Differential Expression of Genes Between Dorsal and Ventral Iris Undergoing Lens Regeneration in Notophthalmus viridescens Revealed by Next Generation RNA Sequencing

Notophthalmus viridescens, the red-spotted newt, shows great regenerate capabilities. They can regenerate their limbs, heart, tail and eye parts. Noteworthy, the eye lens can be regenerated after complete removal (lentectomy) from the dorsal iris. Thus, lens regeneration involves the change of iris cells to lens cells, a process called transdifferentiation. Ventral iris does not participate in the process and can serve as natural negative control. In order to study what genes are expressed during this remarkable process, we utilized high-throughput RNA-sequencing, a method that gives mRNA sequence information and corresponding expression in the tested samples. We used dorsal and ventral iris 4 and 8 days post-lentectomy, two major time points for cell cycle re-entry and dedifferentiation, respectively. Differential expression of more than 38,000 annotated genes was studied between dorsal and ventral iris at both these time points. Highly differentially expressed genes in the dorsal or ventral iris were validated using quantitative real-time polymerase chain reaction. Those genes were TBX5, UNC5B and FGF10 in the dorsal iris and VAX2, NTN1 and NR2F5 in the ventral iris. Genes up-regulated in dorsal or ventral iris were grouped based on gene ontology terms (GO) and fisher\u27s exact test was used to determine over-represented GO in the dorsal or ventral iris. We found that GO related to gene regulation, cytoskeleton, cell cycle and immune response were enriched in the dorsal iris, whereas GO related to transposons were enriched in the ventral iris. This study showed differences between dorsal and ventral iris which account for dorsal iris\u27 ability to regenerate the lens. In addition, we found markers that specify dorsal or ventral iris. Based on this valuable resource, functional future studies can elucidate the mechanism of lens regeneration which can shed light to potential therapeutic applications to higher vertebrates and eventually to humans.https://ecommons.udayton.edu/stander_posters/1349/thumbnail.jp