19 September 2017

Reducing calories prolongs life

Now scientists know why

Anna Kerman, XX2 century, based on Medical Xpress: Researchers discover mechanism behind calorie restriction and prolonged lifespan

Almost a century ago, scientists discovered that reducing the amount of calories consumed significantly increases the life expectancy of individuals of some species. However, despite the fact that a number of studies have been devoted to the problem, it has not yet been known how it works. But recently, scientists from the Lewis Katz School of Medicine at Temple University managed to make a breakthrough. The results of the study are published online in the publication Nature Communications (Maegawa et al, Caloric restriction delays age-related methylation drift).

The authors of the work demonstrated for the first time that the rate of occurrence of age-related epigenetic changes in the genome is associated with life expectancy, and restrictions on the number of calories consumed slow down these changes and thus affect longevity.

"Our study showed that epigenetic drift, characterized by changes in DNA methylation over time, occurs faster in mice than in monkeys, and faster in monkeys than in humans," explains lead researcher Dr. Jean–Pierre Issa, director of the Felsov Cancer Research Institute and Molecular Biology (Fels Institute for Cancer Research & Molecular Biology).

The new work explains why mice live only 2-3 years, rhesus monkeys – about 25 years, and humans – from 70 to 80. Mammalian genes are controlled by chemical changes, such as DNA methylation. They can be compared to "bookmarks" showing which gene to use. This phenomenon is called epigenetics. "Methylation patterns change continuously over the course of life, the intensity of methylation increases in some parts of the genome and decreases in others," explains Dr. Issa. Previous studies have shown that these changes are associated with age, but their relationship with life expectancy has been demonstrated for the first time.

The discovery was made after scientists analyzed the methylation patterns of DNA isolated from the blood of individuals of different ages. The study used not only biomaterial obtained from humans, but also blood samples from mice and monkeys. In the course of the analysis, a deep sequencing technique was used, which made it possible to identify various patterns characteristic of representatives of certain age groups.

After analyzing the data obtained, the scientists came to the following conclusion: the greater the volume of epigenetic changes and the faster they go, the shorter the life expectancy characteristic of a particular species.

Then the researchers wondered if it was possible to change the epigenetic drift in order to increase the life span. One of the most effective known ways to achieve this goal in animals is to limit the caloric content of the diet while preserving all the necessary nutrients in the food. To investigate this effect, scientists reduced the caloric content of the daily diet of young mice by 40%. The researchers reduced the nutritional value of the diet of adult monkeys by 30%. In representatives of both species, a decrease in the rate of epigenetic drift was recorded, due to which changes in methylation in elderly animals on a diet were comparable to changes in young individuals.

Thanks to their observations, Dr. Issa and his colleagues were able to name a new mechanism – slowing epigenetic drift – explaining how the restriction of nutritional value affects the lifespan of animals. The discovery can be applied in health research, as recent work has shown that the greater the severity of epigenetic drift, the higher the risk of age-related diseases, including cancer. Dr. Issa and his co-authors hope to soon discover other factors affecting methylation. Theoretically, these factors could be controlled in order to prevent "age-related" diseases.

Portal "Eternal youth" http://vechnayamolodost.ru  19.09.2017

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