Scientists at Arizona State University (ASU) have discovered the cocktail of genes that facilitate tail regeneration in lizards. With further research, it may eventually be possible to target the pathways identified in human cells in order to regenerate various tissues in patients with injuries or birth defects. The study has been published in PLOS ONE.
The ability of certain vertebrates to regrow lost appendages has intrigued scientists for years. Zebrafish can regenerate their caudal fins and salamanders can regrow both limbs and tails. Perhaps the most interesting example is the lizard which can self-amputate its tail in response to threat and grow a new one. Humans are a little more inadequate in this department, but researchers believe that understanding the process in other organisms could one day help us develop techniques to regenerate human tissue.
While previous research has revealed the genes at play in this regenerative process in zebrafish and salamanders, these are anamniote species (lack an embryonic membrane called an amnion), whereas lizards are amniotes and are thus are evolutionarily more closely related to humans. Findings from these animals may therefore be easier to translate into human therapies.
In order to unlock the secrets of lizard tail regeneration, ASU scientists turned to the green anole lizard (Anolis carolinensis). They applied pressure to the tails of several lizards until they were released and then sequenced various tissues, including cells of the regenerating tail, in order to identify the genes involved in the regeneration process.
They identified 326 genes at play that activated numerous developmental and repair pathways. More specifically, they found that genes involved in wound response, hormonal regulation and musculoskeletal development were expressed along the regenerating tail.
Interestingly, they also found some differences between lizards and the anamniotes. When the latter regenerate their tails, growth mostly occurs at the tip, but in lizards the researchers observed several different types of cell proliferating along the tail. Both, however, seem to switch on genes involved in a pathway called Wnt. This pathway controls stem cells in various organs such as the brain and blood vessels.
The discoveries are exciting because one day, it may be possible to target the pathways activated in human cells in order to regenerate damaged tissue. “By following the genetic recipe for regeneration that is found in lizards, and then harnessing those same genes in human cells, it may be possible to regrow new cartilage, muscle or even spinal cord in the future,” study author Jeanne Wilson-Rawls said in a news-release. If successful, this could possibly lead to the development of novel ways to treat spinal cord injuries, certain birth defects or diseases such as arthritis.
[Header image "Anole," by Theodore Scott, via Flickr, used in accordance with CC BY 2.0]