. The CAAX isoform contains a C-terminal prenyl group, and is tightly bound to endoplasmic reticulum (ER). The localization pattern and cellular function of the nonCAAX isoform has not been studied. Here, we find that the two isoforms are expressed in a cell type-dependent manner, with CAAX predominant in 3T3 fibroblasts and nonCAAX predominant in U2OS, HeLa, and Jurkats. While INF2-CAAX is ER-localized in an actin-independent manner, INF2-nonCAAX localizes in an actin-dependent mesh... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5360011 Wed, 12 Oct 2011 04:00:00 +0100 5360011 http://www.medworm.com/index.php?rid=5360009&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%3D21998198%26dopt%3DAbstract Authors: Larimore J, Tornieri K, Ryder PV, Gokhale A, Zlatic SA, Craige B, Lee JD, Talbot K, Pare JF, Smith Y, Faundez V Abstract Dysbindin assembles into the biogenesis of lysosome related organelles complex 1 (BLOC-1), which interacts with the adaptor protein complex 3 (AP-3) mediating a common endosome trafficking route. Deficiencies in AP-3 and BLOC-1 affect synaptic vesicle composition. However, whether AP-3-BLOC-1-dependent sorting events that control synapse membrane protein content take place in cell bodies, upstream nerve terminals, remains unknown. We tested this hypothesis analyzing the targeting of phosphatidylinositol-4-kinase type II α (PI4KIIα), a membrane protein present in pre and postsynaptic compartments. PI4KIIα co-purified with BLOC-1 and AP-3 in neuronal ce... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5360009 Wed, 12 Oct 2011 04:00:00 +0100 5360009 http://www.medworm.com/index.php?rid=5360008&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%3D21998199%26dopt%3DAbstract Authors: Gaillard CL, Pallesi-Pocachard E, Massey-Harroche D, Richard F, Arsanto JP, Chauvin JP, Lecine P, Krämer H, Borg JP, Le Bivic A Abstract Primary cilia originate from the centrosome and play essential roles in several cellular, developmental and pathological processes but the underlying mechanisms of ciliogenesis are not fully understood. Given the involvement of the adaptor protein Hook2 in centrosomal homeostasis and protein transport to pericentrosomal aggresomes, we explored its role in ciliogenesis. We found that in human retinal epithelial cells, Hook2 localizes at the Golgi apparatus and centrosome/basal body, a strategic partitioning for ciliogenesis. Importantly, Hook2 depletion disrupts ciliogenesis at a stage before the formation of the ciliary vesicle at the di... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5360008 Wed, 12 Oct 2011 04:00:00 +0100 5360008 http://www.medworm.com/index.php?rid=5360006&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%3D21998201%26dopt%3DAbstract N-GLYCOSYLATION INSTEAD OF CHOLESTEROL MEDIATES OLIGOMERIZATION AND APICAL SORTING OF GPI-APS IN FRT CELLS. Mol Biol Cell. 2011 Oct 12; Authors: Imjeti NS, Lebreton S, Paladino S, de la Fuente E, Gonzales A, Zurzolo C Abstract Sorting of Glycosylphosphatidyl-inositol anchored proteins (GPI-APs) in polarized epithelial cells is not fully understood. Oligomerization in the Golgi complex has emerged as the crucial event driving apical segregation of GPI-APs in two different kind of epithelial cells, MDCK and FRT cells, but whether the mechanism is conserved remains unknown. In MDCK cells cholesterol promotes GPI-AP oligomerization as well as apical sorting of GPI-APs. Here we show that FRT cells lack this cholesterol-driven oligomerization as apical sorting mechanism. In these... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5360006 Wed, 12 Oct 2011 04:00:00 +0100 5360006 http://www.medworm.com/index.php?rid=5360005&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%3D21998202%26dopt%3DAbstract Authors: Kim WK, Jung H, Kim EY, Kim DH, Cho YS, Park BC, Park SG, Ko Y, Bae KH, Lee SC Abstract Adipocyte differentiation can be regulated by the combinatorial activity of protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs). In particular, PTPs act as key regulators in differentiation-associated signaling pathways. We recently found that receptor-type PTPμ (RPTPμ) expression is markedly increased during the adipogenic differentiation of 3T3-L1 preadipocytes and mesenchymal stem cells. Here, we investigate the functional roles of RPTPμ and the mechanism of its involvement in the regulation of signal transduction during adipogenesis of 3T3-L1 cells. Depletion of endogenous RPTPμ by RNAi significantly inhibited adipogenic differentiation, whereas RPTPμ overe... