胚胎期营养不良对大鼠糖尿病易感性的影响及可能的表观遗传学机制

Many studies have found that the malnutrition during the embryonic development period is closely correlated with the pathogenesis of diabetes, and the change of epigenetics may play an important role in this process. However, whether the malnutrition during the embryonic development period increase the susceptibility to diabetes by the way of epigenetics remains to be confirmed.In the study, we will feed the pregnant rat with low-nutrient food and detect the effect of the malnutrition during the embryonic development period on the adult rats: ①detect the change of genomic DNA methylation profiling related to the diabetes by methylated DNA immunoprecipitation-chip(MeDIP-chip); ②detect and screen the expression level of genes, such as Pdx-1 and insulin, related to the diabetes and their status of DNA methylation in their promoter region and acetylation of histone by molecular biology technique; ③detect the susceptibility to diabetes include insulin resistance and glucose tolerance, et al．.This study will provide an important scientific basis to explain the effect of environmental factors during the embryonic development period on the susceptibility to diabetes and its molecular mechanism, especially to understand the epigenetics. It will help to reveal the mechanism that the main adverse factors during the embryonic development period influence the birth quality, and to offer the way of feasible strategy that solve the birth defects and low offspring quality or provide an important experimental basis to solve these questions.

研究已证实，胚胎期营养不良可增加糖尿病的易感性和发病率，有研究提示表观遗传学改变参与糖尿病的发病，但胚胎期营养不良是否通过表观遗传学途径增加糖尿病的易感性和发病率并不清楚。本研究拟采用营养不良因素干预自然受孕的母鼠，采用DNA甲基化芯片技术检测子代大鼠糖尿病易感性相关性DNA甲基化谱；采用分子生物学技术检测及筛选糖尿病相关基因包括Pdx-1、胰岛素等的表达水平及其相应基因启动子区DNA的甲基化和组蛋白的乙酰化改变；采用生物化学等技术检测糖尿病易感性，包括胰岛素抵抗及葡萄糖耐量变化等。.本研究对阐明胚胎发育期环境因素的变化对糖尿病易感性的影响及其分子机制，特别是表观遗传学机制的认识，提供了重要的科学依据；将有助于揭示影响出生素质不高的主要不良因素的作用机制，期望为解决出生缺陷、子代素质不高提供可行的策略思路，或为解决上述问题建立起扎实的实验基础。

宫内发育迟缓（IUGR）可增加糖尿病（DM）的发病，但机制并不明了。有研究提示，表观遗传学可能参与DM的发病，但IUGR是否通过改变表观遗传学的修饰方式增加DM的发病，目前并不清楚。本研究采用低热量饮食法复制具有生长追赶的宫内发育迟缓（CG-IUGR）雄性大鼠模型。CG-IUGR大鼠模型复制后：1.检测了DM易感性：①检测了空腹血糖（FBG）和空腹胰岛素（FINS）水平。②检测了葡萄糖和胰岛素耐受情况。③检测了脂质代谢情况。2.检测了肝脏、骨骼肌、胰腺5909个基因启动子区的甲基化状况，筛选可能具有差异表达的DM相关基因。3.检测了DM相关基因的表达，包括影响胰腺发育的基因PDX-1、胰岛素信号转导相关基因GLUT4、IRS-1及IRS-2和糖代谢相关基因GYS1、GYS2、GSK-3α及GSK-3β等。4.检测了以上基因启动子区DNA甲基化和相应基因的组蛋白乙酰化水平。结果发现: 1.CG-IUGR雄性大鼠DM易感性增加。2. IUGR 可广泛影响基因启动子区CpG岛的甲基化水平，这可能是多种疾病如DM等的发病基础。3. IUGR可改变成年期CG-IUGR雄性大鼠DM相关基因的表达，可能造成胰腺发育受到影响、胰岛素的信号转导效应降低和糖原合成功能下降，后者可能是其DM易感性增加的重要原因。4.IUGR可改变CG-IUGR雄性大鼠DM相关基因基因启动子区的DNA甲基化和组蛋白乙酰化水平，后者可能是DM相关基因表达异常的重要机制。综上所述，IUGR可能通过表观遗传学途径，改变DM相关基因的表达，增加CG-IUGR雄性大鼠DM的易感性。本研究从表观遗传学的角度来分析DM的发病，为解决出生缺陷、子代素质不高提供了新的可行策略思路，并为解决上述问题奠定了扎实的实验基础。