Pax-6 activates endogenous proglucagon gene expression in the rodent gastrointestinal epithelium.
The proglucagon gene encodes pancreatic glucagon and the glucagon-like peptides, which exert diverse effects on nutrient absorption and assimilation. The therapeutic potential of glucagon-like peptide-1 (GLP-1) has fostered interest in development of cellular engineering approaches to augment endogenous intestinal-derived GLP-1 for the treatment of type 2 diabetes. We have used adenovirus technology to examine the potential roles of the transcription factors Cdx-2/3 and Pax-6 as activators of endogenous proglucagon gene expression in enteroendocrine cell lines and in nontransformed rat intestinal cells. Adenoviral-expressed Cdx-2/3 and Pax-6 activated proglucagon promoter-luciferase activity in baby hamster kidney (BHK) fibroblasts, HEK 293 cells, and enteroendocrine cell lines. Pax-6, but not Cdx-2/3, induced expression of the endogenous proglucagon gene in enteroendocrine cell lines, but not in heterologous fibroblasts. Furthermore, transduction of primary rat intestinal cell cultures in vitro, or the rat colonic epithelium in vivo, with Ad-Pax-6 activated endogenous proglucagon gene expression. These data demonstrate that Pax-6, but not Cdx-2/3, is capable of activating the endogenous proglucagon gene in both immortalized enteroendocrine cells and the nontransformed intestinal epithelium in vivo.
Trinh
Denny K Y
DK
Department of Medicine, Banting and Best Diabetes Center, Toronto General Hospital, University of Toronto, Ontario, Canada. d.trinh@utoronto.ca
Zhang
Kai
K
Hossain
Moazzem
M
Brubaker
Patricia L
PL
Drucker
Daniel J
DJ
D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D017931:DNA Primers; D005136:Eye Proteins; D005347:Fibroblasts / Q000502:physiology; D005753:Gastric Mucosa / Q000502:physiology*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D005934:Glucagon / Q000235:genetics*; D018398:Homeodomain Proteins / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D007413:Intestinal Mucosa / Q000502:physiology*; D051379:Mice; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; D052336:Proglucagon; D011498:Protein Precursors / Q000235:genetics*; D051381:Rats; D012097:Repressor Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
D017931:DNA Primers; D005136:Eye Proteins; D018398:Homeodomain Proteins; D000071841:PAX6 Transcription Factor; C000605730:PAX6 protein, human; D051761:Paired Box Transcription Factors; C000605732:Pax6 protein, mouse; C000605733:Pax6 protein, rat; D011498:Protein Precursors; D012097:Repressor Proteins; D052336:Proglucagon; D005934:Glucagon