Insulin induction of c-Ki-ras in rat liver and in cultured normal rat hepatocytes.
1. Insulin administration in neonatal rats causes a dramatic accumulation of the major c-Ki-ras transcript. 2. The level of c-Ki-ras transcript is greatly reduced in alloxan-induced diabetic rats. 3. Injection of insulin in alloxan-induced diabetic rats is able to restore almost completely the level of c-Ki-ras transcript found in insulin-induced normal rats. 4. Results from nuclear run-off experiments reveal that the inductive effect of insulin is at the level of transcription of the c-Ki-ras gene. 5. As in whole animals, insulin is also able to induce the expression of c-Ki-ras in cultured normal hepatocytes. 6. This inductive effect of insulin is markedly reduced in hepatocytes which have been previously treated with the tumour promoter, 12-O-tetradecanoylphorbol-13 acetate for 24 hr, a result suggesting that at least part of the effect of insulin is mediated via protein kinase C.
Chan
S O
SO
Department of Biochemistry, University of Hong Kong.
Wong
S S
SS
Yeung
D C
DC
D000375:Aging / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism; D004789:Enzyme Activation; D015870:Gene Expression / Q000187:drug effects*; D007328:Insulin / Q000494:pharmacology*; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras) / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured
D007328:Insulin; D012333:RNA, Messenger; D011493:Protein Kinase C; D016283:Proto-Oncogene Proteins p21(ras); D013755:Tetradecanoylphorbol Acetate