The proto-oncogene product c-Crk associates with insulin receptor substrate-1 and 4PS. Modulation by insulin growth factor-I (IGF) and enhanced IGF-I signaling.
The Crk proto-oncogene product is an SH2 and SH3 domain-containing adaptor protein which we have previously shown to become rapidly tyrosine phosphorylated in response to stimulation with insulin-like growth factor I (IGF-I) in NIH-3T3 cells. In order to further characterize the role of Crk in the IGF-I signaling pathway, NIH-3T3 and 293 cells were stably transfected with an expression vector containing the Crk cDNA. The various resultant 3T3-Crk clones expressed Crk at approximately 2-15-fold higher levels than parental 3T3 cells. In 3T3-Crk cells, Crk immunoreactivity was detected in insulin receptor substrate-1 (IRS-1) immunoprecipitates. Stimulation with IGF-I resulted in a dissociation of Crk protein from IRS-1. In contrast, the association of the related adaptor protein Grb2 with IRS-1 was enhanced by IGF-I stimulation. Similar results were obtained in stably transfected 293-Crk cells, which express both IRS-1 and the IRS-1-related signaling protein 4PS. In these cells, IRS-1 and 4PS both associated with Crk, and this association was also decreased by IGF-I treatment, whereas the association of Grb2 with IRS-1 and 4PS was enhanced by IGF-I. Overexpression of Crk also enhanced IGF-I-induced mitogenesis of NIH-3T3 cells, as measured by [3H]thymidine incorporation. The levels of IGF-I-induced mitogenesis were proportional to the level of Crk expression. These results suggest that Crk is a positive effector of IGF-I signaling, and may mediate its effects via interaction with IRS-1 and/or 4PS.
Beitner-Johnson
D
D
Diabetes Branch, NIDDK Laboratory of Cellular and Molecular Biology, National Institutes of Health, Bethesda, Maryland 20892, USA.
Blakesley
V A
VA
Shen-Orr
Z
Z
Jimenez
M
M
Stannard
B
B
Wang
L M
LM
Pierce
J
J
LeRoith
D
D
D016475:3T3 Cells; D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D004247:DNA / Q000096:biosynthesis; D051380:GRB2 Adaptor Protein; D006801:Humans; D055504:Insulin Receptor Substrate Proteins; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D047908:Intracellular Signaling Peptides and Proteins; D007700:Kinetics; D051379:Mice; D010750:Phosphoproteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D011506:Proteins / Q000302:isolation & purification / Q000378:metabolism; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D050737:Proto-Oncogene Proteins c-crk; D011519:Proto-Oncogenes; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013936:Thymidine / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured
D048868:Adaptor Proteins, Signal Transducing; D051380:GRB2 Adaptor Protein; C495948:GRB2 protein, human; C495949:Grb2 protein, mouse; C526292:IRS1 protein, human; C526297:IRS2 protein, human; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; C526295:Irs1 protein, mouse; C526298:Irs2 protein, mouse; C000715470:MAS1 protein, human; D010750:Phosphoproteins; D011506:Proteins; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D050737:Proto-Oncogene Proteins c-crk; D011994:Recombinant Proteins; D007334:Insulin-Like Growth Factor I; D004247:DNA; D013936:Thymidine