线粒体DNA突变在脑室周围白质软化少突胶质细胞损伤中的作用机制研究

Premature periventricular leukomalacia (PVL) is an important cause of neonatal cerebral palsy and other neurological sequela. Hypoxia-ischemia (HI) damage of oligodendrocyte progenitor cells (OPCs) plays a key role in the dysfunction of myelination in PVL. Oxidative stress damage caused by HI is an important cause of PVL, but the mechanisms were still unknown. Mitochoridria DNA (mtDNA) deletion mutations were closely associated with oxidative stress and may lead to mitochondrial dysfunction. Our previous study found that mtDNA deletion mutations were detected in premature neonatal rats with PVL. These findings imply that mtDNA deletion mutation may play an important role in the development of PVL. In the present research, we utilize rat models of PVL induced by HI and in vitro OPCs exposured to HI to explore the effect of mtDNA deletion mutation on HI inducing PVL by using molecular biology, proteomics, immunology and neurological behavior methods. We also investigate the relation between base excision repair and mtDNA deletion mutations, and the protection role of base excision repair against HI-inducing OPCs damage. This study may provide new insight into the mechanisms of premature PVL, and new therapeutic target for myelin repair.

早产儿脑室周围白质软化（PVL）是导致脑瘫及其他神经系统后遗症的主要原因，少突胶质前体细胞（OPCs）缺氧缺血损伤是PVL髓鞘化障碍的重要原因，缺氧缺血所致氧化应激损伤是PVL主要机制之一，但机理尚不清楚。线粒体DNA（mtDNA）缺失突变所致线粒体功能异常与氧化应激密切相关，结合我们前期研究发现未成熟新生大鼠PVL模型中存在mtDNA缺失突变，提示mtDNA缺失突变在PVL的发生过程中可能发挥重要作用。本研究将建立新生大鼠PVL模型和体外OPCs缺氧缺血模型，应用分子生物学、蛋白组学、免疫学及神经行为学等方法，探讨mtDNA缺失突变在缺氧缺血PVL中的作用机制，以及碱基切除修复对mtDNA缺失突变的调控机制及对缺氧缺血OPCs损伤的保护作用，为早产儿PVL的发病机制研究提供新的思路，为髓鞘再生修复寻找新靶点。

早产儿脑室周围白质软化(PVL)是导致脑瘫及其他神经系统后遗症的主要原因，少突胶质前体细胞(OPCs)缺氧缺血损伤是PVL髓鞘化障碍的重要原因，缺氧缺血所致氧化应激损伤是PVL主要机制之一，但机理尚不清楚。线粒体DNA(mtDNA)缺失突变所致线粒体功能异常与氧化应激密切相关，结合我们前期研究发现未成熟新生大鼠PVL模型中存在mtDNA缺失突变，提示mtDNA缺失突变在PVL的发生过程中可能发挥重要作用。本研究通过建立新生大鼠PVL模型和体外OPCs缺氧缺血模型，应用分子生物学、蛋白组学、免疫学及神经行为学等方法，探讨mtDNA缺失突变在缺氧缺血PVL中的作用机制。本研究发现，PVL模型大鼠皮质下、运动皮层及海马氧化应激产物显著升高，抗氧化酶明显降低；实验组线粒体呼吸链酶复合体功能明显降低；各脑区线粒体碱基切除修复基因的mRNA和蛋白表达水平均显著降低，而mtDNA 4834bp缺失突变率和mtDNA拷贝数均明显增加。以上结果提示，氧化应激在大鼠缺氧缺血脑损伤过程中发挥重要作用；线粒体氧化磷酸化功能下降可能是导致mtDNA 4834bp缺失的重要原因；线粒体碱基切除修复基因表达降低与mtDNA 4834bp缺失增加在PVL发生过程中可能发挥重要作用。