Overexpression of rat long chain acyl‐CoA synthetase 1 alters fatty acid metabolism in rat primary hepatocytes

Abstract

Disturbance of fatty acid (FA) metabolism in liver plays an important role in disorders such as hepatic steatosis, hyperlipidemia, and insulin resistance. Long chain acyl-CoA synthetases (ACSL) activate FAs in the first step of FA metabolism. We hypothesized that different ACSL isoforms have different functional and tissue-specific roles. In adipose tissue, ACSL1 is related to triacylglycerol (TAG) accumulation; its role in liver is unknown. To elucidate the function of ACSL1 in hepatic FA metabolism, we infected rat primary hepatocytes with adenoviruses carrying either rat ACSL1 or green fluorescent protein, and labeled the cells with 100 or 750 μM [1-14C]oleate for 3 h. Lipids were extracted and subjected to thin layer chromatography. ACSL1 overexpression increased total ACSL activity 4.7-fold. In the presence of both 100 μM and 750 μM oleate, ACSL1 overexpression reduced [1-14C]oleate incorporation into both acid-soluble metabolites (ASM) and cholesterol ester (CE), while increasing [1-14C]oleate incorporation into diacylglycerol (DAG) and phospholipids. However, [1-14C]oleate incorporation into TAG was decreased and cellular TAG mass was unchanged. To examine the effect of ACSL1 on FA recycling, hepatocytes were prelabeled with 750 μM [1-14C]oleate for 3 h and chased for 12 h. During the chase, ACSL1 overexpression attenuated the loss of labeled cellular TAG, attenuated the increase of labeled CE, and decreased the label in ASM. These results indicate that hepatic ACSL1 channels FA towards DAG synthesis and reesterification, and away from CE synthesis and oxidation. (NIH-DK-59935)