GDF15 modulates mitochondrial content and differentiation-associated metabolic remodeling in skeletal muscle cells.
Growth differentiation factor 15 (GDF15) is a distant member of the transforming growth factor-β (TGF-β) superfamily increasingly implicated in metabolic regulation. Evidence points to GDF15 as a myokine that regulates systemic energy homeostasis, yet its role in skeletal muscle remains unclear. Here, we investigated whether GDF15 modulates mitochondrial phenotype during myogenesis using mouse C2C12 myoblasts and complementary models. Bioinformatic analyses of GDF15 interaction networks and gene ontology terms revealed enrichment for pathways related to cell differentiation and metabolic regulation. During myogenic differentiation, GDF15 expression increased at both mRNA and protein levels, with cytoplasmic localization and secretion into the extracellular medium, paralleling enhanced mitochondrial content, mitochondrial DNA copy number, and oxygen consumption. Knockdown of GDF15 reduced mitochondrial markers, increased lactate production, and promoted apoptosis, whereas GDF15 overexpression produced opposite effects. Mechanistically, GDF15 overexpression enhanced peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α) transactivation and peroxisome proliferator-activated receptor (PPAR) response element activity, effects that were abolished by silencing PPARδ or estrogen-related receptor alpha (ERRα), suggesting a PGC1α-dependent mechanism. Transcriptomic profiling further supported enrichment of nuclear receptor-related pathways, including PPAR and cAMP response element-binding protein (CREB1) signaling. Finally, exercise training in male C57BL/6 mice elevated GDF15 levels in soleus muscle and improved aerobic performance. Together, these findings demonstrate that GDF15 promotes an oxidative phenotype in skeletal muscle cells through PGC1α-dependent activation of PPAR and ERRα, identifying GDF15 as an autocrine regulator of mitochondrial metabolism and muscle adaptation.