title: Distinct Grb10 domain requirements for effects on glucose uptake and insulin signaling.
abstract: The adapter protein Grb10 binds to phosphotyrosine residues in insulin receptors via its C-terminal region and regulates insulin signaling. This study investigated Grb10 regulation of glucose uptake and the importance of the Grb10 N-terminal region using 3T3-L1 adipocytes overexpressing full-length (FL-Grb10) or N-terminally truncated Grb10 (BPS-SH2). Overexpression of FL-Grb10 inhibited insulin-stimulated receptor autophosphorylation and glucose uptake. In contrast, the BPS-SH2 fragment of Grb10 had no effect on receptor phosphorylation or glucose uptake. In spite of these differences, both FL-Grb10 and the BPS-SH2 fragment inhibited insulin-stimulated phosphorylation of IRS1, IRS2, Akt/PKB, Shc, ERK1/2, APS, and c-Cbl to a similar extent. Co-precipitation studies demonstrated more sustained binding of the BPS-SH2 fragment than FL-Grb10 to insulin receptors. Although receptor binding domains of Grb10 are sufficient to inhibit insulin effects on proximal post-receptor signaling responses, N-terminal domains of Grb10 are essential for the effects of this adapter protein on receptor phosphorylation and glucose uptake.
authors.affiliation: Endocrinology Division and the Hallett Center for Diabetes and Endocrinology, Rhode Island Hospital, Brown Medical School, One Hoppin Street, Suite 200, Providence, RI 02903, USA.
authors.forename: Katsuhito
authors.initials: K
authors.lastname: Mori
authors.forename: Barbara
authors.initials: B
authors.lastname: Giovannone
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Smith
mesh_terms: D041721:3T3-L1 Cells; D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D017667:Adipocytes / Q000378:metabolism; D000818:Animals; D051383:GRB10 Adaptor Protein; D005947:Glucose / Q000378:metabolism*; D051275:Glucose Transporter Type 4; D007328:Insulin / Q000494:pharmacology / Q000502:physiology*; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D009004:Monosaccharide Transport Proteins / Q000378:metabolism; D009124:Muscle Proteins / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor); D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D050721:Proto-Oncogene Proteins c-cbl; D011972:Receptor, Insulin / Q000378:metabolism*; D055765:Shc Signaling Adaptor Proteins; D015398:Signal Transduction; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D014162:Transfection; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051275:Glucose Transporter Type 4; C495959:Grb10 protein, mouse; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; C526295:Irs1 protein, mouse; C526298:Irs2 protein, mouse; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D010750:Phosphoproteins; D011506:Proteins; D011518:Proto-Oncogene Proteins; D055765:Shc Signaling Adaptor Proteins; C528034:Shc1 protein, mouse; C495693:Slc2a4 protein, mouse; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D051383:GRB10 Adaptor Protein; D050721:Proto-Oncogene Proteins c-cbl; D044767:Ubiquitin-Protein Ligases; D017853:Phosphotransferases (Alcohol Group Acceptor); D011972:Receptor, Insulin; C493849:Cbl protein, mouse; D005947:Glucose