表皮生长因子对正常细胞与转化细胞染色质蛋白激酶活性的影响

本文研究了正常C3H/10T1/2CI8细胞(一种源于小鼠胚胎的成纤维细胞,简称NC3H/10)与用~3H-TdR转化的C3H/10T1/2CI8细胞(简称TC3H/10)染色质蛋白激酶(CAPK)的作用物特异性,发现这两种细胞的CAPK均能以外源性酸性酪蛋白为作用物,而不以外源性碱性组蛋白为作用物,由此推测CAPK的天然作用物主要为非组蛋白。观察了表皮生长因子(EGF)对培养细胞的CAPK活性的影响,EGF能使NC_3H/10和TC3H/10的CAPK活性分别增加105.6％(P<0.01)和50.7％(P<0.01),后者增加的幅度仅为前者的1/2,说明转化细胞CAPK活性对EGF刺激的敏感性较正常细胞低。EGF和1-油酰-2-乙酰-消旋-甘油(OAG)对无细胞体系的CAPK活性无直接影响,提示EGF可能通过核内受体或OAG以外的其它第二信使来影响CAPK的活性。

Effect of Epidermal Growth Factor on the Activity of Chromatin-Associated Protein Kinases of Normal and Transformed C3H/10T1/2 CI8 Cells

The substrate specificity of chromatin-associated protein kinase (CAPK) of both normal C3H/10T1/2CI8 (NC3H/10) and 3H-TdR transformed C3H/10T1/2 C18(TC3H/10)cell lines was studied. It was found that casein, but not histone, was the in vitro substrate for CAPK from those two kinds of cells. therefore we suggest that the endogenous substrate for CAPK are probably chromatin nonhistone protein rather than histones. Our results showed that EGF could stimulate the CAPK activity of cultured cells. The activity of CAPK from NC3H/10 and TC3H/10 was increased 105.6% and 50.7% respectively. Suggesting that the CAPK activity of normal cells was more sensitive to EGF stimulation than that of transformed cells. Neither EGF or OAG(1-oleoyl-2-acetyl-rac-gly cerol) influenced directly on the CAPK activity of cell-free system,showing that EGF could stimulate the CAPK activity of cultured cells through the action of nuclear receptor or other message transducers except OAG.