The introduction of dominant-negative p53 mutants suppresses temperature shift-induced senescence in immortal human fibroblasts expressing a thermolabile SV40 large T antigen.
Immortal human fibroblasts, SVts8 cells, which express a heat-labile SV40 large T antigen, induces a senescence-like phenomenon in response to upward shift in temperature. Cells with arrested division show strong induction of senescence-associated beta-galactosidase. We examined how p53 and pRB are involved in this phenomenon since they are major targets of the T antigen. Transfection of cells with plasmids encoding the wild-type T antigen or human papilloma virus type 16 E6/E7 proteins completely abolished the arrest in cell division, a plasmid encoding the E6 protein suppressed it markedly, while a plasmid encoding E7 had no effect. Plasmids encoding dominant-negative p53 mutants also suppressed the arrest in cell division to various degrees. Upon temperature shift, p21 mRNA was upregulated 10-fold in SVts8 cells, but only slightly in clones expressing the wild-type T antigen or dominant-negative p53 mutants. These data demonstrate that p53 plays a major role in this senescence-like phenomenon.
Kihara Institute for Biological Research, Yokohama City University, Totsuka-ku, Yokohama, 244-0813, Japan.
M
M
Fujii
A
A
Ide
K
K
Nakabayashi
A
A
Joguchi
H
H
Ogino
D
D
Ayusawa
D000952:Antigens, Polyomavirus Transforming / Q000096:biosynthesis / Q000235:genetics*; D002455:Cell Division / Q000235:genetics; D002461:Cell Line, Transformed; D002472:Cell Transformation, Viral / Q000235:genetics*; D005347:Fibroblasts / Q000473:pathology / Q000502:physiology*; D005786:Gene Expression Regulation; D006801:Humans; D009154:Mutation; D013696:Temperature; D016159:Tumor Suppressor Protein p53 / Q000235:genetics*
D000952:Antigens, Polyomavirus Transforming; D016159:Tumor Suppressor Protein p53