グリアによる神経軸索機能の調節

Functional roles of glial cells on reorganization of myelinated axons

髄鞘形成に伴って有髄神経軸索表面は大きく変化し，ランビエ絞輪，パラノード，ジャクスタパラノード，インターノードの4つの機能ドメインに分かれる。それぞれの部位には活動電位発生に重要なイオンチャネル，あるいは接着分子などの機能タンパク質が特徴的な集積を示す。このような機能ドメインの形成にはニューロンとグリア間のクロストークが関与し，脱髄や軸索-髄鞘間のジャンクションの障害によって変化する。また，後者の場合脱髄は生じないが，軸索変化と一致して，その周囲のアストロサイトの活性化が生じる。したがって，これらのグリアの役割を明らかにすることが，正常な神経機能および脱髄などに伴う軸索障害の治療を考える上で重要である。

Surface of the myelinated axons are divided into four discrete functional regions, the node of Ranvier, paranode, juxtaparanode, and internode. At paranodal regions, paranodal junctions are formed between axon and myelinating glia. Each region is characterized by specific localization of axonal proteins, including voltage-gated ion channels as well as adhesion molecules and adaptor proteins to cytoskeltons. Such specificity is strictly controlled by neuron-glial interaction. Both in demyelination and disruption of paranodal axo-glial junction, such functional domain structures are altered, and neurological deficits occur in animals. Moreover, although demyelination does not occur in the latter condition, activation of astrocytes around the axons becomes prominent in parallel to the progressive changes of axonal channel localization. Thus, it is important to understand the functional roles of these glial cells in reorganizaion of axonal proteins for developing novel therapies against demyelinating diseases.