Increase in expression level of p21sdi1/cip1/waf1 with increasing division age in both normal and SV40-transformed human fibroblasts.
p21sdi1/cip1/waf1 gene, whose product inhibits Cyclin/Cdk kinase and blocks cell proliferation, is known to be up-regulated by p53 and to be expressed at high levels in senescent human fibroblasts. The present paper reports that p21 expression level was much lower in SV40tsT-antigen transformed cells than in normal cells and that after inactivation of tsT-antigen it recovered to that of normal cells. However, cell division age-dependent increase in expression level of p21 occurred not only in normal human fibroblasts but also in SV40tsT-antigen transformed fibroblasts with active T-antigen. These results suggest that cell age-dependent increase in p21 occurs independently upon the function of T-antigen binding proteins including p53, while the basal expression level of p21 is up-regulated by p53 as previously reported.
Tahara
H
H
Department of Cellular and Molecular Biology, Hiroshima University School of Medicine, Japan.
Sato
E
E
Noda
A
A
Ide
T
T
D000952:Antigens, Polyomavirus Transforming / Q000502:physiology; D002461:Cell Line, Transformed; D002471:Cell Transformation, Neoplastic / Q000378:metabolism*; D016922:Cellular Senescence; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000032:analysis / Q000235:genetics*; D004247:DNA / Q000096:biosynthesis; D005347:Fibroblasts / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D047428:Protein Kinase Inhibitors; D013539:Simian virus 40 / Q000276:immunology; D013696:Temperature; D016159:Tumor Suppressor Protein p53 / Q000032:analysis
D000952:Antigens, Polyomavirus Transforming; C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D047428:Protein Kinase Inhibitors; D016159:Tumor Suppressor Protein p53; D004247:DNA