Novel Newt Regeneration Genes Regulate Wingless Signaling to Restore Patterning in <i>Drosophila</i> Eye

Abstract

A fundamental process of regeneration, which varies among animals, recruits conserved signaling pathways to restore missing parts. Only a few animals like newts can repeatedly regenerate lost body parts throughout their lifespan that can be attributed to strategic regulation of conserved signaling pathways by newt’s regeneration tool-kit genes. Lack of genetic tools pose challenges to understand the molecular genetic mechanism of regeneration response of these genes. Here we report use of genetically tractable Drosophila eye model to demonstrate the regeneration potential of a group of unique protein(s) from newt (Notophthalmus viridescens), which when ectopically expressed can significantly rescue missing photoreceptor cells in a Drosophila eye mutant. These newt proteins with signal peptides motifs exhibit non-cell-autonomous rescue properties and their regeneration potential even extends into later stages of fly development. Ectopic expression of these newt genes can rescue eye mutant phenotype by promoting cell proliferation and blocking cell death. These novel newt genes downregulate evolutionarily conserved Wingless (Wg)/Wnt signaling pathway to promote rescue. Modulation of Wg/Wnt signaling levels by using antagonists or agonists of Wg/Wnt signaling pathway in eye mutant background where newt gene(s) is ectopically expressed suggests that Wg signaling acts downstream of newt genes. Our data highlights the regeneration potential of novel newt proteins that regulate conserved pathways to trigger a robust regeneration response in Drosophila model with weak regeneration capability.