Bart Staels and his colleagues show that the transcription factor Rev-erb-α is highly expressed in oxidative muscle and, via loss- and gain-of-function experiments, including pharmacological activation, that it plays a key partin regulating the oxidative capacity of the muscle and exercise endurance. The nuclear receptor Rev-erb-α modulates hepatic lipid and glucose metabolism, adipogenesis and the inflammatory response in macrophages. We show here that Rev-erb-α is highly expressed in oxidative skeletal muscle and that its deficiency in muscle leads to reduced mitochondrial content and oxidative function, as well as upregulation of autophagy. These cellular effects resulted in both impaired mitochondrial biogenesis and increased clearance of this organelle, leading to compromised exercise capacity. On a molecular level, Rev-erb-α deficiency resulted in deactivation of the Lkb1-Ampk-Sirt1–Ppargc-1α signaling pathway. These effects were recapitulated in isolated fibers and in muscle cells after knockdown of the gene encoding Rev-erb-α, Nr1d1. In complementary experiments, Rev-erb-α overexpression in vitro increased the number of mitochondria and improved respiratory capacity, whereas muscle overexpression or pharmacological activation of Rev-erb-α in vivo increased exercise capacity. This study identifies Rev-erb-α as a pharmacological target that improves muscle oxidative function by modulating gene networks controlling mitochondrial number and function.

Statins are inhibitors of 3-hydroxy-3-methylglutaryl–coenzyme A (HMG-CoA) reductase used in the prevention of cardiovascular disease (CVD). In addition to their cholesterol-lowering activities, statins exert pleiotropic antiinflammatory effects, which might contribute to their beneficial effects not only on CVD but also on lipid-unrelated immune and inflammatory diseases, such as rheumatoid arthritis, asthma, stroke, and transplant rejection. However, the molecular mechanisms involved in these antiinflammatory properties of statins are unresolved. Here we show that the peroxisome proliferator–activated receptor (PPAR) α mediates antiinflammatory effects of simvastatin in vivo in models of acute inflammation. The inhibitory effects of statins on lipopolysaccharide-induced inflammatory response genes were abolished in PPARα-deficient macrophages and neutrophils. Moreover, simvastatin inhibited PPARα phosphorylation by lipopolysaccharide-activated protein kinase C (PKC) α. A constitutive active form of PKCα inhibited nuclear factor κB transrepression by PPARα whereas simvastatin enhanced transrepression activity of wild-type PPARα, but not of PPARα mutated in its PKC phosphorylation sites. These data indicate that the acute antiinflammatory effect of simvastatin occurs via PPARα by a mechanism involving inhibition of PKCα inactivation of PPARα transrepression activity.