AMPK enhances the expression of pancreatic duodenal homeobox-1 via PPARalpha, but not PPARgamma, in rat insulinoma cell line INS-1

Acta Pharmacol Sin. 2010 Aug;31(8):963-9. doi: 10.1038/aps.2010.78. Epub 2010 Jul 19.

Abstract

Aim: To investigate whether AMP-activated protein kinase (AMPK) regulates the expression of pancreatic duodenal homeobox-1 (PDX-1), a beta-cell-specific transcription factor and whether PPARalpha/gamma is involved in the regulation of pancreatic beta-cell lines after acute stimulation.

Methods: Rat insulinoma cell line INS-1 was treated with an activator (AICAR) or inhibitor (Compound C) of AMPK as well as inhibitors of PPARs (MK886 to PPARalpha and BADGE to PPARgamma). The mRNA levels of PDX-1, PPARalpha and PPARgamma were measured using real-time RT-PCR, and Western blotting was used to detect the protein expression of these factors.

Results: Activation of AMPK by AICAR induced significantly increased the expression of PDX-1, and this increase was abrogated when AMPK was inactivated by Compound C. Similarly, the expression of PPARalpha and PPARgamma was also increased by AICAR or decreased by Compound C. However AMPK activation did not increase nuclear PDX-1 protein levels when PPARalpha was inhibited. In contrast, AMPK activation still up-regulated PDX-1 protein levels during PPARgamma inhibition. Additionally, PPARalpha activation induced by fenofibrate significantly enhanced nuclear PDX-1 protein expression.

Conclusion: AMPK regulates the expression of PDX-1 at both the transcriptional and protein levels, and PPARalpha may be acutely involved in the regulation of INS-1 cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • AMP-Activated Protein Kinases / metabolism*
  • Aminoimidazole Carboxamide / analogs & derivatives
  • Aminoimidazole Carboxamide / pharmacology
  • Animals
  • Blotting, Western
  • Cell Line, Tumor
  • Gene Expression Regulation
  • Homeodomain Proteins / metabolism*
  • Insulinoma / metabolism*
  • PPAR alpha / drug effects
  • PPAR alpha / metabolism*
  • PPAR gamma / drug effects
  • PPAR gamma / metabolism
  • Pyrazoles / pharmacology
  • Pyrimidines / pharmacology
  • RNA, Messenger
  • Rats
  • Reverse Transcriptase Polymerase Chain Reaction
  • Ribonucleotides / pharmacology
  • Trans-Activators / metabolism*

Substances

  • Homeodomain Proteins
  • PPAR alpha
  • PPAR gamma
  • Pyrazoles
  • Pyrimidines
  • RNA, Messenger
  • Ribonucleotides
  • Trans-Activators
  • pancreatic and duodenal homeobox 1 protein
  • dorsomorphin
  • Aminoimidazole Carboxamide
  • AMP-Activated Protein Kinases
  • AICA ribonucleotide