Divergent effects of phorbol esters and insulin on insulin-like growth factor binding protein-1 (IGFBP-1) production and mRNA in rat H4IIE hepatoma cells.
125I-IGF-I binding assay, western ligand and immunoblotting, and northern analysis of total RNA reveal that phorbol ester agonists of protein kinase C rapidly enhance IGFBP-1 production and increase the abundance of IGFBP-1 mRNA in rat H4IIE hepatoma cells. In combination with insulin, a potent inhibitor of IGFBP-1 gene transcription, this early effect of phorbol esters is dominant. These results demonstrate divergent regulation of IGFBP-1 by phorbol esters and insulin and indicate that protein kinase C may play a critical role in the regulation of IGFBP-1 and modulation IGF bioactivity in metabolic disease.
Unterman
T G
TG
Department of Medicine, University of Illinois College of Medicine, Chicago.
Lacson
R G
RG
Jentel
J J
JJ
Oehler
D T
DT
D000818:Animals; D015152:Blotting, Northern; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000235:genetics*; D015342:DNA Probes; D007328:Insulin / Q000494:pharmacology*; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007700:Kinetics; D008114:Liver Neoplasms, Experimental; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology*; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D051381:Rats; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D002352:Carrier Proteins; D015342:DNA Probes; D007328:Insulin; D018969:Insulin-Like Growth Factor Binding Proteins; D012333:RNA, Messenger; D015240:Phorbol 12,13-Dibutyrate; D007334:Insulin-Like Growth Factor I; D013755:Tetradecanoylphorbol Acetate