Understanding how salamanders grow new limbs provides insights into the potential of human regenerative medicine

By studying a real lizard-like amphibian, which can regenerate missing limbs, the Salk researchers discovered that it isn’t enough to activate genes that kick start the regenerative process. In fact, one of the first steps is to halt the activity of so-called jumping genes.

In research published August 23 in Development, Growth & Differentiation, and July 27 in Developmental Biology, the researchers show that in the Mexican axolotl, jumping genes have to be shackled or they might move around in the genomes of cells in the tissue destined to become a new limb, and disrupt the process of regeneration.

They found that two proteins, piwi-like 1 (PL1) and piwi-like 2 (PL2), perform the job of quieting down jumping genes in this immature tadpole-like form of a salamander, known as an axolotl - a creature whose name means water monster and who can regenerate everything from parts of its brain to eyes, spinal cord, and tail.

"What our work suggests is that jumping genes would be an issue in any situation where you wanted to turn on regeneration," says the studies’ senior author, Tony Hunter, a professor in the Molecular and Cell Biology Laboratory and director of the Salk Institute Cancer Center.