title: VAMP-8 segregates mast cell-preformed mediator exocytosis from cytokine trafficking pathways.
abstract: Inflammatory responses by mast cells are characterized by massive exocytosis of prestored granular mediators followed by cytokine/chemokine release. The vesicular trafficking mechanisms involved remain poorly understood. Vesicular-associated membrane protein-8 (VAMP-8), a member of the soluble N-ethylmaleimide-sensitive factor (NSF) attachment protein receptor (SNARE) family of fusion proteins initially characterized in endosomal and endosomal-lysosomal fusion, may also function in regulated exocytosis. Here we show that in bone marrow-derived mast cells (BMMCs) VAMP-8 partially colocalized with secretory granules and redistributed upon stimulation. This was associated with increased SNARE complex formation with the target t-SNAREs, SNAP-23 and syntaxin-4. VAMP-8-deficient BMMCs exhibited a markedly reduced degranulation response after IgE+ antigen-, thapsigargin-, or ionomycin-induced stimulation. VAMP-8-deficient mice also showed reduced plasma histamine levels in passive systemic anaphylaxis experiments, while cytokine/chemokine release was not affected. Unprocessed TNF accumulated at the plasma membrane where it colocalized with a VAMP-3-positive vesicular compartment but not with VAMP-8. The findings demonstrate that VAMP-8 segregates secretory lysosomal granule exocytosis in mast cells from cytokine/chemokine molecular trafficking pathways.
authors.affiliation: Inserm U699, Paris, France.
authors.forename: Neeraj
authors.initials: N
authors.lastname: Tiwari
authors.forename: Cheng-Chun
authors.initials: CC
authors.lastname: Wang
authors.forename: Cristiana
authors.initials: C
authors.lastname: Brochetta
authors.forename: Gou
authors.initials: G
authors.lastname: Ke
authors.forename: Francesca
authors.initials: F
authors.lastname: Vita
authors.forename: Zeng
authors.initials: Z
authors.lastname: Qi
authors.forename: Juan
authors.initials: J
authors.lastname: Rivera
authors.forename: Maria Rosa
authors.initials: MR
authors.lastname: Soranzo
authors.forename: Giuliano
authors.initials: G
authors.lastname: Zabucchi
authors.forename: Wanjin
authors.initials: W
authors.lastname: Hong
authors.forename: Ulrich
authors.initials: U
authors.lastname: Blank
mesh_terms: D000707:Anaphylaxis / Q000235:genetics / Q000276:immunology / Q000473:pathology; D000818:Animals; D000941:Antigens / Q000276:immunology; D015550:Cell Degranulation / Q000187:drug effects / Q000235:genetics / Q000276:immunology*; D016207:Cytokines / Q000235:genetics / Q000276:immunology*; D005089:Exocytosis / Q000235:genetics / Q000276:immunology*; D006632:Histamine / Q000235:genetics / Q000276:immunology; D007073:Immunoglobulin E / Q000276:immunology; D007249:Inflammation / Q000235:genetics / Q000276:immunology; D015759:Ionomycin / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D007783:Lactones / Q000494:pharmacology; D008247:Lysosomes / Q000235:genetics / Q000276:immunology / Q000473:pathology; D008407:Mast Cells / Q000276:immunology* / Q000473:pathology; D008561:Membrane Fusion / Q000235:genetics / Q000276:immunology*; D051379:Mice; D018345:Mice, Knockout; D021381:Protein Transport / Q000235:genetics / Q000276:immunology; D050765:Qa-SNARE Proteins / Q000235:genetics / Q000276:immunology; D050766:Qb-SNARE Proteins / Q000235:genetics / Q000276:immunology; D050683:R-SNARE Proteins / Q000235:genetics / Q000276:immunology*; D022142:Secretory Vesicles / Q000235:genetics / Q000276:immunology / Q000473:pathology; D019284:Thapsigargin / Q000494:pharmacology
chemical_list: D000941:Antigens; D016207:Cytokines; D007476:Ionophores; D007783:Lactones; D050765:Qa-SNARE Proteins; D050766:Qb-SNARE Proteins; D050683:R-SNARE Proteins; C491831:Vamp8 protein, mouse; D007073:Immunoglobulin E; D015759:Ionomycin; D019284:Thapsigargin; D006632:Histamine