Opposite regulation of tyrosine-phosphorylation of p130(Cas) by insulin and insulin-like growth factor I.
To investigate the difference in signaling between insulin and insulin-like growth factor I (IGF-I), we studied the effects of these hormones on the phosphorylation state of Crk-associated substrate (Cas) in cells expressing human insulin receptor (HIRc). In the basal state, Cas was heavily tyrosine-phosphorylated, and insulin dephosphorylated Cas in a time- and dose-dependent manner. On the other hand, IGF-I phosphorylated rather than dephosphorylated Cas in HIRc cells. In HIRY/F2 cells expressing a mutant insulin receptor lacking a binding site of SHP-2, a protein-tyrosine phosphatase containing src homology 2 (SH2) regions, insulin accelerated phosphorylation of Cas, as did IGF-I. In HIRc cells expressing a mutant SHP-2 lacking a PTPase domain (DeltaPTP), which interfered with SHP-2 function, insulin failed to dephosphorylate Cas. In whole cell lysate obtained in the basal state, Cas bound to a glutathione-S transferase fusion protein containing SH2 domains of SHP-2 and dissociated from this GST protein in response to insulin. These results indicate that the opposite regulation of Cas phosphorylation by insulin and IGF-I may be mediated through different properties of their receptors, and that the interaction of the insulin receptor with SHP-2 may play an important role in determining the tyrosine-phosphorylation state of Cas.
Fujita
T
T
The Third Department of Medicine, Shiga University of Medical Science, Otsu, Shiga, 520-2192, Japan.
Maegawa
H
H
Kashiwagi
A
A
Hirai
H
H
Kikkawa
R
R
D000818:Animals; D001665:Binding Sites; D002478:Cells, Cultured; D005347:Fibroblasts; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000378:metabolism* / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000378:metabolism* / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D009154:Mutation; D010766:Phosphorylation / Q000187:drug effects; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000187:drug effects / Q000378:metabolism*; D050721:Proto-Oncogene Proteins c-cbl; D051381:Rats; D011972:Receptor, Insulin / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D014443:Tyrosine / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases
D007328:Insulin; D047908:Intracellular Signaling Peptides and Proteins; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D014443:Tyrosine; D007334:Insulin-Like Growth Factor I; D050721:Proto-Oncogene Proteins c-cbl; D044767:Ubiquitin-Protein Ligases; D005982:Glutathione Transferase; D011972:Receptor, Insulin; 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; C067419:CBL protein, human