Role of SH-PTP2, a protein-tyrosine phosphatase with Src homology 2 domains, in insulin-stimulated Ras activation.
SH-PTP2 is a nontransmembrane human protein-tyrosine phosphatase that contains two Src homology 2 (SH2) domains and binds to insulin receptor substrate 1 (IRS-1) via these domains in response to insulin. The expression of a catalytically inactive mutant of SH-PTP2 (containing the mutation Cys-459-->Ser) in Chinese hamster ovary cells that overexpress human insulin receptors (CHO-IR cells) markedly attenuated insulin-stimulated Ras activation. Expression of mutant SH-PTP2 also inhibited MAP kinase activation in response to insulin but not in response to 12-O-tetradecanoyl phorbol-13-acetate. In contrast, the insulin-induced association of phosphoinositide 3-kinase activity with IRS-1 was not affected by the expression of inactive SH-PTP2. Furthermore, the expression of mutant SH-PTP2 had no effect on the binding of Grb2 to IRS-1, on the tyrosine phosphorylation of Shc, or on the formation of the complex between Shc and Grb2 in response to insulin. However, the amount of SH-PTP2 bound to IRS-1 in insulin-treated CHO-IR cells expressing mutant SH-PTP2 was greater than that observed in CHO-IR cells overexpressing wild-type SH-PTP2. Recombinant SH-PTP2 specifically dephosphorylated a synthetic phosphopeptide corresponding to the sequence surrounding Tyr-1172 of IRS-1, a putative binding site for SH-PTP2. Additionally, phenylarsine oxide, an inhibitor of protein-tyrosine phosphatases, inactivated SH-PTP2 in vitro and increased the insulin-induced association of SH-PTP2 with IRS-1. These results suggest that SH-PTP2 may regulate an upstream element necessary for Ras activation in response to insulin and that this upstream element may be required for the Grb2- or Shc-dependent pathway. Furthermore, these results are consistent with the notion that SH-PTP2 may bind to IRS-1 through its SH2 domains in response to insulin and dephosphorylate the phosphotyrosine residue to which it binds, thereby regulating its association with IRS-1.
Noguchi
T
T
Second Department of Internal Medicine, Kobe University School of Medicine, Japan.
Matozaki
T
T
Horita
K
K
Fujioka
Y
Y
Kasuga
M
M
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001483:Base Sequence; D016466:CHO Cells; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D006224:Cricetinae; D004789:Enzyme Activation; D051380:GRB2 Adaptor Protein; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D015688:Oncogene Protein pp60(v-src) / Q000235:genetics; D010750:Phosphoproteins / Q000378:metabolism; D011485:Protein Binding; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism*; D011972:Receptor, Insulin / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014162:Transfection
D048868:Adaptor Proteins, Signal Transducing; D051380:GRB2 Adaptor Protein; C495948:GRB2 protein, human; C526292:IRS1 protein, human; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; D010750:Phosphoproteins; D011506:Proteins; D011994:Recombinant Proteins; D011972:Receptor, Insulin; D015688:Oncogene Protein pp60(v-src); D017871:Calcium-Calmodulin-Dependent Protein Kinases; C516724:PTPN11 protein, human; C509249:PTPN6 protein, human; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)