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147 records returned

The highly conserved synapsin domain E mediates synapsin dimerization and phospholipid vesicle clusteringEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Synapsins are abundant synaptic vesicle (SV)-associated phosphoproteins that regulate synapse formation and function. The highly conserved COOH-terminal domain E was shown to contribute to several synapsin functions, ranging from formation of the SV reserve pool to regulation of the kinetics of exocytosis and SV cycling, although the molecular mechanisms underlying these effects are unknown. We used a synthetic 25-mer peptide encompassing the most conserved region of domain E (Pep-E) to analyze the role of domain E in regulating the interactions between synapsin I and liposomes mimicking the phospholipid composition of SVs...
Source: BJ Cell - November 19, 2009 Category: Biochemistry Authors: I Monaldi, M Vassalli, A Bachi, S Giovedi, E Millo, F Valtorta, R Raiteri, F Benfenati, A Fassio Tags: BJ Cell Source Type: journals

Paraoxonase 2 is downregulated by the Pseudomonas aeruginosa quorum sensing signal N-(3-oxododecanoyl)-L-homoserine lactone and attenuates oxidative stress induced by pyocyaninEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Two virulence factors produced by Pseudomonas aeruginosa are pyocyanin and N-(3-oxododecanoyl)-L-homoserine lactone (3OC12). Pyocyanin damages host cells by generating reactive oxygen species (ROS). 3OC12 is a quorum-sensing signaling molecule which regulates bacterial gene expression and modulates host immune responses. Paraoxonase-2 (PON2) is an esterase that inactivates 3OC12 and potentially attenuates P. aeruginosa virulence. Because increased intracellular calcium initiates the degradation of PON2 mRNA and protein and 3OC12 causes increases in cytosolic calcium, we hypothesized that 3OC12 would also downregulate PON2....
Source: BJ Cell - November 19, 2009 Category: Biochemistry Authors: S Horke, I Witte, S Altenhöfer, P Wilgenbus, M Goldeck, U Förstermann, J Xiao, G L Kramer, D C Haines, P K Chowdhary, R W Haley, J F Teiber Tags: BJ Disease Source Type: journals

MCP-1 causes cardiomyoblast death via autophagy resulting from ER stress caused by oxidative stress generated by inducing a novel Zn-finger protein, MCPIPEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We present evidence that MCP-1 causes death in cardiac myoblasts, H9c2, by inducing oxidative stress that causes ER stress leading to autophagy via a novel Zn-finger protein, MCP-1 induced protein (MCPIP). MCPIP expression caused cell death and knockdown of MCPIP attenuated MCP-1 induced cell death. It caused induction of iNOS, NADPH oxidase subunit phox47, its translocation from the cytoplasm to the membrane and production of reactive oxygen species (ROS), and induction of ER stress markers HSP40, PDI, GRP78 and IRE1α. It also caused autophagy as indicated by beclin-1 induction, cleavage of LC3 and autophagolysosom...
Source: BJ Cell - November 19, 2009 Category: Biochemistry Authors: C W. Younce, P E Kolattukudy Tags: BJ Signal Source Type: journals

Doppel and PrPC co-immunoprecipitate in detergent-resistant membrane domains of epithelial FRT cells.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Dpl is a paralog of the PrPC, whose misfolded conformer (PrPSc) is responsible for the onset of transmissible spongiform encephalopathies (TSEs), or prion diseases. It has been shown that the ectopic expression of Dpl in the brain of some lines of PrP knock out mice provokes cerebellar ataxia that can be rescued by the reintroduction of the PrP gene, suggesting a functional interaction between the two proteins. It is, however, still unclear where and under which conditions, this event may occur. In the present study we addressed this issue by analyzing the intracellular localization and the interaction between Dpl and PrPC...
Source: BJ Cell - November 5, 2009 Category: Biochemistry Authors: A Caputo, D Sarnataro, V Campana, M Costanzo, A Negro, C M. Sorgato, C Zurzolo Tags: BJ Cell Source Type: journals

FLIM-FRET and FRAP reveal association of influenza virus hemagglutinin with membrane raftsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
It has been supposed that the hemagglutinin (HA) of influenza virus must be recruited to membrane-rafts to perform its function in membrane fusion and virus budding. Here, we aimed at substantiating this association in living cells by biophysical methods. To this end, we fused the cyan-fluorescent protein Cerulean to the cytoplasmic tail of HA. Upon expression in CHO cells HA-Cer was glycosylated and transported to the plasma membrane similarly as authentic HA. We measured Förster’s resonance energy transfer by fluorescence lifetime imaging microscopy (FLIM-FRET) and showed strong association of HA-Cer with M...
Source: BJ Cell - November 4, 2009 Category: Biochemistry Authors: S Engel, S Scolari, B Thaa, N Krebs, T Korte, A Herrmann, M Veit Tags: BJ Cell Source Type: journals

Erybraedin C, a natural compound from the plant Bituminaria bituminosa, inhibits both the cleavage and religation activities of human topoisomerase I.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The interaction of human topoisomerase I and erybraedin C, a pterocarpan purified from the plant Bituminaria bituminosa that has been shown to have an antitumor activity, has been investigated through enzymatic activity assays and molecular docking procedures. Erybraedin C is able to inhibit both the cleavage and the religation steps of the enzyme reaction. In both cases, preincubation of the drug with the enzyme is required to have a complete inhibition. Molecular docking simulations indicate that, when interacting with the enzyme alone, the preferential drug binding site is localized in proximity of the active Tyr723 res...
Source: BJ Cell - November 3, 2009 Category: Biochemistry Authors: C Tesauro, P Fiorani, I D'Annessa, G Chillemi, G Turchi, A Desideri Tags: BJ Gene Source Type: journals

