The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Thierry Galli - One of the best experts on this subject based on the ideXlab platform.
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Cellubrevin and Synaptobrevins: Similar Subcellular Localization and Biochemical Properties in PC12 Ceils
2013Co-Authors: Tamie J. Chiicote, Olaf Mundigl, Kohji Takei, Thierry Galli, Lambert Edelmann, Peter S. Mcpberson, Pietro De CamilliAbstract:Abstract. There is strong evidence to indicate that proteins of the synaptobrevin family play a key role in exocytosis. Synaptobrevin 1 and 2 are expressed at high concentration in brain where they are localized on synaptic vesicles. Cellubrevin, a very similar protein, has a widespread tissue distribution and in fibroblasts is localized on endosome-derived, transferrin receptor-positive vesicles. Since brain Cellubrevin is not detectable in synaptic vesicles, we investigated whether Cellubrevin and the synaptobrevins are differentially targeted when co-expressed in the same cell. We report that in the nervous system Cellubrevin is expressed at significant levels only by glia and vascular cells. However, Cellubrevin is coexpressed with the two synaptobrevins in PC12 cells, a neuroendocrin
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JCB Article Early/recycling endosomes-to-TGN transport involves two SNARE complexes and a Rab6 isoform
2013Co-Authors: Frédéric Mallard, Danièle Tenza, Bruno Goud, Bor Luen Tang, Claude Antony, Wanjin Hong, Thierry Galli, Agnès Saint-pol, Xu Yue, Ludger JohannesAbstract:The molecular mechanisms underlying early/recycling endosomes-to-TGN transport are still not understood. We identified interactions between the TGN-localized putative t-SNAREs syntaxin 6, syntaxin 16, and Vti1a, and two early/recycling endosomal v-SNAREs, VAMP3/Cellubrevin, and VAMP4. Using a novel permeabilized cell system, these proteins were functionally implicated in the post-Golgi retrograde transport step. The function of Rab6a ’ was also required, whereas its closely related isoform, Rab6a, has previously been implicated in Golgi-to-endoplasmic reticulum transport. Thus, our study shows that membrane exchange between the early endocytic and the biosynthetic/ secretory pathways involves specific components of the Rab and SNARE machinery, and suggests that retrograde transport between early/recycling endosomes and the endoplasmic reticulum is critically dependent on the sequential action of two members of the Rab6 subfamily
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transport of the major myelin proteolipid protein is directed by vamp3 and vamp7
The Journal of Neuroscience, 2011Co-Authors: Anke Feldmann, Jesa Amphornrat, Christine Winterstein, Madeleine Schonherr, Lydia Danglot, Torben Ruhwedel, Thierry Galli, Wiebke Mobius, Klaus-armin Nave, Dieter BrunsAbstract:CNS myelination by oligodendrocytes requires directed transport of myelin membrane components and a timely and spatially controlled membrane expansion. In this study, we show the functional involvement of the R-soluble N-ethylmaleimide-sensitive factor attachment protein receptor (R-SNARE) proteins VAMP3/Cellubrevin and VAMP7/TI-VAMP in myelin membrane trafficking. VAMP3 and VAMP7 colocalize with the major myelin proteolipid protein (PLP) in recycling endosomes and late endosomes/lysosomes, respectively. Interference with VAMP3 or VAMP7 function using small interfering RNA-mediated silencing and exogenous expression of dominant-negative proteins diminished transport of PLP to the oligodendroglial cell surface. In addition, the association of PLP with myelin-like membranes produced by oligodendrocytes cocultured with cortical neurons was reduced. We furthermore identified Syntaxin-4 and Syntaxin-3 as prime acceptor Q-SNAREs of VAMP3 and VAMP7, respectively. Analysis of VAMP3-deficient mice revealed no myelination defects. Interestingly, AP-3δ-deficient mocha mice, which suffer from impaired secretion of lysosome-related organelles and missorting of VAMP7, exhibit a mild dysmyelination characterized by reduced levels of select myelin proteins, including PLP. We conclude that PLP reaches the cell surface via at least two trafficking pathways with distinct regulations: (1) VAMP3 mediates fusion of recycling endosome-derived vesicles with the oligodendroglial plasma membrane in the course of the secretory pathway; (2) VAMP7 controls exocytosis of PLP from late endosomal/lysosomal organelles as part of a transcytosis pathway. Our in vivo data suggest that exocytosis of lysosome-related organelles controlled by VAMP7 contributes to myelin biogenesis by delivering cargo to the myelin membrane.