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5360005 Wed, 12 Oct 2011 04:00:00 +0100 5360005 http://www.medworm.com/index.php?rid=5360004&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%3D21998203%26dopt%3DAbstract Authors: Fan S, Whiteman EL, Hurd TW, McIntyre JC, Dishinger JE, Liu CJ, Martens JR, Verhey KJ, Sajjan U, Margolis BL Abstract The small GTPase Ran and the importin proteins regulate nucleocytoplasmic transport. New evidence suggests that Ran GTP and the importins are also involved in conveying proteins into cilia. In this manuscript, we find that Ran GTP accumulation at the basal bodies is coordinated with the initiation of ciliogenesis. The Ran Binding Protein 1 (RanBP1), which indirectly accelerates Ran GTP→Ran GDP hydrolysis and promotes the dissociation of the Ran/importin complex, also localizes to basal bodies and cilia. To confirm the crucial link between Ran GTP and ciliogenesis, we manipulated the levels of RanBP1 and determined the effects on Ran GTP and primary cilia ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5360004 Wed, 12 Oct 2011 04:00:00 +0100 5360004 http://www.medworm.com/index.php?rid=5360003&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%3D21998204%26dopt%3DAbstract Authors: Gaillard J, Ramabhadran V, Neumann E, Gurel P, Blanchoin L, Vantard M, Higgs HN Abstract A number of cellular processes utilize both microtubules and actin filaments, but the molecular machinery linking these two cytoskeletal elements remains to be elucidated in detail. Formins are actin-binding proteins that have multiple effects on actin dynamics, and one formin, mDia2, has been shown to bind and stabilize microtubules through its Formin Homology 2 (FH2) domain. In this paper, we show that three formins, INF2, mDia1, and mDia2, display important differences in their interactions with microtubules and actin. Constructs containing FH1, FH2, and C-terminal domains of all three formins bind microtubules with high affinity (K(d) < 100 nM). However, only mDia2 binds microtu... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5360003 Wed, 12 Oct 2011 04:00:00 +0100 5360003 http://www.medworm.com/index.php?rid=5360002&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%3D21998205%26dopt%3DAbstract Authors: Sellin ME, Holmfeldt P, Stenmark S, Gullberg M Abstract Septin family proteins oligomerize through GTP-binding domains into core heteromers, which in turn polymerize at the cleavage furrow of dividing fungal and animal cells. Septin assemblies during the interphase of animal cells remain poorly defined and are the topic of this report. Here we developed protocols for visualization of authentic higher-order assemblies using tagged septins to effectively replace the endogenous gene-product within septin core heteromers in human cells. Our analysis revealed that septins assemble into microtubule-supported disc-like structures at the plasma membrane. In the absence of cell substrate-adhesion, this is the predominant higher-order arrangement in interphase cells and each one of ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5360002 Wed, 12 Oct 2011 04:00:00 +0100 5360002 http://www.medworm.com/index.php?rid=5360015&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%3D21986922%26dopt%3DAbstract Authors: Nascimento R, Costa H, Parkhouse RM Abstract Viruses depend on host cell resources for replication and access to those resources may be limited to a particular phase of the cell cycle. Thus manipulation of cell cycle is a commonly employed strategy of viruses for achieving a favorable cellular environment. For example, viruses capable of infecting nondividing cells induce S phase in order to activate the host DNA replication machinery and provide the nucleotide triphosphates necessary for viral DNA replication (Flemington in J Virol 75:4475-4481, 2001; Sullivan and Pipas in Microbiol Mol Biol Rev 66:179-202, 2002). Viruses have developed several strategies to subvert the cell cycle by association with cyclin and cyclin-dependent kinase complexes and molecules that regulate... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5360015 Tue, 11 Oct 2011 04:00:00 +0100 5360015 http://www.medworm.com/index.php?rid=5295036&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%3D21976697%26dopt%3DAbstract Authors: Komatsu N, Aoki K, Yamada M, Yukinaga H, Fujita Y, Kamioka Y, Matsuda M Abstract Biosensors based on the principle of Förster (or fluorescence) resonance energy transfer (FRET) have shed a new light on the spatio-temporal dynamics of signaling molecules. Among them, intramolecular FRET biosensors have been increasingly used due to their high sensitivity and user-friendliness. However, time-consuming optimizations by trial-and-error obstructed the development of intramolecular FRET biosensors. Here we report an optimized backbone for rapid development of highly sensitive intramolecular FRET biosensors. The key concept is to exclude the "orientation-dependent" FRET and to render the biosensors completely "distance-dependent" with a long flexible linker. We