Modulation of insulin-stimulated glycogen synthesis by Src Homology Phosphatase 2.
We have examined the requirement of the protein tyrosine phosphatase Src Homology Phosphatase 2 (SHP2) for insulin-stimulated glycogen synthesis. To this end, 3T3L1 fibroblasts were stably transfected with either wild type or a catalytically inactive C463A-mutant of SHP2, and analysed for insulin-induced glycogen synthesis, tyrosine phosphorylation of the insulin receptor and IRS-1, and activation of phosphatidylinositol 3'-kinase (PI 3'-kinase). Glycogen synthesis was stimulated 9.1+/-0.9-fold by insulin in untransfected cells. In cells expressing the dominant-negative C463A-SHP2 mutant, the stimulation of glycogen synthesis by insulin was strongly enhanced (18.7+/-2.7-fold stimulation), while this response was impaired in cells overexpressing wild-type SHP2 (6.6+/-1.1-fold stimulation). When exploring the early post-receptor signalling pathways that contribute to glycogen synthesis, we found that insulin stimulated the tyrosine phosphorylation of IRS-1, and the activation of IRS-1-associated PI 3'-kinase more strongly in C463A-SHP2 expressing 3T3L1-cells (18.1+/-4.7-fold) than in parental 3T3L1 cells (6.8+/-0.5-fold). In 3T3L1 cells overexpressing wild-type SHP2, the insulin stimulation of IRS-1 tyrosine phosphorylation and the activation of PI 3'-kinase (4.5+/-1.0-fold) were impaired. An enhanced activity of SHP2 leads to negative modulation of insulin signalling by reducing the tyrosine phosphorylation of IRS-1 and the concomitant activation of PI 3'-kinase. This results in an impaired ability of insulin to stimulate glycogen synthesis.
Ouwens
D M
DM
Department of Molecular Cell Biology, Leiden University Medical Center, Wassenaarseweg 72, 2333 AL, Leiden, The Netherlands. d.m.ouwens@lumc.nl
van der Zon
G C
GC
Maassen
J A
JA
D016475:3T3 Cells; D000818:Animals; D020134:Catalytic Domain / Q000235:genetics; D002417:Cattle; D004789:Enzyme Activation / Q000187:drug effects; D006003:Glycogen / Q000096:biosynthesis*; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D009154:Mutation; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D054648:Protein Phosphatase 2; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D011972:Receptor, Insulin / Q000378:metabolism; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases; D015398:Signal Transduction / Q000187:drug effects; D014162:Transfection; D018909:src Homology Domains
C526292:IRS1 protein, human; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; C526295:Irs1 protein, mouse; D010750:Phosphoproteins; D006003:Glycogen; D019869:Phosphatidylinositol 3-Kinases; D011972:Receptor, Insulin; D054648:Protein Phosphatase 2; 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; C516725:Ptpn11 protein, mouse; C509248:Ptpn6 protein, mouse; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases