Reduced expression of adipose triglyceride lipase decreases arachidonic acid release and prostacyclin secretion in human aortic endothelial cells

Background: Vascular endothelial cells represent an important source of arachidonic acid (AA)-derived mediators involved in the generation of anti- or proatherogenic environments. Evidence emerged (in mast cells), that in addition to phospholipases, neutral lipid hydrolases as adipose triglyceride lipase (ATGL) also participate in this process. Objective: To examine the impact of ATGL on AA-release from cellular phospholipids (PL) and on prostacyclin secretion in human aortic endothelial cells (HAEC). Methods and results: siRNA-mediated silencing of ATGL promoted lipid droplet formation and TG accumulation in HAEC (nile red stain). ATGL knockdown decreased the basal and A23187 (calcium ionophore)-induced release of (14)C-AA from ((14)C-AA-labeled) HAEC. In A23187-stimulated ATGL silenced cells, this was accompanied by a decreased content of (14)C-AA in cellular PL and a decreased secretion of prostacyclin (determined by 6-keto PGF1α EIA). Conclusions: In vascular endothelial cells, the efficiency of stimulus-induced AA release and prostacyclin secretion is dependent on ATGL.