Explore the vast range of titles available.

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 α -adrenergic receptor, and local regeneration responses via β-adrenergic receptors. Both α - and β-adrenergic signaling act upstream of mTOR signaling. Notably, systemically-activated axolotls regenerate limbs faster than naïve 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.

Previous studies have reported that amputation invokes body-wide responses in regenerative organisms, but most have not examined the implications of these changes beyond the region of tissue regrowth. Specifically, long-range epidermal responses to amputation are largely uncharacterized, with research on amputation-induced epidermal responses in regenerative organisms traditionally being restricted to the wound site. Here, we investigate the effect of amputation on long-range epidermal permeability in two evolutionarily distant, regenerative organisms: axolotls and planarians. We find that amputation triggers a long-range increase in epidermal permeability in axolotls, accompanied by a long-range epidermal downregulation in MAPK signaling. Additionally, we provide functional evidence that pharmacologically inhibiting MAPK signaling in regenerating planarians increases long-range epidermal permeability. These findings advance our knowledge of body-wide changes due to amputation in regenerative organisms and warrant further study on whether epidermal permeability dysregulation in the context of amputation may lead to pathology in both regenerative and non-regenerative organisms.

Salamanders are capable of regenerating whole limbs throughout life, a feat that is unmatched within tetrapods. Limb regeneration is dependent upon the formation of a blastema, which contains undifferentiated cells capable of giving rise to most cells of the regenerated limb. Innervation is required for regeneration, along with many signaling pathways, including FGF, BMP and Wnt, but the role of VEGF signaling during salamander limb regeneration is not well understood. Here we show that VEGF signaling is essential for limb regeneration and that blastema cells and limb fibroblasts display impaired proliferation in the absence of VEGF signaling. By performing analogous experiments in planaria, which lack vasculature, we show a potential evolutionarily conserved role for VEGF in the expansion of blastema tissues that is separable from angiogenesis. Moreover, loss of VEGF signaling reduces induction of EMT-like processes, suggesting VEGF signaling functions upstream of the expression of EMT transcription factors, including Snai2. These findings highlight potential roles for VEGF signaling during regeneration which may extend beyond typical findings related to angiogenesis.