De Benedetti A, Joshi-Barve S, Rinker-Schaeffer C, Rhoads R E
Department of Biochemistry, University of Kentucky Medical Center, Lexington 40536.
Mol Cell Biol. 1991 Nov;11(11):5435-45. doi: 10.1128/mcb.11.11.5435-5445.1991.
HeLa cells were transformed to express antisense RNA against initiation factor eIF-4E mRNA from an inducible promoter. In the absence of inducer, these cells (AS cells) were morphologically similar to control cells but grew four- to sevenfold more slowly. Induction of antisense RNA production was lethal. Both eIF-4E mRNA and protein levels were reduced in proportion to the degree of antisense RNA expression, as were the rates of protein synthesis in vivo and in vitro. Polysomes were disaggregated with a concomitant increase in ribosomal subunits. Translation in vitro was restored by addition of the initiation factor complex eIF-4F but not by eIF-4E alone. Immunological analysis revealed that the p220 component of eIF-4F was decreased in extracts of AS cells and undetectable in AS cells treated with inducer, suggesting that p220 and eIF-4E levels are coordinately regulated. eIF-4A, another component of eIF-4F, was unaltered.
将HeLa细胞进行转化,使其从一个可诱导启动子表达针对起始因子eIF - 4E mRNA的反义RNA。在没有诱导剂的情况下,这些细胞(AS细胞)在形态上与对照细胞相似,但生长速度慢4至7倍。反义RNA产生的诱导是致死性的。eIF - 4E mRNA和蛋白质水平与反义RNA表达程度成比例降低,体内和体外蛋白质合成速率也是如此。多核糖体解聚,同时核糖体亚基增加。通过添加起始因子复合物eIF - 4F可恢复体外翻译,但单独添加eIF - 4E则不能。免疫分析显示,eIF - 4F的p220组分在AS细胞提取物中减少,在用诱导剂处理的AS细胞中无法检测到,这表明p220和eIF - 4E水平受到协同调节。eIF - 4F的另一个组分eIF - 4A未发生改变。