NASA Twins Study Reveals How Human Genes Behave In Outer Space

NASA's Twins Study has already yielded some interesting discoveries about its subjects, astronauts Mark and Scott Kelly. And while the full findings won't be released until next year, the latest partial findings now offer an interesting look at how gene expression takes place in outer space.

According to a recent press release from the space agency, the Twins Study's preliminary results suggest that space travel results in an increase in methylation. NASA explains this as the process of turning genes on and off, which is necessary as the body tries to adjust to the unusual environment of zero gravity.

"Some of the most exciting things that we've seen from looking at gene expression in space is that we really see an explosion, like fireworks taking off, as soon as the human body gets into space," read a statement from NASA Twins Study principal investigator Chris Mason, a geneticist from Weill Cornell Medicine.

"With this study, we've seen thousands and thousands of genes change how they are turned on and turned off. This happens as soon as an astronaut gets into space, and some of the activity persists temporarily upon return to Earth."
As PBS recalled, the studies were carried out as NASA's Scott Kelly spent a year aboard the International Space Station, while his identical twin brother Mark, a retired NASA astronaut, stayed at home on Earth. One of the main observations noted as early as last year was the fact that Scott returned to Earth about two inches taller than his twin, but that was something NASA was expecting all along.

With NASA's Twins Study focusing on the internal changes in Scott and Mark Kelly's bodies, researchers revealed this week that Scott's methylation rate had gone up while he was in space. That meant that thousands of his genes had turned on and off the moment that he entered space, and that this process of gene expression was still ongoing for some time after he had returned from the ISS.

"There are over 50,000 genes in the human genome, and when floating in zero gravity, the body is trying to manage that situation in new ways," Mason explained.

As PBS continued, gene expression is a complex process with several steps, and it takes place when our genes create protein. This then leads to the creation of cells and their respective tasks. Gene expression is also the process that determines how likely we are to develop cancer, metabolic disorders, or other diseases, or how we react to stressful situations. PBS cited a few examples of this process, including the mutation of genes that could cause cancer after a person is exposed to excessive radiation.

NASA's Twins Study mentioned that DNA methylation changes genes, and might affect the odds of gene expression happening in the human body. This, according to the researchers, could point to some new risks in extended space travel, mainly "unprecedented changes" in cell function. Based on the Twins Study's post-ISS data on Scott Kelly, these changes included a growth in the astronaut's telomeres, or the small caps at the tips of DNA strands. This could be a good thing, as having longer telomeres often points to a slower or more stable aging process. However, if this change is accompanied by increases in radiation exposure, it could also mean a higher risk of developing aggressive forms of cancer.

Considering the potentially high risks methylation could pose on astronauts, scientists are now hoping to use CRISPR-Cas9 and other genetic tools to reduce the chances of methylation leading to cancer-causing genetic mutations, and to fix any cells that may have been damaged.

[Featured Image by Bill Ingalls/NASA via Getty Images]