title: Dok-2 adaptor protein regulates the shear-dependent adhesive function of platelet integrin αIIbβ3 in mice.
abstract: The Dok proteins are a family of adaptor molecules that have a well defined role in regulating cellular migration, immune responses, and tumor progression. Previous studies have demonstrated that Doks-1 to 3 are expressed in platelets and that Dok-2 is tyrosine-phosphorylated downstream of integrin αIIbβ3, raising the possibility that it participates in integrin αIIbβ3 outside-in signaling. We demonstrate that Dok-2 in platelets is primarily phosphorylated by Lyn kinase. Moreover, deficiency of Dok-2 leads to dysregulated integrin αIIbβ3-dependent cytosolic calcium flux and phosphatidylinositol(3,4)P2 accumulation. Although agonist-induced integrin αIIbβ3 affinity regulation was unaltered in Dok-2(-/-) platelets, Dok-2 deficiency was associated with a shear-dependent increase in integrin αIIbβ3 adhesive function, resulting in enhanced platelet-fibrinogen and platelet-platelet adhesive interactions under flow. This increase in adhesion was restricted to discoid platelets and involved the shear-dependent regulation of membrane tethers. Dok-2 deficiency was associated with an increased rate of platelet aggregate formation on thrombogenic surfaces, leading to accelerated thrombus growth in vivo. Overall, this study defines an important role for Dok-2 in regulating biomechanical adhesive function of discoid platelets. Moreover, they define a previously unrecognized prothrombotic mechanism that is not detected by conventional platelet function assays.
authors.affiliation: From the Australian Centre for Blood Diseases, Faculty of Medicine, Nursing, and Health Sciences, Monash University, Alfred Medical Research and Education Precinct, Commercial Road, Melbourne, Victoria 3004.
authors.forename: Sascha C
authors.initials: SC
authors.lastname: Hughan
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Spring
authors.forename: Simone M
authors.initials: SM
authors.lastname: Schoenwaelder
authors.forename: Sharelle
authors.initials: S
authors.lastname: Sturgeon
authors.forename: Imala
authors.initials: I
authors.lastname: Alwis
authors.forename: Yuping
authors.initials: Y
authors.lastname: Yuan
authors.forename: James D
authors.initials: JD
authors.lastname: McFadyen
authors.forename: Erik
authors.initials: E
authors.lastname: Westein
authors.forename: Duncan
authors.initials: D
authors.lastname: Goddard
authors.forename: Akiko
authors.initials: A
authors.lastname: Ono
authors.forename: Yuji
authors.initials: Y
authors.lastname: Yamanashi
authors.forename: Warwick S
authors.initials: WS
authors.lastname: Nesbitt
authors.forename: Shaun P
authors.initials: SP
authors.lastname: Jackson
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000172:deficiency / Q000378:metabolism*; D000818:Animals; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D005340:Fibrinogen / Q000494:pharmacology; D018056:Hemorheology / Q000187:drug effects; D006801:Humans; D055767:Immobilized Proteins / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism; D010750:Phosphoproteins / Q000172:deficiency / Q000378:metabolism*; D010973:Platelet Adhesiveness / Q000187:drug effects / Q000502:physiology*; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000378:metabolism*; D033081:Shear Strength / Q000187:drug effects; D013927:Thrombosis / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D013997:Time Factors
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C498444:Dok2 protein, mouse; D055767:Immobilized Proteins; D018129:Phosphatidylinositol Phosphates; D010750:Phosphoproteins; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; C060980:phosphatidylinositol 3,4-diphosphate; D005340:Fibrinogen; D002118:Calcium
keywords: Adaptor Proteins; Integrins; Mechanotransduction; Platelets; Shear Stress