1996 Fiscal Year Final Research Report Summary
The significance of phosphorylation of neurofilament protein
| Project/Area Number |
06680738
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Nerve anatomy/Neuropathology
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| Research Institution | Osaka University |
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Principal Investigator |
GOTOW Takahiro Osaka University Medical School, Lecturer, 医学部, 講師 (20135693)
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| Co-Investigator(Kenkyū-buntansha) |
TAKEDA Masatoshi Osaka University Medical School, Professor, 医学部, 教授 (00179649)
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| Project Period (FY) |
1994 – 1996
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| Keywords | Neurofilament / NF-H / phosphorylation / axon / node of Ranvier / crossbridge / myelin sheath / nonphosphorylation |
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| Research Abstract |
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
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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
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