TSPAN8参与小鼠非酒精性脂肪性肝病的脂质代谢

目的 探讨四跨膜蛋白8（TSPAN8）在非酒精性脂肪性肝病（NAFLD）发生发展中的变化及其在脂质代谢中的作用。方法 将30只C57BL/6J 雄性小鼠随机分为普通饲料组（ND，n=15）和高脂饲料组（HFD，n=15）。Western blot检测1、3、6月末各组小鼠肝脏组织中TSPAN8的表达水平。HepG2细胞分成6组：完全培养基培养，无其他处理的命名为对照组（CON）；游离脂肪酸（FFA）处理以构建NAFLD细胞模型的命名为FFA组；TSPAN8过表达细胞命名为PCDNA-TSPAN8组，其对照为PCDNA3.1 组；FFA处理后的PCDNA-TSPAN8命名为PCDNA-TSPAN8+FFA组，其对照为PCDNA3.1+FFA组；qRT-PCR及Western blot检测CON组和FFA组细胞中TSPAN8表达水平；油红O染色法和全自动生化仪检测PCDNA-TSPAN8+FFA和PCDNA3.1+FFA组细胞内脂质蓄积情况。qRT-PCR检测与脂质代谢相关基因mRNA的表达情况。结果 Western blot显示，与同喂养时间ND组相比，HFD喂养3、6月的小鼠肝组织中TSPAN8的表达下降（P<0.05）。qRT-PCR与Western blot显示，与CON组比较，TSPAN8在FFA组中的表达下降（P<0.01）。与PCDNA3.1+FFA组相比，PCDNA-TSPAN8+FFA组中细胞内甘油三酯（TG）水平下降（P<0.001）。qRT-PCR示，与PCDNA3.1组比较，脂肪酸转运蛋白 5（FATP5）在PCDNA-TSPAN8组中表达降低（P<0.01），与CON组相比，FATP5在FFA组表达上调（P<0.001）。结论 TSPAN8参与NAFLD的脂质代谢，细胞过表达TSPAN8可能通过降低FATP5的表达来抑制细胞内脂质的沉积，可能具有潜在的临床价值。

TSPAN8 is involved in lipid metabolism in non-alcoholic fatty liver disease in mice

Objective To investigate the changes of tetraspanin 8 (TSPAN8) expression levels and its role in lipid metabolism during the development of non-alcoholic fatty liver disease (NAFLD). Methods Thirty male C57BL/6J mice were randomly divided into normal diet group and high-fat diet (HFD) group (n=15), and after feeding for 1, 3, and 6 months, the expression levels of TSPAN8 in the liver tissues of the mice were detected with Western blotting. In a HepG2 cell model of NAFLD induced by free fatty acids (FFA), the effect of TSPAN8 overexpression on lipid accumulation was examined using Oil Red O staining and an automated biochemical analyzer, and the mRNA expressions of the key genes involved in lipid metabolism were detected using qRT-PCR. Results Western blotting showed that compared with that in mice with normal feeding, the expression of TSPAN8 was significantly decreased in the liver tissues of mice with HFD feeding for 3 and 6 months (P<0.05). In HepG2 cells, treatment with FFA significantly decreased the expression of TSPAN8 at both the mRNA and protein levels (P< 0.01). TSPAN8 overexpression in FFA-treated cells showed significantly lowered intracellular triglyceride levels (P<0.001) and obviously reduced mRNA expression of fatty acid transport protein 5 (FATP5) (P<0.01). The expression of FATP5 was significantly increased in FFA- treated cells as compared with the control cells (P<0.001). Conclusion TSPAN8 is involved in lipid metabolism in NAFLD, and overexpression of TSPAN8 may inhibit cellular lipid deposition by reducing the expression of FATP5.