Kuwata Hiroshi, Yoshimura Makiko, Sasaki Yuka, Yoda Emiko, Nakatani Yoshihito, Kudo Ichiro, Hara Shuntaro
Division of Health Chemistry, Department of Healthcare and Regulatory Sciences, School of Pharmacy, Showa University, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan.
Biochim Biophys Acta. 2014 Jan;1841(1):44-53. doi: 10.1016/j.bbalip.2013.09.015. Epub 2013 Oct 1.
Acyl coenzyme A synthetase long-chain family members (ACSLs) are a family of enzymes that convert long-chain free fatty acids into their acyl-CoAs and play an important role in fatty acid metabolism. Here we show the role of ACSL isozymes in interleukin (IL)-1β-induced arachidonic acid (AA) metabolism in rat fibroblastic 3Y1 cells. Treatment of 3Y1 cells with triacsin C, an ACSL inhibitor, markedly enhanced the IL-1β-induced prostaglandin (PG) biosynthesis. Small interfering RNA-mediated knockdown of endogenous Acsl4 expression increased significantly the release of AA metabolites, including PGE2, PGD2, and PGF2α, compared with replicated control cells, whereas knockdown of Acsl1 expression reduced the IL-1β-induced release of AA metabolites. Experiments with double knockdown of Acsl4 and intracellular phospholipase A2 (PLA2) isozymes revealed that cytosolic PLA2α, but not calcium-independent PLA2s, is involved in the Acsl4 knockdown-enhanced PG biosynthesis. Electrospray ionization mass spectrometry of cellular phospholipids bearing AA showed that the levels of some, if not all, phosphatidylcholine (PC) and phosphatidylinositol species in Acsl4 knockdown cells were decreased after IL-1β stimulation, while those in control cells were not so obviously decreased. In Acsl1 knockdown cells, the levels of some AA-bearing PC species were reduced even in the unstimulated condition. Collectively, these results suggest that Acsl isozymes play distinct roles in the control of AA remodeling in rat fibroblasts: Acsl4 acts as the first step of enzyme for AA remodeling following IL-1β stimulation, and Acsl1 is involved in the maintenance of some AA-containing PC species.
酰基辅酶A合成酶长链家族成员（ACSLs）是一类将长链游离脂肪酸转化为其酰基辅酶A的酶家族，在脂肪酸代谢中起重要作用。在此，我们展示了ACSL同工酶在大鼠成纤维细胞3Y1中白细胞介素（IL）-1β诱导的花生四烯酸（AA）代谢中的作用。用ACSL抑制剂三辛酰甘油（triacsin C）处理3Y1细胞，显著增强了IL-1β诱导的前列腺素（PG）生物合成。与复制的对照细胞相比，小干扰RNA介导的内源性Acsl4表达敲低显著增加了AA代谢产物的释放，包括前列腺素E2（PGE2）、前列腺素D2（PGD2）和前列腺素F2α（PGF2α），而Acsl1表达的敲低则减少了IL-1β诱导的AA代谢产物的释放。对Acsl4和细胞内磷脂酶A2（PLA2）同工酶进行双重敲低的实验表明，胞质型PLA2α而非钙非依赖性PLA2参与了Acsl4敲低增强的PG生物合成。对含有AA的细胞磷脂进行电喷雾电离质谱分析表明，在IL-1β刺激后，Acsl4敲低细胞中部分（即使不是全部）磷脂酰胆碱（PC）和磷脂酰肌醇种类的水平降低，而对照细胞中的水平没有如此明显的降低。在Acsl1敲低细胞中，即使在未刺激的条件下，一些含有AA的PC种类的水平也会降低。总的来说，这些结果表明，Acsl同工酶在大鼠成纤维细胞中AA重塑的控制中发挥着不同的作用：Acsl4作为IL-1β刺激后AA重塑的第一步酶，而Acsl1参与维持一些含AA的PC种类。
