Nerve-mediated amputation-induced stem cell activation primes distant appendages for future regeneration events in axolotl
Many species regenerate lost body parts following amputation. Most limb regeneration research has focused on the immediate injury site. Meanwhile, body-wide injury responses remain largely unexplored but may be critical for regeneration. Here, we discovered a role for the sympathetic nervous system in stimulating a body-wide stem cell activation response to amputation that drives enhanced limb regeneration in axolotls. This response is mediated by adrenergic signaling, which coordinates distant cellular activation responses via the 2A-adrenergic receptor, and local regeneration responses via {beta}-adrenergic receptors. Both 2A- and {beta}-adrenergic signaling act upstream of mTOR signaling. Notably, systemically-activated axolotls regenerate limbs faster than naive animals, suggesting a potential selective advantage in environments where injury from cannibalism or predation is common. This work challenges the predominant view that cellular responses underlying regeneration are confined to the injury site and argues instead for body-wide cellular priming as a foundational step that enables localized tissue regrowth.