Exendin-4 differentiation of a human pancreatic duct cell line into endocrine cells: Involvement of PDX-1 and HNF3β transcription factors

Jie Zhou, Marco A. Pineyro, Xiaolin Wang, Maire E. Doyle, Josephine M. Egan

Research output: Contribution to journalArticle

Abstract

Exendin-4 (EX-4), a long acting agonist of GLP-1, induces an endocrine phenotype in Capan-1 cells. Under culture conditions which include serum, ∼10% of the cells contain insulin and glucagon. When exposed to EX-4 (0.1 Nm, up to 5 days), the number of cells containing insulin and glucagon increased to ∼40%. Western blot analysis detected a progressive increase in protein levels of glucokinase and GLUT2 over 3 days of EX-4 treatment. We explored the sequence of activation of certain transcription factors known to be essential for the beta cell phenotype: PDX-1, Beta2/NeuroD, and hepatocyte nuclear factor 3β (HNF3 β). Double immunostaining showed that PDX-1 coexisted with insulin and glucagon in EX-4-treated cells. Treatment caused an increase in PDX-1 protein levels by 24 h and induced its nuclear translocation. Beta2/NeuroD protein levels also increased progressively over 24 h. HNF3β protein level increased twofold as early as 6 h after EX-4 treatment. EMSA results indicated that EX-4 caused a 1 2-fold increase in HNF3β binding to PDX-1 promoter area II. Beta2/NeuroD protein levels progressively increased after 24 h treatment. Differentiation to insulin-producing cells was also seen when Capan-1 cells were transfected with pdx-1, with 80% of these cells expressing insulin 3 days after transfection. PDX-1 antisense totally inhibited such conversion. During the differentiation of duct cells to endocrine cells, CAMP levels (EX-4 is a ligand for the GLP-1, G-protein coupled receptor) and MAP kinase activity increased. Our results indicate that EX-4 activates adenylyl cyclase and MAP kinase which, in turn, may lead to activation of transcription factors necessary for an endocrine phenotype.

Original languageEnglish (US)
Pages (from-to)304-314
Number of pages11
JournalJournal of Cellular Physiology
Volume192
Issue number3
DOIs
StatePublished - Aug 10 2002
Externally publishedYes

ASJC Scopus subject areas

  • Physiology
  • Clinical Biochemistry
  • Cell Biology

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