title: Enterocyte expression of epidermal growth factor receptor is not required for intestinal adaptation in response to massive small bowel resection.
abstract: OBJECTIVE
  Intestinal adaptation after massive small bowel resection (SBR) permits improved absorption of enteral nutrition despite significant loss of bowel length. Epidermal growth factor (EGF) and its receptor (EGFR) have previously been established to play major roles in the pathogenesis of adaptation. This study tested the hypothesis that EGFR signaling within the epithelial cell compartment (enterocytes) is required for intestinal adaptation.
  
  
  METHODS
  We developed a tamoxifen-inducible Villin-Cre/LoxP recombinant system for enterocyte-directed EGFR deletion using EGFR-floxed mice. Epidermal growth factor receptor-null mice and wild-type littermates underwent either 50% proximal SBR or sham operation. Ileal tissue was harvested on postoperative day 7. To assess for adaptation, villus height and crypt depth as well as rates of crypt cell proliferation and apoptosis were measured.
  
  
  RESULTS
  Adaptation after SBR occurred normally, as demonstrated by significant increases in villus height, crypt depth, and crypt proliferative and apoptotic index in both the wild-type and EGFR-null mice.
  
  
  CONCLUSIONS
  Enterocyte EGFR expression is not required for the adaptation response to massive SBR. This novel finding suggests that enterocyte proliferation during adaptation is regulated by EGFR signaling in cells other than enterocytes, perhaps within the mesenchymal cell compartment of the bowel wall via factor(s) that are presently unknown.
authors.affiliation: Division of Pediatric Surgery, St Louis Children's Hospital, Department of Surgery, Washington University School of Medicine, St Louis, MO 63110, USA.
authors.forename: Kathryn J
authors.initials: KJ
authors.lastname: Rowland
authors.forename: Mark E
authors.initials: ME
authors.lastname: McMellen
authors.forename: Derek
authors.initials: D
authors.lastname: Wakeman
authors.forename: Wambul S
authors.initials: WS
authors.lastname: Wandu
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Erwin
authors.forename: Brad W
authors.initials: BW
authors.lastname: Warner
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D015153:Blotting, Western; D049109:Cell Proliferation; D020895:Enterocytes / Q000378:metabolism* / Q000502:physiology; D066246:ErbB Receptors / Q000378:metabolism*; D005260:Female; D007082:Ileum / Q000378:metabolism / Q000473:pathology / Q000502:physiology; D007421:Intestine, Small / Q000378:metabolism / Q000473:pathology / Q000502:physiology / Q000601:surgery*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D015415:Biomarkers; C541485:EGFR protein, mouse; D066246:ErbB Receptors