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


CONCLUSIONS
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.
Guo
Hua
H
Central Laboratory, Provincial Hospital affiliated to Shandong University, Ji'nan, China.
Sun
Shui
S
Zhang
Xu
X
Zhang
Xiu-juan
XJ
Gao
Ling
L
Zhao
Jia-jun
JJ
D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western; D045744:Cell Line, Tumor; D005786:Gene Expression Regulation; D018398:Homeodomain Proteins / Q000378:metabolism*; D007340:Insulinoma / Q000378:metabolism*; D047493:PPAR alpha / Q000187:drug effects / Q000378:metabolism*; D047495:PPAR gamma / Q000187:drug effects / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D012333:RNA, Messenger; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012265:Ribonucleotides / Q000494:pharmacology; D015534:Trans-Activators / Q000378:metabolism*
D018398:Homeodomain Proteins; D047493:PPAR alpha; D047495:PPAR gamma; D011720:Pyrazoles; D011743:Pyrimidines; D012333:RNA, Messenger; D012265:Ribonucleotides; D015534:Trans-Activators; C084010:pancreatic and duodenal homeobox 1 protein; C516138:dorsomorphin; D000620:Aminoimidazole Carboxamide; D055372:AMP-Activated Protein Kinases; C031143:AICA ribonucleotide