title: Notch signaling regulates tubular morphogenesis during repair from biliary damage in mice.
abstract: OBJECTIVE
  Repair from biliary damages requires the biliary specification of hepatic progenitor cells and the remodeling of ductular reactive structures into branching biliary tubules. We hypothesized that the morphogenetic role of Notch signaling is maintained during the repair process and have addressed this hypothesis using pharmacologic and genetic models of defective Notch signaling.
  
  
  METHODS
  Treatment with DDC (3,5-diethoxycarbonyl-1,4-dihydrocollidine) or ANIT (alpha-naphthyl-isothiocyanate) was used to induce biliary damage in wild type mice and in mice with a liver specific defect in the Notch-2 receptor (Notch-2-cKO) or in RPB-Jk. Hepatic progenitor cells, ductular reaction, and mature ductules were quantified using K19 and SOX-9.
  
  
  RESULTS
  In DDC treated wild type mice, pharmacologic Notch inhibition with dibenzazepine decreased the number of both ductular reaction and hepatic progenitor cells. Notch-2-cKO mice treated with DDC or ANIT accumulated hepatic progenitor cells that failed to progress into mature ducts. In RBP-Jk-cKO mice, mature ducts and hepatic progenitor cells were both significantly reduced with respect to similarly treated wild type mice. The mouse progenitor cell line BMOL cultured on matrigel, formed a tubular network allowing the study of tubule formation in vitro; γ-secretase inhibitor treatment and siRNAs silencing of Notch-1, Notch-2 or Jagged-1 significantly reduced both the length and number of tubular branches.
  
  
  CONCLUSIONS
  These data demonstrate that Notch signaling plays an essential role in biliary repair. Lack of Notch-2 prevents biliary tubule formation, both in vivo and in vitro. Lack of RBP-Jk inhibits the generation of biliary-committed precursors and tubule formation.
authors.affiliation: Liver Center & Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520, USA.
authors.forename: Romina
authors.initials: R
authors.lastname: Fiorotto
authors.forename: Aileen
authors.initials: A
authors.lastname: Raizner
authors.forename: Carola M
authors.initials: CM
authors.lastname: Morell
authors.forename: Barbara
authors.initials: B
authors.lastname: Torsello
authors.forename: Roberto
authors.initials: R
authors.lastname: Scirpo
authors.forename: Luca
authors.initials: L
authors.lastname: Fabris
authors.forename: Carlo
authors.initials: C
authors.lastname: Spirli
authors.forename: Mario
authors.initials: M
authors.lastname: Strazzabosco
mesh_terms: D015058:1-Naphthylisothiocyanate / Q000633:toxicity; D053829:Amyloid Precursor Protein Secretases / Q000037:antagonists & inhibitors; D000818:Animals; D001653:Bile Ducts, Intrahepatic / Q000293:injuries* / Q000473:pathology / Q000503:physiopathology*; D002135:Calcium-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein / Q000172:deficiency / Q000235:genetics / Q000502:physiology; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000502:physiology; D000072100:Jagged-1 Protein; D008115:Liver Regeneration / Q000187:drug effects / Q000502:physiology; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009024:Morphogenesis / Q000187:drug effects / Q000502:physiology; D011725:Pyridines / Q000633:toxicity; D034741:RNA, Small Interfering / Q000235:genetics; D051883:Receptor, Notch2 / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D000072099:Serrate-Jagged Proteins; D015398:Signal Transduction / Q000187:drug effects; D013234:Stem Cells / Q000187:drug effects / Q000473:pathology / Q000502:physiology
chemical_list: C530773:3,5-diethoxycarbonyl-1,4-dihydrocollidine; D002135:Calcium-Binding Proteins; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein; D036341:Intercellular Signaling Peptides and Proteins; C000606274:Jag1 protein, mouse; D000072100:Jagged-1 Protein; D008565:Membrane Proteins; C497765:Notch2 protein, mouse; D011725:Pyridines; D034741:RNA, Small Interfering; C497571:Rbpj protein, mouse; D051883:Receptor, Notch2; D000072099:Serrate-Jagged Proteins; D015058:1-Naphthylisothiocyanate; D053829:Amyloid Precursor Protein Secretases