Mechanism behind calorie restriction, lengthened lifespan revealed
"Our study shows that epigenetic drift, which is characterized by gains and losses in DNA methylation in the genome over time, occurs more rapidly in mice than in monkeys and more rapidly in monkeys than in humans," explains Jean-Pierre Issa, MD, Director of the Fels Institute for Cancer Research at LKSOM, and senior investigator on the new study. The findings help to explain why mice live only about two to three years on average, rhesus monkeys about 25 years, and humans 70 or 80 years. Chemical modifications such as DNA methylation control mammalian genes, serving as bookmarks for when a gene should be used -- a phenomenon known as epigenetics. "Methylation patterns drift steadily throughout life, with methylation increasing in some areas of the genome, and decreasing in others," says Dr. Issa. Previous studies had shown that these changes occur with age, but whether they were also related to lifespan was unknown. Dr. Issa's team made their discovery a...