Machine learning allowed Spanish scientists to analyze in detail micrographs of DNA “repair” in living cells. Researchers have discovered several new proteins involved in this process, and have demonstrated the important role that proteins play actively leaving the site of injury.

The DNA of living cells is constantly damaged by background radiation, ultraviolet radiation, chemicals and simply duplication errors. Single or double breaks in the DNA strand, nucleotide substitutions - all this can have disastrous consequences for the functioning of the body. Therefore, in the cell there are special mechanisms for the "repair" of DNA: they are called repair systems. In this process, many proteins are involved that signal the violation, bind to the corresponding site and repair the damage.

Each cell of the human body receives and "fixes" about 10 thousand DNA breaks a day. In neurons, repair is especially active during sleep. But it plays an extremely important role in chemotherapy. This procedure leads to deep damage not only to tumor cells, but also to healthy cells. By better understanding how they recover, physicians will be able to find ways to help this process and accelerate the recovery of these patients.

Recently, scientists, led by Alejo Efeyan of Spain's National Cancer Research Center (CNIO), were able to look at the repair system in unprecedented detail and discovered nine new proteins that are involved in DNA repair. To do this, they used fluorescence photomicrography, and they used machine learning to analyze and interpret the huge amount of collected data - many thousands of images captured.

By artificially damaging the DNA of human cells with an ultraviolet laser, biologists have followed the behavior of about 300 individual proteins involved in repair. Some of them moved to the place of damage, contacting him for recovery. Others, on the contrary, were previously associated with chromatin, but when damaged, they actively moved away, making room for "repair" and attracting new proteins to action. For efficient DNA repair, this reverse movement turned out to be no less important than the arrival of the “repairing” proteins in place.

Thus, the PHF20 protein discovered by the authors of the new work leaves the damaged areas in a matter of seconds, providing the appearance of the 53BP1 protein, which is critical for repair. Cells with artificially impaired PHF20 activity coped significantly worse with DNA repair and demonstrated reduced - compared to normal - resistance to radiation.

Article published in the journal Cell Reports
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