FoxO1 regulates asymmetric dimethylarginine via downregulation of dimethylaminohydrolase 1 in human endothelial cells and subjects with atherosclerosis.

The O subfamily of forkhead (FoxO) 1 is a pivotal element in the regulation of endothelial activation. Compartmentalization and activity of FoxO1 is regulated by post translational modifications, but the implication in endothelial dysfunction and atherosclerosis remain controversial. Our aim was to identify FoxO1 related metabolic signatures in endothelial cells. Using metabolomics in human umbilical endothelial cells (HUVECs) overexpressing the wild type FoxO1 (FoxO1-WT), the acetylation defective mutant (FoxO1-KR), the unphosphorylated nuclear localized mutant (FoxO1-ADA) and the Green Fluorescent Protein (GFP) control vector, we identify metabolic pathways differentially affected by the different FoxO1 localization and activity. Among metabolites, asymmetric dimethylarginine (ADMA) was increased in FoxO1-ADA compared with FoxO1-WT and FoxO1-KR infected cells (p < 0.01). ADMA was further investigated to identify the molecular mechanisms to explain its link to FoxO1. We found that unrestrained FoxO1 activity leads to increase of ADMA via downregulation of its degrading enzyme, dimethylaminohydrolase (DDAH) 1. In human subjects (n = 89) the FoxO1/DDAH1/ADMA pathway marks unstable atherosclerosis. Our results point to ADMA as a biomarker to track deregulated FoxO1 activity in vivo.