Secret of longevity of the liver is in the balance between DNA and enzymes interacting with it

(ORDO NEWS) — The liver is one of the most enduring organs of the human body: even in old age, its cells retain a high ability to regenerate, despite major DNA rearrangements.

Now scientists have figured out why this happens: it turned out that liver cells constantly maintain a balance between unwinding DNA and becoming less active enzymes that interact with it.

The liver remains remarkably healthy even in the elderly and regenerates remarkably well, although the DNA in its cells undergoes significant rearrangements due to epigenetic changes.

For a long time, scientists could not understand why changes that lead to noticeable decrepitude in other organs do not have a significant effect on the liver. Now it looks like they have found the answer.

After studying the changes that occur with liver cells as they age, the authors of the new work found that with age, DNA in cell nuclei becomes less and less twisted, and this makes it easier for various enzymes to access it.

It would seem that in such a situation, more mRNA should be produced in the cells of older people – molecules that “read” information from a DNA molecule and serve as a matrix for protein synthesis – which will inevitably lead to the depletion of cellular resources.

However, this does not happen due to the maintained balance between DNA unwinding and a decrease in the activity of the main enzyme responsible for RNA synthesis, RNA polymerase.

It turned out that in the cells of the elderly, this enzyme forms less stable complexes and more often falls away from the DNA molecule without completing the construction of the RNA molecule.

As a result, the “imperfection” is broken down by other enzymes into components, and protein synthesis does not begin. This keeps the cell’s resources virtually intact and allows the liver to stay active longer.

Thus, liver cells compensate for epigenetic changes in DNA that occur with age. Now scientists have to find out if similar DNA changes occur in other organs. And if so, is it possible to launch such a compensatory mechanism in them to maintain their health and longevity.

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