Objectives. A strong association between genetic variants and obesity was found for the fat mass and obesity associated (FTO) gene. However, few details are known concerning the expression and function of FTO in skeletal muscle of patients with metabolic diseases.
Research Design and Methods. We investigated basal FTO expression in skeletal muscle from obese non diabetic subjects and type 1 and type 2 diabetic patients, compared to age-matched control subjects, and its regulation in vivo by insulin, glucose or rosiglitazone. The function of FTO was further studied in myotubes by over-expression experiments.
Results. We found a significant increase of FTO mRNA and protein levels in muscle from type 2 diabetic patients, whereas its expression was unchanged in obese or type 1 diabetic patients. Moreover, insulin or glucose infusion during specific clamps did not regulate FTO expression in skeletal muscle from control or type 2 diabetic patients. Interestingly, rosiglitazone treatment improved insulin sensitivity and reduced FTO expression in muscle from type 2 diabetic patients. In myotubes, adenoviral FTO over-expression increased basal PKB phosphorylation, enhanced lipogenesis and oxidative stress, and reduced mitochondrial oxidative function, a cluster of metabolic defects associated with type 2 diabetes.
Conclusions. This study demonstrates increased FTO expression in skeletal muscle from type 2 diabetic patients, which can be normalized by thiazolidinedione treatment. Furthermore, in vitro data support a potential implication of FTO in oxidative metabolism, lipogenesis and oxidative stress in muscle, suggesting that it could be involved in the muscle defects that characterize type 2 diabetes.
- Received February 25, 2010.
- Accepted October 4, 2010.
- Copyright © American Diabetes Association