Scientists have worked out the genetic ‘recipe’ that lets lizards regrow their tails

Researchers have discovered the genes that prompt tail regeneration in lizards, which takes them a step closer to understanding how to stimulate regeneration in humans

When lizards are caught by predators, they can drop their tails to escape and then grow the appendage back. Scientists have studied this regeneration process for decades, in the hopes of understanding how to regenerate human tissues, such as damaged spinal chords and even lost limbs. 

Now a team of scientists from Arizona State University in the US has performed the first analysis of all RNA molecules, which translate genes into proteins, during the tail regeneration of a green anole lizard  (Anolis carolinensis), and worked out the genetic “recipe” that controls the regrowth process. Their results have been published in PLOS ONE.

"Using next-generation technologies to sequence all the genes expressed during regeneration, we have unlocked the mystery of what genes are needed to regrow the lizard tail,” said lead author Kenro Kusumi in a press release.

“Lizards are the most closely-related animals to humans that can regenerate entire appendages. We discovered that they turn on at least 326 genes in specific regions of the regenerating tail, including genes involved in embryonic development, response to hormonal signals and wound healing."

Interestingly, 302 of those 326 genes have already had homologues (similar genes) identified in mammalian DNA.

The scientists also found that tail regeneration in lizards involves genetic activity along the entire tail, not just at the tip, which is the case for other animals with regenerative abilities, such as salamanders and zebrafish. 

"Regeneration is not an instant process," said Elizabeth Hutchins, a co-author of the paper. "In fact, it takes lizards more than 60 days to regenerate a functional tail. Lizards form a complex regenerating structure with cells growing into tissues at a number of sites along the tail.”

For the first 10 days, the lizard’s tail heals similarly to any other wound—new blood vessels form, and epithelial tissue (the soft, white skin under a scab) closes the gap over raw flesh. Then the tail starts to regrow, beginning with nerve tissue from the spinal cord (days 10-15), soft muscle, and tissue for transporting fluids. By day 20, the muscular tissue is starting to firm up around a cartilaginous tube that will eventually harden, and segment into tail bones.” 

This research is a big step forward for scientists hoping to use the abilities of lizards to improve therapeutic options for humans.

“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,” said Kusumi.