Skeletal muscle DNMT3A plays a necessary role in endurance exercise by regulating oxidative capacity of red muscles

Abstract

Exercise interventions alter the DNA methylation profile in skeletal muscle, yet little is known about the role of the DNA methylation machinery in exercise capacity. In this study, we found that in oxidative red muscle, DNMT3A expression increases greatly following a bout of endurance exercise. Mice lacking Dnmt3a in skeletal muscle fibers had reduced tolerance to endurance exercise, accompanied by reduced oxidative capacity and reduced mitochondrial counts. Moreover, during exercise, the knockout muscles overproduced reactive oxygen species (ROS), which are major contributors to muscle dysfunction. In mechanistic terms, we demonstrated that Aldh1l1 is a key target of repression by DNMT3A in red muscles.DNMT3A directly regulated the Aldh1l1 transcription by binding to the Aldh1l1 promoter region and altering DNA methylation and histone modification. Enforcing ALDH1L1 expression, leading to elevated NADPH, led to overproduction of ROS by the NADPH oxidase complex (NOX) in myotubes, ultimately resulting in mitochondrial defects. Moreover, both genetic inhibition of ALDH1L1 and pharmacological inhibition of NOX rescued oxidative stress and mitochondrial decline in Dnmt3a-deficient myotubes, confirming the essential role of ALDH1L1-dependent ROS generation as a downstream effector of DNMT3A loss of function. Together, our results reveal that DNMT3A in skeletal muscle plays a pivotal role in endurance exercise by controlling intracellular oxidative stress. 10].Reactive oxygen species (ROS), including oxygen-derived molecules such as hydrogen peroxide (H2O2) and free radicals such as superoxide (•O2 −) and hydroxyl radical (HO•), cause oxidative stress [11,12] . A moderate increase in skeletal muscle ROS production in the acute phase of exercise is thought to activate signaling pathways that lead to cellular adaptation, thereby protecting against future stress [13][14][15][16][17].However, excessive ROS can oxidatively damage macromolecules including DNA, lipids, and proteins, as well as modify cellular redox status and cellular functions; consequently, ROS elevation is also associated with pathophysiological states of muscle and contractile dysfunction [13][14][15][16]. Mitochondria make a large contribution to ROS production at rest, but not during muscle contraction [13,[17][18][19]. The majority of ROS produced during contraction arise from non-mitochondrial sources, such as NADPH oxidase (NOX), located in the microtubules [16,20,21] . The redox-mediated crosstalk between NOX and mitochondria exacerbates ROS production and disrupts redox homeostasis [21][22][23][24]. For example, NOX-derived ROS promote the opening of mitochondrial ATP-sensitive K+ channels [23][24][25]. The resultant potassium influx into the matrix lowers the mitochondrial membrane potential, which causes mitochondrial swelling, opening of permeability transition pores, and elevated ROS production [23][24][25]. In addition, NOX-derived ROS causes leakage of Ca2+ from the sarcoplasmic reticulum or entry of extracellular Ca2+, resulting in mitocho...