Association of Hypoxia-Induced Lactate Accumulation with AARS2 Expression, PDHA1/CPT2 Lactylation, and Energy Metabolism in Yak Skeletal Muscle Cells.

Yaks (Bos grunniens) are a typical species inhabiting high-altitude environments; however, their molecular responses to hypoxic conditions remain incompletely understood. This study aimed to investigate associations among alanyl-transfer RNA synthetase 2 (AARS2) expression, lactylation of pyruvate dehydrogenase E1 alpha 1 (PDHA1) and carnitine palmitoyltransferase 2 (CPT2), and energy metabolism under hypoxic conditions in yaks. Oxygen-sensitive tissues (skeletal muscle, cardiac muscle, and lungs) collected from yaks at different altitudes, along with primary yak skeletal muscle cells, were analyzed using RT-qPCR, Western blotting, immunofluorescence (IF), and co-immunoprecipitation (co-IP). In tissues from the three altitude groups, AARS2 expression was higher in the higher-altitude groups (p < 0.05), whereas PDHA1 and CPT2 expression was lower (p < 0.01). Overall protein lactylation levels were also higher in tissues from the higher-altitude groups. Under hypoxic conditions, lactate levels and AARS2 expression increased in skeletal muscle cells, accompanied by increased activities of key glycolytic enzymes and decreased activities of enzymes related to mitochondrial oxidative phosphorylation. Galloflavin treatment reduced lactate levels and partially attenuated these metabolic changes. Endogenous co-IP detected lactylation of both PDHA1 and CPT2. Following siRNA-mediated knockdown of AARS2, the protein abundance of PDHA1 and CPT2 increased. Taken together, these findings support an association between hypoxia-induced lactate accumulation, increased AARS2 expression, PDHA1/CPT2 lactylation, and a shift in cellular energy metabolism toward glycolysis. This study provides a theoretical basis for further understanding hypoxia-related metabolic remodeling in yaks.