Role of radial fibers in controlling the onset of myelination
Role of radial fibers in controlling the onset of myelination
复制标题
径向纤维在控制髓鞘形成中的作用
DOI：
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发表时间：
2003
影响因子：
4.2
通讯作者：
K. Tan‐Takeuchi
中科院分区：
文献类型：
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作者：
J. Nakahara;M. Takemura;H. Gomi;Kenichiro Tsunematsu;S. Itohara;H. Asou;M. Ogawa;S. Aiso;K. Tan‐Takeuchi
最近的体外研究表明，星形胶质细胞诱导少突胶质细胞突起粘附到轴突上。然而，星形胶质细胞在体内髓鞘形成中的作用仍然未知。因此，我们进行了一项研究，以阐明星形胶质细胞在最初的髓鞘形成过程中可能的参与。在新生小鼠中，胶质纤维酸性蛋白（GFAP）（星形胶质细胞的标志物）的表达仅限于脑室下区（SVZ）的少数纤维结构，但我们没有观察到任何 GFAP 阳性星形胶质细胞。在髓鞘形成开始之前，GFAP 在从 SVZ 延伸到大脑皮层软脑膜的放射状纤维的细胞中短暂表达，髓磷脂相关糖蛋白（MAG）阳性的髓鞘形成前少突胶质细胞似乎与它们相邻，其突起附着在放射状纤维上，但不附着在轴突上。这些 GFAP 阳性“放射状”细胞在出生后约 10 天（髓鞘形成开始时）失去了纤维结构，并成为典型的 GFAP 阳性星形胶质细胞，表明放射状纤维的消失与髓鞘形成的开始相协调。从这些结果中，我们提出髓鞘形成前少突胶质细胞与放射状纤维而不是轴突接触，并且放射状纤维向星形胶质细胞的细胞结构转变基本上参与控制初始髓鞘化的开始。我们的建议得到了 GFAP 缺陷小鼠的进一步证实，其中这些径向纤维的消失和髓鞘形成的开始同时延迟。我们的研究结果表明，体内髓鞘形成与星形胶质细胞分化一致，涉及其中的放射状纤维，而不仅仅是轴突-少突胶质细胞的相互作用。 © 2003 Wiley-Liss, Inc.
Recent in vitro study showed that astrocytes induce oligodendrocyte processes to adhere to axons. However, the role of astrocytes in myelination in vivo remains unknown. We have, therefore, conducted a study to clarify the possible involvement of astrocytes during the initial myelination process. In newborn mice, the expression of glial fibrillary acidic protein (GFAP), a marker for astrocytes, was restricted to a few fibrous architectures in the subventricular zone (SVZ), but we did not observe any GFAP‐positive astrocytes. Prior to the onset of myelination, GFAP became transiently expressed in the cells with radial fibers elongating from the SVZ to the pia of cerebral cortex, and myelin‐associated glycoprotein (MAG)‐positive premyelinating oligodendrocytes appeared as neighbors to them, with the processes attaching to radial fibers, but not to axons. These GFAP‐positive “radial” cells lost their fibrous architecture and became typical GFAP‐positive astrocytes at about 10 days postnatally, when myelination set in, indicating that the disappearance of radial fibers coordinates with the initiation of myelination. From these results, we propose that premyelinating oligodendrocytes are in contact with radial fibers rather than axons and that the cytoarchitectural transformation of radial fibers into astrocytes is involved substantially in controlling the onset of initial myelination. Our proposal was further confirmed by GFAP‐deficient mice, in which the disappearance of these radial fibers and the initiation of myelination were delayed in parallel. Our findings together suggest that myelination in vivo is in concert with astrocytic differentiation, involving radial fibers therein, rather than being a mere axon–oligodendrocyte interaction. © 2003 Wiley‐Liss, Inc.