ROS诱导肌细胞增强因子2D氧化调控线粒体功能及肌萎缩侧索硬化症早期致病机制

Amyotrophic lateral sclerosis (ALS) is a deadly progressive neurodegenerative disorder. Neuromuscular junction disassembly is the early step in the pathogenesis of ALS, and malfunction of mitochondria initiates this devastating event. Our recently studies identified that mitochondrial myocyte enhancer factor 2D (MEFD) regulated mitochondrial function through direct controlling the expression of NADH dehydrogenase 6 (ND6), and oxidization levels of mitochondrial MEF2D in the spinal cords of ALS mice and patients were much higher than that in the controls. Oxidative damage was one of the early characters of ALS, and MEF2D was extremely sensitive to cellular ROS. Based on all of the above, we hypothesize that early cellular ROS may damage mitochondrial function through oxidization of mitochondrial MEF2D, which is the early step in the pathogenesis of ALS. We propose to investigate the roles of ROS scavenger and anti-oxidative mitochondrial MEF2D in protecting mitochondrial function and neuromuscular junction in both cellular and animal models of ALS. A positive outcome of this project will significantly advance our knowledge of the basic mechanism during the early stage of ALS pathogenesis, identify useful biomarker for efficient early diagnosis, and provide new therapeutic target.

肌萎缩侧索硬化症（ALS）为致命性神经退行性疾病，神经－肌肉接头蜕变是其始因，而线粒体异常是神经－肌肉接头蜕变的直接诱因。我们前期研究发现线粒体肌细胞增强因子2D（MEF2D）通过调节NADH脱氢酶6（ND6）的转录可调控线粒体功能，ALS小鼠和病人脊髓线粒体MEF2D氧化程度明显升高。细胞内氧化应激损伤是ALS的特征表现，而MEF2D对细胞内活性氧（ROS）非常敏感。因此，我们推测早期ROS参与MEF2D氧化调控线粒体功能，该通路可能是导致ALS发生的早期原因。本研究拟采用ALS细胞模型和动物模型，通过ROS清除及抵抗MEF2D氧化后，检测细胞和组织内ND6表达、MEF2D氧化水平及Complex I活性，评价线粒体功能。并通过神经元轴突变性、神经－肌肉接头蜕变的检测和运动功能评价，探讨ROS清除剂及抗MEF2D氧化对线粒体和神经－肌肉接头的保护作用，为ALS的临床治疗提供新的靶点。

肌萎缩侧索硬化症（ALS）为致命性神经退行性疾病，神经－肌肉接头蜕变是其始因，而线粒体异常是神经－肌肉接头蜕变的直接诱因。我们的前期研究发现线粒体肌细胞增强因子2D（MEF2D）通过调节NADH脱氢酶6（ND6）的转录可调控线粒体功能。本项目的研究发现体内外BMAA处理或表达SOD1（G93A）诱导线粒体MEF2D氧化，从而抑制了其DNA结合能力和转录活性，导致线粒体complex I蛋白和活性下降，并诱导小鼠神经-肌肉接头（NMJ）慢性蜕变和运动能力下降，这些都能被阻断线粒体MEF2D氧化的DMPO有效抑制。此外，BMAA处理或表达SOD1（G93A）引起线粒体MEF2D的直接转录产物ND6表达下降。在ALS小鼠模型上其降低（P30）早于神经-肌肉接头蜕变（P45）。本项研究结果拓展了对ALS 发病早期分子机制的认识， 将有助于发掘准确可靠的ALS 早期诊断分子标记物，并为临床攻克ALS 提供了新的研究方向。