title: Involvement of Src kinases and PLCgamma2 in clot retraction.
abstract: The integrin alpha(IIb)beta(3) plays a critical role in mediating clot retraction by platelets which is important in vivo in consolidating thrombus formation. Actin-myosin interaction is essential for clot retraction. In the present study, we demonstrate that the structurally distinct Src kinase inhibitors, PP2 and PD173952, significantly reduced the rate of clot retraction, but did not prevent it reaching completion. This effect was accompanied by abolition of alpha(IIb)beta(3)-dependent protein tyrosine phosphorylation, including PLCgamma2. A role for PLCgamma2 in mediating clot retraction was demonstrated using PLCgamma2-deficient murine platelets. Furthermore, platelet adhesion to fibrinogen leads to MLC phosphorylation through a pathway that is inhibited by PP2 and by the PLC inhibitor, U73122. These results demonstrate a partial role for Src kinase-dependent activation of PLCgamma2 and MLC phosphorylation in mediating clot retraction downstream of integrin alpha(IIb)beta(3).
authors.affiliation: Department of Clinical and Laboratory Medicine, Faculty of Medicine, Yamanashi University, 1110 Shimokato, Chuo, Yamanashi, 409-3898, Japan. katsuei@yamanashi.ac.jp
authors.forename: Katsue
authors.initials: K
authors.lastname: Suzuki-Inoue
authors.forename: Craig E
authors.initials: CE
authors.lastname: Hughes
authors.forename: Osamu
authors.initials: O
authors.lastname: Inoue
authors.forename: Makoto
authors.initials: M
authors.lastname: Kaneko
authors.forename: Olga
authors.initials: O
authors.lastname: Cuyun-Lira
authors.forename: Toshiro
authors.initials: T
authors.lastname: Takafuta
authors.forename: Steve P
authors.initials: SP
authors.lastname: Watson
authors.forename: Yukio
authors.initials: Y
authors.lastname: Ozaki
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000187:drug effects / Q000502:physiology; D003018:Clot Retraction / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D008954:Models, Biological; D018994:Myosin Light Chains / Q000097:blood; D051966:Phospholipase C gamma / Q000097:blood* / Q000172:deficiency; D010766:Phosphorylation; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D015398:Signal Transduction; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000097:blood*
chemical_list: D018994:Myosin Light Chains; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D047428:Protein Kinase Inhibitors; D019061:src-Family Kinases; D051966:Phospholipase C gamma