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SRC-DEPENDENT PHOSPHORYLATION OF THE EPIDERMAL GROWTH FACTOR RECEPTOR ON TYROSINE 845 IS REQUIRED FOR ZINC-INDUCED RAS ACTIVATION
Citation:
Wu, W., L. Graves, G. N. Gill, S. Parsons, AND J M. Samet. SRC-DEPENDENT PHOSPHORYLATION OF THE EPIDERMAL GROWTH FACTOR RECEPTOR ON TYROSINE 845 IS REQUIRED FOR ZINC-INDUCED RAS ACTIVATION. 24257, JOURNAL OF BIOLOGICAL CHEMISTRY. JBC Papers in Press, 277(27):24252, (2002).
Description:
Src-dependent Phosphorylation of the Epidermal Growth Factor Receptor on Tyrosine 845 Is Required for Zinc-induced Ras Activation
Weidong Wu 1 , Lee M. Graves 2 , Gordon N. Gill 3 , Sarah J. Parsons 4 , and James M. Samet 5
1 Center for Environmental Medicine and Lung Biology; 2 Department of Pharmacology, University of North Carolina, Chapel Hill, NC 27599; 3 Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA 92093-0650; 4 Department of Microbiology and Cancer Center, University of Virginia Health Center, Charlottesville, VA 22908; 5 Human Studies Division, National Health Effects and Environmental Research Laboratory, ORD, United States Environmental Protection Agency, Research Triangle Park, NC 27711
Address correspondence to :
James M. Samet, Ph.D.
Human Studies Division, MD58-A
National Health and Environmental Effects Research Laboratory
ORD, US Environmental Protection Agency,
Research Triangle Park, NC 27711
Tel.: (919) 966-0665
FAX: (919) 966-6271
E-mail: Samet.jim@epa.gov
Running title: Zn-induced EGF Receptor Signaling Requires Src
SUMMARY
Previous studies have shown that exposure of cells to Zn ions induces Ras and MAPK activation through the EGF receptor (EGFR). To further determine the role of EGFR in Zn-induced signaling, mouse B82Lfibroblasts expressing no detectable EGFR protein (B82L-par), wild-type EGFR (B82L-wt), kinase deficient EGFR (B82L-K721M), or COOH truncated EGFR (B82L-c'958) were tested. Exposure to Zn induced Ras activity in B82L-wt, B82L-K721M and B82L-c'958 but not in B82L-par cells, indicating that the tyrosine kinase domain and the auto-phosphorylation sites of the EGFR were not required for Zn-induced Ras activation. Zn induced Src activation in all B82L cell lines including B82L-par, indicating that Src activation is independent of the presence of the EGFR. A Src kinase inhibitor blocked Zn-induced Ras activation in all the B82L cell lines capable of this response, suggesting the involvement of Src kinase in Zn-induced Ras activation via the EGFR. Zn induced the association of the EGFR with Src and specifically increased the phosphorylation of EGFR at tyrosine 845 (Y845), a known Src phosphorylation site. Stably transfected B82L cells with a point mutation of the EGFR at Y845 (B82L-Y845F) exhibited only basal Ras activity following exposure to Zn. These data demonstrate that Src-dependent phosphorylation of the EGFR at Y845 is required for EGFR transactivation and Zn-induced Ras activation.