title: Activation of the developmental pathway neurogenin-3/microRNA-7a regulates cholangiocyte proliferation in response to injury.
abstract: The activation of the biliary stem-cell signaling pathway hairy and enhancer of split 1/pancreatic duodenal homeobox-1 (Hes-1/PDX-1) in mature cholangiocytes determines cell proliferation. Neurogenin-3 (Ngn-3) is required for pancreas development and ductal cell neogenesis. PDX-1-dependent activation of Ngn-3 initiates the differentiation program by inducing microRNA (miR)-7 expression. Here we investigated the role Ngn-3 on cholangiocyte proliferation. Expression levels of Ngn-3 and miR-7 isoforms were tested in cholangiocytes from normal and cholestatic human livers. Ngn-3 was knocked-down in vitro in normal rat cholangiocytes by short interfering RNA (siRNA). In vivo, wild-type and Ngn-3-heterozygous (+/-) mice were subjected to 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) feeding (a model of sclerosing cholangitis) or bile duct ligation (BDL). In the liver, Ngn-3 is expressed specifically in cholangiocytes of primary sclerosing cholangitis (PSC) patients and in mice subjected to DDC or BDL, but not in normal human and mouse livers. Expression of miR-7a-1 and miR-7a-2 isoforms, but not miR-7b, was increased in DDC cholangiocytes compared to normal ones. In normal rat cholangiocytes, siRNA against Ngn-3 blocked the proliferation stimulated by exendin-4. In addition, Ngn-3 knockdown neutralized the overexpression of insulin growth factor-1 (IGF1; promitotic effector) observed after exposure to exendin-4, but not that of PDX-1 or VEGF-A/C. Oligonucleotides anti-miR-7 inhibited the exendin-4-induced proliferation in normal rat cholangiocytes, but did not affect Ngn-3 synthesis. Biliary hyperplasia and collagen deposition induced by DDC or BDL were significantly reduced in Ngn-3(+/-) mice compared to wild-type.
  
  
  CONCLUSIONS
  Ngn-3-dependent activation of miR-7a is a determinant of cholangiocyte proliferation. These findings indicate that the reacquisition of a molecular profile typical of organ development is essential for the biological response to injury by mature cholangiocytes.
authors.affiliation: Department of Gastroenterology and Hepatology, Università Politecnica delle Marche, Ancona, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Marzioni
authors.forename: Laura
authors.initials: L
authors.lastname: Agostinelli
authors.forename: Cinzia
authors.initials: C
authors.lastname: Candelaresi
authors.forename: Stefania
authors.initials: S
authors.lastname: Saccomanno
authors.forename: Samuele
authors.initials: S
authors.lastname: De Minicis
authors.forename: Luca
authors.initials: L
authors.lastname: Maroni
authors.forename: Eleonora
authors.initials: E
authors.lastname: Mingarelli
authors.forename: Chiara
authors.initials: C
authors.lastname: Rychlicki
authors.forename: Luciano
authors.initials: L
authors.lastname: Trozzi
authors.forename: Jesus M
authors.initials: JM
authors.lastname: Banales
authors.forename: Antonio
authors.initials: A
authors.lastname: Benedetti
authors.forename: Gianluca Svegliati
authors.initials: GS
authors.lastname: Baroni
mesh_terms: D055371:Acute Lung Injury / Q000378:metabolism / Q000503:physiopathology*; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D001652:Bile Ducts / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D049109:Cell Proliferation / Q000502:physiology*; D002779:Cholestasis / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D003094:Collagen / Q000378:metabolism; D004195:Disease Models, Animal; D000077270:Exenatide; D006801:Humans; D066298:In Vitro Techniques; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D051379:Mice; D008815:Mice, Inbred Strains; D035683:MicroRNAs / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D009841:Oligonucleotides / Q000494:pharmacology; D010455:Peptides / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D051381:Rats; D015398:Signal Transduction / Q000502:physiology*; D014688:Venoms / Q000378:metabolism
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D003094:Collagen; D000077270:Exenatide; D007334:Insulin-Like Growth Factor I; D035683:MicroRNAs; D009419:Nerve Tissue Proteins; D009841:Oligonucleotides; D010455:Peptides; D034741:RNA, Small Interfering; D014688:Venoms; C549242:MIRN7-1 microRNA, human; C498695:NEUROG3 protein, human