Nitrosation of CD36 regulates endothelial function and serum lipids

During obesity, endothelial cells (ECs) become lipid laden leading to endothelial dysfunction. We demonstrate endothelium downregulates caveolin-1 (Cav1) in mouse and human in response to obesity. Using an EC-specific Cav1 knockout mouse, we find mice are hyperlipidemic regardless of diet, but retain endothelial cell function. Whereas initially this was thought to be due to Cav1 mediate endocytosis, we find instead the mice have significantly increased nitric oxide (NO) in response to the lack of Cav1. The presence or absence of NO toggled inversely EC lipid content and plasma lipid in mice. We found the fatty acid translocase CD36 was directly nitrosated by endogenous NO at the same cysteines that are palmitoylated on CD36. The nitrosation of CD36 prevented it’s trafficking to the plasma membrane and decreased lipid uptake. The physiological effect of this mechanism was a reliance on NO for endothelial function. This work suggests that CD36 nitrosation occurs as a protective mechanism to prevent EC lipotoxicity and preserve function.