Disease relevance of VAMP2

• Cleavage of VAMP2 with tetanus toxin (TeNT) did not prevent delivery of TRPC3 to the plasma membrane region but reduced its surface expression [1].
• In this work, VAMP-2 and SNAP-25 were effectively cleaved before they formed toxin-insensitive complexes by transient transfection of insulinoma HIT or INS-1 cells with tetanus toxin (TeTx) or botulinum neurotoxin A (BoNT/A), as shown by immunoblotting and immunofluorescence microscopy [2].

High impact information on VAMP2

• The vesicle-targeting proteins synaptobrevin-2 and syntaxin-4 are proposed to play roles in this process [3].
• According to a popular theory, the three presynaptic SNARE proteins (syntaxin 1, synaptobrevin 2 and SNAP-25) drive neuroexocytosis by forming a complex that forces vesicle and plasma membranes together [4].
• VAMP2-dependent exocytosis regulates plasma membrane insertion of TRPC3 channels and contributes to agonist-stimulated Ca2+ influx [1].
• In aggregate, these data suggest that VAMP2-dependent exocytosis regulates plasma membrane insertion of TRPC3 channels and contributes to carbachol-stimulation of Ca2+ influx [1].
• Furthermore, pharmacological inhibition of VAMP2-mediated exocytosis prevented growth cone attraction, but not repulsion [5].

Biological context of VAMP2

• Transient transfection of HIT-T15 cells with VAMP-1, VAMP-2 or cellubrevin made resistant to the proteolytic action of TeTx by amino acid replacements in the cleavage site restored Ca2+-stimulated secretion [6].
• Mutations of putative phosphorylation sites or of negatively charged amino acids in the SNARE motif recognized by clostridial toxins had no effect on the ability of VAMP-2 to mediate Ca2+-triggered secretion [6].
• We found that a point mutation in VAMP-2 preventing targeting to synaptic vesicles also impairs the localization on insulin-containing secretory granules, suggesting a similar requirement for vesicular targeting [6].
• The Piccolo zinc fingers were found to interact with the dual prenylated rab3A and VAMP2/Synaptobrevin II receptor PRA1 [7].
• We describe the complete sequence, genomic organization, and FISH chromosome mapping of the human VAMP2 [8].

Anatomical context of VAMP2

• SNAP-25, syntaxin 13, and VAMP2 were bound from rat brain membranes to the Hrs coiled-coil domain [9].
• Wild-type VAMP-2, wild-type cellubrevin or a mutant of VAMP-2 resistant to TeTx but not targeted to secretory granules were unable to rescue Ca2+-evoked insulin release [6].
• Vesicle-associated membrane protein-2 (VAMP-2) and cellubrevin are associated with the membrane of insulin-containing secretory granules and of gamma-aminobutyric acid (GABA)-containing synaptic-like vesicles of pancreatic beta-cells [6].
• VAMP-2 was also found on the external membrane region of granules docking to the plasma membrane in activated neutrophils [10].
• Expression of eosinophil target SNAREs as potential cognate receptors for vesicle-associated membrane protein-2 in exocytosis [11].

Associations of VAMP2 with chemical compounds

• In contrast, addition of PIP2 to Stx4/SNAP23 vesicles inhibited the fusion reaction, and its addition to VAMP2 vesicles was stimulatory [12].
• Addition of PA to Stx4/SNAP23 vesicles markedly enhanced the fusion rate, whereas its addition to VAMP2 vesicles was inhibitory [12].
• Furthermore, we show that the COOH of nephrin interacts with the vesicular SNARE protein VAMP2 in vitro and ex vivo (using yeast-2 hybrid and coimmunoprecipitation studies) [13].
• Accordingly, ionomycin induced translocation of VAMP-2 toward the plasma membrane [14].
• Moreover, within these fractions Cdc42 and VAMP2 were found to co-immunoprecipitate under basal and glucose-stimulated conditions, suggesting that they moved as a complex [15].
• Alanine-scanning mutagenesis and kinetic analysis identified three regions within VAMP-2 that were recognized by BoNT/B and TeNT: residues adjacent to the site of scissile bond cleavage (cleavage region) and residues located within N-terminal and C-terminal regions relative to the cleavage region [16].

