Silber J R, Galick H, Wu J M, Siperstein M D
Department of Medicine, University of California, San Francisco.
Biochem J. 1992 Dec 15;288 ( Pt 3)(Pt 3):883-9. doi: 10.1042/bj2880883.
We have investigated the biochemical basis of the mevalonate dependence of DNA replication. Stimulating quiescent rat hepatoma cells to proliferate in the presence of compactin, an inhibitor of mevalonate synthesis, prevented DNA replication in as many as 80% of these cells. The percentage of cells that failed to replicate DNA increased with the increased duration of quiescence. Aphidicolin-sensitive DNA polymerase and ornithine decarboxylase activities were selectively decreased in compactin-treated cells, whereas RNA and protein synthesis, the level of dihydrofolate reductase and aphidicolin-resistant DNA polymerase activity were unaffected. Adding putrescine, the product of ornithine decarboxylase and the precursor of other polyamines, did not restore DNA replication. Our results demonstrate that the decreased activities of at least two DNA-replication enzymes are among the proximal causes of the failure of mevalonate-deprived cells to synthesize DNA. More importantly, our data indicate that a mevalonate-dependent factor(s) is progressively depleted during quiescence, and that inability to resynthesize this factor(s) may be the ultimate cause of the failure of resting cells to replicate DNA when stimulated to proliferate in the absence of mevalonate.
我们研究了DNA复制对甲羟戊酸依赖性的生化基础。在甲羟戊酸合成抑制剂洛伐他汀存在的情况下，刺激静止的大鼠肝癌细胞增殖，多达80%的这些细胞的DNA复制受到抑制。未能复制DNA的细胞百分比随着静止时间的延长而增加。在洛伐他汀处理的细胞中，对阿非科林敏感的DNA聚合酶和鸟氨酸脱羧酶活性选择性降低，而RNA和蛋白质合成、二氢叶酸还原酶水平以及对阿非科林耐药的DNA聚合酶活性未受影响。添加腐胺（鸟氨酸脱羧酶的产物和其他多胺的前体）并不能恢复DNA复制。我们的结果表明，至少两种DNA复制酶活性降低是甲羟戊酸缺乏的细胞无法合成DNA的近端原因之一。更重要的是，我们的数据表明，一种甲羟戊酸依赖性因子在静止期间逐渐耗尽，并且在没有甲羟戊酸的情况下，当受到刺激增殖时，静止细胞无法重新合成这种因子可能是其无法复制DNA的最终原因。
