A novel tetanus neurotoxin-insensitive vesicle-associated membrane protein in SNARE complexes of the apical plasma membrane of epithelial cells.
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 in clostridial NT-resistant pathways.
Galli
T
T
Centre National de la Recherche Scientifique Unité Mixte de Recherche 144 "Compartimentation et Dynamique Cellulaires," Institut Curie, F-75248 Paris Cedex 05, France. tgalli@curie.fr
Zahraoui
A
A
Vaidyanathan
V V
VV
Raposo
G
G
Tian
J M
JM
Karin
M
M
Niemann
H
H
Louvard
D
D
D000595:Amino Acid Sequence; D000818:Animals; D000954:Antigens, Surface / Q000378:metabolism; D001483:Base Sequence; D001905:Botulinum Toxins / Q000494:pharmacology; D018938:Caco-2 Cells; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D018076:DNA, Complementary; D004229:Dithiothreitol / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D005033:Ethylmaleimide / Q000494:pharmacology; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008666:Metalloendopeptidases / Q000494:pharmacology*; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000378:metabolism; D050765:Qa-SNARE Proteins; D050766:Qb-SNARE Proteins; D050767:Qc-SNARE Proteins; D050683:R-SNARE Proteins; D011817:Rabbits; D051381:Rats; D050600:SNARE Proteins; D017386:Sequence Homology, Amino Acid; D050825:Synaptosomal-Associated Protein 25; D050827:Syntaxin 1; D013744:Tetanus Toxin / Q000494:pharmacology*; D051040:Vesicle-Associated Membrane Protein 3; D033921:Vesicular Transport Proteins
D000954:Antigens, Surface; D002352:Carrier Proteins; D018076:DNA, Complementary; D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D050765:Qa-SNARE Proteins; D050766:Qb-SNARE Proteins; D050767:Qc-SNARE Proteins; D050683:R-SNARE Proteins; C100493:SNAP23 protein, human; C494208:SNAP25 protein, human; D050600:SNARE Proteins; C494212:STX1A protein, human; C494210:Snap25 protein, rat; C494213:Stx1a protein, rat; D050825:Synaptosomal-Associated Protein 25; D050827:Syntaxin 1; D013744:Tetanus Toxin; C121241:VAMP7 protein, human; C496926:Vamp7 protein, rat; D051040:Vesicle-Associated Membrane Protein 3; D033921:Vesicular Transport Proteins; C035979:tetanospasmin; D008666:Metalloendopeptidases; D001905:Botulinum Toxins; D005033:Ethylmaleimide; D004229:Dithiothreitol