Association of insulin receptor substrate 1 with simian virus 40 large T antigen.
Mouse embryo cells expressing a wild-type number of insulin-like growth factor I receptors (IGF-IR) (W cells) can be transformed either by simian virus 40 large T antigen (SV40 T) or by overexpressed insulin receptor substrate 1 (IRS-1), singly transfected. Neither SV40 T antigen nor IRS-1, individually, can transform mouse embryo cells with a targeted disruption of the IGF-IR genes (R- cells). However, cotransfection of SV40 T antigen and IRS-1 does transform R- cells. In this study, using different antibodies and different cell lines, we found that SV40 T antigen and IRS-1 are coprecipitated from cell lysates in a specific fashion, regardless of whether the lysates are immunoprecipitated with an antibody to SV40 T antigen or an antibody to IRS-1. The same antibody to SV40 T antigen, however, fails to coprecipitate another substrate of IGF-IR, the transforming protein Shc, and two other signal-transducing molecules, Grb2 and Sos. Finally, an SV40 T antigen lacking the amino-terminal 250 amino acids fails to coprecipitate IRS-1 and also fails to transform R- cells overexpressing mouse IRS-1. These experiments indicate that IRS-1 associates with SV40 T antigen and that this association plays a critical role in the combined ability of these proteins to transform R- cells. This finding is discussed in light of the crucial role of the IGF-IR in the establishment and maintenance of the transformed phenotype.
Fei
Z L
ZL
Jefferson Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
D'Ambrosio
C
C
Li
S
S
Surmacz
E
E
Baserga
R
R
D016475:3T3 Cells; D000818:Animals; D000957:Antigens, Viral, Tumor / Q000235:genetics / Q000378:metabolism*; D002471:Cell Transformation, Neoplastic; D055504:Insulin Receptor Substrate Proteins; D051379:Mice; D008807:Mice, Inbred BALB C; D010446:Peptide Fragments / Q000378:metabolism; D010750:Phosphoproteins / Q000276:immunology / Q000378:metabolism*; D011233:Precipitin Tests; D011485:Protein Binding; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000235:genetics; D017526:Receptor, IGF Type 1 / Q000378:metabolism; D017385:Sequence Homology; D015398:Signal Transduction; D013539:Simian virus 40 / Q000276:immunology*
D000957:Antigens, Viral, Tumor; D055504:Insulin Receptor Substrate Proteins; C526295:Irs1 protein, mouse; D010446:Peptide Fragments; D010750:Phosphoproteins; D017526:Receptor, IGF Type 1; D016392:Proto-Oncogene Proteins pp60(c-src)