PBP is essential for the growth of active Notch4-immortalized mammary epithelial cells by activating SOX10 expressionEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PBP (Peroxisome proliferator-activated receptor Binding Protein) (Med1/TRAP220) is essential for mammary gland development. We established a mammary epithelial cell line with genotype of PBPLoxP/LoxP by expressing an active form of Notch4. Null mutation of PBP caused severe growth inhibition of the Notch4-immortalized mammary cells. We found that truncated PBP without the two LXXLL motifs could reverse the growth inhibition due to the deficiency of endogenous PBP, indicating that signaling through nuclear receptors is unlikely responsible for the growth inhibition as the result of PBP deficiency. Loss of PBP expression was...
Source: BJ Cell - October 26, 2009 Category: Biochemistry Authors: Y Tony Zhu, Y Jia, L Hu, C Qi, M K Prasad, A S McCallion, Y Zhu Tags: BJ Cell Source Type: journals

Wild-type and missense mutants of retinoschisin co-assemble resulting in either intra-cellular retention or incorrect assembly of the functionally active octomerEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The X-linked disease retinoschisis is caused by mutations in the RS1 gene encoding retinoschisin, most commonly missense mutations leading to a lack of secretion of functional protein. One potential approach to treat this disease would be the introduction of the wild-type protein by gene therapy in affected individuals. Retinoschisin normally forms homooctamers so co-expression of the wild-type protein with the mutant could result in their co-assembly. Here we show that retinoschisin assembles into an octamer prior to transport from the endoplasmic reticulum and that co-assembly of wild-type and mutant protein can occur wh...
Source: BJ Cell - October 21, 2009 Category: Biochemistry Authors: L J. Gleghorn, D Trump, N J. Bulleid Tags: BJ Cell Source Type: journals

Targeting of inositol 1,4,5-trisphosphate receptor to the endoplasmic reticulum by its first transmembrane domainEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Targeting of inositol 1,4,5-trisphosphate receptors (IP3R) to membranes of the endoplasmic reticulum (ER) and their retention within ER or trafficking to other membranes underlies their ability to generate spatially organized Ca2+ signals. N-terminal fragments of type 1 IP3R (IP3R1) were tagged with enhanced green fluorescent protein, expressed in COS-7 cells and their distribution was determined by confocal microscopy and subcellular fractionation. Localization of IP3R1 in the ER requires translation of between 26 and 34 residues beyond the end of the first transmembrane domain (TMD1), a region that includes TMD2. ...
Source: BJ Cell - October 20, 2009 Category: Biochemistry Authors: E Pantazaka, C W. Taylor Tags: BJ Signal Source Type: journals

Reversible bleb formation in mast cells stimulated with antigen is Ca2{+}-calmodulin {-}dependent and bleb size is regulated by ARF6Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Mast cells stimulated with antigen undergo extensive changes in their cytoskeleton. We assess here the impact of actin-modifying drugs and report that in the presence of cytochalasin D, mast cells stop membrane ruffling but instead bleb. Bleb formation is reversible following washout of the cytochalasin D and occurs in an actin polymerization-dependent manner. Bleb formation is inhibited by expression of dominant-negative ezrin-T567D. Blebbing is also inhibited by blebbistatin, a myosin II inhibitor, implying myosin II activation in the process. We used a selection of inhibitors and observed that myosin II activation is de...
Source: BJ Cell - October 20, 2009 Category: Biochemistry Authors: Y Yanase, N Carvou, M A. Frohman, S Cockcroft Tags: BJ Cell Source Type: journals

Identification of the key structural motifs involved in HspB8/HspB6-Bag3 interactionEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We present evidence that HspB8 binds to Bag3 through the hydrophobic groove formed by its strands β4 and β8, a region previously known to be responsible for the formation and stability of higher order oligomers of many sHsp. Moreover, we demonstrate that two conserved IPV motifs in Bag3 mediate its binding to HspB8 and that deletion of these motifs suppresses HspB8 chaperone activity towards mutant Htt43Q. In addition, we show that Bag3 can bind to the molecular chaperone HspB6. The interaction between HspB6 and Bag3 requires the same regions involved in HspB8-Bag3 association and promotes clearance of aggreg...
Source: BJ Cell - October 20, 2009 Category: Biochemistry Authors: M Fuchs, D J. Poirier, S Seguin, H Lambert, S Carra, S J. Charrette, J Landry Tags: BJ Structure Source Type: journals

Role of phosphoinositides in STIM1 dynamics and store-operated calcium entryEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Ca2+ entry through store-operated Ca2+ channels involves the interaction at endoplasmic reticulum-plasma membrane (ER-PM) junctions of STIM and Orai. STIM proteins are sensors of the luminal ER Ca2+ concentration and following depletion of ER Ca2+, they oligomerise and translocate to ER-PM junctions where they form STIM puncta. Direct binding to Orai proteins activates their Ca2+ channel function. It has been suggested that an additional interaction of the C-terminal polybasic domain of STIM1 with plasma membrane phosphoinositides could contribute to STIM1 puncta formation prior to bindin...
Source: BJ Cell - October 19, 2009 Category: Biochemistry Authors: C M. Walsh, M Chvanov, L P. Haynes, O H. Petersen, A V. Tepikin, R D. Burgoyne Tags: BJ Signal Source Type: journals

