Induced Cre-mediated knockdown of Brca1 in skeletal muscle reduces mitochondrial respiration and prevents glucose intolerance in adult mice on a high-fat diet

The breast cancer type 1 susceptibility protein (Brca1) is a regulator of DNA repair in mammary gland cells; however, recent cell culture evidence suggests that Brca1 influences other processes, including those in nonmammary cells. In this study, we sought to determine whether Brca1 is necessary for metabolic regulation of skeletal muscle using a . novel in vivo mouse model. We developed an inducible skeletal muscle-specific Brca1-knockout (BRCA1KO(smi)) model to test whether Brca1 expression is necessary for maintenance of metabolic function of skeletal muscle when exposed to a high-fat diet (HFD). Our data demonstrated that deletion of Brca1 prevented HFD-induced alterations in glucose and insulin tolerance. Irrespective of diet, BRCA1KO(smi) mice exhibited significantly lower ADP-stimulated complex I mitochondrial respiration rates compared to age-matched wild-type (WT) mice. The data show that Brca1 has the ability to localize to the mitochondria in skeletal muscle and that BRCA1KO(smi) mice exhibit higher whole-body CO2 production, respiratory exchange ratio, and energy expenditure, compared with the WT mice. Our results demonstrate that loss of Brca1 in skeletal muscle leads to dysregulated metabolic function, characterized by decreased mitochondrial respiration. Thus, any condition that results in loss of Brca1 function could induce metabolic imbalance in skeletal muscle.