PNPLA3 I148M突变与血清甘油三酯水平的交互作用对肝脏脂肪蓄积的作用及机制研究

Hepatic fat accumulation is not only the initiating factor of fatty liver disease, but also associated with a variety of chronic metabolic diseases. Adiponutrin (PNPLA3) possesses both lipolysis and lipogenesis functions, and its I148M variant is involved in the regulation of hepatic fat accumulation. However, the specific mechanism remains unclear. Our previous studies have found that there existed an interaction between PNPLA3 rs738409 (I148M) and plasma triglyceride concentrations. Based on the hypothesis that the above interaction takes part in the regulation of hepatic fat accumulation, the present study will be designed to build hypertriglyceridemia rat model to evaluate the effects of serum triglyceride concentrations, PNPLA3 I148M variant, and its interaction on hepatic fat accumulation by altered gene expression levels. Moreover, we further discuss the potential influence in primary rat hepatocytes and HepG2 cell lines under oleic acid treatment and the application of RNAi technology. Meanwhile, the expression levels of key genes and proteins participated in the lipogenesis and lipolysis pathways will be detected to explore the underlying mechanism. The implementation of the present project is not only useful to provide new clues for the mechanism of hepatic fat accumulation, but also helpful to the early detection of high risk populations, with theoretical significance and application value.

肝脏脂肪蓄积是脂肪性肝病的始动因素，与多种慢性代谢性疾病显著相关。脂肪营养蛋白（PNPLA3）具有脂肪合成和水解的双重功能，其I148M突变所引起的肝脏脂肪蓄积的机制还未有定论。课题组前期的研究发现，PNPLA3 rs738409与血浆甘油三酯（TG）水平存在一定的交互作用。我们假设该交互作用参与了肝脏脂肪蓄积的调节。基于此，我们拟首先建立高甘油三酯血症大鼠模型，通过基因表达水平的改变分析血清TG水平、PNPLA3 I148M突变以及两者的交互作用对大鼠肝脏脂肪蓄积的影响。以大鼠原代肝细胞和HepG2细胞为研究对象，体外层面分析该交互作用对肝细胞脂肪蓄积的影响，同时检测脂肪合成及分解通路关键基因和蛋白的表达水平进行初步的机制研究。本项目的实施将为肝脏脂肪蓄积的机制研究提供一定的思路，也有利于从遗传和环境方面早期发现相关疾病的高危人群，具有重要的理论意义和应用价值。

脂肪营养蛋白（PNPLA3）具有脂肪合成和水解的双重功能，其I148M突变在肝脏脂肪蓄积中起到了一定的作用。有人群研究表明PNPLA3 I148M突变和高甘油三酯血症的交互作用与非酒精性脂肪性肝病的患病风险显著相关。本研究以HepG2细胞为研究对象，通过油酸干预建立高甘油三酯血症模型。结果发现油酸干预可以显著增加细胞甘油三酯水平，但PNPLA3不同基因型干预对细胞甘油三酯水平未见显著影响。与此同时，也未发现油酸及PNPLA3不同基因型干预对甘油三酯水平的影响存在交互作用。人群病例-对照研究进一步发现无论是否经过传统危险因素的校正，与CC基因型相比，PNPLA3 rs738409基因位点GG及GC基因型均显著增加脂肪性肝病的患病风险。随着血浆甘油三酯水平的升高，研究对象患脂肪性肝病的风险也显著增加。但未发现两者之间存在显著的交互作用。联合效应发现，GG基因型并且血浆甘油三酯浓度较高的个体比CC基因型且血浆甘油三酯水平较低的个体有更高的脂肪性肝病患病风险。本项目为脂肪性肝病的精准预防与治疗提供了一定的思路，也有利于从遗传和环境方面早期发现脂肪性肝病的高危人群。