Experts at Karolinska Institutet have led to sequence the large genome of a salamander, the Iberian ribbed newt, which is an entire six instances higher than the human genome. Amongst the early findings is a family of genes that can supply clues to the unique means of salamanders to rebuild advanced tissue, even overall body areas. The study is published in Nature Communications. This is the first time that an entirely new genome has been sequenced, an accomplishment that can give rise to discoveries on the amphibian’s ability to recreate brain neurons as well as whole body parts. Amongst the first findings are a multitude of copies of a particular microRNA group, which in animals is mainly found in embryonic stem cells, but also in tumour cells.
“It will be overwhelming to figure out how regeneration in the adult organism re-activates embryonic genes,” states study leader Professor András Simon at Karolinska Institutet’s Department of Cell and Molecular Biology. “What’s required now are functional studies of these microRNA molecules to learn their function in regeneration. The link to cancer cells is also fascinating, especially bearing in mind newts’ marked resistance to tumour formation.”
One of the causes, why salamander genomes have not been sequenced before, is its sheer size six times larger than the human genome in the state of the Iberian newt, which has created a vast technical and methodological difficulty. “It is only now that the technology is available to manage such a huge genome,” states Professor Simon. “The sequencing per se doesn’t take that long – it’s recreating the genome from the sequences that are so time-consuming.”
Even though the plenty of stem cell microRNA genes is quite surprising, it alone cannot describe how salamanders revive so well. Professor Simon foretells that the answer lies in a combination of genes unique to salamanders and how other more common genes orchestrate and control the actual regeneration process.
“We showed ten years ago that salamanders could recreate all the cells that die in Parkinson’s disease in the space of four weeks,” tells Professor Simon. “We can now delve deeper into the molecular methods underlying this ability. Although we’re doing basic analysis, our findings can hopefully lead to the development of new regenerative strategies for humans.”
The sequencing project was led in collaboration with SciLifeLab and Uppsala University and was financed mainly with grants from the Swedish Research Council, the National Institutes of Health, the European Research Council, the Swedish Cancer Society and the Wenner-Gren Foundation.