In APCs, antigen processing compartments often have the phenotypic characteristics of multivesicular bodies (MVB). In studies examining MHC-II trafficking to antigen processing compartments we found that activated (but not resting) B cells secrete significant amounts of their total pool of pMHC-II on MVB-derived vesicles termed exosomes. Surprisingly, it was predominantly Ii-free surface pMHC-II that internalized and trafficked to these MVB, highlighting a previously unrecognized transport pathway followed by pMHC-II. We also found that interaction of antigen-loaded B cells with antigen-specific T cells stimulates exosome release from B cells, and these exosomes in turn can stimulate primed (but not nave) T cells to proliferate. Our results support a model that T cell stimulated exosome release from activated B cells serves to augment T cell responses. The movement of proteins and lipids from one intracellular compartment to another is carried out by a well-orchestrated process of transport vesicle formation, vesicle docking with a target compartment, and finally vesicle-target membrane fusion. The proteins that catalyze membrane fusion are termed SNAREs. We have been investigating the role of distinct SNARE isoforms in regulating secretory granule exocytosis from immune cells using a variety of SNARE knock-out mice and have found that VAMP-8, but not VAMP-2 or VAMP-3, regulates mast cell secretory granule exocytosis. Surprisingly, VAMP-8-deletion only affects serotonin exocytosis but not histamine or TNF-alpha exocytosis, showing for the first time that secretory granule heterogeneity exists in mast cells. We are currently using these mice to examine the role of specific SNARE proteins in regulated exocytosis from other immune cells.

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Da, Q; Shaw, T; Pradhan, S et al. (2017) Disruption of protein complexes containing protein phosphatase 2B and Munc18c reduces the secretion of von Willebrand factor from endothelial cells. J Thromb Haemost 15:1032-1039
Ren, Binhui; Azzegagh, Zoulikha; Jaramillo, Ana M et al. (2015) SNAP23 is selectively expressed in airway secretory cells and mediates baseline and stimulated mucin secretion. Biosci Rep 35:
Kaul, Sunil; Mittal, Sharad K; Feigenbaum, Lionel et al. (2015) Expression of the SNARE protein SNAP-23 is essential for cell survival. PLoS One 10:e0118311
Nair-Gupta, Priyanka; Baccarini, Alessia; Tung, Navpreet et al. (2014) TLR signals induce phagosomal MHC-I delivery from the endosomal recycling compartment to allow cross-presentation. Cell 158:506-21
Wu, Zhengli; Chen, Xiaochun; Liu, Fang et al. (2014) Calpain-1 contributes to IgE-mediated mast cell activation. J Immunol 192:5130-9
Karim, Zubair A; Zhang, Jinchao; Banerjee, Meenakshi et al. (2013) I?B kinase phosphorylation of SNAP-23 controls platelet secretion. Blood 121:4567-74
Suh, Young Ho; Yoshimoto-Furusawa, Aki; Weih, Karis A et al. (2011) Deletion of SNAP-23 results in pre-implantation embryonic lethality in mice. PLoS One 6:e18444
Suh, Young Ho; Terashima, Akira; Petralia, Ronald S et al. (2010) A neuronal role for SNAP-23 in postsynaptic glutamate receptor trafficking. Nat Neurosci 13:338-43
Tang, Tina Tze-Tsang; Badger 2nd, John D; Roche, Paul A et al. (2010) Novel approach to probe subunit-specific contributions to N-methyl-D-aspartate (NMDA) receptor trafficking reveals a dominant role for NR2B in receptor recycling. J Biol Chem 285:20975-81
Danielian, Silvia; Basile, Natalia; Rocco, Carlos et al. (2010) Novel syntaxin 11 gene (STX11) mutation in three Argentinean patients with hemophagocytic lymphohistiocytosis. J Clin Immunol 30:330-7

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