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Synaptotagmin regulates mast cell functions
Author(s) -
Baram Dana,
Mekori Yoseph A.,
SagiEisenberg Ronit
Publication year - 2001
Publication title -
immunological reviews
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.839
H-Index - 223
eISSN - 1600-065X
pISSN - 0105-2896
DOI - 10.1034/j.1600-065x.2001.790103.x
Subject(s) - exocytosis , synaptotagmin 1 , microbiology and biotechnology , mast cell , munc 18 , biology , secretory vesicle , secretion , biochemistry , vesicle , immunology , synaptic vesicle , membrane
Summary: Synaptotagmin(s) (Syts), are products of a gene family implicated in the control of Ca 2+ ‐dependent exocytosis. Mast cells, specialized secretory cells that release mediators of inflammatory and allergic reactions in a process of regulated exocytosis, express Syt homologues and SNAREs (Soluble NSF Attachment proteins Receptors), which together with Syt constitute the core complex which mediates exocytotic vesicle docking and fusion. Rat basophilic leukemia cells (RBL‐2H3), a tumor analogue of mucosal mast cells, express the Syt homologues Syt II, Syt III and Syt V. Expression of Syt I, the neuronal Ca 2+ sensor, in the RBL cells, resulted in its targeting to secretory granules and in prominent potentiation and acceleration of Ca 2+ ‐dependent exocytosis. Syt II is localized to an amine‐free lysosomal compartment, which is also subjected to regulated exocytosis. Lysosomal exocytosis is negatively regulated by Syt II: overexpression of Syt II inhibited Ca 2+ ‐triggered exocytosis of lysosomes, while suppression of Syt II expression markedly potentiated this release. These findings implicate Syt homologues as key regulators of mast cell function. We thank Drs. T.C. Sudhof, R.H. Scheller and M. Takahashi for their generous gifts of antibodies and cDNAs.