凝血酶信号传导过程中PI3-K与MLCK激酶的作用

Role of Phosphatidylinositol 3-Kinase and Myosin Light Chain Kinase during the Activation of Thrombin Receptors

本研究比较凝血酶受体活化过程中不同浓度的wortmannin对血小板聚集率以及血小板膜表面活化标记物糖蛋白GPIb表达的影响,探讨脂酰肌醇-3-激酶(PI3-K)与肌球蛋白轻链激酶(MLCK)在凝血酶信号传递机制中的作用。分别以凝血酶受体活化肽PAR1-AP(SFLLRN)与PAR4-AP(AYPGKF)诱导血小板活化。检测100nmol/L wortmannin(抑制PI3-K)与10μmol/L wortmannin(抑制MLCK)作用过程中血小板聚集与血小板膜表面糖蛋白GPIb的改变。结果显示:wortmannin作用对两类凝血酶受体诱导血小板活化的过程均有不同程度的影响。100nmol/L的wortmannin部分抑制PAR1-AP引起的血小板聚集,对PAR4-AP诱导的聚集过程没有影响;10μmol/Lwortmannin明显抑制两类PAR肽引起的血小板活化,抑制程度达到60%-80%,仅出现少部分聚集。流式细胞仪检测显示,GPIbα的动态分布过程中100nmol/L wortmannin能部份抑制GPIbα向胞内移动,PAR1-AP刺激后5分钟内wort-mannin起效明显(1、2、5分钟p<0.05),对PAR4-AP的反应则稍延迟,在2到10分钟有意义(2、5、10分钟p<0.05)。10μmol/L wortmannin对整个PAR活化过程中的GPIbα逆转没有任何影响,只对PAR1刺激过程中GPIbα的恢复起作用,延缓GPIbα重返血小板膜表面的进程;而PAR4-AP作用后各时间段GPIbα的动态分布不受10μmol/L wortmannin任何影响。结论:PI3-K与MLCK在凝血酶受体的活化过程中作用不同,PI3-K在GPIbα内转的短暂过程中起着重要作用;而MLCK磷酸化仅仅对PAR1受体介导的GPIbα回复起促进作用。

The objective of study was to compare the influences of worttnannin on platelet aggregation and platelet membrane surface glycoproteins GPIb expression after thrombin receptor activation, and to investigate the role of phosphatidylinositol 3-kinase （PI3-K） and myosin light chain kinase （MLCK） in the course of thrombin receptor activation. Peptide SFLLRN （PAR1-AP） and AYPGKF （PAR4-AP）were used for stimulating platelet, and the changes of platelet aggregation and GPIb were analyzed with 100 nmol/L wortmannin （inhibitor of PI3-K） and 10 μmol/L wortmannin （ inhibitor of MLCK）. The results indicated that the platelet activation was influenced by either concentration of wortmannin in response to PAR stimulation. Platelet aggregation was apparently inhibited by 10 μmol/L wortmannin through both PAR peptides, and was slightly inhibited by 100 nmol/L wortmannin only under PAR1-AP activation. In addition, GPIbα interalisation was partly inhibited by 100nmol/L wortmannin in response to PAR1 （p 〈0.05 at 1, 2 ,5 min） and PAR4 （p 〈 0.05 at 2 ,5,10 min） activation. Meanwhile, 10 μmol/L wortmannin induced little change for GPIbct cent- ralisation in the course of PAR activation, with a delayed restoration of surface GPIboL observed under PAR1-AP activation, and no change of GPlba redistribution existed under PAR4-AP activation. It is concluded that the different roles of PI3-K and MLCK exist in the course of thrombin receptor activation. PI3-K accelerates the short course of GPIb centralisation for two PAR signal pathways, while MLCK inhibits the restoration of GP1bα in PAR1 pathway.