Chang Z F, Huang D Y
Department of Biochemistry, Chang Gung Medical College, Tao-Yuan, Taiwan, R.O.C.
Biochem Biophys Res Commun. 1994 Apr 15;200(1):16-27. doi: 10.1006/bbrc.1994.1408.
We have studied the activation of protein kinase C (PKC) during senescence of human IMR-90 fibroblasts by analyzing the phosphorylation of its in vivo substrate MARCKS (myristoylated alanine-rich C kinase substrate). It was found that the extent of TPA-induced phosphorylation of MARCKS was not significantly different between young and old IMR-90 fibroblasts. In contrast, the increase of MARCKS phosphorylation after serum stimulation was 4.5-fold in young fibroblasts as compared to 1.8-fold in old fibroblasts. Analysis of PKC by Western blotting showed that the levels of PKC were not changed during senescence of IMR-90 fibroblasts. However, the generation of diacylglycerol in response to serum stimulation declined in old fibroblasts. These results suggest that the efficiency of signal transduction mediated by diacylglycerol generation and PKC activation during the mitogenic response is age-dependent in human IMR-90 fibroblasts.
我们通过分析蛋白激酶C（PKC）的体内底物MARCKS（富含肉豆蔻酰化丙氨酸的C激酶底物）的磷酸化情况，研究了人IMR - 90成纤维细胞衰老过程中PKC的激活。结果发现，佛波酯（TPA）诱导的MARCKS磷酸化程度在年轻和衰老的IMR - 90成纤维细胞之间没有显著差异。相比之下，血清刺激后，年轻成纤维细胞中MARCKS磷酸化的增加是4.5倍，而衰老成纤维细胞中是1.8倍。通过蛋白质免疫印迹法（Western blotting）分析PKC表明，在IMR - 90成纤维细胞衰老过程中PKC的水平没有变化。然而，衰老成纤维细胞中对血清刺激产生的二酰甘油减少。这些结果表明，在人IMR - 90成纤维细胞的有丝分裂反应中，由二酰甘油生成和PKC激活介导的信号转导效率是年龄依赖性的。
