title: Reduced Human α-defensin 6 in Noninflamed Jejunal Tissue of Patients with Crohn's Disease.
abstract: BACKGROUND
  Mucosal barrier dysfunction is considered a critical component of Crohn's disease (CD) pathogenesis after the identification of susceptibility genes. However, the precise mechanism underlying mucosal barrier dysfunction has not yet been elucidated. We therefore aimed to elucidate the molecular mechanism underlying the expression of human α-defensin 6 (HD6) in patients with CD.
  
  
  METHODS
  HD6 expression was induced by the transfection of an atonal homolog 1 (Atoh1) transgene and was assessed by reverse transcription polymerase chain reaction. The HD6 promoter region targeted by Atoh1 and β-catenin was determined by reporter analysis and chromatin immunoprecipitation assay. HD5/HD6/Atoh1/β-catenin expression in noninflamed jejunal samples collected by balloon endoscopy from 15 patients with CD and 9 non-inflammatory bowel disease patients were assessed by immunofluorescence.
  
  
  RESULTS
  Both promoter activity and gene expression of HD6 was significantly upregulated by the Atoh1 transgene in human colonic cancer cell line. We identified a TCF4 binding site and an E-box site, critical for the regulation of HD6 transcriptional activity by directly binding of Atoh1 in the 200-bp HD6 promoter region. The treatment with β-catenin inhibitor also decreases HD6 promoter activity and gene expression. Moreover, HD6 expression, but not HD5 expression, was found to be decreased in noninflamed jejunal regions from patients with CD. In HD6-negative crypts, nuclear accumulation of β-catenin was impaired.
  
  
  CONCLUSIONS
  HD6 expression was found to be regulated by cooperation between Atoh1 and β-catenin within the HD6 promoter region. Downregulation of HD6 in noninflamed mucosa may contribute to mucosal barrier dysfunction of patients with CD.
authors.affiliation: *Department of Gastroenterology and Metabolism, Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan; †Department of Gastroenterology and Hepatology, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan; ‡Department of Pathology, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan; §Department of Endoscopic Diagnosis and Therapy, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan; ‖Laboratory for Intestinal Ecosystem, RIKEN Center for Integrative Medical Sciences (IMS) AMEDCREST, Japan Agency for Medical Research and Development, Yokohama, Japan; ¶Institute for Advanced Biosciences, Keio University, Tsuruoka, Japan; **Center for Stem Cell and Regenerative Medicine and Graduate School, Tokyo Medical and Dental University, Tokyo, Japan; ††Department of Advanced Therapeutics for Gastrointestinal Diseases, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan; and ‡‡Endoscopy and Medicine, Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan.
authors.forename: Ryohei
authors.initials: R
authors.lastname: Hayashi
authors.forename: Kiichiro
authors.initials: K
authors.lastname: Tsuchiya
authors.forename: Keita
authors.initials: K
authors.lastname: Fukushima
authors.forename: Nobukatsu
authors.initials: N
authors.lastname: Horita
authors.forename: Shuji
authors.initials: S
authors.lastname: Hibiya
authors.forename: Keisuke
authors.initials: K
authors.lastname: Kitagaki
authors.forename: Mariko
authors.initials: M
authors.lastname: Negi
authors.forename: Eisaku
authors.initials: E
authors.lastname: Itoh
authors.forename: Takumi
authors.initials: T
authors.lastname: Akashi
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Eishi
authors.forename: Eriko
authors.initials: E
authors.lastname: Okada
authors.forename: Akihiro
authors.initials: A
authors.lastname: Araki
authors.forename: Kazuo
authors.initials: K
authors.lastname: Ohtsuka
authors.forename: Shinji
authors.initials: S
authors.lastname: Fukuda
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ohno
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Okamoto
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Nakamura
authors.forename: Shinji
authors.initials: S
authors.lastname: Tanaka
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Chayama
authors.forename: Mamoru
authors.initials: M
authors.lastname: Watanabe
mesh_terms: D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D015153:Blotting, Western; D016022:Case-Control Studies; D047369:Chromatin Immunoprecipitation; D003424:Crohn Disease / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D006801:Humans; D007124:Immunoenzyme Techniques; D007421:Intestine, Small / Q000378:metabolism / Q000473:pathology*; D007583:Jejunum / Q000378:metabolism / Q000473:pathology*; D008156:Luciferases / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D023084:alpha-Defensins / Q000235:genetics* / Q000378:metabolism; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D015415:Biomarkers; D008156:Luciferases; D012333:RNA, Messenger; D023084:alpha-Defensins; D051176:beta Catenin; C500942:ATOH1 protein, human; C517765:DEFA6 protein, human