Bodie S L, Ford I, Greaves M, Nixon G F
Department of Biomedical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK.
Biochem Biophys Res Commun. 2001 Sep 14;287(1):71-6. doi: 10.1006/bbrc.2001.5547.
Thrombin-induced activation of RhoA and its involvement in the regulation of myosin II light chain(20) phosphorylation (MLC-P) in alpha-toxin permeabilized platelets was investigated. Permeabilized platelets, expressing normal levels of P-selectin, displayed a Ca(2+)-dependent increase in shape change and MLC-P. Thrombin activated RhoA as measured by a rhotekin-binding assay within 30 s of stimulation under conditions of constant Ca(2+). Under the same conditions and timecourse, thrombin or GTPgammaS induced an increase in MLC-P and platelet shape change which was not dependent on an increase in Ca(2+). The thrombin- and GTPgammaS-induced MLC-P in constant Ca(2+) was inhibited by the addition of Y27632, a Rho-kinase inhibitor. This study directly demonstrates that thrombin can activate RhoA in platelets in a timecourse compatible with a role in increasing MLC-P and shape change (not involving an increase in Ca(2+)). This is also Rho-kinase-dependent.
研究了凝血酶诱导的RhoA激活及其在α-毒素通透的血小板中对肌球蛋白轻链（20）磷酸化（MLC-P）调节的参与情况。表达正常水平P-选择素的通透血小板在形状变化和MLC-P方面表现出钙依赖性增加。在细胞内钙离子浓度（Ca(2+)）恒定的条件下，通过rhotekin结合试验测量，凝血酶在刺激后30秒内激活了RhoA。在相同条件和时间进程下，凝血酶或GTPγS诱导MLC-P增加和血小板形状变化，这并不依赖于Ca(2+)的增加。添加Rho激酶抑制剂Y27632可抑制在Ca(2+)恒定情况下凝血酶和GTPγS诱导的MLC-P。这项研究直接表明，凝血酶可在与增加MLC-P和形状变化（不涉及Ca(2+)增加）相关的时间进程中激活血小板中的RhoA。这也是Rho激酶依赖性的。
