Scientists have discovered mutations that cause aging of organs
Scientists have discovered mutations in DNA that cause aging of organs
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Scientists have discovered a mechanism that explains why certain organs age faster than others. According to scientists, this happens due to the accumulation of mutations in DNA.
The study was carried out by a team from the University of Geneva in collaboration with the Inselspital, the University Hospital of Bern and the University of Bern. The results published in the journal Cell, writes MedicalXpress.
Organs and tissues do not all age at the same rate. Aging is caused by damage to the genetic material (DNA) that accumulates with age.
DNA molecules contain coding sites (genes that encode proteins) and non-coding sites (which participate in the mechanisms that regulate or organize the genome). At the same time, cells have special DNA repair systems that prevent the accumulation of mutations.
Errors in coding regions can be detected during gene activation. And in non-coding areas – only during cell renewal. However, cell renewal does not occur with a different frequency, which depends on the type of tissue or organ.
So, for example, the intestines or the skin, which is in constant contact with the external environment, often renew their cells (1-2 times a week).
Whereas cells of internal organs – liver or kidneys – reproduce only a few times a year. A group of scientists studied liver cells (hepatocytes), which rarely reproduce.
Scientists analyzed the potential connection between faster aging of the liver and a lower frequency of DNA replication in its cells.
“The mouse liver is an ideal organ for studying the mechanisms of DNA replication in vivo. In adult mammals, hepatocytes rarely proliferate (grow) unless they have been partially removed.
After removing two-thirds of the liver of young or old mice, we were able to investigate the mechanisms of replication (doubling of DNA) in a young or aging organ directly in a living organism“, says co-author of the study, Professor Deborah Stroka.
Scientists found out that after removing a part of the organ, liver cells begin to duplicate DNA from non-coding regions.
The scientists also noticed that replication initiation was much more efficient in young mice than in old mice.
“Non-coding areas are not regularly checked for errors, so damage accumulates over time. After removal of the liver in young mice, damage is still minimal and DNA replication is possible“, explains Giacomo Rossetti, researcher at the Department of Molecular and Cell Biology, Faculty of Natural Sciences, UNIGE.
He adds that in old mice, due to the accumulation of errors in DNA, replication is impossible, as is the renewal of the cells of this organ. The same cells that remain often lose their functions (degrade), and this leads to tissue aging.
Next, the scientists want to test whether organ aging can be prevented if DNA damage is repaired before replication begins.
It will be recalled that scientists recently found out that the Y-chromosome shrinks and evolves faster than the X-chromosome.
