The Regulation of Deoxypyrimidine Kinases in Normal, Transformed, and Infected Mouse Cells in Culture
The small DNA tumor viruses, such as SV40 and the adenoviruses, contain a limited amount of genetic information and yet can initiate a large number of changes in the cells they infect. For example, infection of resting or confluent monolayer cultures of mouse cells with SV40 results in an abortive (no virus production), nonkilling response where at least some early viral functions are expressed (10). A number of alterations in cellular functions have been detected as well. There is an increase in the specific activities of several enzymes involved in the biosynthesis of the deoxypyrimidine neucleotides and deoxyribonucleic acid (12). The rate of cellular DNA synthesis is markedly increased after viral infection, and these cells usually undergo one or several rounds of cell division (11). Infected cells frequently have an altered cell morphology and can divide even in the absence of normal cell serum factors (13). This series of complex events has been termed abortive transformation (15). Established mouse cell lines, such as 3T3 cells, grow until they reach characteristically low saturation densities, at which time the rate of cell division is drastically reduced. Viral-transformed cells have apparently overcome this regulatory control and grow to much higher saturation densities (18). It has been suggested that one or a limited number of viral gene products can alter the regulation of this type of growth control (9).
KeywordsKinase Activity Thymidine Kinase Mouse Cell Thymidine Kinase Activity Deoxycytidine Kinase
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