TY - JOUR
T1 - Munc18-2, but not Munc18-1 or Munc18-3, regulates platelet exocytosis, hemostasis, and thrombosis
AU - Cardenas, Eduardo I.
AU - Gonzalez, Ricardo
AU - Breaux, Keegan
AU - Da, Qi
AU - Gutierrez, Berenice A.
AU - Ramos, Marco A.
AU - Cardenas, Rodolfo A.
AU - Burns, Alan R.
AU - Rumbaut, Rolando E.
AU - Adachi, Roberto
N1 - Funding Information:
1 These authors were supported by PhD Grant Scholarships 352566 (to E. I. C.), 446906 (to R. G.), and 448085 (to B. A. G.) from the Consejo Nacional de Ciencia y Tecnología (CONACyT).
Funding Information:
This project was supported by National Institutes of Health Grants AI093533A, AI137319, and CA016672 (to R. A.), HL116524 (to R. E. R.), and EY007551 (to A. R. B.). This project was also supported by Merit Review Award I01 BX002551 (to R. E. R.) from the U. S. Dept. of Veterans Affairs. The authors declare that they have no conflicts of interest with the contents of this article. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Insti-tutes of Health, the Department of Veterans Affairs, or the United States government.
Publisher Copyright:
© 2019 American Society for Biochemistry and Molecular Biology Inc. All Rights Reserved.
PY - 2019/3/29
Y1 - 2019/3/29
N2 - Platelet degranulation, a form of regulated exocytosis, is crucial for hemostasis and thrombosis. Exocytosis in platelets is mediated by SNARE proteins, and in most mammalian cells this process is controlled by Munc18 (mammalian homolog of Caenorhabditis elegans uncoordinated gene 18) proteins. Platelets express all Munc18 paralogs (Munc18-1, -2, and -3), but their roles in platelet secretion and function have not been fully characterized. Using Munc18-1, -2, and -3 conditional knockout mice, here we deleted expression of these proteins in platelets and assessed granule exocytosis. We measured products secreted by each type of platelet granule and analyzed EM platelet profiles by design-based stereology. We observed that the removal of Munc18-2 ablates the release of alpha, dense, and lysosomal granules from platelets, but we found no exocytic role for Munc18-1 or -3 in platelets. In vitro, Munc18-2– deficient platelets exhibited defective aggregation at low doses of collagen and impaired thrombus formation under shear stress. In vivo, megakaryocyte-specific Munc18-2 conditional knockout mice had a severe hemostatic defect and prolonged arterial and venous bleeding times. They were also protected against arterial thrombosis in a chemically induced model of arterial injury. Taken together, our results indicate that Munc18-2, but not Munc18-1 or Munc18-3, is essential for regulated exocytosis in platelets and platelet participation in thrombosis and hemostasis.
AB - Platelet degranulation, a form of regulated exocytosis, is crucial for hemostasis and thrombosis. Exocytosis in platelets is mediated by SNARE proteins, and in most mammalian cells this process is controlled by Munc18 (mammalian homolog of Caenorhabditis elegans uncoordinated gene 18) proteins. Platelets express all Munc18 paralogs (Munc18-1, -2, and -3), but their roles in platelet secretion and function have not been fully characterized. Using Munc18-1, -2, and -3 conditional knockout mice, here we deleted expression of these proteins in platelets and assessed granule exocytosis. We measured products secreted by each type of platelet granule and analyzed EM platelet profiles by design-based stereology. We observed that the removal of Munc18-2 ablates the release of alpha, dense, and lysosomal granules from platelets, but we found no exocytic role for Munc18-1 or -3 in platelets. In vitro, Munc18-2– deficient platelets exhibited defective aggregation at low doses of collagen and impaired thrombus formation under shear stress. In vivo, megakaryocyte-specific Munc18-2 conditional knockout mice had a severe hemostatic defect and prolonged arterial and venous bleeding times. They were also protected against arterial thrombosis in a chemically induced model of arterial injury. Taken together, our results indicate that Munc18-2, but not Munc18-1 or Munc18-3, is essential for regulated exocytosis in platelets and platelet participation in thrombosis and hemostasis.
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U2 - 10.1074/jbc.RA118.006922
DO - 10.1074/jbc.RA118.006922
M3 - Article
C2 - 30696774
AN - SCOPUS:85063959422
SN - 0021-9258
VL - 294
SP - 4784
EP - 4792
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 13
ER -