genetic analysis of the role of protein kinase cθ in platelet function and thrombus formation遗传分析蛋白激酶的作用cθ血小板功能和血栓形成.pdfVIP

Genetic Analysis of the Role of Protein Kinase Ch in Platelet Function and Thrombus Formation 1 1 2 2 2 Kellie J. Hall , Matthew T. Harper , Karen Gilio , Judith M. Cosemans , Johan W. M. Heemskerk , Alastair W. Poole1* 1 Department of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom, 2 Department of Biochemistry, University of Maastricht, Maastricht, The Netherlands Abstract Background: PKCh is a novel protein kinase C isozyme, predominately expressed in T cells and platelets. PKCh 2/ 2 T cells exhibit reduced activation and PKCh 2/ 2 mice are resistant to autoimmune disease, making PKCh an attractive therapeutic target for immune modulation. Collagen is a major agonist for platelets, operating through an immunoreceptor-like signalling pathway from its receptor GPVI. Although it has recently been shown that PKCh positively regulates outside-in signalling through integrin aIIbb3 in platelets, the role of PKCh in GPVI-dependent signalling and functional activation of platelets has not been assessed. Methodology/Principal Findings: In the present study we assessed static adhesion, cell spreading, granule secretion, integrin aIIbb3 activation and platelet aggregation in washed mouse platelets lacking PKCh. Thrombus formation on a collagen-coated surface was assessed in vitro under flow. PKCh 2/ 2 platelets exhibited reduced static adhesion and filopodia generation on fibrinogen, suggesting that PKCh positively regulates outside-in signalling, in agreement with a previous report. In contrast, PKCh 2/ 2 platelets also exhibited markedly enhanced GPVI-dependent a-granule secretion, although dense granule secretion wa