Intersection of the tocopherol and plastoquinol metabolic pathways at the plastoglobuleEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Plastoglobules, lipid-protein bodies in the stroma of plant chloroplasts, are enriched in non-polar lipids, in particular prenyl quinols. Here we show that in addition to the thylakoids, plastoglobules also contain a considerable proportion of the plastidial plastoquinol-9 (PQ-9), the redox component of photosystem II, and of the cyclized product of PQ-9, plastochromanol-8 (PC-8), a tocochromanol with a structure similar to γ-tocopherol and γ-tocotrienol, but with a C40 prenyl side chain. PC-8 formation was abolished in the Arabidopsis thaliana tocopherol cyclase mutant vte1, but accumulated in VTE1 overexpre...
Source: BJ Cell - October 19, 2009 Category: Biochemistry Authors: A Maria Zbierzak, M Kanwischer, C Wille, P Vidi, P Giavalisco, A Lohmann, I Briesen, S Porfirova, C Bréhélin, F Kessler, P Dörmann Tags: BJ Plant Source Type: journals

Mitochondrial targeting of cyclosporin A enables selective inhibition of cyclophilin-D and enhanced cytoprotection after glucose and oxygen deprivationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Cyclosporin A is a hydrophobic undecapeptide that inhibits cyclophilins, a family of peptidylprolyl cis-trans-isomerases. In some experimental models, cyclosporin A offers partial protection against lethal cell injury brought about by transient ischaemia; this is believed to reflect inhibition of cyclophilin-D, a mitochondrial isoform that facilitates formation of the permeability transition pore in the mitochondrial inner membrane. To evaluate this further, we have targeted cyclosporin A to mitochondria so that it becomes selective for cyclophilin-D in cells. This was achieved by conjugating the inhibitor to the lipophili...
Source: BJ Cell - October 14, 2009 Category: Biochemistry Authors: S Malouitre, H Dube, D Selwood, M Crompton Tags: BJ Cell Source Type: journals

CD95/Fas downregulation in lymphoma cells through acquired alkyl-lysophospholipid resistance; partial role of associated sphingomyelin deficiencyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The alkyl-lysophospholipid (ALP) 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine induces apoptosis in S49 mouse lymphoma cells. A variant cell line, S49AR, made resistant to ALP, was previously found impaired in ALP uptake via lipid raft-mediated endocytosis. Here, we report that these cells display cross-resistance to Fas/CD95 ligation (FasL), and can be gradually resensitized by prolonged culturing in the absence of ALP. Fas and ALP activate distinct apoptotic pathways, since ALP-induced apoptosis was not abrogated by dominant-negative FADD, cFLIP or the caspase 8 inhibitor IETD. ALP-resistant cells showed decrease...
Source: BJ Cell - October 13, 2009 Category: Biochemistry Authors: W J van Blitterswijk, J Klarenbeek, A H. van der Luit, M C. Alderliesten, M van Lummel, M Verheij Tags: BJ Signal Source Type: journals

A putrescine-anthracene conjugate: a paradigm for selective drug deliveryEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Increased polyamine concentrations play an important role in the development of cancer at all stages from initiation through to maintenance of the transformed phenotype. One way cancer cells accumulate increased concentrations of polyamines is by increased uptake of preformed polyamines via their polyamine transport system (PTS). The PTS is promiscuous and will transport a range of polyamine based molecules. Therefore it may be that cytotoxic drugs could be attached to polyamine vectors and targeted selectively to cancer cells by utilising the PTS. The aim of this study was to investigate the potential of Ant 4, a putres...
Source: BJ Cell - October 7, 2009 Category: Biochemistry Authors: A J Palmer, R A Ghani, N Kaur, O Phanstiel, H M Wallace Tags: BJ Disease Source Type: journals

A di-arginine motif contributes to the ER-localization of the type I transmembrane ER oxidoreductase TMX4Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The thiol-disulfide oxidoreductases of the protein disulfide isomerase (PDI) family assist disulfide-bond formation in the endoplasmic reticulum (ER). Here, we show that the previously uncharacterized PDI-family member TMX4 is an N-glycosylated type I membrane protein that localizes to the ER. We also demonstrate that TMX4 contains a single ER-lumenal thioredoxin-like domain, which – in contrast to similar domains in other PDIs – is mainly oxidized in living cells. The TMX4 transcript displays a wide tissue distribution, and is strongly expressed in melanoma cells. Unlike many type I membrane proteins, TMX4 l...
Source: BJ Cell - October 7, 2009 Category: Biochemistry Authors: D Roth, E Lynes, J Riemer, H G. Hansen, N Althaus, T Simmen, L Ellgaard Tags: BJ Cell Source Type: journals

A putrescine-anthracence conjugate: a paradigm for selective drug deliveryEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Increased polyamine concentrations play an important role in the development of cancer at all stages from initiation through to maintenance of the transformed phenotype. One way cancer cells accumulate increased concentrations of polyamines is by increased uptake of preformed polyamines via their polyamine transport system (PTS). The PTS is promiscuous and will transport a range of polyamine based molecules. Therefore it may be that cytotoxic drugs could be attached to polyamine vectors and targeted selectively to cancer cells by utilising the PTS. The aim of this study was to investigate the potential of Ant 4, a putres...
Source: BJ Cell - October 7, 2009 Category: Biochemistry Authors: A J Palmer, R A Ghani, N Kaur, O Phanstiel, H M Wallace Tags: BJ Disease Source Type: journals

C/EBP transcription factors regulate SREBP1c gene expression during adipogenesisEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The transcription factor SREBP1c is highly expressed in adipose tissue and plays a central role in several aspects of adipocyte development including the induction of PPARγ, the generation of an endogenous PPARγ ligand and the expression of several genes critical for lipid biosynthesis. Despite its significance, the regulation of SREBP1c expression during adipogenesis is not well characterised. We noted that in several models of adipogenesis SREBP1c expression closely mimics that of known C/EBPβ targets. Inhibition of C/EBP activity during adipogenesis by expressing either the dominant negative C/EBP&#...
Source: BJ Cell - October 7, 2009 Category: Biochemistry Authors: V A Payne, W Au, C E Lowe, S M Rahman, J E Friedman, S O'Rahilly, J J Rochford Tags: BJ Metabolism Source Type: journals

