Juxtanodin(JN)表达下调对少突胶质细胞氧化应激损伤的影响

The Effects of Juxtanodin(JN) Downregulation on the Oxidative Stress Injury of Oligodendrocytes

目的:探讨JN表达下调对少突胶质细胞氧化应激损伤的影响及其可能的机制。方法:采用大脑中动脉线栓法制备小鼠局灶性脑缺血模型,通过m NSS评分分析JN-/-小鼠及其同窝阴性对照鼠神经功能缺损的情况。通过制备少突胶质细胞系OLN93的氧糖剥夺模型(oxygen glucose deprivation, OGD)模拟脑白质缺血的病理改变。使用si RNA下调模型细胞中JN的表达,分析JN表达下调后模型细胞的存活情况以及与氧化应激有关的指标如乳酸盐脱氢酶(Lactate Dehydrogenase,LDH)、超氧化物歧化酶(Superoxide Dismutase,SOD)活性、一氧化氮(Nitric Oxide,NO)及丙二醛(Methane Dicarboxylic Aldehyde,MDA)等的变化情况;并通过western blot检测BNIP3(Bcl-2/E1B-19K-interacting protein 3, BNIP3)的表达变化。结果:JN-/-小鼠m NSS评分较其同窝阴性对照鼠升高(P<0.05)。OGD模型细胞与对照组相比,其存活率及SOD活性分别下降35.82%及37.27%,LDH活性、MDA及NO水平分别升高52.01%,86.15%及149.78%,且BNIP3蛋白表达上调461%(P<0.01)。而与OGD模型组相比,JN表达下调可使细胞存活率和SOD活性分别下降33.23%及33.31%,而LDH的释放、MDA及NO水平分别增加58.12%,57.02%及52.64%,且BNIP3表达上调72%(P<0.01)。结论:敲除JN使小鼠在脑缺血后神经功能恶化,而JN表达下调可使少突胶质细胞对氧化应激损伤更敏感,其机制可能与BNIP3表达上调有关。

Objective: To investigate the effects and the related mechanism of Juxtanodin (JN) downregulation on the oxidative stress injury of oligodendrocytes. Methods: The mNSS neuroscore for cerebral ischemic changes was performed on JN-/- mice and its negative control littermates through middle cerebral artery occlusion (MCAO). To simulate cerebral white matter ischemia, oligodendrocyte cell line OLN93 was induced by oxygen glucose deprivation (OGD). Then the cell viability, the levels of LDH, SOD, NO, MDA and the expression of BNIP3 that related to the process of oxidative stress were analyzed with or without JN siRNA. Results: The mNSS neuroscore of JN-/- mice was higher than its negative control littermates after MCAO and there was a significant difference between the two groups (P<0.05). Compared with the control group,the cell survival rate and SOD activities in OGD injury group were significantly reduced by 35.82% and 37.27%, respectively (P<0.01). Meanwhile, the LDH leakage rate was increased by 52.01%, and the level of MDA and NO was increased by 86.15% and 149.78%, respectively (P<0.01). In addition, the expression of BNIP3 in OGD injury group was upregulated by 461%(P<0.01). More importantly, compared with the OGD group,decreased expression of JN by siRNA significantly further reduced the cell viability and SOD activities by 33.23% and 33.31%,respectively (P<0.01). Meanwhile, the LDH leakage rate was increased by 58.12% (P<0.01), and the level of MDA and NO was increased by 57.02% and 52.64%, respectively (P<0.01). The expression of BNIP3 was significantly upregulated by 72% (P<0.01). Conclusions: Knockdown of JN deteriorated the neurological function of mice suffered from cerebral ischemic disease. The oligodendrocytes was more vulnerable to oxidative stress injury when JN was downregulated, which may be associated with the increased expression of BNIP3.