title: Developmental regulation of epidermal growth factor receptor kinase in rat intestine.
abstract: OBJECTIVE
  Intraluminal epidermal growth factor (EGF) may regulate intestinal growth and function. The ontogeny, localization, and phosphorylation of the EGF receptor in rat small intestine were studied.
  
  
  METHODS
  EGF-receptor phosphorylation was assayed by antiphosphotyrosine Western blot after EGF administration in vivo and EGF incubation to everted sacs in vitro. EGF-receptor abundance and localization were assayed by Western blot and immunofluorescence using anti-EGF-receptor antibodies.
  
  
  RESULTS
  In vivo, orogastric EGF enhanced EGF-receptor phosphorylation in newborn rat jejunum and liver. However, intraluminal EGF had no effect on EGF-receptor phosphorylation in adult intestine or liver. In vitro, mucosal EGF stimulated a fourfold increase in EGF-receptor phosphorylation in suckling jejunum but not in weanling or adult jejunum. In Western blot, EGF-receptor abundance was similar in 22-day-old fetal, 8-day-old suckling, and adult jejunum. In both crypt and villus, EGF-receptor was localized to the basolateral membrane but not to the apical membrane in fetal, suckling, and adult jejunum.
  
  
  CONCLUSIONS
  Mucosal EGF stimulates EGF-receptor phosphorylation in immature but not in mature intestine. These differences are not explained by EGF-receptor abundance or localization and suggest that the greater mucosal permeability of the immature gut may allow EGF to bind to the EGF-receptor in the basolateral membrane to mediate its effects in suckling rat intestine.
authors.affiliation: Department of Pediatrics, New England Medical Center/Tufts University School of Medicine, Boston, Massachusetts.
authors.forename: J F
authors.initials: JF
authors.lastname: Thompson
authors.forename: M
authors.initials: M
authors.lastname: van den Berg
authors.forename: P C
authors.initials: PC
authors.lastname: Stokkers
mesh_terms: D000818:Animals; D015153:Blotting, Western; D004815:Epidermal Growth Factor / Q000378:metabolism / Q000494:pharmacology; D004848:Epithelium / Q000201:enzymology; D066246:ErbB Receptors / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D007082:Ileum / Q000201:enzymology; D007421:Intestine, Small / Q000196:embryology / Q000201:enzymology* / Q000254:growth & development*; D007583:Jejunum / Q000201:enzymology; D008099:Liver / Q000201:enzymology; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D004815:Epidermal Growth Factor; D066246:ErbB Receptors