Polyamine regulation of the synthesis of thymidine kinase in bovine lymphocytes
Abstract
Concanavalin A-activated lymphocytes were made polyamine deficient by treatment with alpha-difluoromethylornithine and ethylglyoxal bis(guanylhydrazone). Thymidine kinase activity in polyamine-deficient cells was 17% of the level in normal cells. Thymidine kinase mRNA increased with time after concanavalin A activation and reached a maximum at 36 h after concanavalin A addition. The amount of thymidine kinase mRNA in polyamine-deficient cells was approximately 75% of that in normal cells. The transcription of thymidine kinase gene in isolated nuclei of polyamine-deficient cells was also 75% of that from normal cells. The turnover rate of thymidine kinase mRNA in both normal and polyamine-deficient cells was nearly equal. In normal cells, 95% of thymidine kinase mRNA was polysome associated, while in polyamine-deficient cells, 60% of the mRNA was polysome associated. In addition, the size of polysomes associated with thymidine kinase mRNA in polyamine-deficient cells was smaller than that in normal cells. Synthesis of thymidine kinase was stimulated approximately seven-fold by 0.3 mM spermidine in a rabbit reticulocyte polyamine-free protein synthetic system. The half-life of thymidine kinase activity in both normal and polyamin...Continue Reading
References
Evidence for transcriptional and post-transcriptional control of the cellular thymidine kinase gene.
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