Derlin-1通过调控L-FABP泛素化降解干预肝脏脂质沉积的机制研究

Liver fatty acid binding protein (L-FABP) mainly regulates lipid metabolism and is an important factor in the development of lipid deposition in the liver. However, people have known little about the molecular mechanism of L-FABP degradation. Recent studies show that Derlin-1 plays a critical role in ubiquitin mediated protein degradation. We found Derlin-1 maybe regulate L-FABP through mass spectrometry of the IP products that compared Derlin-1 overexpression and control. We and constructed lipid-deposited cells and animal models to observe the expression of L-FABP and Derlin-1 and found that both had interaction，then we overexpressed Derlin-1 and found that the level of lipid deposition decreased. Further finding, the expression of L-FABP was affected by Derlin-1. So, we have a hypothesis that Derlin-1 can regulate ubiquitin-mediated L-FABP degradation, then intervene liver lipid deposition. Successful completion of this proposal will explore if Derlin-1 regulates the ubiquitination of L-FABP, then intervenes lipid deposition through HepG2 and Derlin-1 knockout mice and the expression level of L-FABP in NAFLD patients , which is extremely important for identifying novel potential therapeutic targets of NAFLD.

肝脏脂肪酸结合蛋白（L-FABP）主要协调脂肪酸的新陈代谢，是肝脏脂质沉积发生的关键因素之一。目前人们对L-FABP降解的分子机制知之甚少。Derlin-1是内质网相关降解蛋白，在泛素化降解中至关重要。我们首先对过表达Derlin-1的IP产物进行质谱分析，发现Derlin-1可能参与L-FABP的特定功能。我们利用脂质沉积的细胞与动物模型，发现Derlin-1能够降低L-FABP的表达，同时二者具有相互作用，并且过表达Derlin-1可以缓解细胞脂质沉积水平。进一步发现L-FABP具有泛素化降解途径。由此我们猜想：Derlin-1可以调控L-FABP泛素化降解干预肝脏脂质沉积。本课题接下来将从细胞和动物水平，深入阐述Derlin-1能否调控L-FABP泛素化降解，进而缓解肝脏脂质沉积，并且在NAFLD病人中观察L-FABP的表达水平，为临床上寻找预防和治疗NAFLD新的靶点奠定理论基础。

肝脏脂肪酸结合蛋白（L-FABP）主要协调脂肪酸的新陈代谢，是肝脏脂质沉积发生的关键因素之一。目前人们对L-FABP降解的分子机制知之甚少。Derlin-1是内质网相关降解蛋白，在泛素化降解中至关重要。基于此，我们得到如下结论：1.临床水平：NAFLD组，血清L-FABP表达量比正常组高。2.动物水平：高脂喂养小鼠中L-FABP mRNA与对照组相比无明显差异，而蛋白水平显著上升。高脂组Derlin1的mRNA及蛋白水平均比对照组低，并且二者在肝脏组织中具有共定位。3.细胞水平：L-FABP具有泛素蛋白酶体降解途径，同时随着油酸浓度增加，L-FABP表达上升，Derlin1表达下降，二者具有直接相互作用。此部分内容正在补实验中，预计今年下半年发表。同时因绝大部分肥胖患者都具有非酒精性脂肪肝，而减重手术作为病态肥胖的主要治疗方法，我们入组74例行袖状胃切除术的肥胖患者，发现血清L-FABP水平可能作为预测腹腔镜下袖状胃切除术后肥胖患者肝脏功能改善的指标，此部分内容已在《Obesity Surgery》审稿中。并且我们还入组187例正常人样本及回顾性收集25例重度肥胖患者术前、术后3月、6月、12月临床资料，发现血清L-FABP与BMI、ALT，AST，m-AST，γ-GT，DBIL，UA，FBG具有正相关，同时校正多因素后，L-FABP与BMI仍具有强相关性，并且袖状胃切除术后， L-FABP随着BMI呈梯度性下降，并且在术后12月与基线值具有统计学差异，此部分已发表在《Obesity Surgery》。另外我们还探究线粒体单倍体G与非酒精性相关脂肪肝疾病相关性分析，该部分研究发表在《Endocrinology Diabetes & Metabolism》。基于上述研究，我们试图寻找L-FABP与脂质代谢的内在联系，为临床上寻找预防和治疗NAFLD及肥胖新的靶点奠定理论基础。