运动激活TFEB调控溶酶体生成在突变蛋白蓄积类神经退行性疾病进展中的作用

There is clinical evidence that exercise can slow the progress of neurodegenerative disorders with mutant protein aggregation, including Parkinson’s disease (PD), Huntington's disease (HD) , Ataxia Spinocerebellar (SCA) and others. However, the mechanism is not so clear. Mutant protein aggregation is a common symptom and the main pathological cause in these age-related diseases. Autophagy can enhance the degradation of the mutant protein and plays an important role in neuroprotection. Previous research found that exercise could facilitate autophagy, and our recent findings also showed that exercise could ameliorate the skeletal muscle toxicity caused by the chloroquine, an alkaline regent of lysosome. In the same experiment, exercise also increased the nuclear translocation of TFEB, a transcription factor which can up-regulate the genes expression related to autophagy and lysosome. These findings gave us a hint that exercise may enhance the lysosome biogenesis. As the final step in autophagy pathway, the importance of lysosomal function still needs more study. Therefore, we hypothesized that the mechanism of exercise delaying the disease development of neurodegenerative disorders with mutant proteins aggregations can be associated with the enhanced autophagy/lysosome pathway. Autophagy/lysosome pathway in skeletal muscle and the central nervous system can be enhanced by exercise, then can decrease the aggregation of the mutant proteins and can protect the skeletal muscle and neurons from the toxicity of mutant proteins. To find evidence for this hypothesis, we will establish a long term aerobic exercise animal model as well as a cell model to study the effect of exercise on lysosomal biogenesis and its function in skeletal muscles and neurons in cerebral cortex and striatum. TFEB silencing will be used in mice, C2C12 cells and primary skeletal muscle cells to check the effect of TFEB in response to exercise. Furthermore, HD transgenic mice will be used to explore the effect of exercise on mutant Htt aggregation in neurons and skeletal muscles and the change in their cell function. The results will provide us evidence on the effect of long-term aerobic exercise on lysosomal biogenesis and function. It will also highlight the significance of exercise on the neurodegenerative diseases with mutant protein aggregations.

临床发现运动可延缓帕金森病、亨廷顿病和脊髓小脑共济失调等神经退行性疾病的进程，但机制不明。突变蛋白蓄积是此类增龄性疾病的共同致病因素。研究表明自噬激活可减少突变蛋白蓄积，并有神经保护作用。有报道运动可激活自噬，我们最近又发现运动可缓解溶酶体碱化剂氯喹导致的肌肉毒性，并可促进溶酶体生成相关转录因子TFEB在骨骼肌和大脑皮层的核转位，提示运动可激活溶酶体生成。因而我们认为运动延缓此类疾病进程的机制可能与其激活溶酶体，促进突变蛋白降解，提升肌肉功能和增强神经保护有关。本课题将建立动物长期运动模型，结合电刺激促进肌细胞收缩的方式建立细胞运动模型，通过沉默TFEB，评价运动对骨骼肌和中枢神经系统溶酶体生成和功能的影响；同时利用亨廷顿病小鼠探讨运动对突变蛋白在骨骼肌和神经元中的蓄积及其对细胞生存的影响，阐明溶酶体的功能及其在运动延缓神经退行性疾病中的意义，以期寻找遏制神经退行性疾病病程的新靶点和措施。

临床发现运动可延缓帕金森病、亨廷顿病和脊髓小脑共济失调等神经退行性疾病的进程，但机制不明。突变蛋白蓄积是此类增龄性疾病的共同致病因素。根据前期研究，我们提出猜想：运动延缓此类疾病进程的机制可能与其激活溶酶体，促进突变蛋白降解，提升肌肉功能和增强神经保护有关。本课题先建立了正常小鼠的短期与长期运动模型，发现运动能通过增强AMPK-sirt1信号途径, 增强溶酶体相关转录因子TFEB的核转位，增强溶酶体的生物合成。此后，建立了AD转基因小鼠和HD转基因小鼠的运动模型，发现长期运动能减缓AD小鼠的认知与行为能力的退化，减少神经元死亡。电镜结果显示，长期运动能增加正常溶酶体的数量，减少含不溶物的溶酶体的数量。免疫组化、western blot以及实时定量PCR结果显示，长期运动能增强TFEB的核定位，增加TFEB调控的基因表达，增加溶酶体相关蛋白的水平，增加成熟型溶酶体酶的水平。运动还能减少AD与PD小鼠神经元空泡化线粒体的数量，研究发现运动能增强PGC 1α调控的的线粒体生物合成，增加PINK1/PARKIN相关的线粒体自噬。在HD小鼠中也得到了类似的结果。本研究说明运动能通过激活溶酶体合成和增强功能减缓AD和HD疾病进展。本项目提示运动是良医，它对有突变蛋白聚集的神经退行性疾病病情进展能起到延缓作用。