The Tyrosine Phosphatase SHP-2 Is Required for Sustained Activation of Extracellular Signal-Regulated Kinase and Epithelial Morphogenesis Downstream from the Met Receptor Tyrosine Kinase

Abstract

Epithelial morphogenesis is critical during development and wound healing, and alterations in this program contribute to neoplasia. Met, the hepatocyte growth factor (HGF) receptor, promotes a morphogenic program in epithelial cell lines in matrix cultures. Previous studies have identified Gab1, the major phosphorylated protein following Met activation, as important for the morphogenic response. Gab1 is a docking protein that couples the Met receptor with multiple signaling proteins, including phosphatidylinositol-3 kinase, phospholipase Cγ, the adapter protein Crk, and the tyrosine specific phosphatase SHP-2. HGF induces sustained phosphorylation of Gab1 and sustained activation of extracellular signal-regulated kinase (Erk) in epithelial Madin-Darby canine kidney cells. In contrast, epidermal growth factor fails to promote a morphogenic program and induces transient Gab1 phosphorylation and Erk activation. To elucidate the Gab1-dependent signals required for epithelial morphogenesis, we undertook a structure-function approach and demonstrate that association of Gab1 with the tyrosine phosphatase SHP-2 is required for sustained Erk activation and for epithelial morphogenesis downstream from the Met receptor. Epithelial cells expressing a Gab1 mutant protein unable to recruit SHP-2 elicit a transient activation of Erk in response to HGF. Moreover, SHP-2 catalytic activity is required, since the expression of a catalytically inactive SHP-2 mutant, C/S, abrogates sustained activation of Erk and epithelial morphogenesis by the Met receptor. These data identify SHP-2 as a positive modulator of Erk activity and epithelial morphogenesis downstream from the Met receptor.

ACKNOWLEDGMENTS

This research was supported by an operating grant from the National Cancer Institute of Canada with funds from the Canadian Cancer Society (to M.P.), an American Cancer Society grant, and National Institutes of Health grants NS34514 and CA69495 (to A.J.W.), with a fellowship from the Medical Research Council (to C.M.) and a fellowship from the Ministerio de Educacion y Ciencia of Spain (to M.H.-M.). M.P. is a Scientist of the Medical Research Council of Canada.

We are grateful to G. F. Vande Woude for HGF, the Genetics Institute for recombinant CSF-1, T. Pawson for anti-p85, G. S. Feng for anti-SHP2, S. Ali for the vector encoding wild-type SHP-2, A. Saltiel for the vector encoding SHP-2 C/S, S. Sadekova for help in confocal microscopy, and members of the Park laboratory for helpful comments.