FOXO1 integrates endothelial hemodynamic, inflammatory and metabolic pathways in atherosclerosis [OSS]

Atherosclerosis occurs preferentially in regions of disturbed or low fluid shear stress (FSS), whereas physiological laminar FSS protects against disease by suppressing endothelial inflammation. Pro- vs anti-inflammatory programs are associated with glycolysis vs mitochondrial metabolism, respectively. Endothelial cells (ECs) sensing FSS from blood flow regulate these responses, but the underlying mechanisms are poorly understood. The transcription factor Forkhead box protein O1 (FOXO1) is known to regulate endothelial metabolism, yet its role in FSS-regulated endothelial inflammation remains largely unclear. We found that Oscillatory FSS and inflammatory cytokines induce, whereas physiological FSS inhibits FOXO1 nuclear translocation. RNA sequencing revealed that FOXO1 depletion in ECs upregulates the protective flow-responsive transcription factors KLF2/4 and reduces oscillatory FSS-induced inflammatory genes. Inhibition of FOXO1 nuclear translocation by physiological FSS is mediated via a KLF2-CDK2 pathway, with the latter phosphorylating FOXO1 at S249. Artery ECs-specific deletion of FOXO1 significantly reduces atherosclerotic plaque formation in hyperlipidemic mice. Inhibition of glycolysis attenuates OSS-induced FOXO1 nuclear translocation, suggesting a role for metabolic regulation. Notably, treatment with lactate promotes FOXO1 nuclear localization and lactylation, which is mediated by a lactyltransferase AARS1 (Alanyl-tRNA synthetase). These findings identify FOXO1 as a key mediator linking atheroprone flow and endothelial inflammation, suggesting potential new therapeutic targets for treating atherosclerotic cardiovascular disease. Overall design: Human aortic endothelial cells (HAECs) were transfected with Ctrl (siCtrl) or FOXO1 (siFOXO1) siRNA for 3 days, then subjected to oscillatory shear stress (OSS; 0.5±4 dynes/cm2) for 24 hours. Total RNA was extracted and subjected to RNAseq, n=3 samples for each group.