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

摘要

We have examined the role of the R-soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) synaptobrevin-\ud2/vesicle-associated membrane protein (VAMP)-2 in neutrophil exocytosis. VAMP-2, localized in the membranes of specific\udand gelatinase-containing tertiary granules in resting human neutrophils, resulted translocated to the cell surface following\udneutrophil activation under experimental conditions that induced exocytosis of specific and tertiary granules. VAMP-2 was also\udfound on the external membrane region of granules docking to the plasma membrane in activated neutrophils. Specific Abs against\udVAMP-2 inhibited Ca2 and GTP- -S-induced exocytosis of CD66b-enriched specific and tertiary granules, but did not affect\udexocytosis of CD63-enriched azurophilic granules, in electropermeabilized neutrophils. Tetanus toxin disrupted VAMP-2 and\udinhibited exocytosis of tertiary and specific granules. Activation of neutrophils led to the interaction of VAMP-2 with the plasma\udmembrane Q-SNARE syntaxin 4, and anti-syntaxin 4 Abs inhibited exocytosis of specific and tertiary granules in electropermeabilized\udneutrophils. Immunoelectron microscopy showed syntaxin 4 on the plasma membrane contacting with docked granules\udin activated neutrophils. These data indicate that VAMP-2 mediates exocytosis of specific and tertiary granules, and that QSNARE/\udR-SNARE complexes containing VAMP-2 and syntaxin 4 are involved in neutrophil exocytosis