Identification of miR-124 as a Major Regulator of Enhanced Endothelial Cell Glycolysis in Pulmonary Arterial Hypertension via PTBP1 and PKM2
Background—Pulmonary arterial hypertension (PAH) is characterized by abnormal growth and enhanced glycolysis of pulmonary artery endothelial cells (PAECs). However, the mechanisms underlying alterations in energy production have not been identified.
Methods—Here, we examined the miRNA and proteomic profiles of blood outgrowth endothelial cells (BOECs) from patients with heritable PAH (HPAH) due to mutations in the bone morphogenetic protein receptor type 2 (BMPR2) gene and patients with idiopathic PAH (IPAH) to determine mechanisms underlying abnormal endothelial glycolysis. We hypothesized that in BOECs from PAH patients, the downregulation of miR-124, determined using a tiered systems biology approach, is responsible for increased expression of the splicing factor polypyrimidine-tract-binding protein (PTBP1), resulting in alternative splicing of pyruvate kinase muscle isoforms 1 and 2 (PKM1 and 2) and consequently, increased PKM2 expression. We questioned whether this alternative regulation plays a critical role in the hyperglycolytic phenotype of PAH endothelial cells.
Results—HPAH and IPAH BOECs recapitulated the metabolic abnormalities observed in PAECs from IPAH patients, confirming a switch from oxidative phosphorylation to aerobic glycolysis. Overexpression of miR-124, or siRNA silencing of PTPB1, restored normal proliferation and glycolysis in HPAH BOECs, corrected the dysregulation of glycolytic genes and lactate production, and partially restored mitochondrial respiration. BMPR2 knockdown in control BOECs reduced expression of miR-124, increased PTPB1, and enhanced glycolysis. Moreover, we observed reduced miR-124, increased PTPB1 and PKM2 expression and significant dysregulation of glycolytic genes in the rat SUGEN-hypoxia model of severe PAH, characterized by reduced BMPR2 expression and endothelial hyperproliferation, supporting the relevance of this mechanism in vivo.
Conclusions—Pulmonary vascular and circulating progenitor endothelial cells isolated from patients with PAH demonstrate downregulation of miR-124 leading to the metabolic and proliferative abnormalities in PAH ECs via PTPB1 and PKM1/PKM2. Therefore, the manipulation of this miRNA, or its targets, could represent a novel therapeutic approach for the treatment of PAH.
- metabolic abnormalities
- endothelial cell dysfunction
- pulmonary hypertension
- endothelial cell
- endothelial progenitor cells
- Received February 28, 2017.
- Revision received August 29, 2017.
- Accepted September 8, 2017.