title: Role of FcRgamma and factor XIIIA in coated platelet formation.
abstract: Platelet activation in response to dual stimulation with collagen and thrombin results in the formation of a subpopulation of activated platelets known as coated platelets. Coated platelets are characterized by high surface levels of alpha-granule proteins and phosphatidylserine, which support the assembly of procoagulant protein complexes. Using murine models, we tested the hypothesis that the collagen receptor-associated molecule FcRgamma and the transglutaminase factor XIIIA are required for the formation of coated platelets. Following dual stimulation with the collagen receptor agonist convulxin and thrombin, 68% of platelets from C57BL/6 mice acquired the coated platelet phenotype, defined by high surface levels of fibrinogen and von Willebrand factor and decreased binding of the alphaIIbbeta3 activation-dependent antibody PE-JON/A. In FcRgamma-/- mice, only 10% of platelets became "coated" after dual stimulation with convulxin plus thrombin (P < .05 vs C57BL/6 platelets). Decreased coated platelet formation in FcRgamma-/- platelets was accompanied by decreased annexin V binding (P < .01) and decreased platelet procoagulant activity (P < .05). Platelets from FXIIIA-/- mice did not differ from control platelets in coated platelet formation or annexin V binding. We conclude that FcRgamma, but not factor XIIIA, is essential for formation of highly procoagulant coated platelets following dual stimulation with collagen and thrombin.
authors.affiliation: Department of Pediatrics, University of Iowa College of Medicine, Iowa City, IA 52242, USA.
authors.forename: Shawn M
authors.initials: SM
authors.lastname: Jobe
authors.forename: Lorie
authors.initials: L
authors.lastname: Leo
authors.forename: Joshua S
authors.initials: JS
authors.lastname: Eastvold
authors.forename: Gerhard
authors.initials: G
authors.lastname: Dickneite
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Ratliff
authors.forename: Steven R
authors.initials: SR
authors.lastname: Lentz
authors.forename: Jorge
authors.initials: J
authors.lastname: Di Paola
mesh_terms: D000818:Animals; D017304:Annexin A5 / Q000378:metabolism; D001792:Blood Platelets / Q000166:cytology* / Q000378:metabolism*; D002417:Cattle; D002454:Cell Differentiation; D026122:Factor XIIIa / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D019007:P-Selectin / Q000378:metabolism; D011485:Protein Binding; D017452:Receptors, IgG / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors
chemical_list: D017304:Annexin A5; D019007:P-Selectin; D017452:Receptors, IgG; D026122:Factor XIIIa