Functional rescue of temperature-sensitive defects in the cell-cycle mutants of rat 3Y1 fibroblasts by the small t-antigen deletion mutant of simian virus 40.
We examined the effects of large T antigen of simian virus 40 (SV40) on the proliferation phenotypes of temperature-sensitive (ts) mutants of rat 3Y1 fibroblasts, which cease proliferating in the G1 phase of the cell cycle at a restrictive temperature (39.8 degrees C). Four ts mutants, each representing independent complementation groups, were transformed with the dl-884 mutant of SV40 which lacks the unique coding region for small t antigen. In the case of two ts mutants, their transformed derivatives did not cease proliferation at 39.8 degrees C. In the other two mutants, the transformed cells continued to enter the S phase but the cells became detached from the dishes thereafter, at 39.8 degrees C. The proliferation phenotypes of the dl-884-transformed cells at 39.8 degrees C were quite similar with those of the same mutants transformed with the wild-type SV40. These results indicate that large T antigen alone is sufficient to overcome the inhibition of cellular entry into S phase caused by four different ts defects and determines the proliferation phenotypes of the cells after entering the S phase at a restrictive temperature, and that small t antigen does not alter the cellular phenotypes determined by large T antigen.
Matsuzaki
A
A
Department of Virology, Kyushu University, Fukuoka, Japan.
Ohno
K
K
Ohtsu
M
M
Kimura
G
G
D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000235:genetics*; D002453:Cell Cycle; D002455:Cell Division; D002460:Cell Line; D002872:Chromosome Deletion; D005347:Fibroblasts / Q000166:cytology* / Q000502:physiology; D009154:Mutation; D010641:Phenotype; D051381:Rats; D011922:Rats, Mutant Strains; D013539:Simian virus 40 / Q000276:immunology*; D013696:Temperature
D000952:Antigens, Polyomavirus Transforming