Role of the simian virus 40 gene A product in regulation of DNA synthesis in transformed cells.
AUTOR(ES)
Butel, J S
RESUMO
Cells transformed by tsA mutants of simian virus 40 (SV40) are temperature sensitive for the maintenance of the transformed phenotype. The kinetics of induction of DNA synthesis were determined for hamster cell transformants shifted to the permissive temperature after a 48-h serum arrest at the nonpermissive temperature. DNAsynthesis was initiated in the tsA transformants by 8 h after shiftdown was maximal by 12 h. The presence or absence of fetal bovine serum at the time of temperature shift had no effect on the kinetics of initiation of DNA synthesis. Analysis of TTP in tsA transformants revealed similar levels of incorporation of [3H]thymidine into TTP at both permissive and nonpermissive temperatures. Autoradiography revealed that by 12 h after a shift to the permissive temperature, approximately 50% of the cells exhibited labeled nuclei after a 60-min pulse with [3H]thymidine, indicating that a majority of the cells were actively synthesizing DNA. By 8 to 12 h after a shiftup of confluent tsA transformants to the nonpermissive temperature, the number of labeled nuclei was reduced to approximately 16%, regardless of serum concentration. These data indicate that the SV40 gene A product, either directly or indirectly, regulates cellular DNA synthesis in transformed cells.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=525884Documentos Relacionados
- Simian virus 40 gene A regulation of cellular DNA synthesis. II. In nonpermissive cells.
- Simian virus 40 gene A regulation of cellular DNA synthesis. I. In permissive cells.
- Presence of free viral DNA in simian virus 40-transformed nonproducer cells.
- DNA-transformed murine teratocarcinoma cells: regulation of expression of simian virus 40 tumor antigen in stem versus differentiated cells.
- Transcription of the simian virus 40 genome in DNA-transformed murine teratocarcinoma stem cells.