Abstract
The impairment of autophagy can cause cellular metabolic perturbations involved in endothelial-to-mesenchymal transition (EndoMT). However, the interplay between the cellular autophagy machinery and endothelial metabolism remains elusive. Sirtuin 3 (SIRT3), an NAD-dependent deacetylase, is a major cellular sensor of energy metabolism. The aim of this work was to determine the role of SIRT3-mediated autophagy in cellular metabolism and the process of EndoMT. We demonstrated that Angiotensin II (Ang II) led to defective autophagic flux and high levels of glycolysis in endothelial cells (ECs) accompanied by a loss of mitochondrial SIRT3 during EndoMT. The loss of SIRT3 further induced the hyperacetylation of endogenous autophagy-regulated gene 5 (ATG5), which in turn inhibited autophagosome maturation and increased pyruvate kinase M2 (PKM2) dimer expression. The M2 dimer is the less active form of PKM2, which drives glucose through aerobic glycolysis. Additionally, TEPP-46, a selective PKM2 tetramer activator, produced lower concentrations of lactate and led to the reduction of EndoMT both in vitro and in vivo. In parallel, the blockade of lactate influx from ECs into vascular smooth muscle cells (VSMCs) downregulated synthetic VSMC markers. EC-specific SIRT3 transgenic mice exhibited reduced endothelial cell transition but partial rescue of vascular fibrosis and collagen accumulation. Taken together, these findings reveal that SIRT3 regulates EndoMT by improving the autophagic degradation of PKM2. Pharmacological targeting of glycolysis metabolism may, therefore, represent an effective therapeutic strategy for hypertensive vascular remodeling.