摘要： 研究背景 脑缺血可诱导非神经再生区（如基底节）神经再生和神经干细胞分化，但其调节机制尚不明确。本研究旨在探索缺血性卒中后基底节神经干细胞分化过程中可能的表观遗传学调控机制。方法 采用Western blotting 法检测表观遗传学调节因子甲基化结合蛋白2（MeCP2）及其磷酸化修饰形式pMeCP2 在脑缺血大鼠基底节的表达变化，免疫组织化学染色观察MeCP2 和pMeCP2 阳性细胞形态特征，以及pMeCP2 与神经干细胞标志物巢蛋白和神经元标志物微管相关蛋白2（MAP-2）的共定位情况。结果 （1）脑缺血后基底节MeCP2 发生磷酸化形成pMeCP2，MeCP2 阳性细胞数目减少（t = 12.239，P = 0.000）、pMeCP2 阳性细胞数目增加（t = 5.808，P = 0.000）。（2）脑缺血后基底节神经细胞胞核MeCP2 表达水平降低（t = 14.949，P = 0.000）、胞质pMeCP2 表达水平升高（t = 5.026，P = 0.001）。（3）MeCP2磷酸化可介导MeCP2 从细胞核转移至细胞质。（4）脑缺血第3 天，pMeCP2 可与神经干细胞标志物巢蛋白共存于同一细胞；第7 天时，pMeCP2 可与神经元标志物MAP?2 共存于同一细胞。结论 脑缺血损伤诱导的MeCP2 磷酸化可以改变MeCP2 空间分布特征，使其从细胞核转移至细胞质，并影响其生物学功能。本研究结果进一步提高了对成年动物脑组织神经再生的认识，为神经再生治疗神经退行性疾病和损伤性疾病提供了新的视角。

关键词: 脑缺血, 基底神经节, 神经再生, DNA 甲基化, DNA 结合蛋白质类, 磷酰化, 疾病模型, 动物

Abstract: Background  It is accepted that cerebral ischemia induces neurogenesis and neural stem cells (NSCs) differentiation in non-neurogenic regions (especially in the basal ganglia). However, the mechanisms possibly involved in modulating the differentiation plasticity of NSCs are still let to known. This study aims to investigate the possible epigenetic mechanisms involved in the differentiation process of NSCs after ischemic stroke. Methods  Western blotting analysis was used to detect the protein levels of methyl CpG-binding protien 2 (MeCP2) and phosphorylated MeCP2 (pMeCP2) in the ischemic basal ganglia of rat model at 3 d following middle cerebral artery occlusion (MCAO). Immunohistochemical staining was performed to observe the cellular distribution of MeCP2 and pMeCP2, the cellular colocalization of pMeCP2 with NSCs marker nestin and neuronal marker microtubule?associated protein 2 (MAP-2) in the ischemic basal ganglia of rat brains.  Results  1) MeCP2 was phosphorylated in the basal ganglia after ischemic stroke, forming pMeCP2. MeCP2 positive cell number was decreased in the ischemic basal ganglia (t = 12.239, P = 0.000), while pMeCP2 positive cell number was increased in the ischemic basal ganglia (t = 5.808, P = 0.000). 2) Ischemic stroke induced a reduction of MeCP2 levels in the nucleus (t = 14.949, P = 0.000) and an elevation of pMeCP2 levels in the cytoplasm (t = 5.026, P = 0.001). 3) MeCP2 phosphorylation mediated the translocation of MeCP2 from nucleus to cytoplasm. 4) pMeCP2 was colocalized with NSCs marker protein nestin in the ischemic basal ganglia at 3 d after MCAO; pMeCP2 was colocalized with the neuronal marker MAP-2 in the ischemic basal ganglia at 1 week after MCAO.  Conclusion  Ischemic stroke-induced MeCP2 phosphorylation was able to alter the spatial distribution of MeCP2, transferring it from nucleus to cytoplasm and affecting its biological functions. This study further improved our awareness of brain neurogenesis in adult animals, providing new perspective for making use of neuronal regeneration in the treatment of neurodegenerative diseases and nerve injuries.

Key words: Brain ischemia, Basal ganglia, Nerve regeneration, DNA methylation, DNA-binding proteins, Phosphorylation, Disease models, animal