Triacylglycerol deposition with group IVC phospholipase A2 expression in oleate- and linoleate-stimulated Huh-7 hepatocytes.
Triacylglycerol deposition with group IVC phospholipase A2 expression in oleate- and linoleate-stimulated Huh-7 hepatocytes.
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DOI：
10.1248/bpb.34.191
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发表时间：
2011-02
影响因子：
2
通讯作者：
K. Ishihara;Kengo Tachibana;Asuka Kuroda;Ayano Terakawa;S. Baba;Shiho Kanai;S. Akiba
中科院分区：
文献类型：
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作者：
K. Ishihara;Kengo Tachibana;Asuka Kuroda;Ayano Terakawa;S. Baba;Shiho Kanai;S. Akiba
肝细胞三酰甘油（TG）的积累是脂肪肝的主要症状，与外源性游离脂肪酸过量掺入肝细胞有关，游离脂肪酸诱导甘油三酯（TG）的增加，其中甘油三酰基链不仅来自自身，还来自内源性脂肪酸。然而，负责供应内源脂肪酸（主要被酯化为磷脂）的机制仍不清楚。在本研究中，我们研究了细胞内磷脂酶A（2）（PLA（2）），包括IVA，IVC，VIA和VIB PLA（2）组，其催化内源性脂肪酸的释放，可能参与肝细胞中TG的沉积。用油酸或亚油酸刺激人肝癌Huh-7细胞48小时，TG含量随时间依赖性增加。在此条件下，刺激后6-12小时和24-48小时分别观察到IVC组PLA(2) mRNA和蛋白表达增加。然而，IVA、VIA 或 VIB PLA(2) 组的 mRNA 水平没有变化。当细胞用花生四烯基氟膦酸甲酯作为IVC PLA(2)组的抑制剂处理时，脂肪酸诱导的TG沉积在48小时时部分但显着受到抑制，尽管在24小时时没有观察到显着的抑制。野生型IVC PLA(2)组的过度表达而非IVC PLA(2)组的催化失活突变体的过度表达倾向于增加细胞TG水平。目前的研究结果表明，用游离脂肪酸刺激Huh-7肝细胞会诱导IVC PLA(2)组的表达，该组参与脂肪酸诱导的TG沉积。
The accumulation of hepatocellular triacylglycerol (TG), a major symptom of fatty liver, is associated with the excessive incorporation of exogenous free fatty acids into hepatocytes, the free fatty acids inducing an increase in TG bearing acyl chains derived from not only themselves but also endogenous fatty acids. However, the mechanisms responsible for the supply of endogenous fatty acids, which are mainly esterified into phospholipids, remain unclear. In the present study, we examined the possible involvement of intracellular phospholipase A(2) (PLA(2))s including group IVA, IVC, VIA, and VIB PLA(2)s, which catalyze the release of endogenous fatty acids, in the deposition of TG in hepatocytes. Stimulation of human hepatoma Huh-7 cells with oleate or linoleate for 48 h increased TG contents time-dependently. Under the conditions, increased expression of group IVC PLA(2) mRNA and protein was observed at 6-12 h and 24-48 h after the stimulation, respectively. However, mRNA levels of group IVA, VIA, or VIB PLA(2) did not change. When cells were treated with methyl arachidonyl fluorophosphonate used as an inhibitor of group IVC PLA(2), the fatty acid-induced deposition of TG was partially but significantly suppressed at 48 h, although no significant inhibition was observed at 24 h. Overexpression of wild-type group IVC PLA(2) but not a catalytically inactive mutant of group IVC PLA(2) tended to increase cellular TG levels. The present findings suggest that stimulation of Huh-7 hepatocytes with free fatty acids induces the expression of group IVC PLA(2), which is involved in the fatty acid-induced deposition of TG.