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v-SNARE Cellubrevin is required for basolateral sorting of AP-1B-dependent cargo in polarized epithelial cells.
Journal of Cell Biology, 2007Co-Authors: Ian C. Fields, Véronique Proux-gillardeaux, Thierry Galli, Elina Shteyn, Marc Pypaert, Richard S. Kang, Heike FölschAbstract:The epithelial cell–specific adaptor complex AP-1B is crucial for correct delivery of many transmembrane proteins from recycling endosomes to the basolateral plasma membrane. Subsequently, membrane fusion is dependent on the formation of complexes between SNARE proteins located at the target membrane and on transport vesicles. Although the t-SNARE syntaxin 4 has been localized to the basolateral membrane, the v-SNARE operative in the AP-1B pathway remained unknown. We show that the ubiquitously expressed v-SNARE Cellubrevin localizes to the basolateral membrane and to recycling endosomes, where it colocalizes with AP-1B. Furthermore, we demonstrate that Cellubrevin coimmunoprecipitates preferentially with syntaxin 4, implicating this v-SNARE in basolateral fusion events. Cleavage of Cellubrevin with tetanus neurotoxin (TeNT) results in scattering of AP-1B localization and missorting of AP-1B–dependent cargos, such as transferrin receptor and a truncated low-density lipoprotein receptor, LDLR-CT27. These data suggest that Cellubrevin and AP-1B cooperate in basolateral membrane trafficking.
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Identification of the Amino Acid Residues Rendering TI-VAMP Insensitive toward Botulinum Neurotoxin B.
Journal of Molecular Biology, 2006Co-Authors: Stefan Sikorra, Thierry Galli, Tina Henke, Subramanyam Swaminathan, Thomas BinzAbstract:Botulinum neurotoxins types B, D, F, and G, and tetanus neurotoxin inhibit vesicular fusion via proteolytic cleavage of VAMP/Synaptobrevin, a core component of the membrane fusion machinery. Thus, these neurotoxins became widely used tools for investigating vesicular trafficking routes. Except for VAMP-1, VAMP-2, and Cellubrevin, no other member of the VAMP family represents a substrate for these neurotoxins. The molecular basis for this discrepancy is not known. A 34 amino acid residue segment of VAMP-2 was previously suggested to mediate the interaction with botulinum neurotoxin B, but the validity of the data was later questioned. To check whether this segment alone controls the susceptibility toward botulinum neurotoxin B, it was used to replace the corresponding segment in TI-VAMP. The resulting VAMP hybrid and VAMP-2 were hydrolysed at virtually identical rates. Resetting the VAMP-2 portion in the hybrid from either end to TI-VAMP residues gradually reduced the cleavability. A hybrid encompassing merely the VAMP-2 segment 71–80 around the Gln76/Phe77 scissile bond was still hydrolysed, albeit at a not, vert, similartenfold lower cleavage rate. The contribution of each non-conserved amino acid of the whole 34-mer segment to the interaction was investigated employing VAMP-2. We find that the eight non-conserved residues of the 71–80 segment are all necessary for efficient cleavage. Mutation of an additional six residues located upstream and downstream of this segment affects substrate hydrolysis as well. Vice versa, a readily cleavable TI-VAMP molecule requires at the least the replacement of Ile158, Thr161, and the section 165–174 by Asp64, Ala67, and the 71–80 segment of VAMP-2, respectively. However, the insensitivity of TI-VAMP to botulinum neurotoxin B relies on at least 12 amino acid changes versus VAMP-2. These are scattered along an interface of 22 amino acid residues in length.
