science
This discovery became sensational . Scientists managed to increase the threshold of division of ordinary human cells in half . At the same time , the cells remained healthy and young .
It was shown that with the introduction of telomerase , human fibroblast cells , which normally divide only 50 times plus or minus 10 times , are able to share 280 times without any signs of aging and pathology .
At about the same time , the telomerase gene was first cloned from human tissue . Until now , he " lives " in vitro in the form of a plasmid sample , that is , a ring DNA , where this gene is embedded .
Earlier , the bacterium Escherichia coli ( Escherichia coli ) was used for the propagation of this gene in laboratories . The bacterium repeatedly copied the plasmid inside itself , then the wand was killed and the part of the DNA that was needed was extracted from its genome .
But now everything is much simpler . Modern technologies allow obtaining in the laboratory conditions necessary copies of a particular gene using the method of polymerase chain reaction ( PCR ).
Later it was proved that in our body there are only two types of cells - sex and stem cells , in which telomerase is present , extending telomeres with the help of a special RNA matrix . This is why stem and sex cells are able to divide endlessly , copying our genetic material for reproduction and performing function of regeneration .
Telomerase is active in embryonic and embryonic tissues , in stem and proliferating cells . It is found in 90 % of cancerous tumors , which ensures uncontrolled reproduction of cancer cells .
But in most somatic cells of the adult organism , telomerase is not active .
All other human cells do not produce telomerase and sooner or later die .
In 2011 , scientists from the German Cancer Research Center ( Deutsches Krebsforschungszentrum , DKFZ ), as a result of the studies , received another confirmation regarding the alternative mechanism of telomere extension by enzymes that repair DNA damage .
Scientists have proved that tumor cells , including cancer , have learned to bypass this mechanism and thus have access to an unlimited number of divisions .
This occurs by activating the already mentioned telomerase , an enzyme that normally extends telomeres of embryonic cells .
Thus , tumor cells " zero out " the work of the cell clock , which allows them to divide an infinite number of times .
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