摘要
The regulation of DNA topoisomerase I was studied in human T lymphocytes following phytohemagglutinin (PHA) stimulation. As T lymphocytes began to enter the S phase 24 h after stimulation, there was a rapid increase in DNA topoisomerase I mRNA. The level of DNA topoisomerase I mRNA increased continuously over the next 18 h and peaked (>50-fold increase) 42 h after stimulation with PHA. A concomitant increase in DNA topoisomerase I protein was also observed. However, the maximal increase in DNA topoisomerase I protein was only 6-fold. To explain the quantitative difference between the mRNA and protein levels, we investigated the change in the rates of DNA topoisomerase I protein synthesis versus degradation in human T lymphocytes following PHA stimulation. The increase in the mRNA parallels the increase in protein synthesis. However, the half-life of the enzyme protein was reduced to 9 h in proliferating T lymphocytes compared to a half-life of 36 h in resting lymphocytes. These results indicate that, in addition to the growth-regulated increase in the expression of DNA topoisomerase I, there was also a concomitant increase in the degradation of DNA topoisomerase I protein.
原文 | 英語 |
---|---|
頁(從 - 到) | 18982-18986 |
頁數 | 5 |
期刊 | Journal of Biological Chemistry |
卷 | 268 |
發行號 | 25 |
出版狀態 | 已發佈 - 9月 5 1993 |
對外發佈 | 是 |
ASJC Scopus subject areas
- 生物化學