NO介导的低氧信号传递对星形胶质细胞启动低氧保护反应的机制研究

High altitude-induced cerebral hypoxia can cause cognitive dysfunction. At the beginning of mild hypoxia, effective transmission of the hypoxia signal can be timely boot adaptation to hypoxia for nerve cells so as to alleviate the symptoms of cerebral hypoxia, but the hypoxia signal transmission path has not yet been fully clarified in the neurovascular units. Our previous studies found that hypoxia co-cultured primary mice brain capillary endothelial cell-derived NO can significantly upregulate the expression of HIF-1α in primary astrocytes. In this study, we intend to use the hypoxic cell incubator for precise controlling the partial pressure of oxygen in culture medium to explore the timing relationships between endothelial cells produce NO and astrocytes perceive hypoxia signal. In addition, the exogenous NO preprocessing and endothelial cell-derived NO co-culture will be applied to confirm that endothelial cell-derived NO could boot adaptation to hypoxia for astrocytes. Meanwhile, blocking endogenous NO produce and NO signal transduction in astrocytes as well as the use of RNAi silent HIF-1α gene to explore whether the NO-hypoxia signal mediated adaptation to hypoxia via HIF-1α. With the above study, we are expecting to clarify systematically the mechanism of NO-mediated hypoxia signaling for adaptation to hypoxia in astrocytes.

高原性脑缺氧可引起大脑认知障碍。轻度缺氧初期低氧信号的有效传递可适时启动神经细胞低氧保护反应从而缓解脑缺氧症状，但低氧信号在神经血管单位中的传递路径尚未完全阐明。课题组前期研究发现：Transwell低氧共培养的小鼠大脑原代毛细血管内皮细胞源性NO可上调原代星形胶质细胞HIF-1α的表达，籍此，本项目拟采用低氧细胞培养箱精确控制培养液氧分压，研究内皮细胞产生NO信号与星形胶质细胞感知低氧的时序关系；借助外源性NO预处理和内皮细胞源性NO共培养细胞，明确内皮细胞源性NO可启动星形胶质细胞低氧保护反应；同时对照阻断星形胶质细胞内源性NO产生和NO信号转导通路，以及运用RNAi技术静默HIF-1α基因转录，探索NO-低氧信号如何通过HIF-1α介导星形胶质细胞的低氧保护反应，以期系统阐明内皮细胞源性NO介导的低氧信号传递对于星形胶质细胞启动低氧保护反应的机制。

轻度缺氧初期低氧信号的有效传递可适时启动神经细胞低氧保护反应从而缓解脑缺氧症状，但低氧信号在神经血管单位中的传递路径尚未完全阐明。本课题研究发现：⑴5%氧气浓度低氧培养条件下，星形胶质细胞较脑微血管内皮细胞更耐受低氧；⑵5%氧气浓度低氧培养条件下，外源性NO（NO供体DETA NONOate）作用可诱导启动原代星形胶质细胞的低氧代偿反应；⑶5%氧气浓度低氧培养条件下，脑微血管内皮细胞源性NO作用可诱导启动原代星形胶质细胞的低氧代偿反应；⑷NO启动原代星形胶质细胞的低氧代偿反应包括：HIF-1a降解减少，受HIF-1a调控的下游基因LDHA、VEGF、PDK1、HK1、GLUT1、MCT4转录水平上调，LAC释放水平和VEGF蛋白水平上调。本课题研究明确了内皮细胞源性NO可介导星形胶质细胞氧信号的传递，初步阐明NO-低氧信号可通过HIF-1α介导星形胶质细胞低氧保护反应。