A novel role of Mef2a in mitochondrial homeostasis and muscle regeneration during sarcopenia

Abstract

Sarcopenia, characterized by an age-related decline in skeletal muscle mass and function, is closely associated with mitochondrial dysfunction. This study aimed to explore the role of myocyte enhancer factor 2A (MEF2A) in alleviating sarcopenia, focusing on its regulatory effect on mitochondrial homeostasis. AAV9-MEF2A was administered to 24-month-old male SAMP8 mice, and their endurance capacity and muscle histology were assessed. In vitro, MEF2A was overexpressed in C2C12 cells to examine its impact on myoblast proliferation and differentiation. Chromatin immunoprecipitation (ChIP), luciferase assays, and rescue experiments were conducted to identify downstream targets and validate the MEF2A-regulated signaling pathway. MEF2A overexpression significantly enhanced endurance performance, with a 1.17-fold increase in muscle mass, a 2.4 to 4.9-fold decrease in muscle atrophy markers compared to the AAV9-NC group, and a nearly 2 to 3-fold increase in mitochondrial biogenesis and antioxidant enzyme expression in aged mice. In C2C12 cells, MEF2A stimulated proliferation (1.8 fold increase in EdU-positive cells vs vector group) and differentiation (2 to 3-fold increase in differentiation markers vs vector group) while improving mitochondrial function through 1.5 to 2-fold increases in both OxPhos complex proteins and mitochondrial biogenesis genes compared to vector control. Mechanistically, MEF2A directly activated the PGC-1α/NRF2 axis, as validated by ChIP and reporter assays. Rescue experiments further verified the critical role of this pathway in MEF2A-mediated effects. These findings demonstrate that MEF2A mitigates sarcopenia by improving mitochondrial function and promoting muscle regeneration via activation of the PGC-1α/NRF2 signaling axis. MEF2A represents a promising therapeutic target for combating age-related muscle degeneration.