title: Insulin receptor substrate 1 mediates the stimulatory effect of insulin on GLUT4 translocation in transfected rat adipose cells.
abstract: Insulin signaling is initiated at least in part by activation of the insulin receptor tyrosine kinase and subsequent phosphorylation of cellular substrates such as insulin receptor substrate 1 (IRS-1). Previous studies have focused on the role of IRS-1 in the mitogenic actions of insulin. We have now investigated the possible role of IRS-1 in mediating the effect of insulin to stimulate glucose transport in a physiologically relevant insulin target tissue. In this study, we transfected rat adipose cells in primary culture with an antisense ribozyme directed against rat IRS-1. Expression of the ribozyme in these cells caused a 4.4-fold increase in the concentration of insulin required to achieve half-maximal stimulation of the translocation of cotransfected epitope-tagged GLUT4 without changing the maximal insulin response. Overexpression of human IRS-1 increased the basal cell surface GLUT4 to nearly the maximal level in the absence of insulin. When the ribozyme (specific to rat IRS-1) was cotransfected along with human IRS-1, the insulin dose-response curve was shifted to the left when compared with cells transfected with the ribozyme alone. These data provide strong support for the hypothesis that IRS-1 plays a role in insulin-stimulated glucose transport in insulin-responsive cells.
authors.affiliation: Diabetes Branch, NIDDKD, National Institutes of Health, Bethesda, Maryland 20892.
authors.forename: M J
authors.initials: MJ
authors.lastname: Quon
authors.forename: A J
authors.initials: AJ
authors.lastname: Butte
authors.forename: M J
authors.initials: MJ
authors.lastname: Zarnowski
authors.forename: G
authors.initials: G
authors.lastname: Sesti
authors.forename: S W
authors.initials: SW
authors.lastname: Cushman
authors.forename: S I
authors.initials: SI
authors.lastname: Taylor
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D004822:Epididymis; D000939:Epitopes / Q000032:analysis; D051275:Glucose Transporter Type 4; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D055504:Insulin Receptor Substrate Proteins; D007700:Kinetics; D008297:Male; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins / Q000096:biosynthesis / Q000378:metabolism*; D009124:Muscle Proteins; D016376:Oligonucleotides, Antisense / Q000494:pharmacology*; D010750:Phosphoproteins / Q000096:biosynthesis / Q000378:metabolism*; D016337:RNA, Catalytic / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D014162:Transfection
chemical_list: D000939:Epitopes; D051275:Glucose Transporter Type 4; C526292:IRS1 protein, human; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; C526296:Irs1 protein, rat; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D016376:Oligonucleotides, Antisense; D010750:Phosphoproteins; D016337:RNA, Catalytic; D012333:RNA, Messenger; C495692:SLC2A4 protein, human; C495694:Slc2a4 protein, rat