DNA甲基化异常介导腺苷A2A受体表达抑制在缺血性白质脑病中的作用及机制

Chronic cerebral hypoperfusion can cause ischemic leukoencephalopathy. It is one of the main pathological types of vascular cognitive impairment in the elderly, because of its unclear mechanism resulting in the lack of effective interventions. Previous study have showed that chronic cerebral hypoperfusion could induced white matter damage associated with the ROS increased.We previously found that the spatial learning,memory disorders and degree of white matter injury of adenosine A2A receptor knockout mice were significantly increased than wild type mice under chronic hypoperfusion. We also found that the expression of adenosine A2A receptor was significantly down-regulated in chronic hypoperfusion mice and the DNA methylation changed in its promoter region by MSP detection. Combined with literature, we hypothesize that the reduced A2A receptor exacerbates cerebral white matter injury after chronic hypoperfusion and aberrant DNA methylation involved in the inhibition of gene expression. Therefore, the project intends to clear the biological significance of A2A receptor and analysis relationship between DNA methylation and inhibition of A2A expression in chronic hypoperfusion animal model. We want to describe the role of oxidative stress and explore the therapeutic effect of DNA methyltransferase inhibitor for this disease.The study results are helpful to reveal the molecular mechanism of white matter damage in chronic cerebral hypoperfusion and provide new ideas and target molecule for prevention and control of disease.

慢性脑低灌注(CCH)可导致缺血性白质脑病，是中老年血管性认知损害主要病理类型之一，因机制不明缺乏有效干预。前期发现：CCH小鼠空间学习记忆障碍较正常小鼠明显加重，白质损伤程度增加，胼胝体及少突胶质细胞腺苷A2A受体表达显著下调，白质主要成分蛋白脂质蛋白表达下降，提示A2A在CCH白质损害中发挥重要作用。文献提示CCH白质损伤中活性氧增加。预实验MSP检测显示CCH中A2A启动子区域DNA甲基化模式发生改变。为此提出“CCH致机体氧化应激，引起DNA甲基化关键酶DNMTs表达改变，导致细胞中A2A启动子高甲基化，致A2A表达降低，促进脑白质功能损害”的假说。拟在前期基础上，采用动物模型明确A2A在CCH中的生物学意义，阐述氧化应激在其中的作用，解析DNA甲基化与其表达抑制的关系，探讨DNA甲基化酶抑制剂对该病的治疗效果。研究结果有助于揭示CCH白质损伤分子机理，为疾病防治提供新思路和靶点。

脑慢性低灌注(CCH)可导致缺血性白质脑病，是中老年血管性认知损害主要病理类型之一，因机制不明缺乏有效干预。为进一步阐明其机制，我们根据前期研究结果，对慢性低灌注下A2aR的变化规律和机制进行了研究。该项目中我们建立了BACCO法慢性低灌注大鼠模型，并在此基础上明确了腺苷A2a受体在慢性低灌注白质损伤中的作用；明确了A2aR表达和脑白质损伤程度、炎性因子表达的相关性；探索了慢性低灌注中A2aR下调的上游表观遗传学机制；解析DNA甲基化与其表达抑制的关系，探讨DNA甲基化酶抑制剂对该病的治疗效果。我们发现：1、CCH状态下，A2AR表达降低，促进脑白质功能损害；2、DNA甲基化关键酶DNMTs表达改变，导致细胞中A2A启动子高甲基化；3、抑制A2AR启动子区域甲基化，有助于保护CCH下脑白质损伤。本研究拟从表观遗传信息的改变入手，在缺血性白质脑病的研究中，探索A2aR的表达变化规律及其深层机制。假设在慢性低灌注模型下，DNA 甲基转移酶表达异常诱导的DNA 异常甲基化参与了A2aR基因表达调控，进而参与了缺血缺氧后的脑白质损伤。初步揭示了DNMTs→DNA 异常甲基化→腺苷A2aR基因异常表达这一连锁机制，为疾病的防治提供新思路和靶点分子。