Sortilin Modulates Schwann Cell Signaling and Remak Bundle Regeneration Following Nerve Injury

Maj Ulrichsen*, Nadia P. Conclaves, Simin Mohseni, Simone Hjæresen, Thomas L. Lisle, Simon Molgaard, Niels K. Madsen, Olav M. Andersen, Åsa Fex Svenningsen, Simon Glerup, Anders Nykjær, Christian B. Vægter*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

Peripheral nerve regeneration relies on the ability of Schwann cells to support the regrowth of damaged axons. Schwann cells re-differentiate when reestablishing contact with the sprouting axons, with large fibers becoming remyelinated and small nociceptive fibers ensheathed and collected into Remak bundles. We have previously described how the receptor sortilin facilitates neurotrophin signaling in peripheral neurons via regulated trafficking of Trk receptors. This study aims to characterize the effects of sortilin deletion on nerve regeneration following sciatic crush injury. We found that Sort1–/– mice displayed functional motor recovery like that of WT mice, with no detectable differences in relation to nerve conduction velocities and morphological aspects of myelinated fibers. In contrast, we found abnormal ensheathment of regenerated C-fibers in injured Sort1–/– mice, demonstrating a role of sortilin for Remak bundle formation following injury. Further studies on Schwann cell signaling pathways showed a significant reduction of MAPK/ERK, RSK, and CREB phosphorylation in Sort1–/– Schwann cells after stimulation with neurotrophin-3 (NT-3), while Schwann cell migration and myelination remained unaffected. In conclusion, our results demonstrate that loss of sortilin blunts NT-3 signaling in Schwann cells which might contribute to the impaired Remak bundle regeneration after sciatic nerve injury.
Original languageEnglish
Article number856734
JournalFrontiers in Cellular Neuroscience
Volume16
Number of pages15
ISSN1662-5102
DOIs
Publication statusPublished - 11. May 2022

Keywords

  • nerve injury
  • NT-3
  • Trk C
  • Sortilin
  • Schwann cell
  • Remak bundle

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