Epidermal growth factor receptor (EGF-R) localization in the apical membrane of the enterocytes of rat duodenum

The maintenance of gastrointestinal epithelium integrity requires a fine balance between proliferation and differentiation as well as protection against gastric acid secretion. Some growth factors, such as epidermal growth factor (EGF) and transforming growth factor alpha (TGF-alpha), bind to epidermal growth factor receptor (EGF-R) to exert these functions. The exact location of EGF-R within the duodenal area is controversial and still not completely known. Immunohistochemical and Western blot techniques using a monoclonal anti-EGF-R antibody were performed on the adult rat duodenum. The duodenal enterocytes expressed EGF-R in the apical membrane and in the supranuclear area along the length of the villuos. The Lieberkhüm crypts and Brunner's glands also showed a positive immunostaining. By Western blot analysis we identified in the duodenal scrape a band with an apparent molecular weight of 175 kDa. Our results suggest a functional role for the luminal EGF and/or TGF-alpha in the establishment and maintenance of the epithelial renewal, probably by stimulation of cell proliferation, differentiation and migration.