title: Knockout of secretin receptor reduces large cholangiocyte hyperplasia in mice with extrahepatic cholestasis induced by bile duct ligation.
abstract: During bile duct ligation (BDL), the growth of large cholangiocytes is regulated by the cyclic adenosine monophosphate (cAMP)/extracellular signal-regulated kinase 1/2 (ERK1/2) pathway and is closely associated with increased secretin receptor (SR) expression. Although it has been suggested that SR modulates cholangiocyte growth, direct evidence for secretin-dependent proliferation is lacking. SR wild-type (WT) (SR(+/+)) or SR knockout (SR(-/-)) mice underwent sham surgery or BDL for 3 or 7 days. We evaluated SR expression, cholangiocyte proliferation, and apoptosis in liver sections and proliferating cell nuclear antigen (PCNA) protein expression and ERK1/2 phosphorylation in purified large cholangiocytes from WT and SR(-/-) BDL mice. Normal WT mice were treated with secretin (2.5 nmoles/kg/day by way of osmotic minipumps for 1 week), and biliary mass was evaluated. Small and large cholangiocytes were used to evaluate the in vitro effect of secretin (100 nM) on proliferation, protein kinase A (PKA) activity, and ERK1/2 phosphorylation. SR expression was also stably knocked down by short hairpin RNA, and basal and secretin-stimulated cAMP levels (a functional index of biliary growth) and proliferation were determined. SR was expressed by large cholangiocytes. Knockout of SR significantly decreased large cholangiocyte growth induced by BDL, which was associated with enhanced apoptosis. PCNA expression and ERK1/2 phosphorylation were decreased in large cholangiocytes from SR(-/-) BDL compared with WT BDL mice. In vivo administration of secretin to normal WT mice increased ductal mass. In vitro, secretin increased proliferation, PKA activity, and ERK1/2 phosphorylation of large cholangiocytes that was blocked by PKA and mitogen-activated protein kinase kinase inhibitors. Stable knockdown of SR expression reduced basal cholangiocyte proliferation. SR is an important trophic regulator sustaining biliary growth.
  
  
  CONCLUSIONS
  The current study provides strong support for the potential use of secretin as a therapy for ductopenic liver diseases.
authors.affiliation: Scott & White Digestive Disease Research Center, College of Medicine, Temple, TX, USA. sglaser@medicine.tamhsc.edu
authors.forename: Shannon
authors.initials: S
authors.lastname: Glaser
authors.forename: Ian P
authors.initials: IP
authors.lastname: Lam
authors.forename: Antonio
authors.initials: A
authors.lastname: Franchitto
authors.forename: Eugenio
authors.initials: E
authors.lastname: Gaudio
authors.forename: Paolo
authors.initials: P
authors.lastname: Onori
authors.forename: Billy K
authors.initials: BK
authors.lastname: Chow
authors.forename: Candace
authors.initials: C
authors.lastname: Wise
authors.forename: Shelley
authors.initials: S
authors.lastname: Kopriva
authors.forename: Julie
authors.initials: J
authors.lastname: Venter
authors.forename: Mellanie
authors.initials: M
authors.lastname: White
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Ueno
authors.forename: David
authors.initials: D
authors.lastname: Dostal
authors.forename: Guido
authors.initials: G
authors.lastname: Carpino
authors.forename: Romina
authors.initials: R
authors.lastname: Mancinelli
authors.forename: Wendy
authors.initials: W
authors.lastname: Butler
authors.forename: Valorie
authors.initials: V
authors.lastname: Chiasson
authors.forename: Sharon
authors.initials: S
authors.lastname: DeMorrow
authors.forename: Heather
authors.initials: H
authors.lastname: Francis
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Alpini
mesh_terms: D000818:Animals; D017209:Apoptosis; D001652:Bile Ducts / Q000187:drug effects / Q000473:pathology*; D049109:Cell Proliferation; D001651:Cholestasis, Extrahepatic / Q000150:complications* / Q000235:genetics / Q000473:pathology; D055786:Gene Knockout Techniques; D006965:Hyperplasia / Q000235:genetics / Q000473:pathology; D008099:Liver / Q000187:drug effects / Q000473:pathology*; D008107:Liver Diseases / Q000209:etiology* / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009929:Organ Size; D010766:Phosphorylation; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000502:physiology*; D011964:Receptors, Gastrointestinal Hormone / Q000235:genetics / Q000502:physiology*; D012633:Secretin / Q000494:pharmacology
chemical_list: D018809:Proliferating Cell Nuclear Antigen; D043562:Receptors, G-Protein-Coupled; D011964:Receptors, Gastrointestinal Hormone; C029937:secretin receptor; D012633:Secretin; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3