Schwann cells selectively myelinate primary motor axons via neuregulin-ErbB signaling

Dong Won Lee, Eunmi Kim, Inyoung Jeong, Hwan Ki Kim, Suhyun Kim, Hae Chul Park

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


Spinal motor neurons project their axons out of the spinal cord via the motor exit point (MEP) and regulate their target muscle fibers for diverse behaviors. Several populations of glial cells including Schwann cells, MEP glia, and perineurial glia are tightly associated with spinal motor axons in nerve fascicles. Zebrafish have two types of spinal motor neurons, primary motor neurons (PMNs) and secondary motor neurons (SMNs). PMNs are implicated in the rapid response, whereas SMNs are implicated in normal and slow movements. However, the precise mechanisms mediating the distinct functions of PMNs and SMNs in zebrafish are unclear. In this study, we found that PMNs were myelinated by MEP glia and Schwann cells, whereas SMNs remained unmyelinated at the examined stages. Immunohistochemical analysis revealed that myelinated PMNs solely innervated fast muscle through a distributed neuromuscular junction (NMJ), whereas unmyelinated SMNs innervated both fast and slow muscle through distributed and myoseptal NMJs, respectively, indicating that myelinated PMNs could provide rapid responses for startle and escape movements, while unmyelinated SMNs regulated normal, slow movement. Further, we demonstrate that neuregulin 1 (Nrg1) type III-ErbB signaling provides a key instructive signal that determines the myelination of primary motor axons by MEP glia and Schwann cells. Perineurial glia ensheathed unmyelinated secondary motor axons and myelinated primary motor nerves. Ensheathment required interaction with both MEP glia and Schwann cells. Collectively, these data suggest that primary and secondary motor neurons contribute to the regulation of movement in zebrafish with distinct patterns of myelination.

Original languageEnglish
Pages (from-to)2585-2600
Number of pages16
Issue number12
Publication statusPublished - 2020 Dec 1


  • MEP glia
  • Nrg1 type III
  • Schwann cells
  • myelination
  • perineurial glia
  • spinal motor axon
  • zebrafish

ASJC Scopus subject areas

  • Neurology
  • Cellular and Molecular Neuroscience


Dive into the research topics of 'Schwann cells selectively myelinate primary motor axons via neuregulin-ErbB signaling'. Together they form a unique fingerprint.

Cite this