How DNA “repairing” itself and how DNA breaks associated with genetic diseases, the Chemistry Department of Moscow State University doctoral specified Khoronenkova Svetlana and her colleagues.
The DNA molecule in human cells chemically unstable, causing her injuries of different nature. There is a mechanism providing a response to DNA damage, which includes the processes of DNA damage detection, signal generation and damage of the “fix” the DNA molecule – so-called repair.
Response to DNA damage is extremely important, for example, in order to ensure the highest possible quality of DNA replication before – last DNA duplication at the cellular level. If damaged DNA is replicated, the risk of cancer and other diseases will increase significantly as a result of mutations. All this may lead to cell death.
repair system includes enzymes that are responsible for ensuring that damaged DNA in some way to verify the quality and save before it enters the daughter cell.
In this system, there are a lot of different enzymes, and one of the ways of checking and Salvation cells – recognition of damaged bases and other signaling enzymes, which will be their “fix” – to repair.
Among these enzymes – kinase ATM, which transmits a signal from damaged DNA cell system reparation. Scientists suggest that the only ATM detects so-called double DNA strand breaks. These discontinuities are very dangerous because they can lead to loss of genetic information.
Doctoral Faculty of Chemistry, Moscow State University Svetlana Khoronenkova also has affiliation Oxford University, became part of an international group of scientists, which could open a new role molecules ATM. Her role was to design the project, its experimental design and execution of the results for publication.
The results of research published in the prestigious scientific journal PNAS.
«endogenous (internal) double DNA strand breaks in cells under normal conditions do not occur in large quantities, – said Svetlana Khoronenkova. – The idea of cell function is to prevent the formation of double-strand breaks. We have found that ATM is activated and begins to perform its function not only in the case of double gaps, but also in response to single-strand breaks. ”
Svetlana Khoronenkova explained that single-strand breaks occur in the cell with insane speed: 10-20 thousand. Per day. In contrast, the double breaks occur at a rate of 10-20 units per day. This underlines the importance of signaling the presence of uncorrected DNA single-strand breaks to repair the system.
In response to the single-strand breaks activates the ATM itself and sends a signal about the damage. This gives pause in DNA replication, and the cells will have more time for repair.
If timely repair has not occurred, then a double-break DNA that much worse because of increased risk of cancer and other diseases.
In particular, the mutation in the gene ATM associated with genetic disease ataxia telangiectasia (Louis-Bar syndrome) – a rare inheritable disease that manifests itself mainly in children: they can be observed immunodeficiency, neurodegeneration, a predisposition to cancer, and they die at the age of 14-15 years. In addition, these children may be a delay in development. The incidence of this syndrome is different: in the US it appears slightly more often than in Europe.
In general, according to statistics, there is approximately one documented case in the 40-100 thousand. births, ie a mutation in the gene have 1% of the population. In this case, the probability is high that doctors diagnose only a small percentage of the disease, which leads to the difference in numbers.
«Now we want to understand the mechanism of how the activation of ATM in response to single-strand breaks. Future work should eventually help improve the living standards of suffering from such diseases patients “- summarized Svetlana Khoronenkova.
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