Requirement for protein-tyrosine phosphatase SHP-2 in insulin-induced activation of c-Jun NH(2)-terminal kinase.
Mitogen-activated protein kinases, including extracellular signal-regulated kinases and c-Jun NH(2)-terminal kinases (JNKs), are activated by insulin. Although the mechanism by which the insulin receptor activates extracellular signal-regulated kinases is relatively well defined, the pathway that leads to JNK activation is poorly understood. Overexpression of a catalytically inactive mutant (SHP-2C/S) of the protein-tyrosine phosphatase SHP-2 in Rat-1 fibroblasts that also express human insulin receptors has now revealed that activation of JNKs by insulin and epidermal growth factor, but not that by anisomycin or sorbitol, requires SHP-2. A dominant negative mutant (RasN17) of Ha-Ras blocked insulin-induced JNK activation, whereas a dominant negative mutant (RacN17) of Rac1 or a specific inhibitor (LY294002) of phosphoinositide 3-kinase did not, indicating a role for Ras, but not for Rac or phosphoinositide 3-kinase, in this effect. SHP-2C/S markedly inhibited Ras activation in response to insulin without affecting insulin-induced tyrosine phosphorylation of cellular substrates or the dissociation of the Crk-p130(Cas) complex. In contrast, SHP-2C/S did not inhibit activation of JNKs induced by a constitutively active mutant (RasV12) of Ha-Ras. Furthermore, expression of myristoylated SOS, which functions as a potent activator of Ras, induced JNK activation even when SHP-2 was inactivated. These results suggest that SHP-2 contributes to JNK activation in response to insulin by positively regulating the Ras signaling pathway at the same level as, or upstream from, SOS.
Fukunaga
K
K
Second Department of Internal Medicine, Kobe University School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan.
Noguchi
T
T
Takeda
H
H
Matozaki
T
T
Hayashi
Y
Y
Itoh
H
H
Kasuga
M
M
D000818:Animals; D002384:Catalysis; D002460:Cell Line; D002867:Chromones / Q000494:pharmacology; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000502:physiology; D006801:Humans; D007328:Insulin / Q000378:metabolism / Q000494:pharmacology* / Q000502:physiology; D047908:Intracellular Signaling Peptides and Proteins; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009025:Morpholines / Q000494:pharmacology; D015689:Oncogene Protein p21(ras) / Q000378:metabolism; D018384:Oxidative Stress; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction
D002867:Chromones; D004791:Enzyme Inhibitors; D007328:Insulin; D047908:Intracellular Signaling Peptides and Proteins; D009025:Morpholines; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D004815:Epidermal Growth Factor; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated 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; C516727:Ptpn11 protein, rat; C509250:Ptpn6 protein, rat; D015689:Oncogene Protein p21(ras)