Visualization of peripheral nerves in developing and regenerating limbs using a novel peripherin reporter line of <i>Xenopus laevis</i>

Peripherin (PRPH) is a class III intermediate filament protein expressed in peripheral nerves and upregulated during axon outgrowth and regeneration. In this study, we developed a transgenic Xenopus laevis line for long-term in vivo visualization of the peripheral nervous system. Deletion and motif analyses identified cis-regulatory regions within the promoter and intron 1 that are important for neuronal expression of the X. laevis prph gene. Stable lines exhibited robust EGFP reporter activity in developing neural primordia in embryos and in the peripheral nerves of tadpoles. Transgenic tadpoles enabled in vivo imaging of peripheral nerves throughout limb development. During larval limb regeneration, we observed modest early nerve entry into the blastema, recapitulating that seen in early limb development. In contrast, post-metamorphic limb blastemas displayed extensive innervation from the early phase of regeneration. Moreover, increased reporter activity in the nerves of the regenerating adult forelimb suggests regeneration-associated regulation of peripheral innervation and its potential role in blastema formation. This transgenic line will serve as a versatile tool for analyzing such large-scale neural remodeling across development, metamorphosis, and regeneration.