Role of radial fibers in controlling the onset of myelination

Jin Nakahara, Masaaki Takemura, Hiroshi Gomi, Ken ichiro Tsunematsu, Shigeyoshi Itohara, Hiroaki Asou, Masaharu Ogawa, Sadakazu Aiso, Kyoko Tan-Takeuchi

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17 Citations (Scopus)

Abstract

Recent in vitro study showed that astrocytes induce oli-godendrocyte 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.

Original languageEnglish
Pages (from-to)279-289
Number of pages11
JournalJournal of Neuroscience Research
Volume72
Issue number3
DOIs
Publication statusPublished - 2003 May 1

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Keywords

  • Axon
  • GFAP-deficient mouse
  • Myelination
  • Oligodendrocyte
  • Radial fibers

ASJC Scopus subject areas

  • Cellular and Molecular Neuroscience

Cite this

Nakahara, J., Takemura, M., Gomi, H., Tsunematsu, K. I., Itohara, S., Asou, H., Ogawa, M., Aiso, S., & Tan-Takeuchi, K. (2003). Role of radial fibers in controlling the onset of myelination. Journal of Neuroscience Research, 72(3), 279-289. https://doi.org/10.1002/jnr.10593