PRDM16基因甲基化与肥胖关系的分子流行病学研究

The relationship between gene methylation and obesity has drawn a large amount of attention, but only a few studies have been investigated abroad with a choice of small sample sizes. More and more attentions were paid on PRDM16 because of its role in regulation on brown adipocyte differentiation. We are engaged in the study of obesity susceptibility. In our previous research, we found that there was little relationship between some SNPs in PRDM16 gene and obesity, and there was methylation at PRDM16 promoter. Therefore, a cross-sectional study and a matched case-control study will be carried on in the established epidemiological field through random sampling. The methylation at PRDM16 gene promoter in white blood cell and abdominal adipose tissue, the transcription level of mRNA and PRDM16 content in abdominal adipose tissue will be measured. The relationship between above indicators and obesity or related metabolic markers will be further analyzed. And the interaction between methylation at PRDM16 promoter and related environmental factors will be analyzed as well. Then the level of methylation will be used to predict the obesity and its related diseases. This is the first study to test methylation at the PRDM16 gene by choosing the Chinese People as the sample, and it is also an integrated research about the methylation -mRNA-protein research with a large sample size for exploring the molecular epidemiological characteristics and predicting obesity and related diseases. This study plays a significant role in early detection of obesity susceptible populations, prevention and control of obesity and its related diseases.

基因甲基化与肥胖的关系已引起重视，但人体方面的研究仅有个别国外报道且样本量小。PRDM16因与棕色脂肪分化调控有关而受到肥胖研究的关注。课题组致力于肥胖易感性研究，但发现PRDM16基因的部分SNP多态性与肥胖关系不大，且明确该基因存在甲基化。因此本课题拟在已建立的流行病学现场随机抽样进行大样本横断面研究和病例对照研究，检测血白细胞和腹部脂肪组织中PRDM16基因启动子甲基化的情况、腹部脂肪中mRNA转录水平和PRDM16的含量，分析它们与肥胖及相关代谢指标的关系及与肥胖相关环境因素的交互作用；并进一步以PRDM16基因甲基化水平为指标预测肥胖及其相关疾病。本课题首次在中国人群中开展PRDM16基因甲基化检测，应用大样本进行PRDM16甲基化修饰-mRNA-蛋白质的综合研究，探讨肥胖发生的分子流行病学特征并进行相关疾病预测，对早期发现肥胖易感人群、预防和控制肥胖及相关疾病具有重要意义。

成人体内含棕色脂肪且在人体热量代谢中发挥一定作用，棕色脂肪细胞分化障碍或产热减少可能引起能耗减低。本课题对影响棕色脂肪细胞分化和产热活性的主要基因启动子甲基化与超重肥胖的关系进行了研究。.通过分子流行病学方法，对可能在棕色脂肪细胞分化过程中发挥重要作用的PRDM16基因启动子采用质谱法进行甲基化检测，结果显示：虽分层分析发现超重肥胖组CpG26.27位点与BMI存在线性关系，偏回归系数为46.93（P=0.011），甲基化程度越高，BMI越大，但PRDM16基因启动子区全部有效检测位点的甲基化水平在正常体重组和超重肥胖组之间无统计学差异；脂肪组织中PRDM16基因mRNA的水平在超重肥胖与正常组之间亦未发现统计学差异。.遂进一步对棕色脂肪细胞产热相关的UCP1基因启动子甲基化进行了探索，发现：UCP1基因启动子UCP1_2_CpG_10-13位点甲基化水平与BMI存在线性关系，偏回归系数为15.37（P=0.004），提示UCP1甲基化可能与超重肥胖有关。.为进一步明确PRDM16基因与肥胖的关系，对该基因多态性及其单倍体型与肥胖的关系进行研究。发现rs2651899 位点的A等位基因及单倍体型AAT 可能是超重肥胖发生的危险因素，单倍体型GAC、GCT 可能是保护因素。.进一步对脂肪细胞糖脂代谢相关基因CIDEB/C基因多态性与血脂及BMI的关系研究发现：CIDE B/C基因多态性及其单倍型与高甘油三酯血症的发生风险有关。CIDEB 基因的rs2144493 位点的C等位基因可能对肥胖具有保护作用，CIDE B/C基因及其单倍型对超重肥胖可能具有单独及交互作用。.基于肥胖等复杂疾病多种遗传因素交互作用理论，通过统计模拟实验，运用核典型相关分析，构建PRDM16和肥胖相关基因交互作用的KCCU 统计量，发现该方法在大样本高交互分析时能有效检验整体基因交互作用，为复杂疾病基因整体交互作用分析进行了有意义的探索。并采用CiteSpace Ⅲ对近年来肥胖和癌症关系之研究领域的热点及前沿问题进行了探索，为今后的研究提供了依据和方向。.总之，课题组按计划完成了棕色脂肪细胞分化相关基因PRDM16甲基化与肥胖的关系研究，并在脂肪细胞产热及糖脂代谢相关基因遗传及表观遗传与肥胖的关系方面进行了一定研究，亦在复杂疾病遗传因素分析等方法学方面进行了有意义的探索。