Are transposons another cause of aging?
The body ages due to the "leakage" of DNA sections
Anna Govorova, Infox.ru
Scientists led by specialists from Brown University (USA) have proposed a new theory of aging of the body, reports Infox.
They conducted an experiment that showed that aging is associated with the migration of transposons (sections of DNA that move freely inside the genome) from one chromosome to another. It also turned out that this migration, and hence aging itself, can be slowed down – with the help of starvation and activation of certain genes.
Currently, there are several theories of aging. It is believed that the body ages due to many factors. For example, with age, the work of proteins and mitochondria begins to deteriorate, genetic damage accumulates, the mechanism of gene regulation breaks down, histone proteins in which DNA is "packed" deteriorate. The two most popular theories of aging are the accumulation of reactive oxygen species in cells and the shortening of the length of telomeres (repeats of short sequences of nucleotides at the ends of chromosomes).
It seems that another theory has been added to this list – the transposon theory of aging.
Transposons are sections of DNA that can move within the genome. Like viruses, they are introduced into the host genome and multiply themselves in the form of many copies. Some of them subsequently begin to influence the work of genes and sometimes turn out to be very useful. But if the tranposons leave "their" chromosome, this leads to a malfunction of the cell.
It is known that as the body ages, transposons break through the chromatin shell and come out to "wander" to freedom.
In their current experiment on fruit flies, scientists decided to find out exactly how this happens.
Under a microscope, they observed the behavior of transposons and saw how these sections of DNA begin to "flow out" of chromatin as drosophila age. Interestingly, the rate of such "outflow" was not uniform. "The fruit flies reached a certain age, and then the transposons began to come out of the chromatin. Further, the rate at which they left the chromosomes increased exponentially," says the study's lead author Jason Wood.
A snapshot from the press release of Brown University Study results advance ‘transposon theory of aging' – VM
The results of the second experiment were also interesting, when with the help of genetic manipulations it was possible to suspend the aging process, slowing down the "outflow" of transposons from the chromosome.
For example, activation of the Su(var)3-9 gene, which is responsible for chromatin packaging (this gene is present not only in drosophila, but also in mammals), led to the fact that the flies increased their lifespan by 20 days (from 60 to 80).
Another manipulation also led to success: activation of the Dicer-2 gene, which is able to inhibit the activity of transposons and prevents their free movement, also led to an increase in the lifespan of fruit flies.
Interestingly, when insects were restricted in food, this also led to an increase in their life expectancy.
Of course, the authors add, there are still a lot of questions here.
"There are many mechanisms that are responsible for aging. We will work to understand the full picture of this process," says Wood.
Scientists have already received a grant of $ 9.5 million for further research.
They report on the results of their work in the latest issue of the journal Proceedings of the National Academy of Sciences (Chromatin-modifying genetic interventions suppress age-associated transposable element activation and extend life span in Drosophila).
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14.09.2016