Martin Oheim - One of the best experts on this subject based on the ideXlab platform.
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astrocyte vamp3 vesicles undergo ca2 independent cycling and modulate glutamate transporter trafficking
The Journal of Physiology, 2015Co-Authors: Karine Herault, Kathleen Zylbersztejn, Martin Oheim, Marcel A. Lauterbach, Marc Guillon, Dongdong LiAbstract:Key points Mouse cortical astrocytes express VAMP3 but not VAMP2. VAMP3 vesicles undergo Ca2+-independent exo- and endocytotic cycling at the plasma membrane. VAMP3 vesicle traffic regulates the recycling of plasma membrane glutamate transporters. cAMP modulates VAMP3 vesicle cycling and glutamate uptake. Abstract Previous studies suggest that small synaptic-like vesicles in astrocytes carry vesicle-associated vSNARE proteins, VAMP3 (Cellubrevin) and VAMP2 (synaptobrevin 2), both contributing to the Ca2+-regulated exocytosis of gliotransmitters, thereby modulating brain information processing. Here, using cortical astrocytes taken from VAMP2 and VAMP3 knock-out mice, we find that astrocytes express only VAMP3. The morphology and function of VAMP3 vesicles were studied in cultured astrocytes at single vesicle level with stimulated emission depletion (STED) and total internal reflection fluorescence (TIRF) microscopies. We show that VAMP3 antibodies label small diameter (∼80 nm) vesicles and that VAMP3 vesicles undergo Ca2+-independent exo-endocytosis. We also show that this pathway modulates the surface expression of plasma membrane glutamate transporters and the glutamate uptake by astrocytes. Finally, using pharmacological and optogenetic tools, we provide evidence suggesting that the cytosolic cAMP level influences astrocytic VAMP3 vesicle trafficking and glutamate transport. Our results suggest a new role for VAMP3 vesicles in astrocytes.
Kathleen Zylbersztejn - One of the best experts on this subject based on the ideXlab platform.
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astrocyte vamp3 vesicles undergo ca2 independent cycling and modulate glutamate transporter trafficking
The Journal of Physiology, 2015Co-Authors: Karine Herault, Kathleen Zylbersztejn, Martin Oheim, Marcel A. Lauterbach, Marc Guillon, Dongdong LiAbstract:Key points Mouse cortical astrocytes express VAMP3 but not VAMP2. VAMP3 vesicles undergo Ca2+-independent exo- and endocytotic cycling at the plasma membrane. VAMP3 vesicle traffic regulates the recycling of plasma membrane glutamate transporters. cAMP modulates VAMP3 vesicle cycling and glutamate uptake. Abstract Previous studies suggest that small synaptic-like vesicles in astrocytes carry vesicle-associated vSNARE proteins, VAMP3 (Cellubrevin) and VAMP2 (synaptobrevin 2), both contributing to the Ca2+-regulated exocytosis of gliotransmitters, thereby modulating brain information processing. Here, using cortical astrocytes taken from VAMP2 and VAMP3 knock-out mice, we find that astrocytes express only VAMP3. The morphology and function of VAMP3 vesicles were studied in cultured astrocytes at single vesicle level with stimulated emission depletion (STED) and total internal reflection fluorescence (TIRF) microscopies. We show that VAMP3 antibodies label small diameter (∼80 nm) vesicles and that VAMP3 vesicles undergo Ca2+-independent exo-endocytosis. We also show that this pathway modulates the surface expression of plasma membrane glutamate transporters and the glutamate uptake by astrocytes. Finally, using pharmacological and optogenetic tools, we provide evidence suggesting that the cytosolic cAMP level influences astrocytic VAMP3 vesicle trafficking and glutamate transport. Our results suggest a new role for VAMP3 vesicles in astrocytes.
Dongdong Li - One of the best experts on this subject based on the ideXlab platform.