Physical interactions of VAMP2

• OBJECTIVE: We sought to determine whether eosinophils express the t-SNARE isoforms SNAP-23 and syntaxin-4 as potential binding targets for VAMP-2 during exocytosis [11].
• It has been shown that PRA1 interacts with Rab proteins and with VAMP2 [17].
• Whereas Ca(2+) dissociates the Hrs-containing complex but not the VAMP-2-containing SNARE complex [18].
• Using atomic force microscopy we show that the SNARE-like domain of tomosyn-1 can form a complex with syntaxin-1 and SNAP25 but displays binding forces that are weaker than those observed for VAMP2 (237+/-13 versus 279+/-3 pN) [19].
• In addition, Munc18c binds to the syntaxin4/SNAP23/VAMP2 SNARE complex [20].

Regulatory relationships of VAMP2

• Subcellular fractionation analyses revealed a parallel redistribution of Cdc42 and VAMP2 from the granule fraction to the plasma membrane in response to glucose that temporally corresponded with the glucose-induced activation of Cdc42 [15].
• We propose that hyperosmolarity increases surface GLUT4myc by preventing GLUT4 endocytosis and stimulating its exocytosis via a pathway independent of phosphatidylinositol 3-kinase activity and of VAMP2 or VAMP3 [21].

Other interactions of VAMP2

• To examine the effect of VAMP proteins on platelet secretion, soluble recombinant (r) VAMP-2, rVAMP-3, and rVAMP-8 were incubated with streptolysin O-permeabilized platelets [22].
• Here, we have designed three peptides, which correspond to sequences located in the syntaxin-1A H3 domain, the C-terminal domain of SNAP-25, and a conserved central domain of synaptobrevin-2, that exhibit a high propensity to form a minimal trimeric coiled-coil [23].
• Activation of neutrophils led to the interaction of VAMP-2 with the plasma membrane Q-SNARE syntaxin 4, and anti-syntaxin 4 Abs inhibited exocytosis of specific and tertiary granules in electropermeabilized neutrophils [10].
• Tetanus toxin (TeTx) treatment of permeabilized HIT-T15 cells leads to the proteolytic cleavage of VAMP-2 and cellubrevin and causes the inhibition of Ca2+-triggered insulin exocytosis [6].
• Role of vesicle-associated membrane protein-2, through Q-soluble N-ethylmaleimide-sensitive factor attachment protein receptor/R-soluble N-ethylmaleimide-sensitive factor attachment protein receptor interaction, in the exocytosis of specific and tertiary granules of human neutrophils [10].

Analytical, diagnostic and therapeutic context of VAMP2

• METHODS: Human peripheral blood eosinophils (> or =97%) from atopic subjects were subjected to RT-PCR and sequence analysis with specific primers for VAMP-2 mRNA [24].
• Immunoblotting, subcellular fractionation, and immunocytochemistry documented that vesicle-associated membrane protein-2 (VAMP-2), a vesicle-SNARE, was expressed in human eosinophils [25].
• Immunoblotting, subcellular fractionation, and immunocytochemistry documented that vesicle-associated membrane protein-2 (VAMP-2), a vesicle-SNARE, was expressed in human eosinophils [26].
• Here we provide evidence using immunofluorescence microscopy, cell fractionation, and SNARE protein interaction studies that acinar cells contain two distinct populations of zymogen granules (ZGs) expressing either VAMP 2 or VAMP 8 [27].
• Co-immunoprecipitation experiments indicated that syntaxin-1, SNAP-25 and VAMP-2 were present in a complex similar to that identified in brain [28].

References