Two dominant inhibitory mutants of p21ras interfere with insulin-induced gene expression.
Insulin induces a rapid activation of p21ras in NIH 3T3 and Chinese hamster ovary cells that overexpress the insulin receptor. Previously, we suggested that p21ras may mediate insulin-induced gene expression. To test such a function of p21ras more directly, we studied the effect of different dominant inhibitory mutants of p21ras on the induction of gene expression in response to insulin. We transfected a collagenase promoter-chloramphenicol acetyltransferase (CAT) gene or a fos promoter-luciferase gene into NIH 3T3 cells that overexpressed the insulin receptor. The activities of both promoters were strongly induced after treatment with insulin. This induction could be suppressed by cotransfection of two inhibitory mutant ras genes, H-ras(Asn-17) or H-ras(Leu-61,Ser-186). In particular, insulin-induced activation of the fos promoter was inhibited completely by H-ras(Asn-17). These results show that p21ras functions as an intermediate in the insulin signal transduction route leading to the induction of gene expression.
Medema
R H
RH
Department of Physiological Chemistry, University of Utrecht, The Netherlands.
Wubbolts
R
R
Bos
J L
JL
D016475:3T3 Cells; D000818:Animals; D002460:Cell Line; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D003001:Cloning, Molecular; D005786:Gene Expression Regulation; D005799:Genes, Dominant; D006367:HeLa Cells; D006801:Humans; D007328:Insulin / Q000502:physiology*; D051379:Mice; D003012:Microbial Collagenase / Q000235:genetics; D009154:Mutation; D011401:Promoter Regions, Genetic; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics* / Q000378:metabolism; D011972:Receptor, Insulin / Q000096:biosynthesis / Q000235:genetics; D015398:Signal Transduction; D014162:Transfection
D007328:Insulin; D015500:Chloramphenicol O-Acetyltransferase; D011972:Receptor, Insulin; D003012:Microbial Collagenase; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)