Dice J F
J Biol Chem. 1982 Dec 25;257(24):14624-7.
Ribonuclease A was introduced into the cytoplasm of IMR-90 human diploid fibroblasts by red cell-mediated microinjection. Early passage fibroblasts degraded ribonuclease A with a half-life of approximately 90 h in the presence of 10% fetal calf serum and enhanced the degradative rate 1.6-fold upon serum withdrawal. Senescent cells degraded ribonuclease A more slowly with half-lives ranging between 125 and 250 h and had diminished capacities to enhance the catabolism of this protein during serum starvation. Decreased protein degradation in senescent cells was also evident for microinjected RNase S-protein, RNase B, aldolase, lysozyme, and the synthetic copolymer polyglutamate: tyrosine:alanine (1:1:1). These alterations in the mechanisms and regulation of intracellular protein degradation may contribute to several biochemical abnormalities characteristic of aging cells and organisms.
通过红细胞介导的显微注射法，将核糖核酸酶A导入IMR - 90人二倍体成纤维细胞的细胞质中。早期传代的成纤维细胞在10%胎牛血清存在的情况下，以约90小时的半衰期降解核糖核酸酶A，血清撤除后降解速率提高1.6倍。衰老细胞降解核糖核酸酶A的速度较慢，半衰期在125至250小时之间，并且在血清饥饿期间增强该蛋白质分解代谢的能力减弱。对于显微注射的核糖核酸酶S蛋白、核糖核酸酶B、醛缩酶、溶菌酶以及合成共聚物聚谷氨酸：酪氨酸：丙氨酸（1:1:1），衰老细胞中蛋白质降解减少也很明显。细胞内蛋白质降解机制和调节的这些改变可能导致衰老细胞和生物体的几种生化异常。
