title: The epidermal growth factor receptor (EGF-R) is present on the basolateral, but not the apical, surface of enterocytes in the human gastrointestinal tract.
abstract: BACKGROUND
  While it is clear that luminal epidermal growth factor (EGF) stimulates repair of the damaged bowel, its significance in maintaining normal gut growth remains uncertain. If EGF is important in maintaining normal gut growth, the EGF receptor (EGF-R) should be present on the apical (luminal) surface in addition to the basolateral surface. AIMS/SUBJECTS/METHODS: This study examined the distribution of the EGF-R in the epithelium throughout the human gastro-intestinal tract using immunohistochemistry, electron microscopy, and western blotting of brush border preparations.
  
  
  RESULTS
  Immunostaining of the oesophagus showed circumferential EGF-R positivity in the cells of the basal portions of the stratified squamous epithelium but surface cells were EGF-R negative. In the normal stomach, small intestine, and colon, immunostaining localised the receptor to the basolateral surface with the apical membranes being consistently negative. EGF-R positivity within the small intestine appeared to be almost entirely restricted to the proliferative (crypt) region. Western blotting demonstrated a 170 kDa protein in whole tissue homogenates but not in the brush border vesicle preparations.
  
  
  CONCLUSIONS
  As the EGF-R is located only on the basolateral surfaces in the normal adult gastrointestinal tract, the major role of luminal EGF is probably to stimulate repair rather than to maintain normal gut growth.
authors.affiliation: Department of Medicine and Therapeutics, University of Leicester.
authors.forename: R J
authors.initials: RJ
authors.lastname: Playford
authors.forename: A M
authors.initials: AM
authors.lastname: Hanby
authors.forename: S
authors.initials: S
authors.lastname: Gschmeissner
authors.forename: L P
authors.initials: LP
authors.lastname: Peiffer
authors.forename: N A
authors.initials: NA
authors.lastname: Wright
authors.forename: T
authors.initials: T
authors.lastname: McGarrity
mesh_terms: D015153:Blotting, Western; D066246:ErbB Receptors / Q000032:analysis*; D006801:Humans; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000378:metabolism* / Q000473:pathology; D008854:Microscopy, Electron
chemical_list: D066246:ErbB Receptors