Cholesterol-dependent phase separation in cell-derived giant plasma membrane vesiclesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Cell-derived giant plasma membrane vesicles (GPMVs) enable investigation of lipid phase separation in a system with appropriate biological complexity under physiological conditions, and were used to investigate the cholesterol dependence of domain formation and stability. Cholesterol level is directly related to the abundance of the liquid ordered phase fraction, which is the majority phase in vesicles from untreated cells. Miscibility transition temperature depends on cholesterol and correlates strongly with the presence of detergent-insoluble membrane in cell lysates. Fluorescence correlation spectroscopy reveals two dis...
Source: BJ Cell - October 6, 2009 Category: Biochemistry Authors: I Levental, F J Byfield, P Chowdhury, F Gai, T Baumgart, P A Janmey Tags: BJ Cell Source Type: journals

Coactosin-like protein functions as a stabilizing chaperone for 5-lipoxygenase: role of tryptophan 102Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The activity of 5-lipoxygenase (5-LO), which catalyzes two initial steps in biosynthesis of proinflammatory leukotrienes (LT), is strictly regulated. One recently discovered factor, Coactosin-like protein (CLP), binds 5-LO and promotes LT formation. Here we report that CLP also stabilizes 5-LO and prevents non-turnover inactivation of the enzyme in vitro. Mutagenesis of Trp residues in the 5-LO ß-sandwich showed that 5-LO-W102 is essential for binding to CLP, and for CLP to support 5-LO activity. In addition, also the stabilizing effect depended on binding between CLP and 5-LO. After mutations which prevent interact...
Source: BJ Cell - October 5, 2009 Category: Biochemistry Authors: J Esser, M Rakonjac, B Hofmann, L Fischer, P Provost, G Schneider, D Steinhilber, B Samuelsson, O P. Rådmark Tags: BJ Signal Source Type: journals

A constitutively active and uninhibitable caspase-3 zymogen efficiently induces apoptosisEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The caspase-3 zymogen has essentially zero activity until it is cleaved by initiator caspases during apoptosis. However, a mutation of V266E in the dimer interface activates the protease in the absence of chain cleavage. We show that low concentrations of the pseudo-activated procaspase-3 kill mammalian cells rapidly, and importantly, this protein is not cleaved nor is it inhibited efficiently by the endogenous regulator XIAP. The 1.63Å structure of the variant demonstrates that the mutation is accommodated at the dimer interface to generate an enzyme with substantially the same activity and specificity as wild type...
Source: BJ Cell - September 29, 2009 Category: Biochemistry Authors: J Walters, C Pop, F L. Scott, M Drag, P Swartz, C Mattos, G S. Salvesen, A Clark Tags: BJ Structure Source Type: journals

Positive contribution of ERdj5/JPDI to endoplasmic reticulum protein quality control in the salivary glandEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In eukaryotic cells, most membrane and secretory proteins are modified posttranslationally in the endoplasmic reticulum (ER) for correct folding and assembly. Disulfide bond formation is one of the important modifications affecting folding and is catalyzed by protein disulfide isomerase (PDI) family proteins. ERdj5 (also known as JPDI) is a member of the PDI family proteins and has been reported to act as a reductase in ER-associated degradation (ERAD). However, the role of ERdj5 at the whole-body level remains unclear. Therefore, we generated ERdj5 knockout mice and analyzed them. Although ERdj5 knockout mice were viable ...
Source: BJ Cell - September 29, 2009 Category: Biochemistry Authors: A Hosoda, M Tokuda, R Akai, K Kohno, T Iwawaki Tags: BJ Energy Source Type: journals

Extracellular redox status regulates Nrf2 activation through mitochondrial reactive oxygen speciesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The redox status of the extracellular compartment has only just been elucidated as a mechanism controlling intracellular signaling transduction and correlates with aging, diabetes, heart disease and lung fibrosis. Here, we describe a mechanism by which oxidizing extracellular environments, as maintained by the cysteine/cystine (Cys/CySS) redox couple, induce mitochondria-derived reactive oxygen species (ROS) generation and cause the activation of nuclear factor-erythroid 2-related factor 2 (Nrf2), inducing an antioxidant response. 3T3 cells were cultured in media with extracellular Cys/CySS redox potentials (Eh), ranging f...
Source: BJ Cell - September 24, 2009 Category: Biochemistry Authors: B R Imhoff, J M Hansen Tags: BJ Signal Source Type: journals

Posttranslational modifications of connexin26 revealed by mass spectrometryEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Gap junctions play important roles in auditory function and skin biology; mutations in the Cx26 gene are the predominant cause of inherited nonsyndromic deafness and cause disfiguring skin disorders. Mass spectrometry was used to identify posttranslational modifications (PTMs) of Cx26 and determine whether they occur at sites of disease-causing mutations. Cx26 was isolated from transfected HeLa cells by sequential immunoaffinity and metal chelate chromatography using a tandem carboxyl-terminal hemagglutinin epitope and hexa(histidine-asparagine) sequence. In-gel and in-solution enzymatic digestions were carried out in para...
Source: BJ Cell - September 22, 2009 Category: Biochemistry Authors: D Locke, S Bian, H Li, A L. Harris Tags: BJ Cell Source Type: journals

