Regulation of stem cell identity by miR-200a during 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. In this paper we show that miR-200a acts to repress expression of Brachyury in sox2 positive progenitor cells in the axoltol spinal cord after spinal cord injury but after tail amputation when multiple tissue types must be regenerated then mir-200a is downregualted allowing progenitor cells in the spinal cord to naturally become bipotent progenitors which can give rise to muscle and neural cell types. When miR-200a is inhibited after spinal cord injury then these cells also express BRachyury cna can form muscle. Overall design: 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.