Polyoma virus and cyclic AMP-mediated control of dihydrofolate reductase mRNA abundance in methotrexate-resistant mouse fibroblasts.

作者：Rodney Eugene Kellems, Vera B. Morhenn, Eva A. Pfendt, Fred W. Alt, Robert Schimke · 发表于：Journal of Biological Chemistry · 年份：1979 · DOI：10.1016/s0021-9258(17)37919-x · 被引用次数：88 · 研究领域：Polyomavirus and related diseases、Virus-based gene therapy research、Polyamine Metabolism and Applications

As a model cell culture system for studying polyoma-mediated control of host gene expression, we isolated methotrexate-resistant 3T6 cells in which one of the virus-induced enzymes, dihydrofolate reductase, is a major cellular protein. In highly methotrexate-resistant cell lines dihydrofolate reductase synthesis accounts for over 10% that of soluble portein, corresponding to an increase of approximately 100-fold over the level in parental cells. This increase in dihydrofolate reductase synthesis is due to a corresponding increase in the abundance of dihydrofolate reductase mRNA and gene sequences. We have used these cells to show that infection with polyoma virus results in a 4- to 5-fold increase in the relative rate of dihydrofolate reductase synthesis and a corresponding increase in dihydrofolate reductase mRNA abundance. The increase in dihydrofolate reductase synthesis begins 15 to 20 h after infection and continues to increase until cell lysis. These observations represent the first direct evidence that viral infection of eukaryotic cells results in the increased synthesis of a specific cellular enzyme and an increase in the abundance of a specific cellular mRNA. In order to gain additional insight into the control of dihydrofolate reductase synthesis we examined other parameters affecting dihydrofolate reductase synthesis. We found that the addition of fresh serum to stationary phase cells results in a 2-fold stimulation of dihydrofolate reductase synthesis, beginning ...