Postrranslational modifications of connexin26 revealed by mass spectrometryEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Gap junctions play important roles in auditory function and skin biology; mutations in the Cx26 gene are the predominant cause of inherited nonsyndromic deafness and cause disfiguring skin disorders. Mass spectrometry was used to identify posttranslational modifications (PTMs) of Cx26 and determine whether they occur at sites of disease-causing mutations. Cx26 was isolated from transfected HeLa cells by sequential immunoaffinity and metal chelate chromatography using a tandem carboxyl-terminal hemagglutinin epitope and hexa(histidine-asparagine) sequence. In-gel and in-solution enzymatic digestions were carried out in para...
Source: BJ Cell - September 22, 2009 Category: Biochemistry Authors: D Locke, S Bian, H Li, A L. Harris Tags: BJ Cell Source Type: journals

Leishmania donovani RAN-GTPase interacts at the nuclear rim with linker histone H1Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We report for the first time that Ran interacts with a linker histone -histone H1- in vitro and that the two proteins co-localise at the parasite nuclear rim. Interaction of Ran with core histones H3 and H4, creating in metazoans a chromosomal Ran-GTP gradient important for mitotic spindle assembly, is speculative in Leishmania spp., not only because this parasite undergoes a closed mitosis but also because the main localisation of LdRan is different from that of core histone H3. Interaction of Ran with the leishmanial linker histone H1 (LeishH1), suggests that this association maybe involved in modulation of other pathway...
Source: BJ Cell - September 21, 2009 Category: Biochemistry Authors: D Smirlis, H Boleti, M Gaitanou, M Soto, K Soteriadou Tags: BJ Cell Source Type: journals

Functional insights into the role of novel type I cohesin and dockerin domains from Clostridium thermocellumEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Cellulosomes, synthesized by anaerobic microorganisms such as Clostridium thermocellum, are remarkably complex nanomachines that efficiently degrade plant cell wall polysaccharides. Cellulosome assembly results from the interaction of type I dockerin domains, present on the catalytic subunits, and the cohesin domains of a large non-catalytic integrating protein that acts as a molecular scaffold. In general, type I dockerins contain two distinct cohesin binding interfaces that appear to display identical ligand specificities. Inspection of the Clostridium thermocellum genome reveals 72 dockerin-containing proteins. In four ...
Source: BJ Cell - September 16, 2009 Category: Biochemistry Authors: B A. Pinheiro, H J. Gilbert, K Sakka, K Sakka, V O. Fernandes, J A.M. Prates, V D. Alves, D N. Bolam, L M.A. Ferreira, C M.G.A. Fontes Tags: BJ Cell Source Type: journals

Nucleic acids binding properties of the C2-L1Tc Nucleic Acid Chaperone encoded by L1Tc RetrotransposonEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
It has been reported that the C2-L1Tc protein located in the T. cruzi LINE L1Tc 3´ terminal end has nucleic acid chaperone (NAC) activity, an essential activity for retrotransposition of LINE-1. The C2-L1Tc protein contains two cysteine motifs of a C2H2 type, similar to those present in the transcription factor TFIIIA. The cysteine motifs are flanked by positively charged amino acid regions. The data presented in this paper shows that the C2-L1Tc recombinant protein has at least 16-fold higher affinity for single stranded than for double stranded nucleic acids and that it exhibits a clear preference for RNA binding ...
Source: BJ Cell - September 13, 2009 Category: Biochemistry Authors: S R Heras, M Thomas, F Macias, M E. Patarroyo, C Alonso, M C López Tags: BJ Gene Source Type: journals

Activity-dependent translocation of neurogranin to neuronal nucleiEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Long-term changes of synaptic plasticity depend on protein synthesis and transcription. Neurogranin (Ng) is a small protein concentrated at dendrites and spines of forebrain neurons, involved in synaptic plasticity through the regulation of calmodulin (CaM) mediated signalling. Ng presents a central IQ motif that mediates its binding to CaM and phosphatidic acid (PA) and that can be phosphorylated by protein kinase C (PKC). Here, we report that Ng displays a strong nuclear localization when expressed in cell lines and hippocampal neurons, either alone or fused to green fluorescent protein (GFP-Ng). Further, using subcellul...
Source: BJ Cell - September 13, 2009 Category: Biochemistry Authors: A Garrido-García, B Andrés-Pans, L Duran-Trio, F Díez-Guerra Tags: BJ Signal Source Type: journals

Thyroid hormone-dependent activation of the phosphoinositide 3-kinase/Akt cascade requires Src and enhances neuronal survivalEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We previously reported a nongenomic action of T3, which stimulates the phosphoinositide-3-kinase (PI3K)-Akt pathway via p85α, the regulatory subunit of PI3K, in human skin fibroblasts. The goal of this study was to elucidate the mechanism by which T3 activates PI3K, and to investigate the physiological role of this T3 action in neuronal cells. We found that T3 activates PI3K-Akt through Src. First, T3 rapidly induced the activation of Src and Akt in N2a cells expressing thyroid hormone receptor (TR)-α1 (N2aTRα), and both were attenuated by either addition of a Src inhibitor or Src siRNA. In contrast, t...
Source: BJ Cell - September 10, 2009 Category: Biochemistry Authors: X Cao, F Kambe, M Yamauchi, H Seo Tags: BJ Cell Source Type: journals

