When it comes to regeneration, some animals are capable of amazing feats -- if you cut the leg off a salamander, it will grow back. When threatened, some geckos drop their tails as a distraction and regrow them later. Other animals take the process even further. Planarian worms, jellyfish, and sea anemones can actually regenerate their entire bodies after being cut in half.
Using three-banded panther worms to test the process, researchers found that a section of non-coding DNA controls the activation of a "master control gene" called early growth response, or EGR. Once active, EGR controls a number of other processes by switching other genes on or off.
"What we found is that this one master gene comes on...and that's activating genes that are turning on during regeneration," researcher said. "Basically, what's going on is the non-coding regions are telling the coding regions to turn on or off, so a good way to think of it is as though they are switches."
For that process to work, researcher said, the DNA in the worms' cells, which is normally tightly folded and compacted, has to change, making new areas available for activation.
"A lot of those very tightly packed portions of the genome actually physically become more open, because there are regulatory switches in there that have to turn genes on or off," he said. "So one of the big findings in this paper is that the genome is very dynamic and really changes during regeneration as different parts are opening and closing."
Why can't human regenerate
"The reason we called this gene in the worms Egr is because when you look at its sequence, it's similar to a gene that's already been studied in humans and other animals," Srivastava said. "If you have human cells in a dish and stress them, whether it's mechanically or you put toxins on them, they'll express Egr right away.
"But 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?" Srivastava said. "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, and what Andrew has done with this study is come up with a way to get at this wiring. So we want to figure out what those connections are, and then apply that to other animals, including vertebrates that can only do more limited regeneration."
Source: Science Daily
Original title: Study uncovers genetic switches that control process of whole-body regeneration
Reference link: https://www.sciencedaily.com/releases/2019/03/190314151546.htm