Insulin Stimulates the Tyrosine Dephosphorylation of pp125 Focal Adhesion Kinase

doi:10.1074/jbc.270.3.991

Insulin Stimulates the Tyrosine Dephosphorylation of pp125 Focal Adhesion Kinase (*)

From the Division of Endocrinology and Metabolism, Department of Medicine, University of California San Diego, La Jolla, California 92093-0673 and the Research Service, Veterans Administration Medical Center, San Diego, California 92161

↵^¶ Present address: Toyama Medical and Pharmaceutical University, Toyama, Japan 930-01.

** To whom correspondence should be addressed. Tel.: 619-534-6651; Fax: 619-534-6653.

Abstract

The phosphorylation state of pp125 focal adhesion kinase in response to insulin was examined in parental and transfected Rat-1 fibroblasts expressing both wild-type (HIRc cells) and mutant human insulin receptor cDNAs lacking the C-terminal twin tyrosine phosphorylation sites (YF2 cells) or a deletion mutant lacking the distal 43 amino acids of the β-subunit (ΔCT cells). In HIRc cells insulin stimulated the tyrosine dephosphorylation of pp125, whereas IGF-I did not. In contrast, the tyrosine phosphorylation state of pp125 was unchanged in the parental Rat-1 fibroblasts and the YF2 or ΔCT mutant cell lines in response to insulin. Analysis of the supernatants revealed that pp125 was only one component of the major M_r 120-130-kDa phosphotyrosine band seen in HIRc cells. We conclude that: 1) in contrast to other growth factors, insulin stimulates the dephosphorylation of pp125; 2) the presence of the insulin receptor C-terminal tyrosines 1328 and 1334 is required for the insulin-stimulated tyrosine dephosphorylation of pp125, suggesting a possible SH2 domain-dependent interaction; 3) insulin may modulate integrin-mediated signaling through pp125 by altering the phosphorylation state of pp125.

Footnotes

↵^§ Recipient of a Juvenile Diabetes Foundation international fellowship.
↵* This work was supported in part by the National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases Grant DK33651, the Veterans Administration Medical Research Service, the Sankyo Diabetes Research Fund, and the Juvenile Diabetes Foundation. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

BSA

bovine serum albumin

Tricine

N-[2-hydroxy-1,1-bis(hydroxymethyl)ethyl]glycine

IGF

insulin-like growth factor.
- Received November 3, 1994.