RNA-Seq Analysis of the Regenerating Tail in the Green Anole Lizard

Lizards can lose their tails and regrow a functional replacement, which is a unique feature among amniote vertebrates. These regenerated tails include newly formed hyaline cartilage, spinal cord, muscle, vasculature, and skin. Progress in studying the cellular and molecular mechanisms of lizard regeneration has been previously limited by lack of genomic resources. However, the recently published genome of the green anole, Anolis carolinensis, and our RNA-Seq deep transcriptome-based gene annotation of this genome provide the basis for transcriptomic analysis of the cells and pathways activated in lizard tail regeneration. Using Illumina RNA-Seq technology, we have identified over 300 differentially expressed (DE) genes along the proximal/distal axis of the regenerating tail at a mid-growth stage (n=5). DE genes with high expression towards the proximal regenerating tail include myogenic regulators, with enriched Gene Ontology (GO) terms representative of muscle structure and differentiation. DE genes in the regenerating tail tip represent a number of developmental processes, with enriched GO terms representative of wound and inflammatory response, hormonal and homeostatic regulation, and skeletal system development. We have also compared the expression of the regenerating tail to two proliferative and stem-cell rich lizard tissues: early stage embryos, and a purified adult muscle satellite cell population capable of differentiating into skeletal muscle. These studies have identified components of a genetic program for regeneration in the lizard that includes both developmental and adult repair mechanisms, indicating value in the translation of these findings to future regenerative therapies. Acknowledgements: NIH NCRR/ORIP Grant R21RR031305 and Arizona Biomedical Research Commission.