儿童少年脂代谢稳态失衡及其与PPARGC1基因甲基化水平关系的研究

Children and adolescence is a critical stage in the human lifetime, the theory of "the development of the origins of health and disease, DoHaD " also emphasizes the importance and specialty of this stage. The disorder of the homeostasis for lipid metabolism in children and adolescents tend to affect glucose and lipid metabolism in adulthood, also closely associated with many chronic diseases accordingly. Our study will discuss the epidemiological characteristics of homeostasis for lipid metabolism in children and adolescents based on the pre-large epidemiological investigation, then the comparison of PPARGC1A methylation status between lipid metabolism homeostasis children and abnormal children will be conducted. Given the increased levels of methylation occurs corresponding to the principle of reducing the level of mRNA expression, the PPARGC1A mRNA expression analysis will be tested in this study at the same time.If the study could prove that disorder of lipid metabolism homeostasis existed in children and adolscents which lead to the methylation increase, then the role of environmental and genetic factors might lead to the development process of the human individual PPARGC1A methylation increased, accordingly many chronic diseases in adulthood might rise. The purpose of this study is to provide the useful information and clues for the follow up and studies in the furture.

儿童少年时期是决定一生体格和体质的关键阶段,“健康与疾病的发展起源”理论即DoHaD理论强调了生命早期阶段的重要性与特殊性，儿童少年期代谢稳态失衡倾向极可能会影响成年后的糖脂代谢，并与众多成年期的疾病密切关联。国内外这个领域的研究尚处于起步阶段，本研究预期在前期大人群流行病学调查的基础上，首先明确儿童少年人群脂代谢稳态失衡的流行病学特征，进而比较脂代谢稳态失衡和正常的儿童少年这两个人群间是否存在PPARGC1A甲基化状态的差别，同时鉴于甲基化水平增高会出现相对应的mRNA表达水平降低的原理，也拟进行PPARGC1A的mRNA表达水平分析，以利佐证；如脂代谢稳态失衡的儿童少年人群中确实存在甲基化异常现象，则表明环境和遗传因素的作用会导致发育过程中的人类个体PPARGC1A甲基化增高，后续还可能通过特异性通路进一步影响或引发成年后的多种慢性疾病。望本次研究能够提供相关基础线索。

研究背景 儿童少年时期是决定人一生体格和体质的关键阶段, 儿童少年期脂代谢稳态失衡可能会严重影响成年后的代谢状态，与众多慢性病密切关联。主要研究内容 课题选取8000名天津市6~18周岁儿童少年为调查研究对象。明确该人群脂代谢稳态失衡的流行病学特征，并进一步探索脂代谢稳态失衡的潜在影响因素与机理。重要结果及关键数据 研究总结描述了天津市儿童少年超重与肥胖的患病率为53.69%，特别是在男性中更严重（58.56%）；血压增高的构成比例为14.24%；血糖水平异常增高的构成比例为0.23%；血脂异常的患病率为34.53%。在此基础上，课题组围绕遗传危险因素：过氧化物酶体增殖物激活受体γ(PPARγ)辅激活因子1A(PPARGC1A)的DNA甲基化水平与脂代谢稳态失衡的关联展开实验室研究，发现T2DM并脂代谢异常者的PPARGC1A存在甲基化异常，T2DM并见脂代谢异常者PPARGC1A甲基化%为（0.771±0.079），PPARGC1A的mRNA表达水平为（0.006±0.002）AU；且治疗干预后可见水平的改善，PPARGC1A甲基化%减低为（0.376±0.134），PPARGC1A的mRNA表达水平为（0.009±0.002）AU。不仅如此，多种代谢紊乱均与脂代谢紊乱存在复杂相互关联，肥胖、血压异常以及血糖异常与血脂的异常之间相互促进，共同影响代谢的稳态。课题围绕代谢稳态失衡的机制进行了小鼠试验，分析了MiR-30a-5p对 Sirtuin 1的下调作用，进而参与小鼠肥胖以及糖脂代谢的紊乱发生的调控。研究刺激3T3-L1细胞分化，经RT-qPCR分析，定量测定miR-30a-5p水平，发用NC或miR-30a-5p转染的3T3-L1细胞中miR-30a-5p的丰度的变化特征，并且通过WB在分化的终点测定PPARγ，C /EBPα和FABP4蛋白的表达以及使用TG含量测定试剂盒并相对于总蛋白测定TG的积累进行测定，发现MiR-30a-5p对 Sirtuin 1的下调作用。科学意义 脂代谢稳态失衡与PPARGC1A甲基化异常、多通路引发的MiR-30a-5p对 Sirtuin 1的下调等存在潜在关联；并且与成年期众多慢性病存在密切关联。值得关注并予以恰当的预防干预。