DNA secret could give people the power to regenerate limbs

HUMANS may one day have the ability to regrow limbs after scientists at Harvard University uncovered the DNA switch that controls genes for wholebody regeneration.

Some animals achieve extraordinary feats of repair. Salamanders regrow legs, and geckos can shed their tails to escape predators and form new ones in two months. Planarian worms, jellyfish and sea anemones can regenerate their entire bodies after being cut in half.

Now scientists have found that in three-banded panther worms, a section of non-coding or “junk” DNA controls the activation of a “master control gene” called early growth response (EGR). It acts like a switch, turning regeneration on or off.

“We were able to decrease the activity of this gene and we found that if you don’t have EGR, nothing happens,” said Dr Mansi Srivastava, an assistant professor of organismic and evolutionary biology at Harvard. “The animals just can’t regenerate. All those downstream genes won’t turn on, so the other switches don’t work, and the whole house goes dark, basically.”

Crucially, humans also carry EGR, and produce it when cells are stressed

‘Why can’t we regenerate? It’s a very natural question to think: if a gecko can do this, why can’t I?’

and need repair. Yet it does not seem to trigger large-scale regeneration.

Scientists think the master gene is wired differently in humans, and are trying to find a way to tweak its circuitry to reap its regenerative benefits.

Post-doctoral student Andrew Gehrke of Harvard believes the answer lies in the area of non-coding DNA controlling the gene. This DNA was once believed to do nothing, but in recent years scientists have realised it has a major impact.

“Only about two per cent of the genome makes things like proteins,” Mr Gehrke said. “We wanted to know: what is the other 98 per cent doing during whole-body regeneration?

“I think we’ve only scratched the surface. We’ve looked at some of these switches, but there’s a whole other aspect of how the genome is interacting on a larger scale, and all of that is important for turning genes on and off.”

Dr Srivastava added: “The question is: if humans can turn on EGR, and not only turn it on, but do it when our cells are injured, why can’t we regenerate?

“It’s a very natural question to think, if a gecko can do this, why can’t I? The answer may be that if EGR is the power switch, we think the wiring is different. What EGR is talking to in human cells may be different than what it is talking to in the three-banded panther worm.”

The research was published in the journal Science.