基于肝细胞特异性基因敲除小鼠探讨TRUSS在非酒精性脂肪肝中的作用及机制研究

Non-alcoholic fatty liver disease (NAFLD) is rapidly increasing in prevalence worldwide. However, the pathogenesis of NAFLD is still not fully understood. Tumor necrosis factor receptor (TNFR)-associated ubiquitous scaffolding and signaling protein (TRUSS) is a binding protein of TNFR. Some studies have suggested that TRUSS involves in a variety of diseases, but the role of TRUSS in NAFLD remains unclear. Our preliminary results showed a significant increase in TRUSS expression in fatty liver, while hepatocyte-specific TRUSS gene knockout (TRUSS-HKO) dramatically blunted high fat diet (HFD)-induced hepatic lipid deposition and insulin resistance in mice. Thus, we hypothesize that HFD promotes the activation of pro-inflammatory NF-κB and JNK signaling pathways by up-regulating TRUSS expression, which ultimately leads to the development and progression of NAFLD. We will use TRUSS-HKO mice combined with pathological and multiple molecular biological techniques to elucidate the exact role and underlying mechanism of TRUSS in the development and progression of NAFLD. Furthermore, adenovirus-packed TRUSS shRNA expression vectors will be used to further investigate the role of TRUSS in NAFLD in vitro. This research project aims to elucidate the molecular mechanism that HFD induces the development and progression of NAFLD via up-regulating the expression of TRUSS. Our results may provide new theoretical basis and molecular target for the prevention and treatment of NAFLD.

非酒精性脂肪肝（NAFLD）的患病率不断上升，但其发病机制未阐明。TRUSS是一种肿瘤坏死因子受体结合蛋白，目前尚无关于TRUSS对NAFLD作用的相关报道。我们的前期研究发现：TRUSS的表达在脂肪变性的肝脏中明显上调，肝细胞特异性TRUSS基因敲除显著削弱高脂饮食诱导的小鼠肝脏脂质沉积和胰岛素抵抗。因此我们假设：高脂饮食通过上调TRUSS的表达，促进炎症相关的NF-κB和JNK信号通路的活化，最终导致NAFLD的发生和发展。本课题拟应用肝细胞特异性TRUSS基因敲除小鼠，结合病理学和多种分子生物学方法，阐明TRUSS在NAFLD发生和发展中的作用及其分子调控机制。通过构建TRUSS基因干扰的腺病毒载体，在细胞水平进一步验证TRUSS对NAFLD的调控作用。本项目旨在揭示高脂饮食上调肝脏TRUSS表达从而导致NAFLD发生和发展的分子机制，为临床防治NAFLD提供新的理论依据和分子靶点。

非酒精性脂肪肝（non-alcoholic fatty liver disease, NAFLD）是最常见的慢性肝脏疾病，影响全球近四分之一的人口。随着经济水平和生活质量的日益提高，我国NAFLD的城乡发病率呈逐年上升趋势， NAFLD已成为我国慢性肝病的主要病因。另外，NAFLD患者的心血管疾病和癌症的患病风险都明显增加。目前为止，NAFLD的发生机制尚未明确，临床上也尚未有针对NAFLD的有效治疗药物。我们发现在高脂饮食饲养的小鼠肝脏组织中TRUSS （tumor necrosis factor receptor–associated ubiquitous scaffolding and signaling protein）蛋白表达水平显著升高，提示其可能参与NAFLD的发生发展。以肝细胞特异性TRUSS基因敲除小鼠为研究工具，我们发现TRUSS基因敲除明显削弱高脂饮食诱导的小鼠肝脏脂肪变性和血清脂类表达水平。糖耐量和胰岛素耐量实验发现TRUSS缺失改善胰岛素抵抗症状。同时，异常的糖脂代谢也得到缓解。肝脏炎症因子表达水平显著降低，肝脏损伤得到明显改善。细胞实验中得到一致结果，油红O染色发现TRUSS基因敲减显著降低棕榈酸诱导的细胞脂质沉积。进一步的机制研究中发现，TRUSS可以与炎症相关NF-κB信号通路抑制分子IκBα结合，促使其泛素化诱导的蛋白酶体降解，进而释放p65使其异常活化，最终调控NAFLD相关基因的表达。本课题的研究结果为NAFLD的临床防治提供一个潜在靶点，为靶向药物的研发提供一定理论依据。