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astrocyte vamp3 vesicles undergo ca2 independent cycling and modulate glutamate transporter trafficking
The Journal of Physiology, 2015Co-Authors: Karine Herault, Kathleen Zylbersztejn, Martin Oheim, Marcel A. Lauterbach, Marc Guillon, Dongdong LiAbstract:Key points Mouse cortical astrocytes express VAMP3 but not VAMP2. VAMP3 vesicles undergo Ca2+-independent exo- and endocytotic cycling at the plasma membrane. VAMP3 vesicle traffic regulates the recycling of plasma membrane glutamate transporters. cAMP modulates VAMP3 vesicle cycling and glutamate uptake. Abstract Previous studies suggest that small synaptic-like vesicles in astrocytes carry vesicle-associated vSNARE proteins, VAMP3 (Cellubrevin) and VAMP2 (synaptobrevin 2), both contributing to the Ca2+-regulated exocytosis of gliotransmitters, thereby modulating brain information processing. Here, using cortical astrocytes taken from VAMP2 and VAMP3 knock-out mice, we find that astrocytes express only VAMP3. The morphology and function of VAMP3 vesicles were studied in cultured astrocytes at single vesicle level with stimulated emission depletion (STED) and total internal reflection fluorescence (TIRF) microscopies. We show that VAMP3 antibodies label small diameter (∼80 nm) vesicles and that VAMP3 vesicles undergo Ca2+-independent exo-endocytosis. We also show that this pathway modulates the surface expression of plasma membrane glutamate transporters and the glutamate uptake by astrocytes. Finally, using pharmacological and optogenetic tools, we provide evidence suggesting that the cytosolic cAMP level influences astrocytic VAMP3 vesicle trafficking and glutamate transport. Our results suggest a new role for VAMP3 vesicles in astrocytes.
Heiner Niemann - One of the best experts on this subject based on the ideXlab platform.
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A novel tetanus neurotoxin-insensitive vesicle-associated membrane protein in SNARE complexes of the apical plasma membrane of epithelial cells. Mol Biol Cell 9: 1437–1448
1998Co-Authors: Thierry Galli, Heiner Niemann, Ahmed Zahraoui, Vadakkanchery V. Vaidyanathan, Graça Raposo, Jian Min Tian, Michael Karin, Daniel LouvardAbstract:The importance of soluble N-ethyl maleimide (NEM)-sensitive fusion protein (NSF) attachment protein (SNAP) receptors (SNAREs) in synaptic vesicle exocytosis is well established because it has been demonstrated that clostridial neurotoxins (NTs) proteolyze the vesicle SNAREs (v-SNAREs) vesicle-associated membrane protein (VAMP)/brevins and their partners, the target SNAREs (t-SNAREs) syntaxin 1 and SNAP25. Yet, several exocytotic events, including apical exocytosis in epithelial cells, are insensitive to numerous clostridial NTs, suggesting the presence of SNARE-independent mechanisms of exocytosis. In this study we found that syntaxin 3, SNAP23, and a newly identified VAMP/brevin, tetanus neurotoxin (TeNT)-insensitive VAMP (TI-VAMP), are insensitive to clostridial NTs. In epithelial cells, TI-VAMP–containing vesicles were concentrated in the apical domain, and the protein was detected at the apical plasma membrane by immunogold labeling on ultrathin cryosections. Syntaxin 3 and SNAP23 were codistributed at the apical plasma membrane where they formed NEM-dependent SNARE complexes with TI-VAMP and Cellubrevin. We suggest that TI-VAMP, SNAP23, and syntaxin 3 can participate in exocytotic processes at the apical plasma membrane of epithelial cells and, more generally, domain-specific exocytosis i
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tetanus toxin mediated cleavage of Cellubrevin impairs exocytosis of transferrin receptor containing vesicles in cho cells
