从卵母细胞DNA甲基化改变探讨宫内缺氧大鼠出生后肺泡发育不良多代和跨代遗传的机制

Intrauterine hypoxia is a common clinical phenomenon. Our previous study found that intrauterine hypoxia resulted in alveolar dysplasia in the first generation rats, and the phenotype could be inherited to the second generation (reflexing multigeneration inheritance) and the third generation (reflexing transgeneration inheritance) offsprings; Based on the preliminary research, the applicant firstly propose to investigate the effect of intrauterine hypoxia on DNA methylation among oocyte and important organs such as lung, heart, brain and kidney in rats, and to investigate the role of DNA methyltransferase inhibitor in the prevention and cure of alveolar dysplasia in the first, the second and the third offspring rats, and to investigate the role of oocyte DNA methylation in the multigenerational inheritance and transgenerational inheritance of alveolar dysplasia induced by intrauterine hypoxia. We also aim to further observe the direct effect of hypoxia on whole gene expression in oocyte and on DNA mehtylation of key genes that regulate the alveolar development after birth(such as TGF-β1) in vitro .In a whole , the purpose of this project is to clarify the hypothesis that the epigenetic changes of oocyte are the important mechanisms that leads to the lung TGF-β1 DNA methylation enhancement as well as multigenetional and.transgenerional inheritance of alveolar dysplasia induced by intrauterine hypoxia in postnatal rats in vivo, in vitro and at molecular level. This project will provide a new target for the prevention of the multigenetional and transgenerional inheritance of postnatal alveolar dysplasia induced by intrauterine hypoxia in rats.

宫内缺氧是临床常见现象。申请者前期研究发现宫内缺氧可导致第1代仔鼠生后肺泡发育不良，且此种表型可遗传至第2代（反映多代遗传）和第3代（反映跨代遗传）。基于前期初步研究结果，申请者首次提出在整体及卵母细胞体外培养水平探讨宫内缺氧对卵母细胞、肺、心、脑、肾重要器官DNA甲基化的影响，及DNA甲基化酶抑制剂对第1代、第2代及第3代仔鼠生后肺泡发育不良的防治作用，查明卵母细胞DNA甲基化变化在宫内缺氧仔鼠生后肺泡发育不良的多代和跨代遗传中的作用；进一步体外观察缺氧对卵母细胞全基因组及肺泡化发育关键基因（如TGF-β1）DNA甲基化的直接影响，在整体、细胞及分子水平论证卵母细胞表观遗传学改变是导致肺TGF-β1甲基化增强和宫内缺氧所致仔鼠生后肺泡发育不良多代和跨代遗传的重要机制的假说，为宫内缺氧所致仔鼠生后肺泡发育不良遗传的防治研究提供新的思路。

宫内缺氧是临床常见现象，前期研究已发现宫内缺氧可导致仔鼠生后肺发育不良的多代和跨代遗传，本项目在成功制备宫内缺氧所致仔鼠生后肺发育不良的多代遗传及跨代遗传的模型以及卵巢颗粒细胞体外培养模型基础上，在DNA甲基转移酶表达水平、肺组织整体甲基化水平、TGFβ1以及VEGF表达及甲基化水平、生殖细胞卵母细胞甲基化水平探讨宫内缺氧对仔鼠生后肺发育不良的多代遗传及跨代遗传的可能机制。首次发现肺组织TGFβ1位点15甲基化增强以及卵母细胞甲基化改变及表达谱改变是宫内缺氧所致大鼠生后肺发育不良遗传的表观遗传学机制。同时观察到宫内缺氧可影响仔鼠生后脑结构的发育，可导致海马神经元减少，仔鼠成年期空间学习能力下降、仔鼠记忆能力减退和幼年期行为发育落后现象，并且宫内缺氧对仔鼠神经系统结构和功能的影响可出现多代遗传。为宫内缺氧所致仔鼠生后肺和脑发育不良以及其遗传的防治研究提供新的证据和启示，有重要的临床应用前景。