Journal Article

AMP-Activated Protein Kinase-Regulated Activation of the PGC-1α Promoter in Skeletal Muscle Cells

Hood, David A., Ljubicic, Vladimir, Irrcher, Isabella, Kirwan, Angie F.

2008

Overview

The mechanisms by which PGC-1α gene expression is controlled in skeletal muscle remains largely undefined. Thus, we sought to investigate the transcriptional regulation of PGC-1α using AICAR, an activator of AMPK, that is known to increase PGC-1α expression. A 2.2 kb fragment of the human PGC-1α 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-κB, and EBox binding proteins. AMPK activation for 24 hours increased PGC-1α 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-1α 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-1α promoter activity, which was confirmed in vivo by ChIP. Overexpression of either GATA-4 or USF-1 alone increased the p851 PGC-1α 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-1α promoter activity. The USF-1-mediated increase in PGC-1α promoter activation led to similar increases at the mRNA level. Our data identify a novel AMPK-mediated regulatory pathway that regulates PGC-1α gene expression. This could represent a potential therapeutic target to control PGC-1α expression in skeletal muscle.

• Publisher: Public Library of Science
• Subject: Activation / AMP / AMP-activated protein kinase / Binding sites / Biology / Biosynthesis / Cell Biology/Cell Signaling / Cell Biology/Gene Expression / Conserved sequence / Cytochrome / Deoxyribonucleic acid / Diabetes / DNA / Gene expression / Gene regulation / Heart / Housing / Insulin resistance / Kinases / Kinesiology / Medical research / Musculoskeletal system / Mutation / Myocyte enhancer factor 2 / Myocyte-specific enhancer-binding factor 2 / NF-κB protein / Physiology/Cell Signaling / Physiology/Muscle and Connective Tissue / Proteins / Residential areas / Rodents / Skeletal muscle / Transcription activation / Transcription factors