title: Pancreatic epithelial cells can be converted into insulin-producing cells by GLP-1 in conjunction with virus-mediated gene transfer of pdx-1.
abstract: BACKGROUND
  Glucagonlike peptide-1 (GLP-1) stimulates insulin secretion and proliferation by islet cells in vitro and in vivo, associated with an activation of pancreatic duodenal homeobox gene-1 (pdx-1) function. The effect of GLP-1 on the conditionally immortalized pancreatic epithelial cells (IMPE cells) is not clear when they are treated in conjunction with the adenovirus-mediated gene transfer of pdx-1.
  
  
  METHODS
  IMPE cells were established from the pancreas of H-2K(b)-tsA58 transgenic mice. IMPE cells were maintained at 33 degrees C with 10 U/mL interferon (IFN)-gamma and the experiments were performed at 39 degrees C without IFN-gamma. IMPE cells were infected with 20 multiplicities of Ad-pdx-1 or control Ad-lacZ at 39 degrees C without IFN-gamma and were incubated with various concentrations of GLP-1. After 48 hours, immunofluorescence and reverse transcriptase-polymerase chain reaction for insulin and pdx-1 expression were examined. Immunoreactive insulin in the cell lysate and supernatant was also analyzed. The glucose concentration in the culture medium was changed to test the insulin secretory responsiveness of the IMPE cells.
  
  
  RESULTS
  The treatment with GLP-1 in conjunction with Ad-pdx-1 induced insulin production by IMPE cells, but the treatment with either GLP-1 or Ad-pdx-1 alone failed to induce insulin production. Insulin production and secretion were increased by GLP-1 and by glucose in a dose-dependent manner. In addition, the insulin-producing IMPE cells acquired a rapid insulin secretory responsiveness to the changes of extracellular glucose concentration.
  
  
  CONCLUSIONS
  GLP-1 and pdx-1 work together to induce insulin-producing cells from IMPE cells, which bear unique characteristics of pancreatic ductal cells. The results suggest that GLP-1 may be another important determiner of pancreatic endocrine differentiation as is pdx-1.
authors.affiliation: Department of Surgery and Surgical Basic Science, Kyoto University, Sakyo, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Koizumi
authors.forename: Ryuichiro
authors.initials: R
authors.lastname: Doi
authors.forename: Koji
authors.initials: K
authors.lastname: Fujimoto
authors.forename: Daisuke
authors.initials: D
authors.lastname: Ito
authors.forename: Eiji
authors.initials: E
authors.lastname: Toyoda
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Mori
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Kami
authors.forename: Yoshiya
authors.initials: Y
authors.lastname: Kawaguchi
authors.forename: George K
authors.initials: GK
authors.lastname: Gittes
authors.forename: Masayuki
authors.initials: M
authors.lastname: Imamura
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D015415:Biomarkers; D002454:Cell Differentiation / Q000187:drug effects; D002461:Cell Line, Transformed; D004847:Epithelial Cells / Q000166:cytology* / Q000378:metabolism; D018014:Gene Transfer Techniques; D005934:Glucagon / Q000494:pharmacology*; D052216:Glucagon-Like Peptide 1; D005947:Glucose / Q000494:pharmacology; D018398:Homeodomain Proteins / Q000235:genetics*; D007328:Insulin / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D010179:Pancreas / Q000166:cytology*; D010446:Peptide Fragments / Q000494:pharmacology*; D011498:Protein Precursors / Q000494:pharmacology*; D015534:Trans-Activators / Q000235:genetics*
chemical_list: D015415:Biomarkers; D018398:Homeodomain Proteins; D007328:Insulin; D010446:Peptide Fragments; D011498:Protein Precursors; D015534:Trans-Activators; C084010:pancreatic and duodenal homeobox 1 protein; D052216:Glucagon-Like Peptide 1; D005934:Glucagon; D005947:Glucose