LaMorte V J, Kennedy E D, Collins L R, Goldstein D, Harootunian A T, Brown J H, Feramisco J R
Department of Medicine, University of California, San Diego, La Jolla 92093-0636.
J Biol Chem. 1993 Sep 15;268(26):19411-5.
Thrombin stimulation of 1321N1 astrocytoma cells results in polyphosphoinositide hydrolysis, Ca2+ mobilization, AP-1-mediated transcriptional activation, and DNA replication. Thrombin stimulation also activates Ras as assessed by an increase in the proportion of Ras in a GTP bound state. We examined the functional requirement for endogenous Ras protein in mediating thrombin-induced responses. Microinjection of a dominant interfering mutant of H-Ras into 1321N1 cells inhibited DNA synthesis in response to thrombin as did microinjection of an inhibitory antibody to Ras. Stimulation of AP-1-mediated transcriptional activity was also reduced by the expression of interfering Ras mutants. However, neither the stimulation of polyphosphoinositide hydrolysis nor the mobilization of intracellular Ca2+ was dependent on endogenous Ras function. These observations indicate that thrombin stimulation of mitogenesis requires Ras protein function. Our data suggest that the G-protein-coupled thrombin receptor stimulates pathways, which in part are convergent with those stimulated by tyrosine kinase growth factor receptors.
凝血酶刺激1321N1星形细胞瘤细胞会导致多磷酸肌醇水解、钙离子动员、AP-1介导的转录激活以及DNA复制。凝血酶刺激还会激活Ras，这可通过GTP结合状态下Ras比例的增加来评估。我们研究了内源性Ras蛋白在介导凝血酶诱导反应中的功能需求。将H-Ras的显性干扰突变体显微注射到1321N1细胞中会抑制凝血酶诱导的DNA合成，注射Ras抑制性抗体也有同样效果。干扰性Ras突变体的表达也会降低AP-1介导的转录活性的刺激。然而，多磷酸肌醇水解的刺激和细胞内钙离子的动员均不依赖内源性Ras功能。这些观察结果表明，凝血酶刺激的有丝分裂需要Ras蛋白功能。我们的数据表明，G蛋白偶联的凝血酶受体刺激的信号通路部分与酪氨酸激酶生长因子受体刺激的信号通路相同。
