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标题：Triacylglycerol Deposition with Group IVC Phospholipase A2 Expression in Oleate- and Linoleate-Stimulated Huh-7 Hepatocytes
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作者：Keiichi Ishihara ; Kengo Tachibana ; Asuka Kuroda 等
期刊名称：Biological and Pharmaceutical Bulletin
印刷版ISSN：0918-6158
电子版ISSN：1347-5215
出版年度：2011
卷号：34
期号：2
页码：191-196
DOI：10.1248/bpb.34.191
出版社：The Pharmaceutical Society of Japan
摘要：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 A₂ (PLA₂)s including group IVA, IVC, VIA, and VIB PLA₂s, 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 PLA₂ 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 PLA₂ did not change. When cells were treated with methyl arachidonyl fluorophosphonate used as an inhibitor of group IVC PLA₂, 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 PLA₂ but not a catalytically inactive mutant of group IVC PLA₂ 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 PLA₂, which is involved in the fatty acid-induced deposition of TG.
关键词：hepatocellular triacylglycerol;free fatty acid;phospholipase A2;hepatocyte;fatty liver