Adipose tissue PGC1 alpha and PGC1 beta mRNA expression in visceral obesity and in response to exercise training

Aims: The PPARgamma co-activators 1 (PGC1) are major transcriptional regulators of several crucial aspects of oxidative metabolism, including mitochondrial biogenesis and respiration. We examined whether PGC1 alpha and/or PGC1 beta mRNA expression in human adipose tissue is fat-depot specific. We also studied whether their expression in adipose tissue is associated with metabolic parameters and whether their expression is regulated by intensive physical exercise. Research design and methods: We determined metabolic parameters and measured PGC1 alpha and PGC1 beta mRNA expression using quantitative real-time PCR in adipose tissue in an observational study of 153 subjects, and an interventional study of 60 subjects (20 each with normal glucose tolerance, impaired glucose tolerance, and type 2 diabetes) before and after intensive physical training for 4 weeks. Results: PGC1 alpha and PGC1 beta mRNA expression is 2 fold higher in visceral as compared to subcutaneous adipose tissue and highly correlated between the two depots. PGC1 alpha, but not PGC1 beta mRNA expression in visceral fat significantly correlates with measures of obesity and fat distribution as well as with parameters of insulin resistance and hyperglycemia even after adjustment for body fat mass. Physical training for 4 weeks resulted in significantly increased PGC1 alpha and PGC1 beta mRNA expression in subcutaneous fat. Conclusions: PGC1 alpha mRNA expression in visceral fat is associated with obesity and impaired insulin sensitivity. Increased PGC1 alpha and PGC1 beta mRNA expression after a 4 weeks training program may mediate the improvement of insulin sensitivity in response to exercise.