The significance of phosphorylation of neurofilament protein

在神经元中，神经丝（NF）在胞体和树突中相对较少，但在轴突中丰富。除了这种NF极性外，NF亚基蛋白，尤其是NF-H，在轴突中高度磷酸化，而在胞体和树突中磷酸化少得多。NF-H是核心丝之间形成横桥所必需的，我们认为它的磷酸化似乎是形成发育良好的横桥所必需的。为了证实我们的想法，我们在这三年中获得了五个关于NF-H磷酸化和NF组织之间关系的主要结果。1).核心丝和横桥的安排和NF-H是在较厚的有髓轴突磷酸化，而他们不太规则，磷酸化程度较低，在较薄的轴突微管是显眼的。2）在轴突直径变小的Ranvier结中，核心神经元相互靠近，横桥不规则，NF-H磷酸化程度低于对照组。 ...更多信息 同一轴突的剩余部分。3).将NF-H蛋白微量注射到培养的非神经元或神经元样细胞中，NF-H磷酸化后可形成中间纤维，并倾向于在横桥中以较高频率形成纤维束。4）.体外实验表明NF可以通过NF-H形成的横桥与微管或线粒体相互作用，尽管我们现在正在研究NF-H磷酸化的哪种条件对于这种相互作用更有效。（5）目前，我们正在用中枢神经系统髓鞘形成中断的jimpy mutanat小鼠研究髓鞘形成与NF的组织化和NF-H磷酸化之间的关系。刚刚发现，非磷酸化形式的NF-H急剧增加，并且在髓鞘缺乏的轴突中的核心丝比对照组中更紧凑。总之，我们的数据表明，有一个密切的关系NF-H磷酸化和NF的组织，也是必要的轴突有规则的安排，在横桥，并最终在核心丝的NF-H磷酸化。此外，认为髓鞘形成增加了NF-H磷酸化水平，导致轴突中正常的NF形成。少

In neurons, neurofilaments (NF) are relatively fewer in somata and dendrites but abundant in axons. In addition to this NFpolarity, the NF subunit protein, especially NF-H,is extremely phosphorylated in axons, and much less phosphorylated in somata and dendrites. NF-H is essential for forming crossbridges between core filaments, and we are thinking that its phosphorylation seems necessary to form well-developed crossbridges. To confirm our idea, we have obtained five main results on the relationship between NF-H phosphorylation and NF organization during these three years. 1).Both core filaments and crossbridges were regular in arrangement and NF-H was well phosphorylated in thicker myelinated axons, whereas they were less regular and less phosphorylated in thinner axons where microtubules were conspicuous. 2).In the node of Ranvier, where axon becomes smaller in diameter, core filametns were closer to each other and crossbridges were less regular and NF-H wa less phosphorylated than t … More he remainder of the same axon. 3).After microinjection of NF-H protein into cultured nonneuronal or neuron-like cells, NF-H was incorported into intermediate filaments and tended to make bundles of the filaments with rather higher frequency in crossbridges when it was phosphorylated. 4).In vitro experiments showed that NF could interact with microtubules or mitochondria through the crossbridges formed by NF-H,although we are now examining which condition in phosphorylation of NF-H is more efficient for such interactions. 5).At present, we are clarifying the relationship between the myelination and NF organization or NF-H phosphorylation with jimpy mutanat mice, where the myelinogenesis is distrupted in the central nervous system. It has just been found that nonphosphorylated form of NF-H increases drastically and core filaments are much more compact in the myelin-deficient axons than in controls. In conclusion, our data indicate that there is an intimate relationship between NF-H phosphorylation and NF organization, and also that it is necessary for the axon to have regular arrangements in crossbridges and finally in core filaments by NF-H phosphorylation. Furthermore, it is considered that the myelination increases in NF-H phosphorylation level resulting in normal NF oganization in axons. Less