肥胖症相关基因Lyplal1在高脂饮食诱导肥胖小鼠模型中的调控及其对脂肪细胞分化的影响

发布时间：2019-05-13 07:09

【摘要】：肥胖症,是世界范围内的日益严重的健康流行性疾病之一,尤其在欧美等发达国家。除了对健康的影响,肥胖症还会导致许多社会问题,诸如求职中遇到的歧视和不平等情况。近几年关于肥胖症的全基因组序列相关性研究(Genome-wide association study,GWAS)鉴定出了52个基因突变位点与肥胖显著性相关,这些基因变体被认为是主要参与调控脂肪组织的生长与分布过程。其中,位于Lyplal1 (lysophospholipase-like1)基因附近的4个SNP(Single Nucleotide Polymorphisms,即单核苷酸多态性)与肥胖症呈显著性相关,尤其在女性当中。Lyplall编码的蛋白为溶血磷脂酶样蛋白1,是一个分子量为26 KDa的细胞溶质蛋白,属于溶血磷脂酶家族的亚型,与人类乙酰蛋白硫酯酶APT1同源性最高。但Burger的研究表明Lyplal1既没有磷脂酶活性也没有甘油三酯脂肪酶的活性。Lyplal1基因在脂肪组织的形成以及肥胖症中的具体功能还尚未被研究。本研究的目的在于揭示Lyplal1在脂肪分布和肥胖症中的作用。首先我们研究了鼠源性的Lyplal1基因在正常小鼠各个组织中的表达情况以及是否具有性别特异性。然后重点研究高脂饮食诱导的肥胖小鼠的各个脂肪组织中其表达水平的变化。除此之外,为了研究Lyplall基因在脂肪前体细胞分化为成熟脂肪细胞过程中的调控情况,我们采用3T3-L1脂肪前体细胞并通过DMI诱导让其分化为成熟脂肪细胞。接着我们利用轮状病毒和慢病毒表达系统在脂肪前体细胞中过量表达和敲减鼠源Lyplal1,并诱导为成熟脂肪细胞,用以探究Lyplal1在调控脂肪组织分化和甘油三酯累积中的作用。我们的研究结果发现,在正常小鼠中,Lyplal1基因的表达水平具有组织特异性,在肝脏,附睾白色脂肪组织骨骼肌和肾脏中均有很高的表达量,而小肠,肺,肾上腺,脾脏中表达量相对较少,并且在小鼠的白色脂肪组织中其表达具有性二型性。与雄性附睾脂肪相比Lyplal1在雌性小鼠的子宫周围脂肪中有相对更高的表达量。在高脂饮食诱导的肥胖小鼠中,在肥胖小鼠的附睾脂肪与腹膜后脂肪中Lyplal1基因的表达水平显著性减少。体外实验中我们发现Lyplal1的表达水平在脂肪细胞分化的过程中逐步上调,并在成熟细胞中含量很高。然而,基于轮状病毒和慢病毒表达系统对Lyplal1基因进行过量表达与敲减的实验表明,Lyplal1并没有干扰脂肪细胞的分化与甘油三酯的积累。综上所述,在正常小鼠中Lyplal1的表达具有组织特异性和性二型性,而在肥胖小鼠白色脂肪组织中特异性的减少；另一方面,Lyplal1在脂肪细胞的分化过程中是非必需的。
[Abstract]:Obesity is one of the increasingly serious health epidemic diseases in the world, especially in Europe and the United States and other developed countries. In addition to health effects, obesity can lead to many social problems, such as discrimination and inequality in job search. In recent years, the whole genome sequence correlation study (Genome-wide association study,GWAS) of obesity has identified 52 gene mutation sites associated with obesity. These gene variants are thought to be mainly involved in the regulation of adipose tissue growth and distribution. Among them, four SNP (Single Nucleotide Polymorphisms, (single nucleotides polymorphism) near Lyplal1 (lysophospholipase-like1) gene were significantly associated with obesity, especially in women. Lyplall encoded protein 1. It is a cellular solute protein with molecular weight of 26 KDa, which belongs to the subgroup of lysophosphatidylase family and has the highest homology with human acetylprotein thioesterase APT1. However, Burger studies have shown that Lyplal1 has neither phospholipase activity nor TG lipase activity. The specific function of Lyplal1 gene in adipose tissue formation and obesity has not yet been studied. The purpose of this study was to reveal the role of Lyplal1 in fat distribution and obesity. First of all, we studied the expression of mouse-derived Lyplal1 gene in normal mice and whether it was gender-specific. Then the changes of adipose tissue expression in obese mice induced by high fat diet were studied. In addition, in order to study the regulation of Lyplall gene in the differentiation of adipocytes into mature adipocytes, we used 3T3-L1 adipocytes and induced them to differentiate into mature adipocytes by DMI. Then we used rotavirus and lentivirus expression systems to overexpress and knock down mouse Lyplal1, in adipocytes and induce them into mature adipocytes to explore the role of Lyplal1 in regulating adipose tissue differentiation and TG accumulation. Our results showed that the expression level of Lyplal1 gene was tissue-specific in normal mice, and high expression was found in liver, epididymal white adipose tissue, skeletal muscle and kidney, while small intestine, lung and adrenal gland. The expression level in spleen was relatively low, and the expression in white adipose tissue of mice had sex dimorphism. The expression of Lyplal1 in periuterine fat of female mice was higher than that of male epididymal fat. In obese mice induced by high fat diet, the expression of Lyplal1 gene in epididymal fat and retroperitoneal fat of obese mice was significantly decreased. In vitro, we found that the expression of Lyplal1 was up-regulated during adipocyte differentiation and high in mature cells. However, the overexpression and knockout of Lyplal1 gene based on rotavirus and lentivirus expression systems showed that Lyplal1 did not interfere with adipocytes differentiation and TG accumulation. To sum up, the expression of Lyplal1 in normal mice was tissue-specific and sexual dimorphism, but decreased in white adipose tissue of obese mice. On the other hand, Lyplal1 was not necessary in the differentiation of adipocytes.
【学位授予单位】：湖南农业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：R589.2

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