NDRG2调控血脑屏障通透性减轻缺血性脑水肿的作用和机制

The disruption of blood brain barrier (BBB) is a main pathological basis in ischemic brain edema. Astrocytes is a vital component of BBB, however, the key molecules and mechanisms in astrocytes, which are involved in BBB permeability, are largely unknown. NDRG2 is a gene, which was first discovered and cloned in a laboratory of the Department of Biochemistry and Molecular Biology in our University. In the brain, NDRG2 mainly expresses in astrocytes. Our recent study showed: the length of cell processes were significantly shortened and the number of cell processes were obviously reduced in cultured Ndrg2-/- astrocytes; BBB structure damage, BBB permeability, and astrocytes swelling in the brain of Ndrg2-/- mice were significantly higher than the wild-type littermates after ischemia. These findings suggest that NDRG2 is involved in maintaining the stability of BBB by controlling astrocytes. This project intends to investigate the molecular mechanisms that NDRG2 regulates the cell morphology and function of astrocytes on molecular, cellular and animal-based levels. In addition, another goal of this project is to clarify the roles of NDRG2 in maintaining BBB structural integrity and alleviating ischemic brain edema under physiological and pathological conditions. This study will expand the knowledge in the function and mechanism of astrocyte-mediated BBB structural integrity, and provide novel theories and strategies for the prevention and treatment of ischemic brain edema.

血脑屏障（BBB）结构和功能破坏是缺血性脑水肿的重要病理基础。星形胶质细胞是维持BBB结构完整的重要组分，但是星形胶质细胞中哪些关键分子和机制控制其在BBB通透性中的作用尚不完全清楚。NDRG2是本校生化教研室发现并克隆的一个基因，在脑中主要表达于星形胶质细胞。我们近期研究发现：体外培养的Ndrg2-/-小鼠星形胶质细胞突起长度明显缩短，突起数目显著减少；脑缺血后，Ndrg2-/-小鼠BBB结构破坏程度、BBB通透性、星形胶质细胞终足肿胀程度均明显高于野生小鼠。提示NDRG2可能通过调控星形胶质细胞维持BBB稳定。本课题拟从分子、细胞和动物三个水平，深入研究NDRG2调控星形胶质细胞形态和功能的分子机制；在生理和病理两个层次，阐明NDRG2在维持BBB稳定、减轻缺血性脑水肿中的作用。本研究将拓展星形胶质细胞维持BBB完整的机制认识，为缺血性脑水肿的防治提供新理论和新策略。

血脑屏障（BBB）结构和功能破坏是缺血性脑水肿的重要病理基础。星形胶质细胞是维持BBB结构完整的重要组分，但是星形胶质细胞中哪些关键分子和机制控制其在BBB通透性中的作用尚不完全清楚。.本课题有两个重要结果：第一、NDRG2和Na+/K+-ATPase β1是维持星状细胞极性和血脑屏障完整性的关键分子；第二、NDRG2是一个内源性神经保护分子，可以延缓缺血性脑水肿的发生发展。.重要发现一的关键数据：与从Ndrg2 flox对照小鼠分离的星形胶质细胞相比，从Ndrg2-/-小鼠培养的星形胶质细胞表现出短的突起和低水平的phalloidin。来源于Ndrg2-/-小鼠的星形胶质细胞AQP4免疫荧光信号水平显著增强。这些数据表明，NDRG2至少在一定程度上维持了星形胶质细胞在生理条件下的极化和水通道蛋白功能稳态。.重要发现二的关键数据：AQP4免疫反应性沿MCAO假手术组和对照组毛细血管均匀分布。但是Ndrg2 GFAP cKO小鼠中AQP4在缺血半暗带中呈现出无序的分布。免疫电镜结果可见缺血半暗带血管周围星形胶质细胞AQP4和Na+/K+-ATPase β1的亚细胞分布。Sham组AQP4均匀分布于星形细胞膜上，面朝毛细血管基底膜。在tMCAO手术后，Ndrg2 GFAP cKO小鼠星形胶质细胞终足肿胀程度比对照组更严重。Ndrg2 GFAP cKO小鼠大脑中AQP4蛋白水平明显高于Sham组和tMCAO组。此外，与假手术组和Ndrg2 GFAP cKO小鼠相比，MCAO组AQP4蛋白水平显著上调。这些数据表明，Na+-K+-ATPase挽救了NDRG2缺乏时BBB的损伤。因此，NDRG2可通过在生理和病理条件下调节星形胶质细胞Na+-K+-ATPase β1的分化和功能维持BBB的完整性。.本课题以缺血性脑水肿为研究方向，以调控构成BBB的星形胶质细胞形态和功能为突破口，初步阐明NDRG2通过调控Na+/K+-ATPase β1稳定性，调节星形胶质细胞终足极性和水钠转运，以维持BBB完整性；明确NDRG2在缺血性脑水肿不同发展阶段中的重要作用，为缺血性脑水肿的防治提供新策略。