Syntaxin 3, but not syntaxin 4, is required for mast cell–regulated exocytosis, where it plays a primary role mediating compound exocytosis

Mast cells (MCs) participate in allergy, inflammation, and defense against pathogens. They release multiple immune mediators via exocytosis, a process that requires SNARE proteins, including syntaxins (Stxs). The identity of the Stxs involved in MC exocytosis remains controversial. Here, we studied...

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Bibliographic Details
Published in:The Journal of biological chemistry 2019-03, Vol.294 (9), p.3012-3023
Main Authors: Sanchez, Elizabeth, Gonzalez, Erika A., Moreno, David S., Cardenas, Rodolfo A., Ramos, Marco A., Davalos, Alfredo J., Manllo, John, Rodarte, Alejandro I., Petrova, Youlia, Moreira, Daniel C., Chavez, Miguel A., Tortoriello, Alejandro, Lara, Adolfo, Gutierrez, Berenice A., Burns, Alan R., Heidelberger, Ruth, Adachi, Roberto
Format: Article
Language:English
Subjects:
allergy
anaphylaxis
Animals
Cell Count
Cell Degranulation
Cell Differentiation
Exocytosis
Gene Knockout Techniques
immunoglobulin E (IgE)
Kinetics
mast cell
Mast Cells - cytology
Membrane Biology
Mice
Qa-SNARE Proteins - deficiency
Qa-SNARE Proteins - genetics
Qa-SNARE Proteins - metabolism
SNARE proteins
syntaxin
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Summary:Mast cells (MCs) participate in allergy, inflammation, and defense against pathogens. They release multiple immune mediators via exocytosis, a process that requires SNARE proteins, including syntaxins (Stxs). The identity of the Stxs involved in MC exocytosis remains controversial. Here, we studied the roles of Stx3 and -4 in fully developed MCs from conditional knockout mice by electrophysiology and EM, and found that Stx3, and not Stx4, is crucial for MC exocytosis. The main defect seen in Stx3-deficient MCs was their inability to engage multigranular compound exocytosis, while leaving most single-vesicle fusion events intact. We used this defect to show that this form of exocytosis is not only required to accelerate MC degranulation but also essential to achieve full degranulation. The exocytic defect was severe but not absolute, indicating that an Stx other than Stx3 and -4 is also required for exocytosis in MCs. The removal of Stx3 affected only regulated exocytosis, leaving other MC effector responses intact, including the secretion of cytokines via constitutive exocytosis. Our in vivo model of passive systemic anaphylaxis showed that the residual exocytic function of Stx3-deficient MCs was sufficient to drive a full anaphylactic response in mice.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.RA118.005532