The role of neurofilament and mitochondria in the neuronal cell death

我们分析了神经细胞变性或凋亡时，神经丝和线粒体在生化和形态学上的变化，以及这些细胞器与神经细胞这种变化的关系。我们使用的神经元来自jimpy和shiverer突变小鼠，人类神经退行性疾病的模型动物，以及NF-H LacZ基因转染并分化的PC12细胞的小鼠。在中枢轴突发育异常的神经病小鼠中，与野生型对照小鼠相比，轴突内的NFs数量更多、更不规则、更少交叉。NF-H和NF-M mrna在关节中表达非常高，更重要的是，大多数轴突增加的NF-H，也可能是本研究未检测的NF-M，是非磷酸化的。因此，由于髓鞘的缺失，可能是由于NF蛋白的异常表达和磷酸化程度导致了神经轴突内NF的紊乱。在线粒体分布方面，NF- h - LacZ基因转染小鼠在NF几乎缺乏的细轴突中发现了大范围扩大的线粒体，而在老龄小鼠中发现了较少数量的NF轴突。NF-HlacZ转染小鼠后，这些大粒线粒体中Bcl-2蛋白的数量出现增加，这可能阻止了由于泡状结构异常积聚导致的轴突变性，这种变性表现为运输机制受损。这些小鼠的骨骼细胞没有功能变化，这一事实也支持了这一观点，这表明这些线粒体以及NF蛋白（尤其是NF- h）的缺乏抵抗了轴突变性。在血清剥夺导致凋亡改变的分化PC12细胞中，线粒体中的Bcl-2进入细胞质和/或光滑内质网，更重要的是，从线粒体内膜进入外膜。综上所述，当神经元细胞变性或死亡时，nf组织紊乱，线粒体内膜缺乏Bcl-2。少

We analyzed how neurofilament and mitochondria were altered biochemically as well as morphologically when neuronal cells were degenerated or showed apoptosis, and also how these organelles are associated with such changes of neuronal cells. We used neurons from jimpy and shiverer mutant mice, the model animals for human neurodegenerative diseases, and mice in which NF-H LacZ gene in transfected, and differentiated PC12 cells. In the jimpy mice, in which central axons were dysmyelinated, NFs in the axons were more numerous and irregular and less crossbridged than those in the wild-type control mice. NF-H and NF-M mRNAs were expressed much highly in the jimpy, and more importantly, most increased-axonal NF-H, and also probably NF-M that was not examined in this study, was nonphosphorylated. Thus, because of the absence of the myelin sheath, the disorganized NFs in jimpy axons may be brought about by such abnormal expression and Phosphorylation degree of NF proteins. Concerning the mitoch … More ondria, we found large-expanded mitochondria in NF almost-deficient thin axons of NF-H LacZ gene transfected mice and less-numerous-NF axons in old shiverer mice. Bcl-2 protein in these large-sized mitochondria in the NF-HlacZ transfected mice appeared to increase in amount, which may arrest axonal degeneration shown by impairment of the transport mechanism due to the abnormal accumulation of vesicular structures. This was also supported by the fact that there was no functional change in skeletal cells in these mice, suggesting these mitochondria as well as absence of NF proteins, especially of NF-H, resist the axonal degeneration. In the differentiated PC12 cells, which showed apoptotic change by serum deprivation, Bcl-2 in their mitochondria moved into cytoplasm and/or smooth endoplasmic reticulum, and more importantly, from inner mitochondrial membranes to the outer membranes. In conclusion, when the neuronal cells are degenerating or dying, NFs are disorganized and mitochondria lack Bcl-2 in their inner membranes. Less