内毒素诱导血小板20kD蛋白磷酸化、钙转运及纤维蛋白原受体显露

Endotoxin induces phosphorylation of 20kD protein Ca^(2+) transportation and fibrinogen receptor exposure in human platelets

本文观察了E.Coli大肠杆菌内毒素对人血小板蛋白磷酸化,钙转运及纤维蛋白原受体的影响,实验采用SDS-凝胶电泳及放射自显影技术分离血小板蛋白并测定其磷酸化程度,结果发现内毒素刺激血小板后,内源性20kD蛋白迅速磷酸化,这一作用在细胞外Ca^(2+)存在时明显加强。同时还观察到血小板对^(45)Ca^(2+)摄取加强,胞浆游离Ca^(2+)升高,血小板结合荧光标记纤维蛋白原的阳性细胞百分率明显提高。提示:内毒素可能通过诱导Ca^(2+)动员,蛋白磷酸化,使血小板纤维蛋白原受体显露,导致血小板聚集。

The effects of endotoxin on protein phosphorylation, calcium transportation and fibrinogen receptor exposure in human platelets were studied. The proteins from ^(32)P- labled human platelets were separated by SDS-polyacrylamide gel electroporesis, then the protein phosphorylation were observed with autoradiographic method. The result showed that endotoxin rapidly induced phosphorylation of 20kD protein. An enhanced phosphory- lation of 20kD protein was seen in the presence of extracellular Ca^(2+). Meanwhile, endo- toxin induced an increase of the cytoplasmic free Ca^(2+) concentration and promoted ^(45)Ca_(2+) uptake by platelets. In addition, the platelets to which FITC-labled fibrinogen was bound had increased. It suggested that the mechanism of endotoxin induced platelet aggregation involved in Ca^(2+) mobilization and protein phosphorylation, which caused the fibrinogen receptor exposure.