PNPLA3基因I148M多态性通过胆固醇代谢紊乱介导小鼠肝纤维化的机制

PNPLA3 gene I148M polymorphism induces hepatic fibrosis via cholesterol metabolic dysregulation in mice

摘要:

含patatin样磷脂酶结构域3 (patatin-like phospholipase domain-containing 3, PNPLA3)基因多态性(SNP rsID: rs738409; PNPLA3-I148M)是代谢相关脂肪性肝病(metabolic associated fatty liver disease, MAFLD)的关键遗传易感因素，与疾病进展密切相关，然而，其在肝纤维化中的调控机制仍待阐明。为了分析PNPLA3-I148M过表达对肝脏胆固醇代谢、线粒体功能和肝纤维化的影响，本研究分别构建了肝脏特异性过表达野生型PNPLA3蛋白(PNPLA3-wild type, PNPLA3-WT)和PNPLA3-I148M的小鼠模型，并采用高胆固醇-蛋氨酸和胆碱缺乏(high cholesterol-methionine and choline deficient, HC-MCD)饮食诱导肝纤维化。结果显示，与PNPLA3-WT组相比，PNPLA3-I148M组小鼠肝脏中总胆固醇、甘油三酯和游离胆固醇水平显著升高，脂滴蓄积增加，脂肪变性和纤维化程度加重。机制研究表明，PNPLA3-I148M通过抑制酰基辅酶A:胆固醇酰基转移酶1 (acyl-coenzyme A:cholesterol acyltransferase 1, ACAT1)和ATP结合盒转运蛋白G1 (ATP-binding cassette transporter G1, ABCG1)的表达，干扰胆固醇酯化和外排，导致肝脏游离胆固醇异常积累，并激活动力蛋白相关蛋白1 (dynamin-related protein 1, DRP1)，诱导线粒体功能障碍和纤维化相关基因表达。本研究结果为PNPLA3-I148M促进肝纤维化发展提供了重要的体内证据和潜在分子机制，并为靶向PNPLA3-I148M的MAFLD精准治疗策略奠定了基础。

Abstract:

Patatin-like phospholipase domain-containing 3 (PNPLA3) I148M polymorphism (SNP rsID: rs738409; PNPLA3-I148M), a key genetic susceptibility factor for metabolic-associated fatty liver disease (MAFLD), is closely associated with disease progression. However, its mechanism in liver fibrosis remains to be elucidated. This study aimed to investigate the effects of PNPLA3-I148M overexpression on cholesterol metabolism, mitochondrial function, and fibrosis in the liver. We constructed the mouse models specifically overexpressing either the wild-type PNPLA3 (PNPLA3-WT) or PNPLA3-I148M in the liver. Liver fibrosis was induced via a high cholesterol-methionine and choline deficient (HC-MCD) diet. Our results showed that compared with the PNPLA3-WT group, mice overexpressing PNPLA3-I148M exhibited significantly elevated levels of total cholesterol, triglycerides, and free cholesterol, increased lipid droplet accumulation, and exacerbated steatosis and fibrosis in the liver. Mechanism studies revealed that PNPLA3-I148M interfered with cholesterol esterification and efflux by suppressing the expression of acyl-coenzyme A:cholesterol acyltransferase 1 (ACAT1) and ATP-binding cassette transporter G1 (ABCG1). This led to abnormal accumulation of free cholesterol in the liver, activated dynamin-related protein 1 (DRP1), and ultimately induced mitochondrial dysfunction and the expression of fibrosis-related genes. These findings provide important in vivo evidence and reveal a potential molecular mechanism by which PNPLA3-I148M promotes the development of liver fibrosis, laying the groundwork for developing precision therapeutic strategies targeting PNPLA3-I148M in MAFLD.