DROSOPHILA MELANOGASTER IMAGINAL DISC MODEL TO IDENTIFY AND DETERMINE THE REGENERATION POTENTIAL OF NOVEL NOTOPHTHALMUS VIRIDESCENS (RED-SPOTTED NEWT) GENES.

Notophthalmus viridescens possess amazing capabilities to regenerate their organs but molecular-genetic mechanism driving regeneration have been hindered due to lack of genetic tools. However, Drosophila imaginal discs, the primordia for adult fly structures, exhibit stem cell like potency and serve as powerful genetic tools to address fundamental problems in regeneration. Using this system, we demonstrated the regenerative role of 5 novel newt proteins. These proteins, having new sequence motifs, have no counterparts in public databases, were identified by denovo assembly of newt transcriptome combined with proteomic validation. Using transgenic approach these genes were misexpressed in Drosophila, and RNA seq was performed on mRNA sample from third instar larva. Gene ontology terms related to development, apoptosis and cell cycle were highly enriched in the group of differentially regulated Drosophila transcripts. To determine their regenerative potential, we misexpressed candidate genes in the early eye mutant background. Surprisingly, these genes exhibit robust potential to replace missing tissues by inducing compensatory proliferation and blocking cell death. Mitotic index fold change being 6 ± 1.5, and frequency of phenotype rescue was 70%. Using Retinal determination (RD) gene expression we demonstrated that rescued mutant undergo proper differentiation. We found highly conserved Wingless/Wnt, and Jun-N-terminal kinase (JNK) signaling pathway components were downregulated to promote rescue in the domain where candidate genes were misexpressed. These pathways have been implicated in tissue regeneration in Drosophila. We further wanted to test if candidate genes can globally trigger regeneration in all tissues, and to address this question we used an established model for regeneration in wing imaginal disc. Our preliminary data from this model demonstrates that regeneration potential of candidate genes is not confined to the type of tissue or developmental stage. We therefore have identified a novel component of regeneration tool kit in newt that can trigger regeneration response in other organisms by employing highly conserved signaling pathways. In future, these studies can have a significant bearing in the field of tissue repair and maintenance. Keywords: Candidate genes, Newts, Drosophila, Regeneration, Imaginal Discs