Endothelial Metabolism and Redox Imbalance in Vascular Disease

PROJECT SUMMARY Redox imbalance between reactive oxygen species (ROS) and reactive nitrogen species (RNS) (high ROS and low nitric oxide NO) is a fundamental mechanism of endothelial cell (EC) dysfunction and a driver of cardiovascular diseases (CVD) such as atherosclerosis, hypertension and peripheral arterial disease (PAD). Strategies to individually mitigate ROS or amplify NO have experienced limited success. Therefore, a greater understanding of the key factors and events that lead to redox imbalance is therefore essential to develop more effective treatments for cardiovascular disease (classical concept) which remains the leading cause of morbidity and mortality. In ECs, aerobic glycolysis (“Warburg effect”) has been regarded as the dominant metabolic pathway supporting homeostatic functions. An emerging concept is that the pathways of cellular metabolism are not fixed, and that ECs can alter their metabolic pathways or “reprogram” to meet different needs. A major gap in our knowledge is how EC metabolism and ROS/RNS balance are altered in vascular disease and how metabolism informs function. Recent studies have shown that aerobic glycolysis is increased in ECs of atherosclerotic, diabetic and angiogenic blood vessels, however, the functional consequences of this dynamic has yet to be elucidated. Enzymes that produce ROS are not only influenced by metabolism, but may also promote changes in metabolism. Our preliminary data advance the novel hypothesis that imbalance between changes in EC metabolism and ROS/RNS (redox balance), induced by various risk factors, is a key driver of EC dysfunction and an underlying mechanism of vascular disease. To test this hypothesis, a programmatic approach is essential as it is the only mechanism capable of supporting the rigor needed to investigate the complex interplay between metabolism and redox signaling in different vascular beds and disease states. Our program has 3 well aligned projects that benefit from the synergy of model and reagent sharing and dedicated cores. Project 1 is focused on the hypothesis that disturbed copper (Cu) metabolism in ECs arises from dysfunction of the Cu exporter, ATP7A, leading to excessive PFKFB3/glycolysis, ROS/NO imbalance and mitochondrial ROS-epigenetic remodeling that drives EndMT and accelerated atherosclerosis. Project 2 will test the hypothesis that EC metabolism shapes EC function via sex-specific, Nox1 and leptin-dependent mechanisms. Project 3 tests the hypothesis that ability of the mitochondrial dynamics protein, Drp1, to promote reparative angiogenesis via crosstalk between EC mitochondrial redox signaling and glycolysis is impaired in diabetes due to excess PFKFB3/glycolysis-ROS signaling which increases the severity of PAD. To test these concepts directly, we have developed a state-of-the-art approach using CRISPR/Cas9 to generate knock-in mice enabling inducible reduction of glycolysis only in ECs, that will be shared across projects to enhance synergy. Our Program will identify key mechanisms through which changes in metabolism impact ROS/NO balance, EC function and vascular disease.