The state of the methylome is a marker of biological age
Women live longer than men. People may look and feel younger or older than their chronological age. Diseases affect the aging process. From the point of view of biology, it is obvious that the biological clocks of different people count time at different speeds.
As part of a new study, scientists from the University of California at San Diego, working under the guidance of Professor Kang Zhang, describe a model that allows a quantitative description of the aging process at the molecular genetic level. This tool allows not only to determine the biological age of a person with a higher degree of accuracy, but also, possibly, to predict or cure diseases that develop in him over time.
So far, the search for such a tool has not brought success. For example, experts considered the length of telomeres as a marker of aging – DNA sequences shortening over time at the ends of chromosomes – but found that in addition to aging, this indicator is influenced by other factors, including stress.
The authors devoted their work to the study of methylation, a fundamental process that continues throughout life, consisting in the attachment of a methyl residue to cytosine molecules included in DNA or its separation (demethylation), leading to the suppression or activation of gene expression (synthesis of corresponding proteins). The researchers measured the levels of more than 485,000 markers of methylation scattered throughout the genome in the DNA of blood cells isolated from 656 people aged 19 to 101 years.
Analysis of the data obtained showed that changes in the methylome – the entire genome–wide complex of methylation markers - occurring as a person ages are predictable. Knowledge of these patterns provides specialists with a fundamentally new tool for determining the real biological age of a person using a blood test.
According to the authors, the genome of young people is characterized by clearly distinguishable boundaries of clearly structured methylation zones. However, over time, the methylation zones become more blurred, and their boundaries lose clarity. However, the rate at which this happens varies from person to person. Scientists say that at the molecular level, it is obvious that there are differences in the rate of aging of individual individuals and even in the rate of aging of different organs of the same person. Moreover, the rate of aging of malignant cells differs from the rate of aging of the cells surrounding their normal tissues.
Experts believe that knowledge of these patterns has a very wide practical application. The first thing that comes to mind is their use in criminology to determine a person's age based on the results of studying cells isolated from his blood or tissue sample.
More important may be the application of new knowledge to assess the biological age and the rate of aging of a person. This information is potentially of great importance from a medical point of view. It can be used, for example, to assess the effect of therapy or lifestyle changes on the state of the body.
In the near future, the authors plan to evaluate the possibility of using the nature of methylation as a prognostic factor for determining the risk of developing various diseases, as well as the possible advantages of such molecular diagnostics in comparison with traditional clinical and physical markers. They believe that their proposed approach has a great future.
Article by Gregory Hannum et al. Genome-wide Methylation Profiles Reveal Quantitative Views of Human Aging Rates published in the journal Molecular Cell.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of the University of California, San Diego:
Methylome modifications offer new measure of our “biological” age.
28.11.2012