In a joint project between the Harvard Medical School, the National Institute on Aging and the University of New South Wales in Australia, researchers have discovered the cause of aging in mammals.

The aging process is caused by breakdown in communication inside the cells between the nucleus and the mitochondria. When this breakdown occurs, aging accelerates. When scientists administered the same molecule that is naturally produced by the body, they were able to restore communication in older mice. Afterward, tissue samples showed biological hallmarks comparable to much younger mammals.

The general theory among scientists was that the cause of aging was a result of mutations in mitochondrial DNA, which were irreversible. Therefore, researchers have been skeptical as to whether or not aging could ever be reversed. However, David Sinclair, Harvard Medical School professor of genetics and senior author on the project, thought differently.

Sinclair and his group have primarily focused on the group of genes called sirtuins. In previous studies, Sinclair’s lab revealed that one gene, SIRT1, was activated by the compound resveratrol, which is commonly found in grapes, red wine and some nuts. When the SIRT1 gene was removed from certain mice, researchers expected the mice to show signs of aging. However, their results were not what they predicted.

That was when they discovered a chemical called NAD that carries information and coordinates activities between the nucleus and the mitochondria. They discovered that the cells stay healthy as long as the coordination between the two genomes remains. SIRT1’s role is really to make sure that a molecule called HIF-1 does not interfere with communication between the genomes.

Researchers are still unsure why, as humans and animals age, the levels of NAD decline. Without sufficient NAD, SIRT1 loses its ability to keep track of HIF-1 levels, which, if escalated, lead to a breakdown in communication between the genomes.

Researchers are also looking into the connection between NAD and the role HIF-1 might play in diabetes, Alzheimer’s and cancer.

Information collected from Sciencedaily.com.

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