But why no difference in the knockout mice, if SIRT3 is such a key component? In a typical display of youthful exuberance, the blood stem cells of the young mice were able function well enough to stave off oxidative stress, which many believe causes aging when our bodies metabolize oxygen.
“A young person is able to handle the oxygen – making sure that the oxygen is going to the right place,” Brown said. “As we age, our ability to appropriately handle the oxygen and its chemical process is not as good, and because of that, it starts wreaking havoc.”
Sure enough, as the mice aged, the SIRT3-deficient mice started slowing down, showing significantly fewer blood stem cells and a decreased ability to regenerate new blood cells.
As we age, our normal antioxidative system struggles to take care of our cells. That’s when SIRT3 can provide a well-needed boost to our antioxidant system. Unfortunately, SIRT3 levels diminish with age, so eventually our system is engulfed in degeneration.
So researchers decided to see what happened when they boosted the SIRT3 levels in the blood stem cells of the aged mice.
“Our first inclination was that the reason the SIRT3 knockout mice’s blood cells were not doing so well was due to a build up of oxidative damage,” said Brown. “But the surprise was when I reintroduced a mutated form of SIRT3 to the aged knockout cells. It improved their function as well.”
In other words, their experiment rejuvenating the aged stem cells' regenerative potential.
“Aging is just an accumulation of damage,” said Chen. “If you think that way, then it’s probably not reversible, because cells are already damaged and no longer functional. But what we show here is that oxidative stress-induced damage, in fact, is reversible.”
While further studies will be needed to see if this SIRT3 boost can actually make people live longer, Chen asserts that there’s more to this field of study than just the thirst for everlasting youth.
“It’s not so much about expanding lifespan. More so, I think the most important goal is to prevent and ultimately treat age-related diseases,” she said. “The idea is that if we can prevent aging, we can prevent all the diseases that are associated with aging. That’s really the major goal.”
When it comes to age-related diseases, Brown says there’s one aspect about SIRT3 she particularly likes.
“While it seems to be helping function, other researchers have found that it can also act as a tumor suppressor,” she said. “One of the problems that you have when you have a ‘molecular fountain of youth’ is you might be making a cell more useful, but then elsewhere you may be increasing the risk of cancer.”
Asked if this study takes us another step closer to this “molecular fountain of youth,” Brown hesitated with a pregnant pause before ultimately saying, “Yes.” Duly noted, however, was her reluctance about throwing around the phrase “molecular fountain of youth.”
“A lot of times people use phrases and a lot of times I feel like that’s an oversimplification because biology is incredibly complicated,” she said. “But I think that it is interesting because SIRT3 is a single molecule that can have a pretty dramatic effect. It is working at the molecular level.”