Journal of Cell Biology, 1994Co-Authors: Thierry Galli, T J Chilcote, Olaf Mundigl, Thomas Binz, Heiner Niemann, Pietro De CamilliAbstract:Cellubrevin is a member of the synaptobrevin/VAMP family of SNAREs, which has a broad tissue distribution. In fibroblastic cells it is concentrated in the vesicles which recycle transferrin receptors but its role in membrane trafficking and fusion remains to be demonstrated. Cellubrevin, like the synaptic vesicle proteins synaptobrevins I and II, can be cleaved by tetanus toxin, a metallo-endoprotease which blocks neurotransmitter release. However, nonneuronal cells are unaffected by the toxin due to lack of cell surface receptors for its heavy chain. To determine whether Cellubrevin cleavage impairs exocytosis of recycling vesicles, we tested the effect of tetanus toxin light chain on the release of preinternalized transferrin from streptolysin-O-perforated CHO cells. The release was found to be temperature and ATP dependent as well as NEM sensitive. Addition of tetanus toxin light chain, but not of a proteolytically inactive form of the toxin, resulted in a partial inhibition of transferrin release which correlated with the toxin-mediated cleavage of Cellubrevin. The residual release of transferrin occurring after complete Cellubrevin degradation was still ATP dependent. Our results indicate that Cellubrevin plays an important role in the constitutive exocytosis of vesicles which recycle plasmalemma receptors. The incomplete inhibition of transferrin release produced by the toxin suggests the existence of a Cellubrevin-independent exocytotic mechanism, which may involve tetanus toxin-insensitive proteins of the synaptobrevin/VAMP family.
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Cleavage of Cellubrevin by tetanus toxin does not affect fusion of early endosomes
The Journal of biological chemistry, 1993Co-Authors: E Link, Harvey T Mcmahon, G Fischer Von Mollard, S. Yamasaki, Heiner NiemannAbstract:Tetanus toxin is a potent inhibitor of neurotransmitter release, which acts as an intracellular metalloendoprotease that selectively cleaves synaptobrevin, a major membrane protein of synaptic vesicles. Recently, synaptobrevin has been found to form an ATP-dependent complex with N-ethylmaleimide-sensitive fusion protein (NSF) and soluble NSF attachment protein, which are known to function in endosome fusion. Furthermore, a highly homologous isoform of synaptobrevin, named Cellubrevin, was identified that is expressed in virtually all tissues in the endocytic pathway and is cleaved by tetanus toxin light chain in vitro, suggesting that Cellubrevin may have a general function in intracellular fusion events. In the present study, we have analyzed whether cleavage of Cellubrevin by tetanus toxin influences the ATP-dependent, N-ethylmaleimide-sensitive fusion of early endosomes in vitro. Our results show that endosome fusion is not affected by tetanus toxin although Cellubrevin is almost completely proteolyzed, suggesting that the function of NSF in endosome fusion does not involve Cellubrevin.
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Cellubrevin is a ubiquitous tetanus toxin substrate homologous to a putative synaptic vesicle fusion protein
Nature, 1993Co-Authors: Harvey T Mcmahon, E Link, Lisa Edelmann, Yuri A Ushkaryov, Thomas Binz, Heiner NiemannAbstract:TETANUS toxin inhibits neurotransmitter release by selectively blocking fusion of synaptic vesicles1,2. Recently tetanus toxin was shown to proteolytically degrade synaptobrevin II (also named VAMP-2), a synaptic vesicle-specific protein3,4, in vitro and in nerve terminals5,6. As targets of tetanus toxin, synaptobrevins probably function in the exocytotic fusion of synaptic vesicles. Here we describe a new synaptobrevin homologue, Cellubrevin, that is present in all cells and tissues tested and demonstrate that it is a membrane trafficking protein of a constitutively recycling pathway. Like synaptobrevin II, Cellubrevin is proteolysed by tetanus toxin light chain in vitro and after transfection. Our results suggest that constitutive and regulated vesicular pathways use homologous proteins for membrane trafficking, probably for membrane fusion at the plasma membrane, indicating a greater mechanistic and evolutionary similarity between these pathways than previously thought.