optimized a pair ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5295036 Wed, 05 Oct 2011 04:00:00 +0100 5295036 http://www.medworm.com/index.php?rid=5295035&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%3D21976698%26dopt%3DAbstract Authors: Larkins CE, Gonzalez Aviles GD, East MP, Kahn RA, Caspary T Abstract Arl13b is a cilia protein within the Arf family and Ras superfamily of GTPases that is required for cilia structure, but has poorly defined functions there. Here we further characterize the role of Arl13b in cilia by examining mutant cilia in vitro and by determining the localization and dynamics of Arl13b within the cilium. Previously, we showed that mice lacking Arl13b have abnormal Sonic hedgehog (Shh) signaling, and here we show the dynamics of Shh signaling component localization to the cilium are disrupted in the absence of Arl13b. Significantly, we found Smo is enriched in Arl13b null cilia regardless of Shh pathway stimulation, indicating Arl13b regulates the ciliary entry of Smo. Furthermore, our... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5295035 Wed, 05 Oct 2011 04:00:00 +0100 5295035 http://www.medworm.com/index.php?rid=5295034&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%3D21976699%26dopt%3DAbstract Authors: Johnson RI, Sedgwick A, D'Souza-Schorey C, Cagan RL Abstract Patterning of the Drosophila pupal eye is characterized by precise cell movements. Here we demonstrate that these movements require an Arf regulatory cycle that connects surface receptors to Actin-based movement. dArf6 activity-regulated by the ArfGAPs dAsap and dArfGAP3, and the ArfGEFs Schizo and dPsd-promoted large cellular extensions; time-lapse microscopy indicated that these extensions presage cell re-arrangements into correct epithelial niches. During this process, the Drosophila eye also requires interactions between surface Neph1/Nephrin adhesion receptors Roughest and Hibris that bind the adaptor protein Cindr (CD2AP). We provide evidence that Cindr forms a physical complex with dArfGAP3 and dAsap. Our ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5295034 Wed, 05 Oct 2011 04:00:00 +0100 5295034 http://www.medworm.com/index.php?rid=5295033&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%3D21976700%26dopt%3DAbstract Authors: Tapia-Alveal C, O'Connell MJ Abstract Of the three Structural Maintenance of Chromosomes (SMC) complexes, Smc5/6 remains the most poorly understood. Genetic studies have shown that Smc5/6 mutants are defective in homologous recombination (HR), and consistent with this, Smc5/6 is enriched at lesions. However, Smc5/6 is essential for viability but HR is not, and the terminal phenotype of null Smc5/6 mutants is mitotic failure. Here we have analyzed the function of Nse1, which contains a variant RING (vRING) domain that is characteristic of ubiquitin ligases. While deletion of this domain causes DNA damage sensitivity and mitotic failure, serine mutations in conserved cysteines do not. However, these mutations suppress the DNA damage sensitivity of Smc5/6 hypomorphs, but not ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5295033 Wed, 05 Oct 2011 04:00:00 +0100 5295033 http://www.medworm.com/index.php?rid=5295032&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%3D21976701%26dopt%3DAbstract Authors: Matsuzaki F, Shirane M, Matsumoto M, Nakayama KI Abstract Neurons are highly polarized cells with long neurites, with vesicular transport being required for neurite extension. We recently identified protrudin as a key regulator of vesicular transport during neurite extension. Expression of protrudin in nonneuronal cells thus induces formation of neurite-like membrane protrusions. We adopted a proteomics approach to identify proteins that associate with protrudin. Among the protrudin-associated proteins including many with a function related to intracellular trafficking, we focused on KIF5, a motor protein that mediates anterograde vesicular transport in neurons. A co-immunoprecipitation assay confirmed that endogenous protrudin and KIF5 interact in mouse brain. Overexpress... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5295032 Wed, 05 Oct 2011 04:00:00 +0100 5295032 http://www.medworm.com/index.php?rid=5295031&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%3D21976702%26dopt%3DAbstract Authors: Zucchi PC, Zick M Abstract The fusion of sealed biological membranes joins their enclosed aqueous compartments while mixing their membrane bilayers. Reconstituted fusion reactions are commonly assayed by lipid mixing, which can result from either true fusion or from lysis and its attendant reannealing of membranes. Fusion is also frequently assayed by the mixing of lumenal aqueous compartments, using probes of low molecular weight. With several probes (biotin, methylumbelliferyl-N-acetyl-neuraminic acid, and dithionite), we find that yeast vacuolar SNAREs increase the permeability of membranes to small molecules, and that this permeabilization is enhanced by HOPS and Sec17p/Sec18p, the vacuolar tethering and SNARE chaperone proteins. We now report the development of a nove... