胰岛素对血管平滑肌细胞4E结合蛋白1和核糖体蛋白S6激酶磷酸化的刺激作用

Insulin Stimulates Phosphorylation of 4E-binding Protein 1 and p70 S6 Kinase in Vascular Smooth Muscle Cells

目的研究胰岛素对血管平滑肌细胞(VSMC)蛋白质合成翻译过程的两个调节子,4E-结合蛋白1(4E-BP1)和核糖体蛋白S6激酶,磷酸化的调节作用及其生物学意义。方法培养大鼠胸主动脉VSMC。用3H-亮氨酸和3H-TdR掺入法分别测定蛋白质合成和DNA合成;免疫印迹法检测4E-BP1和核糖体蛋白S6激酶的磷酸化。结果与对照相比,100nmol/L胰岛素显著增加了VSMC的3H-亮氨酸和3H-TdR掺入。同样浓度的胰岛素作用于VSMC,可以诱导4E-BP1和核糖体蛋白S6激酶发生磷酸化。二者的磷酸化分别于胰岛素刺激后,30min和10min达高峰。结论胰岛素可以刺激VSMC的4E-BP1和核糖体蛋白S6激酶发生磷酸化,这可能是胰岛素发挥促进VSMC生长作用的机制。

Objective To explore the regulatory effect of insulin on the phosphorylation of two translational regulators, 4E-binding protein 1 （4E-BP1） and p70 S6 kinase, in vascular smooth muscle cells （ VSMC）, and to investigate their functional significance. Methods VSMC obtained from rat thoracic aortas were cultured. Protein and DNA synthesis of VSMC was measured by ^3 H-leucine and ^3 H-TdR incorporation respectively. The phosphorylation of 4E-BP1 and p70 S6 kinase was detected by immunoblotting. Results Insulin （100 nmol/L） increased ^3 H-leucine incorporation and ^3 H-TdR incorporation in VSMC when compared with control. Insulin at similar concentration increased the phosphorylation of 4EBP1 and p70 S6 kinase, with the peaks occurring at 30 rain and 10 rain after the addition of insulin. Condusion Insulin induces the phosphorylation of 4E-BP1 and p70 S6 kinase in VSMC, which might play a role in the growth effect of the hormone.