title: Autophagy is induced upon platelet activation and is essential for hemostasis and thrombosis.
abstract: Autophagy is important for maintaining cellular homeostasis, and thus its deficiency is implicated in a broad spectrum of human diseases. Its role in platelet function has only recently been examined. Our biochemical and imaging studies demonstrate that the core autophagy machinery exists in platelets, and that autophagy is constitutively active in resting platelets. Moreover, autophagy is induced upon platelet activation, as indicated by agonist-induced loss of the autophagy marker LC3II. Additional experiments, using inhibitors of platelet activation, proteases, and lysosomal acidification, as well as platelets from knockout mouse strains, show that agonist-induced LC3II loss is a consequence of platelet signaling cascades and requires proteases, acidic compartments, and membrane fusion. To assess the physiological role of platelet autophagy, we generated a mouse strain with a megakaryocyte- and platelet-specific deletion of Atg7, an enzyme required for LC3II production. Ex vivo analysis of platelets from these mice shows modest defects in aggregation and granule cargo packaging. Although these mice have normal platelet numbers and size distributions, they exhibit a robust bleeding diathesis in the tail-bleeding assay and a prolonged occlusion time in the FeCl3-induced carotid injury model. Our results demonstrate that autophagy occurs in platelets and is important for hemostasis and thrombosis.
authors.affiliation: Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY;
authors.forename: Madhu M
authors.initials: MM
authors.lastname: Ouseph
authors.affiliation: Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY;
authors.forename: Yunjie
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY;
authors.forename: Meenakshi
authors.initials: M
authors.lastname: Banerjee
authors.affiliation: Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY;
authors.forename: Smita
authors.initials: S
authors.lastname: Joshi
authors.affiliation: Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR;
authors.forename: Laura
authors.initials: L
authors.lastname: MacDonald
authors.affiliation: Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY;
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhong
authors.affiliation: Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY;
authors.forename: Huijuan
authors.initials: H
authors.lastname: Liu
authors.affiliation: Department of Neurology and Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY;
authors.forename: Xianting
authors.initials: X
authors.lastname: Li
authors.affiliation: Division of Cardiovascular Medicine, Department of Internal Medicine, University of Kentucky, Lexington, KY;
authors.forename: Binggang
authors.initials: B
authors.lastname: Xiang
authors.affiliation: Division of Cardiovascular Medicine, Department of Internal Medicine, University of Kentucky, Lexington, KY;
authors.forename: Guoying
authors.initials: G
authors.lastname: Zhang
authors.forename: Masaaki
authors.initials: M
authors.lastname: Komatsu
authors.affiliation: Protein Metabolism Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan; and Department of Biochemistry, School of Medicine, Niigata University, Niigata, Japan.
authors.forename: Massaki
authors.initials: M
authors.lastname: Komatsu
authors.affiliation: Department of Neurology and Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY;
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Yue
authors.affiliation: Division of Cardiovascular Medicine, Department of Internal Medicine, University of Kentucky, Lexington, KY;
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Li
authors.affiliation: Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR;
authors.forename: Brian
authors.initials: B
authors.lastname: Storrie
authors.affiliation: Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY;
authors.forename: Sidney W
authors.initials: SW
authors.lastname: Whiteheart
authors.affiliation: Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY;
authors.forename: Qing Jun
authors.initials: QJ
authors.lastname: Wang
mesh_terms: D000818:Animals; D001343:Autophagy / Q000502:physiology*; D001792:Blood Platelets / Q000502:physiology; D015153:Blotting, Western; D002478:Cells, Cultured; D006487:Hemostasis / Q000502:physiology*; D006801:Humans; D051379:Mice; D008817:Mice, Mutant Strains; D015539:Platelet Activation / Q000502:physiology*; D013927:Thrombosis / Q000503:physiopathology*