Scientists Discover New and Reversible Cause of Aging

Scientists have studied aging for years, trying to figure out exactly how it happens and how to slow the process. Now, they not only may have discovered a cause of aging in mammals, but have also found that it may be reversible.

The newly discovered process is actually a series of molecular events that enable communication inside cells between the nucleus and mitochondria. As communication breaks down, aging accelerates.

"The aging process we discovered is like a married couple-when they are young, they communicate well, but over time, living in close quarters for many years, communicating breaks down," said David Sinclair, one of the researchers, in a news release. "And just like with a couple, restoring communication solved the problem."

Mitochondria are the "powerhouses" of the cell. They generate chemical energy to carry out essential biological functions. They've long been identified as key players in aging; as they become increasingly dysfunctional over time, many age-related conditions set in.

In order to better understand aging, the researchers focused on a group of genes called sirtuins. Previous studies showed that one of these genes, SIRT1, was activated by the compound resveratrol, which is found in grapes and red wine. The researchers examined mice that had this SIRT1 gene removed. In the end, they found that the mice showed signs of aging, but that most mitochondrial proteins coming from the cell's nucleus were at normal levels; only those encoded by the mitochondrial genome were reduced.

After pursuing this further, the researchers found an intricate cascade of events that begins with a chemical called NAD and concludes with a key molecule that shuttles information and coordinates activities between the cell's nuclear genome and mitochondrial genome. As long as this coordination remained fluid, the cells stayed healthy.

As we age, levels of initial chemical NAD declines and without it, SIRT1 loses its ability to keep tabs on a molecule HIF-1, which can interfere with communication. Over time, communication is lost and signs of disease and aging become apparent. Currently, researchers are taking a closer look at this particular phenomenon in order to better understand it. In theory, this process could be reversed--as could aging.

The findings are published in the journal Cell.

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Catherine Griffin