title: Critical role for the mitochondrial permeability transition pore and cyclophilin D in platelet activation and thrombosis.
abstract: Many of the cellular responses that occur in activated platelets resemble events that take place following activation of cell-death pathways in nucleated cells. We tested the hypothesis that formation of the mitochondrial permeability transition pore (MPTP), a key signaling event during cell death, also plays a critical role in platelet activation. Stimulation of murine platelets with thrombin plus the glycoprotein VI agonist convulxin resulted in a rapid loss of mitochondrial transmembrane potential (Deltapsi(m)) in a subpopulation of activated platelets. In the absence of cyclophilin D (CypD), an essential regulator of MPTP formation, murine platelet activation responses were altered. CypD-deficient platelets exhibited defects in phosphatidylserine externalization, high-level surface fibrinogen retention, membrane vesiculation, and procoagulant activity. Also, in CypD-deficient platelet-rich plasma, clot retraction was altered. Stimulation with thrombin plus H(2)O(2), a known activator of MPTP formation, also increased high-level surface fibrinogen retention, phosphatidylserine externalization, and platelet procoagulant activity in a CypD-dependent manner. In a model of carotid artery photochemical injury, thrombosis was markedly accelerated in CypD-deficient mice. These results implicate CypD and the MPTP as critical regulators of platelet activation and suggest a novel CypD-dependent negative-feedback mechanism regulating arterial thrombosis.
authors.affiliation: Department of Pediatrics, University of Iowa Carver College of Medicine, Iowa City, IA, USA. shawn.jobe@emory.edu
authors.forename: Shawn M
authors.initials: SM
authors.lastname: Jobe
authors.forename: Katina M
authors.initials: KM
authors.lastname: Wilson
authors.forename: Lorie
authors.initials: L
authors.lastname: Leo
authors.forename: Alejandro
authors.initials: A
authors.lastname: Raimondi
authors.forename: Jeffery D
authors.initials: JD
authors.lastname: Molkentin
authors.forename: Steven R
authors.initials: SR
authors.lastname: Lentz
authors.forename: Jorge
authors.initials: J
authors.lastname: Di Paola
mesh_terms: D000818:Animals; D000081406:Peptidyl-Prolyl Isomerase F; D021983:Cyclophilins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D015759:Ionomycin / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D033681:Mitochondrial Membrane Transport Proteins / Q000378:metabolism*; D000083162:Mitochondrial Permeability Transition Pore; D015539:Platelet Activation / Q000187:drug effects; D013927:Thrombosis / Q000235:genetics / Q000378:metabolism*
chemical_list: D000081406:Peptidyl-Prolyl Isomerase F; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; C000631446:PPIF protein, mouse; D015759:Ionomycin; D006861:Hydrogen Peroxide; D021983:Cyclophilins