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5295031 Wed, 05 Oct 2011 04:00:00 +0100 5295031 http://www.medworm.com/index.php?rid=5295030&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%3D21976703%26dopt%3DAbstract This study demonstrates that both lamin B1 and lamin B2 are essential for brain development, with lamin B1 being required for the integrity of the nuclear lamina, and lamin B2 being important for resistance to nuclear elongation in neurons. PMID: 21976703 [PubMed - as supplied by publisher] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5295030 Wed, 05 Oct 2011 04:00:00 +0100 5295030 http://www.medworm.com/index.php?rid=5275041&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%3D21813735%26dopt%3DAbstract Authors: Chen S, Cai H, Park SK, Menon S, Jackson CL, Ferro-Novick S Abstract The TRAPP complexes are multimeric guanine exchange factors (GEFs) for the Rab GTPase Ypt1p. The three complexes (TRAPPI, TRAPPII, and TRAPPIII) share a core of common subunits required for GEF activity, as well as unique subunits (Trs130p, Trs120p, Trs85p, and Trs65p) that redirect the GEF from the endoplasmic reticulum-Golgi pathway to different cellular locations where TRAPP mediates distinct membrane trafficking events. Roles for three of the four unique TRAPP subunits have been described before; however, the role of the TRAPPII-specific subunit Trs65p has remained elusive. Here we demonstrate that Trs65p directly binds to the C-terminus of the Arf1p exchange factor Gea2p and provide in vivo evidence ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5275041 Sat, 01 Oct 2011 04:00:00 +0100 5275041 http://www.medworm.com/index.php?rid=5275040&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%3D21813737%26dopt%3DAbstract Authors: Shinkawa T, Tan K, Fujimoto M, Hayashida N, Yamamoto K, Takaki E, Takii R, Prakasam R, Inouye S, Mezger V, Nakai A Abstract Heat shock response is characterized by the induction of heat shock proteins (HSPs), which facilitate protein folding, and non-HSP proteins with diverse functions, including protein degradation, and is regulated by heat shock factors (HSFs). HSF1 is a master regulator of HSP expression during heat shock in mammals, as is HSF3 in avians. HSF2 plays roles in development of the brain and reproductive organs. However, the fundamental roles of HSF2 in vertebrate cells have not been identified. Here we find that vertebrate HSF2 is activated during heat shock in the physiological range. HSF2 deficiency reduces threshold for chicken HSF3 or mouse HSF1 activat... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5275040 Sat, 01 Oct 2011 04:00:00 +0100 5275040 http://www.medworm.com/index.php?rid=5275039&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%3D21832151%26dopt%3DAbstract Authors: Kashiwazaki J, Yamasaki Y, Itadani A, Teraguchi E, Maeda Y, Shimoda C, Nakamura T Abstract Syntaxin is a component of the target soluble N-ethylmaleimide-sensitive factor attachment protein receptor complex, which is responsible for fusion of membrane vesicles at the target membrane. The fission yeast syntaxin 1 orthologue Psy1 is essential for both vegetative growth and spore formation. During meiosis, Psy1 disappears from the plasma membrane (PM) and dramatically relocalizes on the nascent forespore membrane, which becomes the PM of the spore. Here we report the molecular details and biological significance of Psy1 relocalization. We find that, immediately after meiosis I, Psy1 is selectively internalized by endocytosis. In addition, a meiosis-specific signal induced by ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5275039 Sat, 01 Oct 2011 04:00:00 +0100 5275039 http://www.medworm.com/index.php?rid=5275038&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%3D21832152%26dopt%3DAbstract Authors: Schuster M, Kilaru S, Fink G, Collemare J, Roger Y, Steinberg G Abstract The polarity of microtubules (MTs) determines the motors for intracellular motility, with kinesins moving to plus ends and dynein to minus ends. In elongated cells of Ustilago maydis, dynein is thought to move early endosomes (EEs) toward the septum (retrograde), whereas kinesin-3 transports them to the growing cell tip (anterograde). Occasionally, EEs run up to 90 μm in one direction. The underlying MT array consists of unipolar MTs at both cell ends and antipolar bundles in the middle region of the cell. Cytoplasmic MT-organizing centers, labeled with a γ-tubulin ring complex protein, are distributed along the