Cell aging slowed by putting brakes on noisy transcription
"We used budding yeast, a single-cell organism, to study the epigenetic regulation of aging and this simple model turned out to be quite powerful," explained Sen. In yeast, aging is measured by the number of times a mother cell divides to form daughters before it stops. This number - a mean of 25 divisions -- is under tight control and can be either reduced or increased by altering histone modifications, as the researchers found. They showed that when fewer chemical groups of a certain type attach to yeast histones, the abnormal transcription greatly increases in old cells. In contrast, the team found that in yeast strains with a certain enzyme deletion, this abnormal transcription is reduced and lifespan is extended by about 30 percent.
"We have started investigating whether such a longevity pathway can also be demonstrated in mammalian cells", says Berger. "However, these investigations are confounded by the complexity of the genome in more advanced organisms. One of our long-term goals is to design drugs that can help retain these beneficial histone modifications and extend healthy lifespan in humans."