Dexras1通过HDAC9浆核穿梭调控卒中后期运动功能恢复的机制研究

Ischemic stroke remains a major public health concern leading to high rates of death and disability worldwide. However, therapeutic target for functional recovery in the delayed phase after stroke is deficient. Our preliminary experiments showed that cerebral ischemia increased the expression and activity of Dexras1 in the delayed phase and importantly, Dexras1 knockdown significantly promoted functional recovery after stroke, suggesting that Dexras1 plays a critical role in post-stroke neural repair. Increased neural activity promotes HDAC9 translocation from nucleus to cytoplasm, elevates transcriptional activity and thus promotes axonal and dendritic development. We found that silencing Dexras1 upregulated neural activity and induced HDAC9 translocation from nucleus to cytoplasm and dendritic remodeling in the delayed phase of stroke. Accordingly, we proposed the scientific hypothesis that Dexras1 affects HDAC9 nucleocytoplasmic shuttling via modulation of neural activity, regulates neural network reorganization in the peri-infarcts and thus regulates post-stroke functional recovery. Here, we will employ electrophysiology recordings, calcium imaging, Golgi-Cox staining, two-photon imaging and BDA staining to confirm the scientific hypothesis in vivo and in vitro. Findings from the current project will explain the pathological mechanisms of stroke in the delayed phase and provided a new theory basis and a novel therapeutic target for post-stroke functional rehabilitation.

缺血性脑卒中具有高死亡率和高致残率的特点，仍然是一个主要的公共健康问题。然而，目前对于卒中后期功能恢复缺乏有效的干预靶点。预实验表明卒中后期Dexras1表达和活性明显上调，敲减Dexras1促进卒中后期功能恢复，提示Dexras1在卒中后期损伤修复中起重要作用。神经元活性升高促使HDAC9由胞核向胞浆穿梭，增加转录活性进而促进神经元轴突和树突发育。我们证实沉默Dexras1上调神经元活性，促进卒中后期HDAC9由胞核向胞浆穿梭以及树突重塑。据此，我们提出科学假说：Dexras1通过调节神经元活性影响HDAC9浆核穿梭，进而影响缺血周围区神经网络重构，最终调控卒中后期功能恢复。本项目将通过体内外实验，运用电生理、钙成像、Golgi-Cox染色、双光子成像以及BDA染色等技术手段对科学假说进行确证。本项目研究成果将从全新角度阐释卒中后期病理机制，为卒中后期功能修复提供新的理论依据和干预靶点。

缺血性脑卒中具有高死亡率、高致残率和高复发率的特点，仍然是一个主要的公共健康问题。组织纤溶酶原激活剂是唯一被FDA批准用于急性缺血性卒中的药物，但是其具有时间窗窄和出血等严重不良反应，因此，只有5%的急性缺血性卒中患者能够接受该药物治疗。流行病学研究显示，脑卒中不止是一个急性的杀手，而演变成了一个慢性疾病。因此，研究卒中后期的病理过程具有显著的现实意义。然而，目前对于卒中后期神经修复依赖于康复锻炼，缺乏有效的干预靶点。在本研究中，我们发现卒中后期Dexras1表达不变，但是其亚硝基化水平显著增加，提示脑缺血后期Dexras1显著激活。通过病毒载体，抑制和增强Dexras1-SNO信号能够显著改善和恶化缺血引起的神经功能障碍。敲减Dexras1上调缺血周围区神经网络活性，促进神经元结构重塑，而对缺血周围区神经元存活和梗死体积没有影响。文献报道，神经元活性升高促使HDAC9由胞核向胞浆穿梭，增加转录活性进而促进神经元轴突和树突发育。沉默Dexras1促进卒中后期HDAC9由胞核向胞浆穿梭。基于以上实验，我们证实Dexras1通过调节神经元活性影响HDAC9浆核穿梭，进而影响树突重塑，最终调控卒中后期功能恢复。本项目从全新角度阐释卒中后期病理机制，为卒中后期功能修复提供新的理论依据和干预靶点。