antipolar MTs but are absent from the unipolar regions. Dynein colocalizes with EEs for ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5275038 Sat, 01 Oct 2011 04:00:00 +0100 5275038 http://www.medworm.com/index.php?rid=5275037&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%3D21849478%26dopt%3DAbstract In this study we seek to demonstrate that the actin-binding proteins ezrin-radixin-moesin (ERM) are effectors of netrin-1/DCC signaling in embryonic cortical neurons. We show that ezrin associates with DCC in a netrin-1-dependent manner. We demonstrate that netrin-1/DCC induces ERM phosphorylation and activation and that the phosphorylation of DCC is required in that context. Moreover, Src kinases and RhoA/Rho kinase activities mediate netrin-1-induced ERM phosphorylation in neurons. We also observed that phosphorylated ERM proteins accumulate in growth cone filopodia, where they colocalize with DCC upon netrin-1 stimulation. Finally, we show that loss of ezrin expression in cortical neurons significantly decreases axon outgrowth induced by netrin-1. Together, our findings demonstrate that... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5275037 Sat, 01 Oct 2011 04:00:00 +0100 5275037 http://www.medworm.com/index.php?rid=5275036&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%3D21960049%26dopt%3DAbstract Authors: PMID: 21960049 [PubMed - as supplied by publisher] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5275036 Sat, 01 Oct 2011 04:00:00 +0100 5275036 http://www.medworm.com/index.php?rid=5275035&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%3D21960050%26dopt%3DAbstract Authors: Bowerman B Abstract Molecular genetic investigation of the early Caenorhabditis elegans embryo has contributed substantially to the discovery and general understanding of the genes, pathways, and mechanisms that regulate and execute developmental and cell biological processes. Initially, worm geneticists relied exclusively on a classical genetics approach, isolating mutants with interesting phenotypes after mutagenesis and then determining the identity of the affected genes. Subsequently, the discovery of RNA interference (RNAi) led to a much greater reliance on a reverse genetics approach: reducing the function of known genes with RNAi and then observing the phenotypic consequences. Now the advent of next-generation DNA sequencing technologies and the ensuing ease and aff... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5275035 Sat, 01 Oct 2011 04:00:00 +0100 5275035 http://www.medworm.com/index.php?rid=5259388&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%3D21937716%26dopt%3DAbstract Authors: Connell M, Cabernard C, Ricketson D, Doe CQ, Prehoda KE Abstract The cytokinetic cleavage furrow is typically positioned symmetrically relative to the cortical cell boundaries but can also be asymmetric. The mechanisms that control furrow site specification have been intensively studied but how polar cortex movements influence ultimate furrow position remains poorly understood. We measured the position of the apical and the basal cortex in asymmetrically dividing Drosophila neuroblasts and observed preferential displacement of the apical cortex that becomes the larger daughter cell during anaphase, effectively shifting the cleavage furrow towards the smaller daughter cell. Asymmetric cortical extension is correlated with the presence of cortical myosin II, which is polariz... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5259388 Wed, 21 Sep 2011 04:00:00 +0100 5259388 http://www.medworm.com/index.php?rid=5259387&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%3D21937717%26dopt%3DAbstract Authors: Balanis N, Yoshigi M, Wendt MK, Schiemann WP, Carlin CR Abstract Active RhoA localizes to plasma membrane where it stimulates formation of focal adhesions and stress fibers. RhoA activity is inhibited by p190RhoGAP following integrin-mediated cell attachment to allow sampling of new adhesive environments. p190RhoGAP is itself activated by Src-dependent tyrosine phosphorylation which facilitates complex formation with p120RasGAP. This complex then translocates to the cell surface where p190RhoGAP down-regulates RhoA. Here we demonstrate that the EGF-receptor co-operates with β3 integrin to regulate p190RhoGAP activity in mouse mammary gland epithelial cells. Adhesion to fibronectin stimulates tyrosine phosphorylation of the EGF-receptor in the absence of receptor ligands. ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5259387 Wed, 21 Sep 2011 04:00:00 +0100 5259387 http://www.medworm.com/index.php?rid=5259386&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%3D21937718%26dopt%3DAbstract Authors: Morgan JT, Pfeiffer ER, Thirkill TL, Peng G, Fridolfsson HN, Douglas GC, Starr DA, Barakat AI Abstract Changes in blood flow regulate gene expression and protein synthesis in vascular endothelial cells, and this regulation is involved in the development of atherosclerosis. How mechanical stimuli are transmitted from the endothelial lumenal surface to the nucleus remains incompletely understood. The LInks Nucleus and Cytoskeleton (LINC) complexes have been proposed as part of a continuous physical link between the plasma membrane and subnuclear structures. LINC proteins nesprin-1, -2, and -4 have been shown to mediate nuclear positioning via microtubule motors and actin. Although nesprin-3 connects intermediate filaments to the nucleus, no functional consequences of nesprin... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5259386 Wed, 21 Sep 2011 04:00:00 +0100 5259386 http://www.medworm.com/index.php?rid=5259385&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%3D21937719%26dopt%3DAbstract Authors: Jia L, Li B, Warrington RT, Hao X, Wang S, Yu H Abstract The spindle checkpoint senses unattached or improperly attached kinetochores during mitosis, inhibits the anaphase-promoting complex or cyclosome (APC/C), and delays anaphase onset to prevent aneuploidy. The mitotic checkpoint complex (MCC) consisting of BubR1, Bub3, Mad2, and Cdc20 is a critical APC/C-inhibitory checkpoint complex in human cells. At the metaphase-anaphase transition, the spindle checkpoint turns off, and MCC disassembles to allow anaphase onset. The molecular mechanisms of checkpoint inactivation are poorly understood. A major unresolved issue is the role of Cdc20 autoubiquitination in this process. While Cdc20 autoubiquitination can promote Mad2 dissociation from Cdc20, a non-ubiquitinatable Cdc20 ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5259385 Wed, 21 Sep 2011 04:00:00 +0100 5259385 http://www.medworm.com/index.php?rid=5259384&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%3D21937720%26dopt%3DAbstract Authors: Troyanovsky RB, Klingelhofer J, Troyanovsky SM Abstract Cadherin - catenin interactions play an important role in cadherin-mediated adhesion. Here we present strong evidence that in the cadherin-catenin complex α-catenin contributes to the binding strength of another catenin, p120, to the same complex. Specifically, we found that a β-catenin-uncoupled cadherin mutant interacts much weaker with p120 than its full-size counterpart and that it is rapidly endocytosed from the surface of A-431 cells. We also showed that p120 overexpression stabilizes this mutant on the cell surface. Examination of the α-catenin deficient MDA-MB-468 cells and their derivates in which α-catenin was reintroduced showed that α-catenin reinforces E-cadherin-p120 association. Finally, a cross-li... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5259384 Wed, 21 Sep 2011 04:00:00 +0100 5259384 http://www.medworm.com/index.php?rid=5259383&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%3D21937721%26dopt%3DAbstract This study highlights a DGKζ-specific function for local DAG metabolism at the IS and offers new clues to its mode of regulation. PMID: 21937721 [PubMed - as supplied by publisher] (Source: Mol Biol Cell) Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5259383 Wed, 21 Sep 2011 04:00:00 +0100 5259383 http://www.medworm.com/index.php?rid=5259382&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%3D21937722%26dopt%3DAbstract Authors: Janostiak R, Tolde O, Bruhová Z, Novotny M, Hanks SK, Rösel D, Brábek J Abstract CAS is a major tyrosine phosphorylated protein in cells transformed by v-crk and v-src oncogenes and plays an important role in invasiveness of Src-transformed cells. A novel phosphorylation site on CAS, tyrosine 12 (Y12) within the ligand binding hydrophobic pocket of the CAS SH3 domain was identified and found to be enriched in Src-transformed cells and invasive human carcinoma cells. To study the biological significance of CAS Y12 phosphorylation, phosphomimicking Y12E and non-phosphorylatable Y12F mutants of CAS were studied. The phosphomimicking mutation decreased interaction of the CAS SH3 domain with FAK and PTP-PEST and reduced tyrosine phosphorylation of FAK. Live cell imaging show... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5259382 Wed, 21 Sep 2011 04:00:00 +0100 5259382 http://www.medworm.com/index.php?rid=5259381&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%3D21937723%26dopt%3DAbstract Authors: Sharp JA, Plant JJ, Ohsumi TK, Borowsky M, Blower MD Abstract RNA localization is an important mechanism to achieve the precise control of post-transcriptional gene expression. Previously, we demonstrated that a subset of cellular mRNAs copurify with mitotic microtubules in egg extracts of Xenopus laevis. Due to limited genomic sequence information available for X. laevis, we used RNA-seq to comprehensively identify the microtubule-interacting trancriptome of the related frog Xenopus tropicalis. We identified ∼450 mRNAs that showed significant enrichment on microtubules (MT-RNAs). In addition, we demonstrate that the MT-RNAs incenp, xrhamm, and tpx2 associate with spindle microtubules in vivo. MT-RNAs are enriched with transcripts associated with cell division, spindle f... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5259381 Wed, 21 Sep 2011 04:00:00 +0100 5259381 http://www.medworm.com/index.php?rid=5259380&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%3D21937724%26dopt%3DAbstract Authors: Moreno-Mateos MA, Espina AG, Torres B, Del Estal MM, Romero-Franco A, Ríos RM, Pintor-Toro JA Abstract Pituitary tumour transforming gene 1 (PTTG1), also known as securin has been involved in many biological functions including inhibition of sister chromatid separation, DNA repair, organ development, and in regulating the expression and secretion of angiogenic and metastatic factors. Although most of these functions of the securin seem to be dependent on the localisation of PTTG1 in the nucleus of the cell, a fraction of the protein has been also detected in the cytoplasm. Here, we demonstrate that, in different cell types, a portion of cytoplasmic PTTG1 is associated with the cis-face of the Golgi apparatus and that this localisation depends on PTTG1 phosphorylation stat... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5259380 Wed, 21 Sep 2011 04:00:00 +0100 5259380 http://www.medworm.com/index.php?rid=5259379&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%3D21937725%26dopt%3DAbstract Authors: Halbsgut N, Linnemannstöns K, Zimmermann LI, Wodarz A Abstract The possession of apical-basal polarity is a common feature of epithelia and neural stem cells, so-called neuroblasts (NBs). In Drosophila, an evolutionarily conserved protein complex, consisting of atypical protein kinase C (aPKC) and the scaffolding proteins Bazooka/PAR-3 and PAR-6 controls the polarity of both cell types. The components of this complex localize to the apical junctional region of epithelial cells and form an apical crescent in NBs. In epithelia, the PAR proteins interact with the cellular machinery for polarized exocytosis and endocytosis, which both are essential for the establishment of plasma membrane polarity. In NBs, many cortical proteins show a strongly polarized subcellular localizat... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5259379 Wed, 21 Sep 2011 04:00:00 +0100 5259379 http://www.medworm.com/index.php?rid=5259378&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%3D21937726%26dopt%3DAbstract Authors: Kim KH, Toomre D, Bender JR Abstract In addition to enhancing or repressing transcription, steroid hormone receptors rapidly transduce kinase activation signals. Upon ligand engagement, an N-terminus truncated splice isoform of estrogen receptor (ER) α, ER46, triggers membrane-initiated signals resulting in eNOS activation and endothelial NO production. The orientation of ER46 at the plasma membrane is incompletely defined. Using ecliptic pHluorin-fused ER46, total internal reflection fluorescence microscopy in live human endothelial cells illustrates that ER46 can topologically conform to a type I transmembrane protein structure. Mutation of isoleucine-386 at the center of ER46's transmembrane hydrophobic core prevents membrane spanning, obscures the N-terminal ectodomai... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5259378 Wed, 21 Sep 2011 04:00:00 +0100 5259378 http://www.medworm.com/index.php?rid=5226988&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%3D21913091%26dopt%3DAbstract Authors: Naniche N, Sau D, Pasinelli P Abstract Mitochondria are key regulators of cellular death. The mitochondrial membranes contain essential enzyme complexes for maintaining metabolic homeostasis and meeting the energy requirements of the cell (Tait and Green, Nat Rev Mol Cell Biol 11:621-632, 2010 and Galluzzi et al., Apoptosis 12:803-813, 2007). Thus, any perturbation of outer or inner mitochondrial membranes can lead to disruptions in the normal fluxes of key ions and metabolic proteins (i.e., ADP/ATP exchange), leading to eventual cellular death. In addition to maintaining cellular viability, mitochondria play a critical role in the initiation of programmed cell death. As initiators of the cell death process, key mitochondrial proteins [Cytochrome C (Cyt C) one of the most ... