title: Endobrevin/VAMP-8 is the primary v-SNARE for the platelet release reaction.
abstract: Platelet secretion is critical to hemostasis. Release of granular cargo is mediated by soluble NSF attachment protein receptors (SNAREs), but despite consensus on t-SNAREs usage, it is unclear which Vesicle Associated Membrane Protein (VAMPs: synaptobrevin/VAMP-2, cellubrevin/VAMP-3, TI-VAMP/VAMP-7, and endobrevin/VAMP-8) is required. We demonstrate that VAMP-8 is required for release from dense core granules, alpha granules, and lysosomes. Platelets from VAMP-8-/- mice have a significant defect in agonist-induced secretion, though signaling, morphology, and cargo levels appear normal. In contrast, VAMP-2+/-, VAMP-3-/-, and VAMP-2+/-/VAMP-3-/- platelets showed no defect. Consistently, tetanus toxin had no effect on secretion from permeabilized mouse VAMP-3-/- platelets or human platelets, despite cleavage of VAMP-2 and/or -3. Tetanus toxin does block the residual release from permeabilized VAMP-8-/- platelets, suggesting a secondary role for VAMP-2 and/or -3. These data imply a ranked redundancy of v-SNARE usage in platelets and suggest that VAMP-8-/- mice will be a useful in vivo model to study platelet exocytosis in hemostasis and vascular inflammation.
authors.affiliation: Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, KY 40536, USA.
authors.forename: Qiansheng
authors.initials: Q
authors.lastname: Ren
authors.forename: Holly Kalani
authors.initials: HK
authors.lastname: Barber
authors.forename: Garland L
authors.initials: GL
authors.lastname: Crawford
authors.forename: Zubair A
authors.initials: ZA
authors.lastname: Karim
authors.forename: Chunxia
authors.initials: C
authors.lastname: Zhao
authors.forename: Wangsun
authors.initials: W
authors.lastname: Choi
authors.forename: Cheng-Chun
authors.initials: CC
authors.lastname: Wang
authors.forename: Wanjin
authors.initials: W
authors.lastname: Hong
authors.forename: Sidney W
authors.initials: SW
authors.lastname: Whiteheart
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D002118:Calcium / Q000378:metabolism; D005089:Exocytosis / Q000187:drug effects; D006801:Humans; D008666:Metalloendopeptidases / Q000494:pharmacology; D051379:Mice; D018345:Mice, Knockout; D010974:Platelet Aggregation / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D050683:R-SNARE Proteins / Q000172:deficiency / Q000378:metabolism*; D050600:SNARE Proteins / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013744:Tetanus Toxin / Q000494:pharmacology; D013917:Thrombin / Q000494:pharmacology; D050988:Vesicle-Associated Membrane Protein 2 / Q000172:deficiency / Q000378:metabolism; D051040:Vesicle-Associated Membrane Protein 3 / Q000172:deficiency
chemical_list: D050683:R-SNARE Proteins; D050600:SNARE Proteins; D013744:Tetanus Toxin; C491831:Vamp8 protein, mouse; D050988:Vesicle-Associated Membrane Protein 2; D051040:Vesicle-Associated Membrane Protein 3; C494808:vesicle-associated membrane protein 2, mouse; C494953:vesicle-associated membrane protein 3, mouse; D000255:Adenosine Triphosphate; D011505:Protein-Tyrosine Kinases; D013917:Thrombin; D008666:Metalloendopeptidases; C093556:zinc-endopeptidase, tetanus neurotoxin; D002118:Calcium