Long-chain acyl-CoA synthetase 4 modulates prostaglandin E2 release from human arterial smooth muscle cells

Abstract

Long-chain acyl-CoA synthetases (ACSLs) catalyze the thioesterification of long-chain FAs into their acyl-CoA derivatives. Purified ACSL4 is an arachidonic acid (20:4)-preferring ACSL isoform, and ACSL4 is therefore a probable regulator of lipid mediator production in intact cells. Eicosanoids play important roles in vascular homeostasis and disease, yet the role of ACSL4 in vascular cells is largely unknown. In the present study, the ACSL4 splice variant expressed in human arterial smooth muscle cells (SMCs) was identified as variant 1. To investigate the function of ACSL4 in SMCs, ACSL4 variant 1 was overexpressed, knocked-down by small interfering RNA, or its enzymatic activity acutely inhibited in these cells. Overexpression of ACSL4 resulted in a markedly increased synthesis of arachidonoyl-CoA, increased 20:4 incorporation into phosphatidylethanolamine, phosphatidylinositol, and triacylglycerol, and reduced cellular levels of unesterified 20:4. Accordingly, secretion of prostaglandin E2 (PGE2) was blunted in ACSL4-overexpressing SMCs compared with controls. Conversely, acute pharmacological inhibition of ACSL4 activity resulted in increased release of PGE2. However, long-term downregulation of ACSL4 resulted in markedly reduced PGE2 secretion. Thus, ACSL4 modulates PGE2 release from human SMCs. ACSL4 may regulate a number of processes dependent on the release of arachidonic acid-derived lipid mediators in the arterial wall.

Keywords

• fatty acid
• vascular biology
• eicosanoid