AMP-activated protein kinase-regulated activation of the PGC-1alpha promoter in skeletal muscle cells.
The mechanisms by which PGC-1alpha gene expression is controlled in skeletal muscle remains largely undefined. Thus, we sought to investigate the transcriptional regulation of PGC-1alpha using AICAR, an activator of AMPK, that is known to increase PGC-1alpha expression. A 2.2 kb fragment of the human PGC-1alpha promoter was cloned and sequence analysis revealed that this TATA-less sequence houses putative consensus sites including a GC-box, a CRE, several IRSs, a SRE, binding sites for GATA, MEF2, p 53, NF-kappaB, and EBox binding proteins. AMPK activation for 24 hours increased PGC-1alpha promoter activity with concomitant increases in mRNA expression. The effect of AICAR on transcriptional activation was mediated by an overlapping GATA/EBox binding site at -495 within the PGC-1alpha promoter based on gel shift analyses that revealed increases in GATA/EBox DNA binding. Mutation of the EBox within the GATA/EBox binding site in the promoter reduced basal promoter activity and completely abolished the AICAR effect. Supershift analyses identified USF-1 as a DNA binding transcription factor potentially involved in regulating PGC-1alpha promoter activity, which was confirmed in vivo by ChIP. Overexpression of either GATA-4 or USF-1 alone increased the p851 PGC-1alpha promoter activity by 1.7- and 2.0-fold respectively, while co-expression of GATA-4 and USF-1 led to an additive increase in PGC-1alpha promoter activity. The USF-1-mediated increase in PGC-1alpha promoter activation led to similar increases at the mRNA level. Our data identify a novel AMPK-mediated regulatory pathway that regulates PGC-1alpha gene expression. This could represent a potential therapeutic target to control PGC-1alpha expression in skeletal muscle.
Irrcher
Isabella
I
Department of Biology, York University, Toronto, Ontario, Canada.
Ljubicic
Vladimir
V
Kirwan
Angie F
AF
Hood
David A
DA
D055372:AMP-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism; D024721:E-Box Elements; D004791:Enzyme Inhibitors / Q000494:pharmacology; D050991:GATA4 Transcription Factor / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D032342:Muscle Cells / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism*; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D011401:Promoter Regions, Genetic; D012265:Ribonucleotides / Q000494:pharmacology; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D015533:Transcriptional Activation; D051720:Upstream Stimulatory Factors / Q000378:metabolism
D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D050991:GATA4 Transcription Factor; D006360:Heat-Shock Proteins; C486497:PPARGC1A protein, human; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D012265:Ribonucleotides; D014157:Transcription Factors; C497181:USF1 protein, human; D051720:Upstream Stimulatory Factors; D000620:Aminoimidazole Carboxamide; D055372:AMP-Activated Protein Kinases; C031143:AICA ribonucleotide