Mesothelin inhibits paclitaxel-induced apoptosis through the PI3-kinase pathwayEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study was to evaluate the possible function of mesothelin. Real-time PCR, RT-PCR, cytotoxicity assay, proliferative assay, apoptotic assay by Hoechst staining, detection of active caspases 3 and 7 by flowcytometric analysis, and immuno-precipitation and immuno-blotting were performed. Cancer tissues in paclitaxel-resistant ovarian cancer patients expressed higher levels of mesothelin by real-time PCR than paclitaxel-sensitive ovarian cancer patients (Mean crossing point value change of mesothelin 26.9±0.4 in resistant group and 34.3±0.7 for sensitive group, p<0.001). Mesothelin also protected cells fr...
Source: BJ Cell - September 10, 2009 Category: Biochemistry Authors: M Chang, C Chen, C Hsieh, C Lee, Y Su, Y Hu, W Cheng Tags: BJ Cell Source Type: journals

Identification of potent nanobodies to neutralize the most poisonous polypeptide from scorpion venomEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Scorpion venom, containing highly toxic, small polypeptides that diffuse rapidly within the patient, causes serious medical problems. Nanobodies, single-domain antigen-binding fragments derived from dromedary Heavy-chain antibodies, have a size that matches closely that of scorpion toxins. Therefore they might be developed into potent immunotherapeutics to treat scorpion envenoming. Multiple Nanobodies of sub-nanomolar affinity to AahII, the most toxic polypeptide within the Androctonus australis hector venom, were isolated from a dromedary immunized with AahII. These Nanobodies neutralize the lethal effect of AahII to var...
Source: BJ Cell - September 3, 2009 Category: Biochemistry Authors: R Ben Abderrazek, I Hmila, C Vincke, Z Benlasfar, M Pellis, H Dabbek, D Saerens, M El Ayeb, S Muyldermans, B Bouhaouala-Zahar Tags: BJ Structure Source Type: journals

Aedes aegypti cadherin serves as a putative receptor of the Cry11Aa toxin from Bacillus thuringiensis subsp. israelensisEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Cry11Aa of Bacillus thuringiensis subsp. israelensis is most active toxin to Aedes aegypti in this strain. We previously reported that in addition to a 65 kDa GPI-anchored alkaline phosphatase (ALP) the toxin also binds a 250 kDa membrane protein. Since this protein is of the size of cadherin, which in lepidopteran insects is an important Cry toxin receptor, we developed an anti-AaeCad antibody. This antibody detects a 250-kDa protein in immunoblots of larval brush border membrane vesicles (BBMV). The antibody inhibits Cry11Aa toxin binding to BBMV and immunolocalizes the cadherin protein to apical membranes of distal and ...
Source: BJ Cell - September 3, 2009 Category: Biochemistry Authors: J Chen, K G. Aimanova, L E Fernandez, A Bravo, M Soberon, S S Gill Tags: BJ Signal Source Type: journals

Disruption of ceramide synthesis by CerS2 down-regulation leads to autophagy and the unfolded protein responseEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Ceramide metabolism has come under recent scrutiny because of its role in cellular stress responses. Ceramide synthase 2 (CerS2) is one of the six mammalian isoforms of ceramide synthase, and it is responsible for the synthesis of very-long chain (VLC) ceramides, e.g. C24, C24:1. To study the role of CerS2 in ceramide metabolism and cellular homeostasis, we down-regulated CerS2 using siRNA and examined several aspects of sphingolipid metabolism and cell stress responses. CerS2 down-regulation had a broad effect on ceramide homeostasis, not just on VLC ceramides. Surprisingly, CerS2 down-regulation resulted in significantly...
Source: BJ Cell - September 2, 2009 Category: Biochemistry Authors: S D Spassieva, T D Mullen, D M Townsend, L M Obeid Tags: BJ Cell Source Type: journals

Analysis of the dual function of the ESCRT-III protein Snf7 in endocytic trafficking and in gene expressionEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
ESCRT-III mediates budding and scission of intralumenal vesicles into multivesicular endosomes. For the main ESCRT-III subunit Snf7, an additional role in activation of the transcription factor Rim101 ("Rim pathway") is now firmly established. Here, we investigate how the two Snf7 functions are related to each other. By generating SNF7 mutations that severely affect endocytic trafficking, but leave the Rim pathway function intact, we show that the two functions of SNF7 can be separated genetically. We analyzed in detail, how the SNF7 mutations affect the interaction of Snf7 with its various binding partners. While interact...
Source: BJ Cell - September 1, 2009 Category: Biochemistry Authors: P Weiß, S Huppert, R Kölling Tags: BJ Cell Source Type: journals

Human and mouse trace amine-associated receptor 1 have distinct pharmacology towards endogenous monoamines and imidazoline receptor ligandsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Trace amine-associated receptors (TAARs) are G protein-coupled receptors that respond to low abundance, endogenous amines such as tyramine and tryptamine, and represent potential targets for neuropsychiatric diseases. However, some members of this receptor subfamily either have no ligand identified or remain difficult to express and characterize using recombinant systems. Here we report the successful expression of human and mouse TAAR1, and the characterization of their responses to various natural and synthetic agonists. In HEK293/CRE-bla cells, mouse TAAR1 showed robust response to trace amines as measured by either cAM...
Source: BJ Cell - September 1, 2009 Category: Biochemistry Authors: L A. Hu, T Zhou, J Ahn, S Wang, J Zhou, Y Hu, Q Liu Tags: BJ Signal Source Type: journals

Regulation of histidine-rich glycoprotein (HRG) function via plasmin-mediated proteolytic cleavageEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The plasminogen/plasmin system is involved in a variety of normal physiological and pathological processes, including tissue remodelling, angiogenesis and tumour metastasis. Plasminogen activators and receptors for plasminogen/plasminogen activators are essential for the processing of plasminogen to the active serine protease, plasmin. Plasmin can in turn positively or negatively regulate further plasminogen activation via plasmin-mediated cleavage of receptors and activators. Histidine-rich glycoprotein (HRG), a relatively abundant (~100-150 μg/ml) plasma glycoprotein, has a multi-domain structure that can interact...
Source: BJ Cell - August 26, 2009 Category: Biochemistry Authors: I K. H. Poon, A Olsson, M D. Hulett, C R. Parish Tags: BJ Cell Source Type: journals

