Yamamoto Masakazu, Tanaka Toshiaki, Hozumi Yasukazu, Saino-Saito Sachiko, Nakano Tomoyuki, Tajima Katsushi, Kato Takeo, Goto Kaoru
Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Iida-nishi 2-2-2, Yamagata 990-9585, Japan.
Biomed Res. 2014;35(1):61-8. doi: 10.2220/biomedres.35.61.
Phosphoinositide metabolism is intimately involved in cellular signal transduction. In response to extracellular stimuli, it generates diacylglycerol (DG), which serves as a lipid second messenger molecule to activate various proteins in various organs under pathophysiological conditions. Diacylglycerolkinase (DGK) constitutes an enzyme family that catalyzes conversion of DG to phosphatidic acid. It is therefore regarded as a regulator of the DG signal. Previous studies have revealed the critical role of α and ζ types of DGK in T cell functions. Nevertheless, little is known about the expression patterns of the DGK family in immune cells of various kinds. After examination of the expression profile of DGK isozymes in immune cells that are isolated from human blood, we investigated whether their mRNA expression levels would be changed during an inflammatory reaction. Results showed that DGK isozyme mRNAs are widely expressed in immune cells, except for DGKβ and DGKι. During an inflammatory reaction, DGKε mRNA was increased transiently in the initial phase (20-40 min) of stimulation with both LPS and IL-2 in T cell-derived HUT-102 cells and macrophage-derived RAW264 cells. At the organismal level, an intraperitoneal injection of LPS also induced upregulation of DGKε mRNA in the spleen in a similar,but not identical, manner. These results suggest that DGKε is involved in inflammatory processes of the cellular immune system.
磷酸肌醇代谢与细胞信号转导密切相关。响应细胞外刺激时，它会生成二酰基甘油（DG），在病理生理条件下，DG作为脂质第二信使分子激活各器官中的多种蛋白质。二酰基甘油激酶（DGK）构成一个催化DG转化为磷脂酸的酶家族。因此，它被视为DG信号的调节剂。先前的研究揭示了α和ζ型DGK在T细胞功能中的关键作用。然而，对于DGK家族在各类免疫细胞中的表达模式知之甚少。在检测从人血中分离出的免疫细胞中DGK同工酶的表达谱后，我们研究了它们的mRNA表达水平在炎症反应过程中是否会发生变化。结果显示，除了DGKβ和DGKι外，DGK同工酶mRNA在免疫细胞中广泛表达。在炎症反应期间，在T细胞来源的HUT-102细胞和巨噬细胞来源的RAW264细胞中，用LPS和IL-2刺激的初始阶段（20 - 40分钟），DGKε mRNA会短暂增加。在机体水平上，腹腔注射LPS也以类似但不完全相同的方式诱导脾脏中DGKε mRNA的上调。这些结果表明DGKε参与了细胞免疫系统的炎症过程。
