Kihara F, Ninomiya-Tsuji J, Ishibashi S, Ide T
Mech Ageing Dev. 1986 Nov 28;37(1):27-40. doi: 10.1016/0047-6374(86)90115-6.
When quiescent young or senescent human diploid cells, TIG-1, were metabolically labeled with 32Pi and stimulated with 10% fetal bovine serum, the phosphorylation of ribosomal S6 protein was enhanced in young cells but not in senescent cells while that of some other proteins were increased in both cells. Inability to stimulate the phosphorylation of S6 protein in senescent cells after serum addition may be the primary cause of the failure of enhancement in protein synthesis followed by the block of prereplicative events dependent on protein synthesis and thus of the failure of cells to enter S phase. However, when the cell-free preparation from serum-stimulated senescent cells was incubated with [gamma-32P]ATP, S6-kinase activity was stimulated and S6 in ribosomal fraction was susceptible to phosphorylation as observed in young cells. Differences in S6 phosphorylation of senescent cells between in vivo and in vitro was discussed.
当静止的年轻或衰老的人二倍体细胞TIG-1用³²Pi进行代谢标记并用10%胎牛血清刺激时，核糖体S6蛋白的磷酸化在年轻细胞中增强，而在衰老细胞中未增强，而其他一些蛋白的磷酸化在两种细胞中均增加。血清添加后衰老细胞中S6蛋白磷酸化无法被刺激可能是蛋白质合成增强失败的主要原因，随后依赖蛋白质合成的复制前事件受阻，从而导致细胞无法进入S期。然而，当将血清刺激的衰老细胞的无细胞制剂与[γ-³²P]ATP一起孵育时，S6激酶活性被刺激，核糖体组分中的S6易于磷酸化，这与在年轻细胞中观察到的情况相同。讨论了衰老细胞在体内和体外S6磷酸化的差异。
