SV40-INDUCED CHANGES OF GROWTH REGULATION IN HOST CELLS

培养物中正常细胞和转化细胞之间的主要区别是 正常细胞限制其生长的能力，当细胞变得 融合，而转化细胞继续分裂下，这些 情节 理解这种差异的基础是显而易见的 对致癌转化研究的重要性。 在这种接触中 抑制了正常细胞中许多与DNA有关的酶的水平， 新陈代谢非常低。 在生长的细胞中，这些酶的水平是 与细胞周期相关，在S期非常高，在其他阶段低 在细胞周期中。 本文提出的研究目标是： 应用是为了了解这种调节的分子基础， 病毒SV 40感染对它的影响。 将被研究的基因是人胸苷激酶（Tk）基因。 胸苷激酶是嘧啶补救途径中的酶，并且 催化胸苷磷酸化为dTMP。 的分子基础 Tk调控将使用克隆的Tk基因和各种 技术包括体外诱变、DNA转染和mRNA， 酶分析，以确定所需的人类DNA序列， 正常调节，以及调节发生的阶段。 当 用病毒SV 40、Tk和其它酶感染汇合的细胞 水平被诱导2-20倍。 这种诱导也将被调查 使用类似的分子技术。

A major difference between normal and transformed cells in culture is the ability of normal cells to limit their growth when the cells become confluent, while transformed cells continue to divide under these circumstances. Understanding the basis of this difference is of obvious importance to the study of oncogenic transformation. In such contact inhibited normal cells, the levels of many of the enzymes involved in DNA metabolism are very low. In growing cells, the levels of these eyzymes are linked to the cell cycle, being very high in S phase, and low at other times in the cell cycle. The goal of the research proposed in this application is to understand the molecular basis of this regulation, and the effect that infection with the virus SV40 has upon it. The specific gene that will be studied is the human thymidine kinase (Tk) gene. Thymidine kinase is an enzyme in the pyrimidine salvage pathway, and catalyzes the phosphorylation of thymidine to dTMP. The molecular basis of Tk regulation will be investigated using a cloned Tk gene and various techniques including in vitro mutagenesis, DNA transfections, and mRNA and enzyme analyses, in order to determine the human DNA sequences required for normal regulation, and the stage at which regulation occurs. When confluent cells are infected with the virus SV40, Tk and other enzyme levels are induced 2-20 fold. This induction will also be investigated using similar molecular techniques.