溶酶体相关膜蛋白3过表达促进肝细胞脂质沉积

目的 探讨溶酶体相关膜蛋白3(lysosome associated membrane protein 3,LAMP3)对肝细胞脂质代谢的作用.方法 以肝癌细胞系Huh7为研究对象,利用qRT-PCR及Western blot法检测游离脂肪酸(free fatty acids,FFAs)0.4 mmol/L处理后肝细胞LAMP3表达变化;过表达LAMP3后,分别使用油红染色及甘油三酯检测试剂盒检测肝细胞内脂滴及甘油三酯沉积情况;采用ATP及β-羟基丁酸检测试剂盒检测细胞内ATP及β-羟基丁酸含量变化;过表达LAMP3,使用qRT-PCR、Western blot法检测脂质合成相关基因PPARγ与SCD-1及脂质分解相关基因CPT1A与PGC-1 α表达变化.结果 FFAs处理后肝细胞Huh7中LAMP3表达显著上调(P＜0.05);过表达LAMP3可显著促进肝细胞内脂滴和甘油三酯的沉积(P＜0.05);过表达LAMP3对肝细胞内ATP及β-羟基丁酸含量的影响差异无统计学意义(P＞0.05);过表达LAMP3可促进PPARγ及SCD-1表达(P＜0.05),但对CPT1A、PGC-1α表达的影响差异无统计学意义(P＞0.05).结论 LAMP3可通过调控脂肪合成促进肝细胞内脂质沉积.

Overexpression of LAMP3 promotes lipid metabolism in liver cells

Objective To illustrate the role of lysosome associated membrane protein 3 (LAMP3) in hepatocellular lipid metabolism.Methods After free fatty acids (FFAs,0.4 mmol/L) were used to treat human hepatocellular carcinoma cell line Huh7,the expression of LAMP3 was detected by qRT-PCR and Western blotting.Then,oil red staining was adopted to observe the lipid droplets in the FFAs-treated Huh7 cells,and intracellular triglyceride level was detected at the same condition.ATP content and β-hydroxybutyrate concentration were measured by the corresponding kits respectively.Finally,the expression of lipogenic molecules,PPARγ and SCD-1,and those involved in lipolysis,CPT1A and PGC-lα,at mRNA and protein levels were detected in Huh7 cells after FFAs treatment by qRT-PCR and Western blotting,respectively.Results FFAs treatment resulted in the up-regulation of LAMP3 in Huh7 cells (P ＜ 0.05).The treatment also promoted the deposition of intracellular lipid droplets and triglycerides in the cells (P ＜ 0.05).However,it had no effect on the intracellular ATP and β-hydroxybutyrate levels (P ＞ 0.05).FFAs-treatment induced up-regulation of LAMP3 also enhanced the expression of PPARγ and SCD-1 (P ＜ 0.05),though showing no effect on the levels of CPT1A and PGC-1α (P ＞ 0.05).Conclusion LAMP3 promotes deposition of lipid droplets via regulating fat synthesis in liver cells.