AP-1cFos/JunB/miR-200a regulate the pro-regenerative glial cell response during axolotl spinal cord regeneration

Salamanders have the remarkable ability to functionally regenerate after spinal cord transection. In response to injury, GFAP+ glial cells in the axolotl spinal cord proliferate and migrate to replace the missing neural tube and create a permissive environment for axon regeneration. Molecular pathways that regulate the pro-regenerative axolotl glial cell response are poorly understood. Here we show axolotl glial cells up-regulate AP-1cFos/JunB after injury, which promotes a pro-regenerative glial cell response. Axolotl glial cells directly repress c-Jun expression via up-regulation of miR-200a. Inhibition of miR-200a during regeneration causes defects in axonal regrowth and transcriptomic analysis revealed that miR-200a inhibition leads to differential regulation of genes involved with reactive gliosis, the glial scar, ECM remodeling and axon guidance. This work identifies a novel role for miR-200a in inhibiting reactive gliosis in glial cell in axolotl during spinal cord regeneration All axolotls used in these experiments were bred in the axolotl facility at the University of Minnesota or at the MBL under the IACUC protocols #1710-35242A, #18-49. Axolotls of 2–3 cm were used for all in vivo experiments, and animals were kept in separate containers and fed daily with artemia; water was changed daily. Animals were anesthetized in 0.01% p-amino benzocaine (Sigma) before microinjection was performed.