Far back in history, scientists believe that a common ancestor of humans and other animals had the ability to regenerate damaged body parts. But of course we don’t have that ability today, so what happened?
Well for some creatures like salamanders or zebrafish, reproducing damaged body parts is still achievable. Researchers say they were able to preserve the genes responsible for the feat. As for humans, we lost those genes.
To try and understand the genes that we misplaced along the way, researchers have built a running list of genes that enable regenerating animals to grow back tails or damaged tissues. And in some cases, they have found that genes important for regeneration in other creatures also have counterparts in humans.
Scientists at Duke University have found some of those genes in zebrafish which they say can be turned on in injury sites. Some can even be engineered to change the ability of other animals to regenerate.
To make the find, Duke researchers had to figure out if these stretches of DNA existed in the first place. They already knew that small chunks of sequence, called enhancer elements, control when genes are turned on in a developing embryo, so they began there.
Scientists looked for genes that were strongly induced during fin and heart regeneration in the zebrafish. They found that a gene called leptin b was turned on in fish with amputated fins or injured hearts. From there, researchers scoured the 150,000 base pairs of sequence surrounding leptin b and identified an enhancer element roughly 7,000 base pairs away from the gene.
From there, they whittled the enhancer down to the shortest required DNA sequence. In the process, scientists found that it could be separated into two distinct parts: one that activates genes in an injured heart, and, next to it, another that activates genes in an injured fin.
These parts were fused to two regeneration genes to create transgenic zebrafish whose fins and hearts had superior regenerative responses after injury.
The next step from there was to test the genes’ abilities to work in mice, which are mammals. Scientists found that borrowing the elements from the genome of zebrafish could activate gene expression in the injured paws and hearts of the mice.
The results are an encouraging proof-of-concept, researchers say. And they think that there may be different types of sequences that turn on genes in many instances, as well as others that only work within specific tissues or in the embryonic stage.
Full results of the investigation are published in the journal Nature.