启动子结合蛋白调控早产儿脑白质损伤后髓鞘形成的新机制

Brain injury in preterm infants is mainly manifested as white matter injury (WMI), which is a hard curable disease often leading to neonatal death. Therefore, it is very important to study the repairing mechanisms by establishing a model of preterm WMI. It is reported that prohibition the maturation of premyelinating oligodendrocyte (pre-OLs) is crucial to the WMI since the prohibition can result in depletion of the mature oligodendrocyte pool and consequently, white matter hypomyelination. These findings laid the foundation of WMI. However, the regulating mechanisms for the myelination inhibition are not clear. Therefore, promoting the differentiation of pre-OLs is very important for the prevention and therapy for WMI. In our preliminary work, we have selected mRNAs differently expressed between WMI and normal cerebral tissues screened by mRNA chip, and found that several myelination related genes such as Sox6 was up-regulated significantly. We also found that the expression of proteins binding with Sox6 promoter was obviously increased, which strongly suggests that the promoter binding-proteins play important roles in regulating the expression of myelination related genes after WMI. Based on these findings, we hypothesized that some differently expressed proteins binding with the promoters of myelination related genes regulate the expression of myelination related genes, which could inhibit maturation of pre-OLs and aggravate WMI. In this study, we will screen and identify the promoter binding proteins participating in the regulation of myelination related genes to explore their function after WMI, so as to provide new ideas for the treatment of brain injury in preterm infants.

早产儿脑损伤主要表现为脑白质损伤（WMI），是引起新生儿死亡和儿童致残的难治性疾病。建立早产儿WMI模型，探索WMI的修复机制意义重大。研究表明，未髓鞘化的少突胶质细胞（pre-OLs）分化受阻致髓鞘形成障碍是WMI的重要病理基础，但髓鞘形成障碍的调控机制不清。因此，阐明促进pre-OLs的分化调控机制，对WMI的修复极为重要。我们在前期工作中，用表达谱芯片筛查，发现WMI后髓鞘形成相关基因Sox6表达增加，Sox6启动子结合蛋白显著上调，强烈提示启动子结合蛋白参与了髓鞘形成相关基因的调控。我们推测，启动子结合蛋白与髓鞘形成相关基因的启动子结合，调控靶基因转录，抑制少突胶质细胞分化，导致髓鞘形成障碍是WMI发生的新机制。因此，本项目拟通过建立早产儿WMI模型，筛选鉴定参与髓鞘形成相关基因调控的启动子结合蛋白，探索启动子结合蛋白调控策略阻断WMI的机制，为临床治疗早产儿脑损伤提供新思路。

早产儿脑白质损伤（White Matter Injury, WMI）是早产儿重大难治性疾病，主要由于少突胶质细胞分化异常引起髓鞘形成障碍，导致神经发育受阻，严重者可致脑白质软化、坏死，不仅威胁其生命，而且存活者常遗留脑瘫、认知和行为障碍等后遗症，严重影响患儿的生活质量，给家庭和社会带来沉重负担。因此，建立早产儿WMI模型，探索WMI的修复机制意义重大。研究表明，未髓鞘化的少突胶质细胞（pre-OLs）分化受阻致髓鞘形成障碍是WMI的重要病理基础，但髓鞘形成障碍的上游调控机制尚不清楚。我们通过磁珠分选得到高纯度的少突胶质细胞前体细胞（OPC）进行转录组测序，结合生物信息学分析及定量PCR验证，发现DNA结合抑制因子2（Inhibitor of DNA Binding 2, Id2）基因是WMI的一个关键调控分子。我们通过DNA pull-down进一步筛选Id2基因的启动子结合蛋白，经生物信息学分析筛选及Western-blot等验证，发现高迁移率族蛋白1（High mobility group protein 1, Hmgb1）是Id2基因的启动子结合蛋白并参与调控Id2转录。我们进而应用Hmgb1 shRNA腺病毒调控策略修复WMI，发现脑白质损伤后，抑制Hmgb1，少突胶质细胞分化及髓鞘形成有明显改善。进一步研究，我们还发现Id2调节分子激活素A（Act A）能促进髓鞘形成，显著减轻脑白质损伤，为临床治疗早产儿脑损伤提供了科学参考。通过本研究，共发表基金资助论文74篇，其中英文论文59篇，中文论文15篇；获批专利3项；获得部省级科技进步奖1项，省部级教学成果奖1项。举办新生儿重大疾病国际研讨会1次。研究成果在国际学术会议交流3次，国内学术会议30余次。培养研究生17名。