Existence of exocytotic hemifusion intermediates with a life time up to seconds in type II pneumocytesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Exocytosis proceeds through prefusion stages such as hemifusion, but hemifusion is still an elusive intermediate of unknown duration. Using darkfield and fluorescence microscopy in alveolar type II (ATII) cells containing large secretory vesicles ("lamellar bodies", LBs), we show that exocytotic fusion events were accompanied by a mostly bi-phasic scattered (darkfield) light intensity decrease (SLID) originating from the vesicle border. Correlation with the diffusional behavior of fluorescence markers for either content or membrane mixing revealed that the onset of the fast, second, phase of SLID corresponded to fusion por...
Source: BJ Cell - August 26, 2009 Category: Biochemistry Authors: P Miklavc, S Albrecht, O H. Wittekindt, P Schullian, T Haller, P Dietl Tags: BJ Cell Source Type: journals

Asporin competes with decorin for collagen binding, binds calcium, and promotes collagen mineralizationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The interactions of extra-cellular matrix (ECM) protein asporin with ECM components have previously not been investigated. Here we show that asporin binds collagen type I. This binding is inhibited by recombinant asporin fragment LRR 10-12 and by full-length decorin, but not by biglycan. We demonstrate that the polyaspartate domain binds calcium and regulates hydroxyapatite formation in vitro. In the presence of asporin the number of collagen nodules, and mRNA of osteoblastic markers Osterix and Runx2, were increased. Moreover, decorin or the collagen-binding asporin fragment LRR 10-12 inhibited the pro-osteoblastic activi...
Source: BJ Cell - July 8, 2009 Category: Biochemistry Authors: S Kalamajski, A Aspberg, K Lindblom, D Heinegård, Å Oldberg Tags: BJ Cell Source Type: journals

GDI-1 preferably interacts with Rab10 in insulin-stimulated GLUT4 translocationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Insulin stimulates GLUT4 translocation in adipocytes and muscles. An emerging picture is that Rab10 could bridge the gap between insulin signaling cascade and GLUT4 translocation. In the present study, two potential effectors of Rab10, GDP dissociation inhibitor 1 and 2 (GDI-1 and GDI-2), are characterized in respect to their roles in insulin-stimulated GLUT4 translocation. It is shown that both GDI-1 and GDI-2 exhibit similar distribution to GLUT4 and Rab10 in the trans-Golgi network (TGN) and periphery structures. Meanwhile, GDI-1 is manifested to interact with Rab10 with higher affinity evidenced by both immunoprecipita...
Source: BJ Cell - July 1, 2009 Category: Biochemistry Authors: Y Chen, Y Deng, J Zhang, L Yang, X Xie, T Xu Tags: BJ Metabolism Source Type: journals

Divergent regulation of the key enzymes of polyamine metabolism by chiral {alpha}-methylated polyamine analogsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The natural polyamines are ubiquitous multifunctional organic cations which play important roles in regulating cellular proliferation and survival. Here we present a novel approach to investigate polyamine functions by using optical isomers of α-methylspermidine (MeSpd) and α,w-bismethylspermine (Me2Spm), metabolically stable functional mimetics of natural polyamines. We studied the ability of α-MeSpd and α,w-Me2Spm to alter the normal polyamine regulation pathways at the level of polyamine uptake and the major control mechanisms known to affect the key polyamine metabolic enzymes. These include...
Source: BJ Cell - June 11, 2009 Category: Biochemistry Authors: M T Hyvönen, M T Howard, C B Anderson, N Grigorenko, A R Khomutov, J Vepsäläinen, L Alhonen, J Jänne, T A Keinänen Tags: BJ Metabolism Source Type: journals

Caenorhabditis elegans utilizes dauer pheromone biosynthesis to dispose of toxic peroxisomal fatty acids for cellular homeostasisEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
C. elegans excretes a dauer pheromone or daumone composed of ascarylose and a fatty acid side chain, perception of which enables worms to enter the dauer state for long-term survival in the adverse environment. During the course of elucidation of the daumone biosynthetic pathway in which DHS-28 and DAF-22 are involved in peroxisomal β-oxidation of very long-chain fatty acid (VLCFA), we sought to investigate the physiological consequences of deficiency in daumone biosynthesis in C. elegans. Our results revealed that two mutants, dhs-28(tm2581) and daf-22(ok693), lacked daumones and thus were dauer defective; this coi...
Source: BJ Cell - June 4, 2009 Category: Biochemistry Authors: H Joo, Y Yim, P Jeong, Y Jin, J Lee, H Kim, S Jeong, D J. Chitwood, Y Paik Tags: BJ Cell Source Type: journals

Zinc transporter-2 (ZnT2) variants are localized to distinct sub-cellular compartments and functionally transport zincEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We examined the localization and function of each ZnT2 isoform in cells generated to express ZnT2-HA fusion proteins. The 42 kDa isoform was localized primarily to the endosomal/secretory compartment, and over-expression resulted in increased zinc vesicularization and secretion. In contrast, the 35 kDa isoform was associated with the plasma membrane. Importantly, zinc transport was higher in cells over-expressing the each isoform indicating that both proteins are functional. Endogenous expression of the secretory vesicle-associated ZnT2 isoform predominates in mammary cells and expression is higher is secreting cells, dire...
Source: BJ Cell - June 4, 2009 Category: Biochemistry Authors: V Lopez, S L. Kelleher Tags: BJ Cell Source Type: journals

