title: Effects of CFTR gene silencing by siRNA or the luminal application of a CFTR activator on fluid secretion from guinea-pig pancreatic duct cells.
abstract: OBJECTIVE
  The cystic fibrosis transmembrane conductance regulator (CFTR) is a cyclic AMP regulated chloride channel expressed in the apical plasma membrane of pancreatic duct cells where it plays an important role in fluid secretion. The purpose of this study was to elucidate the role of the CFTR chloride channel on ion and fluid secretion from the guinea-pig pancreas by manipulating the expression of CFTR by RNA interference or by luminal application of a CFTR selective activator, MPB91, in isolated cultured pancreatic ducts.
  
  
  METHODS
  Using cDNA isolated from the guinea-pig small intestine, fragments of the CFTR gene were generated by polymerase chain reaction and directly sequenced. Two different RNA duplexes for small interference RNA (siRNA) were designed from the sequence obtained. Fluid secretion from the isolated guinea-pig pancreatic ducts was measured using video-microscopy. The amount of CFTR chloride channel or AQP1 water channel expressed in pancreatic ducts was examined by immunoblotting with antibodies against CFTR or AQP1, respectively.
  
  
  RESULTS
  Guinea-pig CFTR consists of 1481 amino acid residues. An additional glutamine residue was found to be inserted between amino acid residues 403 and 404 of human CFTR. Forskolin-stimulated fluid secretion from intact pancreatic ducts was significantly higher in the presence of MPB91 compared to fluid secretion in the absence of MPB91. Both basal and forskolin-stimulated fluid secretion in pancreatic ducts transfected with CFTR specific siRNAs were reduced by ∼50% compared to fluid secretion from ducts transfected with scrambled negative control dsRNAs. The amount of CFTR and AQP1 proteins was reduced to 34% and 45% of control, respectively.
  
  
  CONCLUSIONS
  The activity of the CFTR chloride channel or the amount of CFTR protein expressed determines the rate of fluid secretion from the isolated guinea-pig pancreatic ducts.
authors.affiliation: Department of Gastroenterology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi 466-8550, Japan. sko@med.nagoya-u.ac.jp
authors.forename: Shigeru B H
authors.initials: SB
authors.lastname: Ko
authors.forename: Akiko
authors.initials: A
authors.lastname: Yamamoto
authors.forename: Sakiko
authors.initials: S
authors.lastname: Azuma
authors.forename: Haizhen
authors.initials: H
authors.lastname: Song
authors.forename: Kaori
authors.initials: K
authors.lastname: Kamimura
authors.forename: Miyuki
authors.initials: M
authors.lastname: Nakakuki
authors.forename: Michael A
authors.initials: MA
authors.lastname: Gray
authors.forename: Frédéric
authors.initials: F
authors.lastname: Becq
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ishiguro
authors.forename: Hidemi
authors.initials: H
authors.lastname: Goto
mesh_terms: D000818:Animals; D051398:Aquaporin 1 / Q000235:genetics; D001826:Body Fluids / Q000378:metabolism; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics / Q000502:physiology*; D005260:Female; D055785:Gene Knockdown Techniques; D020868:Gene Silencing; D006168:Guinea Pigs; D006801:Humans; D066298:In Vitro Techniques; D010183:Pancreatic Ducts / Q000187:drug effects / Q000378:metabolism*; D011807:Quinolizines / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics; D017422:Sequence Analysis, DNA; D020539:Sequence Analysis, Protein
chemical_list: C439425:5-butyl-6-hydroxy-10-chlorobenzo(c)quinolizinium chloride; D011807:Quinolizines; D034741:RNA, Small Interfering; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D051398:Aquaporin 1