College of Pharmacy, Pusan National University, Busan, Republic of Korea (J.H., S.-J.L., S.K., D.-S.I.); Molecular Recognition Research Center, Korea Institute of Science and Technology, Seoul, Republic of Korea (M.H.C.); and Laboratory of Pharmacology, College of Pharmacy, and Department of Life and Nanopharmaceutical Scicenses, Graduate School, Kyung Hee University, Seoul, Republic of Korea (D.-S.I.).
College of Pharmacy, Pusan National University, Busan, Republic of Korea (J.H., S.-J.L., S.K., D.-S.I.); Molecular Recognition Research Center, Korea Institute of Science and Technology, Seoul, Republic of Korea (M.H.C.); and Laboratory of Pharmacology, College of Pharmacy, and Department of Life and Nanopharmaceutical Scicenses, Graduate School, Kyung Hee University, Seoul, Republic of Korea (D.-S.I.)
J Pharmacol Exp Ther. 2020 Jul;374(1):142-150. doi: 10.1124/jpet.120.264960. Epub 2020 Apr 27.
Nonalcoholic fatty liver disease is a chronic inflammatory liver disease. It is associated with obesity and type 2 diabetes. Oxycholesterols are metabolites of cholesterol, and several of them can act on the G protein-coupled receptor, G protein-coupled receptor 183 (GPR183)/Epstein-Barr virus-induced gene 2. We found expression of GPR183 in human hepatoma cell lines and in vivo induction of GPR183 expression in mouse livers after high-fat diet feeding. Therefore, the role of oxycholesterols and GPR183 in hepatocytes was studied using a model of hepatic steatosis induced by liver X receptor (LXR) activation. LXR activation by T0901317 resulted in fat accumulation in Hep3B human hepatoma cells. This lipid accumulation was inhibited by 7,25-dihydroxycholesterol, the most potent agonist of GPR183. The protective effects of 7,25-dihydroxycholesterol were suppressed by a specific GPR183 antagonist, NIBR189 [(2E)-3-(4-Bromophenyl)-1-[4-4-methoxybenzoyl)-1-piperazinyl]-2-propene-1-one]. T0901317 treatment induced expression of the major transcription factor for lipogenesis, sterol regulatory element-binding protein 1c (SREBP-1c). 7,25-Dihydroxycholesterol inhibited the induction of SREBP-1c proteins in a GPR183-dependent manner. Using inhibitors specific for intracellular signaling molecules, 7,25-dihydroxycholesterol-induced suppression of hepatocellular steatosis was shown to be mediated through G proteins, p38 mitogen-activated protein kinases, phosphoinositide 3-kinase, and AMP-activated protein kinase. In addition, the inhibitory effect of 7,25-dihydroxycholesterol was validated in HepG2 cells and primary mouse hepatocytes. Therefore, the present report suggests that 7,25-dihydroxycholesterol-GPR183 signaling may suppress hepatocellular steatosis in the liver. SIGNIFICANCE STATEMENT: Oxycholesterols, which are metabolites of cholesterol, act on the G protein-coupled receptor, G protein-coupled receptor 183 (GPR183)/Epstein-Barr virus-induced gene 2, which is expressed in human hepatoma cell lines, and its expression is induced in vivo in mouse livers after high-fat diet feeding. Activation of GPR183 inhibits fat accumulation in primary mouse hepatocytes and HepG2 cells through G proteins, p38 mitogen-activated protein kinases, phosphoinositide 3-kinase, and AMP-activated protein kinase.
非酒精性脂肪性肝病是一种慢性炎症性肝病。它与肥胖和 2 型糖尿病有关。氧化胆固醇是胆固醇的代谢物，其中几种可以作用于 G 蛋白偶联受体 G 蛋白偶联受体 183（GPR183）/Epstein-Barr 病毒诱导基因 2。我们发现 GPR183 在人肝癌细胞系中表达，并在高脂肪饮食喂养后小鼠肝脏中诱导 GPR183 表达。因此，使用肝 X 受体（LXR）激活诱导的肝脂肪变性模型研究了氧化胆固醇和 GPR183 在肝细胞中的作用。T0901317 激活 LXR 导致 Hep3B 人肝癌细胞中的脂肪堆积。这种脂质积累被 GPR183 的最有效激动剂 7,25-二羟胆固醇抑制。7,25-二羟胆固醇的保护作用被特异性 GPR183 拮抗剂 NIBR189 [（2E）-3-（4-溴苯基）-1-[4-4-甲氧基苯甲酰基）-1-哌嗪基]-2-丙烯-1-酮]抑制。T0901317 处理诱导主要脂生成转录因子固醇调节元件结合蛋白 1c（SREBP-1c）的表达。7,25-二羟胆固醇以 GPR183 依赖的方式抑制 SREBP-1c 蛋白的诱导。使用针对细胞内信号分子的特异性抑制剂，表明 7,25-二羟胆固醇诱导的肝细胞脂肪变性抑制是通过 G 蛋白、p38 丝裂原活化蛋白激酶、磷酸肌醇 3-激酶和 AMP 激活的蛋白激酶介导的。此外，在 HepG2 细胞和原代小鼠肝细胞中验证了 7,25-二羟胆固醇的抑制作用。因此，本报告表明氧化胆固醇-GPR183 信号可能抑制肝脏中的肝细胞脂肪变性。意义说明：胆固醇的代谢物氧化胆固醇作用于 G 蛋白偶联受体 G 蛋白偶联受体 183（GPR183）/Epstein-Barr 病毒诱导基因 2，该受体在人肝癌细胞系中表达，在高脂肪饮食喂养后，其在体内表达诱导小鼠肝脏。GPR183 的激活通过 G 蛋白、p38 丝裂原活化蛋白激酶、磷酸肌醇 3-激酶和 AMP 激活的蛋白激酶抑制原代小鼠肝细胞和 HepG2 细胞中的脂肪堆积。
