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M. Matsuba, A.E. K. Hutcheon, J.D. Zieske; Localization of Activated EGF Receptor in Corneal Epithelium . Invest. Ophthalmol. Vis. Sci. 2006;47(13):5016.
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© ARVO (1962-2015); The Authors (2016-present)
We have previously demonstrated that EGF receptor (EGFR) is activated during corneal wound repair using biochemical techniques. The goal of the present study was to localize EGFR activated on specific tyrosine residues in the rat corneal epithelium.
Adult Sprague Dawley rats were killed, corneas were excised, and frozen sections were prepared. Mono–specific antibodies against phospho–tyrosine 845, 992 and 1068 were used with standard immunofluorescence techniques to localize the antibodies.
No Tyr1068 was observed in unwounded rat corneal epithelium. Surprisingly, both Tyr845 and Tyr992 were phosphorylated in unwounded tissue. Phospho–Tyr992 was localized in the majority of the basal cells in the limbal epithelium. In central cornea, phospho–Tyr992 was present throughout the cell layers with the highest levels in the basal layer. In contrast, phospho–Tyr845 was present in a distinct subset (less than 50%) of basal cells in the limbal epithelium. A similar pattern was present in central cornea. Both phospho–Tyr992 and phospho–Tyr845 appeared to be localized primarily in the cell membrane.
Activated EGFR is present in unwounded rat corneal epithelium. This activation appears to be on specific tyrosine residues. Since different tyrosine residues provide binding sites for a variety of proteins involved in different signaling pathways, these results may indicate differential activation of the pathways. The expression pattern of phospho–Tyr992 and phospho–Tyr845 may also reflect the proliferative and differentiation state of the cells.
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