TNF-α induces acyl-CoA synthetase 3 to promote lipid droplet formation in human endothelial cells[S]

Chronic inflammation contributes to cardiovascular disease. Increased levels of the inflammatory cytokine, TNF-alpha, are often present in conditions associated with cardiovascular disease risk, and TNF-alpha induces a number of pro-atherogenic effects in macrovascular endothelial cells, including expression of adhesion molecules and chemokines, and lipoprotein uptake and transcytosis to the subendothelial tissue. However, little is known about the roles of acyl-CoA synthetases (ACSLs), enzymes that esterify free fatty acids into their acyl-CoA derivatives, or about the effects of TNF-alpha on ACSLs in endothelial cells. Therefore, we investigated the effects of TNF-alpha on ACSLs and downstream lipids in cultured human coronary artery endothelial cells and human umbilical vein endothelial cells. We demonstrated that TNF-alpha induces ACSL1, ACSL3, and ACSL5, but not ACSL4, in both cell types. TNF-alpha also increased oleoyl-CoA levels, consistent with the increased ACSL3 expression. RNA-sequencing demonstrated that knockdown of ACSL3 had no marked effects on the TNF-alpha transcriptome. Instead, ACSL3 was required for TNF-alpha-induced lipid droplet formation in cells exposed to oleic acid. These results demonstrate that increased acyl-CoA synthesis as a result of ACSL3 induction is part of the TNF-alpha response in human macrovascular endothelial cells.