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5226988 Mon, 19 Sep 2011 01:44:02 +0100 5226988 http://www.medworm.com/index.php?rid=5216375&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%3D21905737%26dopt%3DAbstract In this study, the photochemistry of ARII was examined using the flash-photolysis technique, and data were analyzed using a sequential irreversible model. Five photochemically defined intermediates (P<sub>i</sub>) were sufficient to simulate the data. Noticeably, both P<sub>3</sub> and P<sub>4</sub> contain an equilibrium mixture of M, N and O. Using a transparent indium tin-oxide electrode, the photo-induced proton transfer was measured over a wide pH range. Analysis of the pH-dependent proton transfer enabled estimation of the pKa values of some amino acid residues. The estimated values were 2.6, 5.9 (or 6.3), 8.4, 9.3, 10.5 and 11.3. These values were assigned as the pKa of Asp81 (Asp85<sup>BR</sup>) in the dark, Asp92 (Asp96<sup>BR&... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5216375 Mon, 12 Sep 2011 04:00:00 +0100 5216375 http://www.medworm.com/index.php?rid=5216391&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%3D21900489%26dopt%3DAbstract Authors: Kabeche R, Baldissard S, Hammond J, Howard L, Moseley JB Abstract The cortical cytoskeleton mediates a range of cellular activities such as endocytosis, cell motility, and the maintenance of cell rigidity. Traditional polymers including actin, microtubules, and septins contribute to the cortical cytoskeleton, but additional filament systems may also exist. In yeast cells, cortical structures called eisosomes generate specialized domains termed MCCs (membrane compartment containing Can1) to cluster specific proteins at sites of membrane invaginations. Here, we show that the core eisosome protein Pil1 forms linear cortical filaments in fission yeast cells, and that purified Pil1 assembles into filaments in vitro. In cells, Pil1 cortical filaments are excluded from regions of... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5216391 Wed, 07 Sep 2011 04:00:00 +0100 5216391 http://www.medworm.com/index.php?rid=5216390&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%3D21900490%26dopt%3DAbstract Authors: Melvin A, Mudie S, Rocha S Abstract The Hypoxia Inducible Factor (HIF) is a master regulator of the cellular response to hypoxia. Its levels and activity are controlled by dioxygenases called Prolyl-Hydroxylases and Factor Inhibiting HIF (FIH). In order to activate genes, HIF has to access sequences in DNA that are integrated in chromatin. It is known that the chromatin remodelling complex SWI/SNF is essential for HIF activity. However, no additional information exists about the role of other chromatin remodelling enzymes in hypoxia. Here, we describe the role of ISWI in the cellular response to hypoxia. We find that unlike SWI/SNF, ISWI depletion enhances HIF activity without altering its levels. Furthermore, ISWI knockdown only alters a subset of HIF target genes. Mechan... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5216390 Wed, 07 Sep 2011 04:00:00 +0100 5216390 http://www.medworm.com/index.php?rid=5216389&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%3D21900491%26dopt%3DAbstract Authors: Bunnell TM, Burbach BJ, Shimizu Y, Ervasti JM Abstract Ubiquitously expressed β-actin and γ-actin isoforms play critical roles in most cellular processes, however their unique contributions are not well understood. We generated whole-body β-actin knockout (Actb(-/-)) mice and demonstrated that β-actin is required for early embryonic development. Lethality of Actb(-/-) embryos correlated with severe growth impairment and migration defects in β-actin knockout primary mouse embryonic fibroblasts (MEFs) that were not observed in γ-actin null MEFs. Migration defects were associated with reduced membrane protrusion dynamics and increased focal adhesions. We also identified migration defects upon conditional ablation of β-actin in highly motile T cells. Most interestingly,... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5216389 Wed, 07 Sep 2011 04:00:00 +0100 5216389 http://www.medworm.com/index.php?rid=5216388&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%3D21900492%26dopt%3DAbstract Authors: Mesmin B, Pipalia NH, Lund FW, Ramlall TF, Sokolov A, Eliezer D, Maxfield FR Abstract Non-vesicular transport of cholesterol plays an essential role in the distribution and regulation of cholesterol within cells, but it has been difficult to identify the key intracellular cholesterol transporters. The StAR-related lipid transfer (START) family of proteins is involved in several pathways of non-vesicular trafficking of sterols. Among them, STARD4 has been shown to increase intracellular cholesteryl ester formation and is controlled at the transcriptional level by sterol levels in cells. We found that STARD4 is very efficient in transporting sterol between membranes in vitro. Cholesterol levels are increased in STARD4-silenced cells, while sterol transport to the endocytic r... Mol Biol Cell journals http://www.medworm.com/rss/comments.php?id=5216388 Wed, 07 Sep 2011 04:00:00 +0100 5216388