Abstract 5207: Role of Endothelial Nitric Oxide Synthase in Endothelial Cell Mitochondrial Biogenesis and Stress Adaptation
Activation of metabolic stress pathways is known to confer stress adaptation and promote longevity in lower organisms. We have recently found that chronic stimulation of AMP-activated protein kinase (AMPK) in endothelial cells promotes both mitochondrial biogenesis and stress adaptation that prevent hypertension-induced endothelial dysfunction. However, the precise mechanisms for endothelial cell mitochondrial biogenesis and stress adaptation are not well defined. To this end, we chronically activated AMPK with 5-aminoimidazole-4-carboxamide riboside (AICAR) and observed enhanced mitochondrial biogenesis in wild-type mouse endothelium as determined by mitochondrial-specific fluorescence (Mitotracker green) and protein expression (cytochrome c and SOD2). In contrast, endothelium from eNOS-null mice exhibited no mitochondrial biogenesis in response to AICAR and this defect was rescued by reintroduction of eNOS by adenoviral-mediated gene transfer. Moreover, eNOS appeared critical for stress adaptation as chronic AMPK stimulation attenuated H2O2-induced cell death in wild type, but not eNOS-null endothelium. To test this pathway in vivo, we used 20-hydroxy-eicosatetraenoic acid (20-HETE) administration to induce endothelial dysfunction measured as prostacyclin-dependent, acetylcholine-induced arterial relaxation. We found that 20-HETE produced equivalent endothelial dysfunction in both wild-type and eNOS-null mice. However, chronic AICAR administration was able to prevent 20-HETE-induced dysfunction in wild-type, but not eNOS-null mice. Thus, these data indicate that eNOS is involved in AICAR-induced mitochondrial biogenesis and stress adaptation in endothelial cells. These results have implications for targeting stress adaptation as a means to prevent endothelial dysfunction and potentially ameliorate vascular disease.