Dual acylation is required for trafficking of growth-associated protein-43 to endosomal recycling compartment via an Arf6-associated endocytic vesicular pathwayEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The growth-associated protein-43 (GAP-43) is a dually palmitoylated protein in cysteine residues at positions 3 and 4 that mostly localizes in plasma membrane both in neural and non-neural cells. In the present study, we have examined membrane association, subcellular distribution and intracellular trafficking of GAP-43 in Chinese hamster ovary (CHO)-K1 cells. Using biochemical assays and confocal and video microscopy in living cells we demonstrated that GAP-43, at steady state, localizes at the recycling endosome in addition to the cytoplasmic leaflet of the plasma membrane and trans-Golgi network (TGN). Pharmacological i...
Source: BJ Cell - May 14, 2009 Category: Biochemistry Authors: A Trenchi, G A. Gomez, J L. Daniotti Tags: BJ BJ Cell Source Type: journals

Interaction of anion exchanger 1 and glycophorin A in human erythroleukemic K562 cellsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study investigates the interaction of GPA with AE1 in K562 cells, a human erythroleukemic cell line that expresses GPA, and the role of GPA in the cell surface expression of AE1. In K562 cells, GPA was dimeric and N- and O-glycosylated similar to erythroid GPA. GPA was localized at the cell surface, but also to the Golgi. AE1 expressed in K562 cells contained both complex and high mannose oligosaccharides, and co-localized with GPA at the cell surface and in the endoplasmic reticulum (ER). The Wrb antigen was detected at the cell surface of AE1-transfected K562 cells, indicating the existence of an AE1-GPA complex. Im...
Source: BJ Cell - May 13, 2009 Category: Biochemistry Authors: A J. Pang, R A. F. Reithmeier Tags: BJ BJ Cell Source Type: journals

Human caspase-7 is positively controlled by SREBP-1 and SREBP-2Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Statins are lipid lowering drugs that may help limit cancer occurrence in humans. They drive blockage of the mevalonate pathway, trigger cancer cell apoptosis in vitro and reduce tumour incidence in animals. We show here that statins induced apoptosis in HGT-1 human gastric cancer cells, and this was prevented by intermediates of the cholesterol synthetic pathway. In addition, similarly to what we reported previously for caspase-2 (Logette, E., Le Jossic-Corcos, C., Masson, D., Solier, S., Sequeira-Legrand, A., Dugail, I., Lemaire-Ewing, S., Desoche, L., Solary, E. and Corcos, L. (2005) Mol Cell Biol 25, 9621-9631), caspas...
Source: BJ Cell - March 25, 2009 Category: Biochemistry Authors: L Gibot, J Follet, J Metges, P Auvray, B Simon, L Corcos, C Le Jossic-Corcos Tags: BJ Cell Source Type: journals

RNA helicase A acts as a bridge factor linking nuclear {beta}-actin with RNA polymerase IIEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Actin, the major component of cytoplasmic skeleton, has been shown to exist in the nucleus. Nuclear actin functions in several steps of transcription process, including chromatin remodeling, transcription initiation and elongation. However, as a part of PICs (pre-initiation complexes), the role of actin remains to be elucidated. Here, we identified RHA (RNA helicase A) as an actin-interacting protein in PICs. Using immunoprecipitation and immunofluorescence techniques, we showed that RHA associated with β-actin in the nucleus. GST pull-down assay using different deletion mutants revealed that RGG region of RHA was r...
Source: BJ Cell - March 23, 2009 Category: Biochemistry Authors: W Tang, W You, F Shi, T Qi, L Wang, Z Djouder, W Liu, X Zeng Tags: BJ Cell Source Type: journals

Triton X-100 promotes a cholesterol-dependent condensation of the plasma membraneEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, we used a combination of epifluorescence and two-photon microscopy to visualize and quantify whether the detergent insolubility reflects a pre-existing organization of the plasma membrane (PM). We found that treatment of cells with cold Triton X-100 (TX) promotes a profound remodelling of the PM including a rapid rearrangement of GM1 and cholesterol into newly formed structures, only partial solubilization of fluid domains and the formation of condensed domains that cover 51% of the remaining membrane. Rather than inducing the coalescence of pre-existing domains, the remaining domains after TX treatment appe...
Source: BJ Cell - March 23, 2009 Category: Biochemistry Authors: M Ingelmo-Torres, K Gaus, A Herms, E González-Moreno, A Kassan, M Bosch, T Grewal, F Tebar, C Enrich, A Pol Tags: BJ Cell Source Type: journals

Chlorella virus ATCV1 encodes a functional potassium channel of eighty-two amino acidsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Chlorella virus PBCV-1 encodes the smallest protein (94 amino acids, named Kcv) previously known to form a functional K+ channel in heterologous systems. In the current manuscript, we characterize another chlorella virus encoded K+ channel protein (82 amino acids, named ATCV-1 Kcv) that forms a functional channel in Xenopus oocytes and rescues Saccharomyces cerevisae mutants that lack endogenous K+ uptake systems. Compared to the larger PBCV-1 Kcv, ATCV-1 Kcv lacks a cytoplasmic N-terminus and has a reduced number of charged amino acids in its turret domain. Despite these deficiencies, ATCV-1 Kcv accom...
Source: BJ Cell - March 6, 2009 Category: Biochemistry Authors: S Gazzarrini, M Kang, A Abenavoli, G Romani, C Olivari, D Gaslini, G Ferrara, J L. Van Etten, M Kreim, S M. Kast, G Thiel, A Moroni Tags: BJ Plant Source Type: journals