Model systems for regeneration: Xenopus.

Understanding how to promote organ and appendage regeneration is a key goal of regenerative medicine. The frog, Xenopus, can achieve both scar-free healing and tissue regeneration during its larval stages, although it predominantly loses these abilities during metamorphosis and adulthood. This transient regenerative capacity, alongside their close evolutionary relationship with humans, makes Xenopus an attractive model to uncover the mechanisms underlying functional regeneration. Here, we present an overview of Xenopus as a key model organism for regeneration research and highlight how studies of Xenopus have led to new insights into the mechanisms governing regeneration.

Foxm1 regulates neural progenitor fate during spinal cord regeneration.

Xenopus tadpoles have the ability to regenerate their tails upon amputation. Although some of the molecular and cellular mechanisms that globally regulate tail regeneration have been characterised, tissue-specific response to injury remains poorly understood. Using a combination of bulk and single-cell RNA sequencing on isolated spinal cords before and after amputation, we identify a number of genes specifically expressed in the spinal cord during regeneration. We show that Foxm1, a transcription factor known to promote proliferation, is essential for spinal cord regeneration. Surprisingly, Foxm1 does not control the cell cycle length of neural progenitors but regulates their fate after division. In foxm1-/- tadpoles, we observe a reduction in the number of neurons in the regenerating spinal cord, suggesting that neuronal differentiation is necessary for the regenerative process. Altogether, our data uncover a spinal cord-specific response to injury and reveal a new role for neuronal differentiation during regeneration.