Abstract 289: Neddylation is Essential for Cardiac Metabolic Maturation in the Developing Heart

Abstract

Changes in metabolic milieu during development trigger a metabolic shift from fetal-type glycolysis to adult-type fatty acid oxidation in the developing heart. Disruption of this metabolic shift has been linked to congenital heart disease, a major cause of birth-related mortality and morbidity worldwide. Neddylation is a post-translational modification that covalently attaches a small ubiquitin-like protein, NEDD8, to target proteins. Previously we reported that neddylation is essential for cardiomyocyte proliferation through sustaining the YAP signaling. However, a link between neddylation and cardiac metabolic maturation has not yet been established. Here, we abrogated neddylation by cardiac-specific deletion of NAE1, an essential subunit of the sole NEDD8 E1 enzyme, via αMHC Cre in mice, which led to significant reduction of NAE1 proteins and neddylated proteins in the heart. Temporal histological and functional analyses revealed that mice lacking neddylation displayed cardiac hypoplasia and ventricular non-compaction at E16.5, which became more pronounced by P1, eventually leading to heart failure and perinatal lethality by P7. Transcriptome analysis identified that the defects in cardiac chamber maturation are associated with upregulation of glycolytic genes and downregulation of oxidative metabolic genes. Transmissive electron microcopy revealed accumulation of lipid droplets and degenerative/immature mitochondria in hearts deficient of neddylation. In vitro, pharmacological inhibition of neddylation impairs mitochondrial membrane potential and respiration, and suppresses fatty acid utilization in oleic acid-primed cultured cardiomyocytes. Mechanistically, HIF1α, a potent regulator of cardiac metabolic reprogramming, is a novel NEDD8 target. Inhibition of neddylation causes accumulation of HIF1α proteins and consequently disrupts the expression of HIF1α downstream targets in vitro and in vivo. Silencing of HIF1α attenuates inhibition of neddylation-induced glycolytic rates in cardiomyocytes. Taken together, our findings highlight the importance of neddylation in the developing heart and identify neddylation as a novel regulator of HIF1α signaling to promote developmental metabolic switch.