Protein that helps salamanders re-grow limbs identified

Scientists have discovered that a protein called nAG plays a significant role in the regeneration of severed limbs in newts, a type of salamander that looks like lizard and live both on land and in water.

Washington, November 3 : Scientists have discovered that a protein called nAG plays a significant role in the regeneration of severed limbs in newts, a type of salamander that looks like lizard and live both on land and in water.

The new finding attains significance as it may provide insights into the field regenerative medicine relating to humans, says Anoop Kumar of the University College London, who led the study published in the journal Science.

The scientists say that when a newt or other amphibian loses a limb, stem cells in the region grow and divide at the tip of the stump, where the limb was once attached, to form a larger mass of cells called blastema.

"Those cells grow and divide and they give rise to the structures that have been amputated. So if you amputate at the wrist, those cells will give rise to a hand; if you amputate at the shoulder, they'll give rise to an arm," LiveScience quoted study team member Jeremy Brockes, of the University College London, as saying.

During the study, the researchers chopped off red-spotted newts' limbs and the attached nerves, which are needed to stimulate the production of the nAG protein.

The researchers then zapped the cells of the now-exposed body region with electrical pulses so that they could deliver little bundles of DNA carrying genes for the protein nAG.

The newts' limbs were regenerated within 30 to 40 days, but the new limbs had less muscle mass than the original ones.

Upon conducting further lab experiments, the researcher observed that the nAG protein works directly on the blastema cells, causing them to grow and divide.

Brockes, however, has admitted that it is too early to say that human-limb regeneration is right around the corner.

"What everybody is interested in, of course, are things about the extension to humans. I'm really very cautious about that," he said.

He also revealed that in order to move one step further towards limb regeneration in humans, scientists needed to figure out whether there exists human equivalent to the blastema that salamanders form after a limb gets amputated.

"I don't think we generate those (blastema) cells after injury in a way that a newt does," Brockes said.

ANI