真實生活的X戰警？ 哈佛科學家們正在解鎖DNA的整個身體再生的秘密

真實生活的X戰警？ 哈佛科學家們正在解鎖DNA的整個身體再生的秘密
Real-Life X-Men? Harvard Scientists Are Unlocking DNA's Secrets of Whole-Body Regeneration

In 2017, Business Insider named the top ten highest-grossing superhero movie franchises in America. Sitting at the number two spot, bested only by the Batman franchises (and remember, this was before the Deadpool sequel) was the X-Men franchise (which included the first Deadpool as well as 2017's Logan). What makes the franchise particularly interesting to us as science-fiction lovers is the fact that each film wrestles with the challenges faced by mutants: humans who, through some genetic twist of fate, have become something more than human, transcending the physical limitations placed upon our species by nature's order. The most basic manifestation of that – epitomized in both Deadpool and Logan/The Wolverine/Weapon X – is the ability to survive physical calamities that would usually prove fatal: an accelerated ability to heal and regenerate. The creators of the Marvel universe didn't invent this: it not only appears in the earliest myths, most notably in the Lernaean Hydra, but also in real-life lizards, starfish, jellyfish, and worms that can regrow tails, sections, and even heads due to some enviable genetic code. Those aspiring to join the X-Men will be excited to know that a team of scientists at Harvard led by Dr. Mansi Srivastava, an Assistant Professor of Organismic and Evolutionary Biology, have started to unlock this genetic code and have found that at least one of the genes responsible is also found in humans.

The findings, which were published in the latest issue of Science, revolved around the remarkable regenerative abilities of Hofstenia miamia, a small flatworm commonly known as the three-banded panther worm. Srivastava and her team found that a section of non-coding, or "junk" DNA activates a "master regulator" known as early growth response (EGR), which triggers or inhibits regeneration. According to the National Library of Medicine, "only about 1 percent of DNA is made up of protein-coding genes; the other 99 percent is noncoding. Noncoding DNA does not provide instructions for making proteins." Although scientists once regarded non-coding DNA as "junk" because it didn't seem to have any obvious purpose, it turns out that some of it plays a regulatory role – acting as a switch – like the one observed. "What we found is that this one master gene comes on [and activates] genes that are turning on during regeneration," researcher Andrew Gehrke told the Harvard Gazette. "Basically, what's going on is the noncoding 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." In other words, a section of "junk" DNA's job seems to be to trigger regeneration through EGR after amputation.

Without EGR, however, the switch doesn't seem to connect to anything else. "We were able to decrease the activity of this gene and we found that if you don't have EGR, nothing happens," Dr. Srivastava told the Gazette. "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."

Although EGR is present in the human genome, it does not seem to play the same role, otherwise we'd be a species of Deadpools. In humans, EGR seems to be activated along different pathways than those found in the worms. The question, Dr. Srivastava, told the Gazette, 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 look at the natural world and 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 questions raised naturally call for more research. "So we want to figure out what those connections are," Srivasatava continued, "and then apply that to other animals, including vertebrates that can only do more limited regeneration."

Hang tight: the ability to grow a new arm or head may be in the future.

https://www.outerplaces.com/science/item/19301-harvard-dna-regenerative-master-switch