Harvard Scientists Have Discovered The DNA Switch That Controls Whole-Body Regeneration

Humans have long envied animals that are able to regenerate parts of their bodies. Arms, legs, tails, even whole chunks of the organism. Yet despite all the technology and best efforts, humans don't have this ability. However, this could all change. Harvard University uncovered the DNA switch that controls genes for whole body regeneration. This means that one day, humans may be able to grow back lost limbs!

Animal Regeneration

Many people know that certain animals are able to achieve extraordinary feats of repair, such as salamanders which grow back legs, or geckos which can shed their tails to escape predators and then form new ones in just two months. It doesn't stop there either. Planarian worms, jellyfish, and sea anemones take this regeneration to a whole new level and can actually regenerate their entire bodies after being cut in half.

How does this work?

After putting a lot of time and effort into gene and DNA research, scientists from Harvard University have now discovered that that in certain worms, a section of non-coding or ‘junk’ DNA controls the activation of a particular gene, nicknamed the ‘master control gene’. It is actually called early growth response (EGR) which acts like a power switch, which is what controls Growth and actually has the ability to turn regeneration on or off. Dr. Mansi Srivastava, Assistant Professor of Organismic and Evolutionary Biology at Harvard University said that the team was able to decrease the activity of the EGR and find out that if you don't have this gene, nothing will happen. For example, if someone cut off a human arm, it will never grow back. However, if you cut off a salamander’s leg and observed it, it will indeed grow back another leg over time.

That said, the animals can't just spontaneously regenerate. All those downstream genes won't turn on, so the other switches don't work and everything basically just stops. The animals tested in these studies were three-banded panther worms. Throughout the studies, the scientists found that during regeneration the tightly-packed DNA in their cells starts to unfold. This then allows new areas to activate, hence the ability to grow new body parts. This is all fine and well but how did this affect humans?

Human Benefit

The crucial part of all this research is that humans are also carriers of EGR. In fact, humans do actually produce it when cells are stressed and in need of repair, for example, when there is a wound, say a cut, over time, this will heal and the damaged areas regenerate until it’s back to normal. However, it doesn’t seem to trigger large scale regeneration, such as lost fingers or limbs.

Due to this, scientists now think that this master gene is completely different in humans compared to animals - it’s wired differently. They are now trying to find a way to tweak its circuitry to hopefully take advantage of its regenerative benefits. Postdoctoral student Andrew Gehrke of Harvard believes the answer lies in the area of non-coding DNA controlling the gene. Non-coding or junk DNA was once believed to do nothing, but in recent years scientists have realized is having a major impact, such as the effect it has in certain animals such as worms and salamanders.

What is the science behind it all?

Mr. Gehrke said that only about 2% of the genome makes proteins so what the team wanted to know was what the other 98 percent of the genome was doing during whole-body regeneration. It's likely that they have only just scratched the surface. Scientists have only 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. Much more research needs to be done to find out more about the genome and how it works exactly.

Marine animals are considered to be masters of regeneration. For example, three years ago back in 2016, a Japanese scientist reported that three months after the death of his pet jellyfish, a sea anemone-like polyp rose out of the carcass and amazingly started to age backward, reverting to a much younger state

Another example is from the 1990s where scientists in Italy discovered that the Turritopsis dohrnii jellyfish switches back and forth from being a baby to an adult. This has resulted in it attracting its nickname, the immortal jellyfish.

Perhaps with a bit of tweaking, we will be able to regenerate limbs too!

Source: http://science.sciencemag.org/content/363/6432/1152