Functional expression of insulin receptor substrate-1 is required for insulin-stimulated mitogenic signaling.
To examine the role of the insulin receptor substrate-1 (IRS-1) in mediating insulin biological responsiveness, we generated Chinese hamster ovary cell lines expressing antisense IRS-1 RNA. These cells displayed morphological alterations as well as markedly reduced growth rates compared to the parental cells. Furthermore, the antisense IRS-1 cell lines had decreased insulin-stimulated IRS-1 tyrosine phosphorylation, reduced phosphatidylinositol 3-kinase activation, and decreased thymidine incorporation relative to the parental cell line. Insulin-dependent transcriptional regulation of a serum response element/luciferase reporter construct (SRE-Luc) was also reduced in the antisense IRS-1-expressing cell lines. However, co-transfection with a plasmid directing the expression of rat IRS-1 fully restored insulin-stimulated SRE-Luc activity in the IRS-1 antisense cell lines. Thus, the inhibition in insulin signaling was a specific effect of decreased IRS-1 tyrosine phosphorylation. Taken together, these data demonstrate that insulin regulation of mitogenic signaling requires the functional expression of IRS-1 and documents its central importance in the insulin intracellular signaling pathway.
Waters
S B
SB
Department of Physiology and Biophysics, University of Iowa, Iowa City 52242.
Yamauchi
K
K
Pessin
J E
JE
D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D002455:Cell Division / Q000187:drug effects; D002999:Clone Cells; D006224:Cricetinae; D015870:Gene Expression; D007328:Insulin / Q000494:pharmacology*; D055504:Insulin Receptor Substrate Proteins; D007700:Kinetics; D008156:Luciferases / Q000096:biosynthesis / Q000378:metabolism; D008934:Mitogens / Q000494:pharmacology*; D008969:Molecular Sequence Data; D019869:Phosphatidylinositol 3-Kinases; D010750:Phosphoproteins / Q000096:biosynthesis* / Q000378:metabolism; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D016372:RNA, Antisense / Q000096:biosynthesis; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection
D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; C526296:Irs1 protein, rat; D008934:Mitogens; D010750:Phosphoproteins; D016372:RNA, Antisense; D011993:Recombinant Fusion Proteins; D008156:Luciferases; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor)