Restoring age-related loss of the lactate receptor GPR81 improves mitochondrial function and mitigates skeletal muscle aging

Skeletal muscle aging is associated with increased lipid accumulation, or myosteatosis, leading to lipotoxicity and loss of muscle function. Here, we report that loss of the novel lactate receptor GPR81 in aged muscle is associated with impaired lipid oxidation and enhanced lipid accumulation. Knockdown of GPR81 in young healthy myoblasts led to an increase in senescence hallmarks such as DNA damage, accumulation of reactive oxygen species (ROS), mitochondrial dysfunction and impaired autophagy. Conversely, treatment of senescent myoblasts with GPR81 agonists enhanced lipid oxidation in senescent myoblasts leading to a decrease in lipid accumulation, ultimately resulting in decreased DNA damage, ROS accumulation and enhanced ability to form myotubes. In agreement with our in vitro findings, we observed significant improvement in muscle regeneration and overall health of aged or progeric mice that were treated with GPR81 agonists. Our findings suggest that GPR81 plays a key role in skeletal muscle lipid metabolism, and agonists of GPR81 might play a promising role in reversing age-associated lipid accumulation and loss of muscle function.