The Prolyl Hydroxylase Domain 2 (PHD2) Deficiency Enhances Maximal Exercise Capacity

PURPOSE: Hypoxic training is beneficial for improving endurance performance. Hypoxia-inducible factor (HIF) is a key transcription factor that regulates the hypoxic-responsive pathway. Stabilization of HIF by inactivating prolyl hydroxylase domain protein 2 (PHD2) under low oxygen tension, triggers angiogenesis, erythropoiesis, and glycolysis. Glycolytic capacity is essential to perform anaerobic exercise. This study aims to verify whether the upregulation of glycolytic metabolism under the hypoxic-responsive pathway enhances exercise capacity. METHODS: We employed tamoxifen-inducible conditional PHD2 knock-out (KO) mice that exhibited stabilized HIF-alpha. To evaluate anaerobic exercise capacity, a rodent treadmill exercise test was performed. RNA sequencing (RNA-seq) analysis was conducted using C2C12 myoblasts after PHD2 siRNA transfection. RESULTS: PHD2KO mice exhibited increased red blood cell counts, hemoglobin, and hematocrit values, along with enhanced maximal exercise performance compared to littermate wild-type (WT) mice. PHD2 deficiency promoted maximal exercise capacity and resulted in lower blood lactate levels. RNAseq analysis revealed that PHD2-deficient myoblasts increased the expression of genes related to glycolysis, gluconeogenesis, and muscle contraction. CONCLUSIONS: These findings suggest that PHD2 deficiency-induced activation of the hypoxic-responsive pathway enhances maximal exercise capacity.