钙离子电压门控通道调节溶酶体与内涵体和自噬体融合及其维持神经系统稳态平衡的功能研究

发布时间：2018-04-02 16:30

本文选题：细胞自噬　切入点：钙离子电压门控通道　出处：《浙江大学》2015年博士论文

【摘要】：细胞自噬通过溶酶体介导的降解系统防止有害物质在细胞内的积累,来维持细胞的稳态平衡,是一个在进化上高度保守的细胞生物学过程。在一个旨在获得能导致神经系统功能异常突变的大规模正向遗传筛选中,我们得到了7个cacophony(cac)基因的突变体,它们的感光神经元终端随着时间的增长逐渐积累了大量自噬泡,并且最终导致了神经元终端和周围神经胶质细胞的退行性变化。cac编码果蝇突触囊泡与细胞膜融合和神经递质释放所必需的钙离子电压门控通道(VGCC)的α1亚基。我们发现cac突变感光神经元终端积累了大量溶酶体和自噬体的融合中间体,提示自噬泡与溶酶体之间的融合过程可能存在障碍。缺失编码VGCC另一个亚基的基因stj得到了和cac突变相似的表型,说明整个VGCC都参与调节了自噬泡与溶酶体之间的融合。同时,我们发现VGCC对神经系统中细胞自噬的调节在进化上是高度保守的,因为小鼠中cac和stj的同源基因Cacnala和Cacna2d2的突变都会导致小鼠小脑出现自噬障碍。而且我们还发现CACNA1A定位于溶酶体上,溶酶体上的而不是细胞膜上的CACNA1A的钙离子通道活性是溶酶体与内涵体及自噬体发生融合所必需的。综上,我们提出了一个模型,在神经细胞中,VGCC在溶酶体膜上通过钙离子通道活性来促进溶酶体与自噬体的融合,从而调节细胞自噬,在维持神经元稳态平衡中发挥重要作用。
[Abstract]:Autophagy maintains the homeostasis of the cell by preventing the accumulation of harmful substances through lysosome mediated degradation system, which is a highly conserved evolutionary cellular biological process.In a large scale forward genetic screening designed to produce mutations in the nervous system, we got seven mutants of the cacophonycaca gene whose photoreceptor terminals gradually accumulated a lot of autophagy over time.It also resulted in the degenerative changes of neuronal terminals and peripheral glial cells. CAC encodes the 伪 1 subunit of VGCCs necessary for the fusion of synaptic vesicles with cell membranes and the release of neurotransmitters in Drosophila melanogaster.We found that a large number of fusion intermediates between lysosome and autophagy were accumulated in the terminal of photoreceptor neurons of cac mutation, suggesting that the fusion process between autophagy and lysosome may be hindered.The deletion of the gene encoding another subunit of VGCC, stj, was similar to that of the cac mutation, suggesting that the whole VGCC was involved in regulating the fusion between autophagy and lysosome.At the same time, we found that the regulation of VGCC on autophagy in the nervous system is highly conserved, because the mutations of the homologous genes Cacnala and Cacna2d2 of cac and stj in mice lead to autophagy disorder in the cerebellum of mice.We also found that CACNA1A is located on lysosome and that the calcium channel activity of lysosome rather than CACNA1A on cell membrane is necessary for the fusion of lysosome with connoisome and autophagy.In conclusion, we present a model in which VGCC promotes the fusion of lysosome and autophagy through calcium channel activity on lysosomal membrane, which regulates autophagy and plays an important role in maintaining the homeostasis of neurons.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：R741

【共引文献】