title: Epidermal growth factor receptor mediates stress-induced expression of its ligands in rat gastric epithelial cells.
abstract: OBJECTIVE
  Epidermal growth factor (EGF)-like growth factors are induced after acute gastric injury and may play an important role in mucosal repair. However, the mechanisms that trigger these growth factors are poorly understood. We determined the role of EGF receptor (EGFR) in stress-induced expression of heparin-binding EGF-like growth factor (HB-EGF) in a rat gastric epithelial cell line (RGM1 cells).
  
  
  METHODS
  RGM1 cells were transfected with a plasmid containing complementary DNA encoding a dominant-negative human EGFR (HERCD533). Cells were treated with hydrogen peroxide (0-400 micromol/L) or sorbitol (600 mmol/L). Tyrosine phosphorylation of EGFR was determined by immunoprecipitation and Western blotting with an antiphosphotyrosine antibody. HB-EGF messenger RNA and protein were determined with Northern and Western blotting, respectively. Cell growth was evaluated by cell number and [(3)H]thymidine incorporation.
  
  
  RESULTS
  Oxidative stress and osmotic stress induced tyrosine phosphorylation of EGFR within 2 minutes, followed by a marked increase in HB-EGF and amphiregulin transcripts in RGM1 cells. Introduction of HERCD533 into the cells inhibited not only tyrosine phosphorylation of EGFR but also growth response to EGF. Furthermore, oxidative stress-induced HB-EGF messenger RNA expression was impaired in HERCD533-expressing cells.
  
  
  CONCLUSIONS
  EGFR plays a crucial role in the stress-induced expression of EGF-like growth factors in gastrointestinal epithelial cells.
authors.affiliation: Department of Internal Medicine and Molecular Science, Graduate School of Medicine, Osaka University, Yamadaoka, Osaka, Japan. miyazaki@imed2.osaka-u.ac.jp
authors.forename: Y
authors.initials: Y
authors.lastname: Miyazaki
authors.forename: S
authors.initials: S
authors.lastname: Hiraoka
authors.forename: S
authors.initials: S
authors.lastname: Tsutsui
authors.forename: S
authors.initials: S
authors.lastname: Kitamura
authors.forename: Y
authors.initials: Y
authors.lastname: Shinomura
authors.forename: Y
authors.initials: Y
authors.lastname: Matsuzawa
mesh_terms: D066258:Amphiregulin; D000818:Animals; D015153:Blotting, Western; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D018076:DNA, Complementary; D066255:EGF Family of Proteins; D004815:Epidermal Growth Factor / Q000032:analysis / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology; D066246:ErbB Receptors / Q000235:genetics* / Q000378:metabolism*; D005753:Gastric Mucosa / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D006023:Glycoproteins / Q000235:genetics; D006133:Growth Substances / Q000235:genetics; D066257:Heparin-binding EGF-like Growth Factor; D036341:Intercellular Signaling Peptides and Proteins; D008024:Ligands; D018384:Oxidative Stress / Q000502:physiology*; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000502:physiology; D019859:Proto-Oncogene Proteins c-met / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D020893:Receptor, ErbB-3 / Q000378:metabolism; D014162:Transfection; D016211:Transforming Growth Factor alpha / Q000235:genetics; D014443:Tyrosine / Q000378:metabolism
chemical_list: D066258:Amphiregulin; D016895:Culture Media, Serum-Free; D018076:DNA, Complementary; D066255:EGF Family of Proteins; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D006023:Glycoproteins; D006133:Growth Substances; D066257:Heparin-binding EGF-like Growth Factor; D036341:Intercellular Signaling Peptides and Proteins; D008024:Ligands; D019859:Proto-Oncogene Proteins c-met; D012333:RNA, Messenger; D018719:Erb-b2 Receptor Tyrosine Kinases; D020893:Receptor, ErbB-3; D016211:Transforming Growth Factor alpha; D014443:Tyrosine; C587848:AREG protein, human; C587850:Areg protein, rat; C587883:HBEGF protein, human; C587885:Hbegf protein, rat