Telomeres, histones and aging. And maybe rejuvenation…
DNA "packaging" will tell you how to rejuvenate the body at the cellular level
Scientists have found out the details of the mechanism of cellular aging, which starts as cells divide and causes changes in the structure of DNA packaging, which can be used to develop new methods of rejuvenation of an aging organism, reports the journal Nature Structural and Molecular Biology (Roderick J O'Sullivan et al., Reduced histone biosynthesis and chromatin changes arising from a damage signal at telomeres – VM).
The aging of a cell, unlike the aging of humans or animals, does not consist in gradual extinction, decrepitude and loss of the ability to perform any functions, but in whether the cell is capable of performing another act of division. Over time, the rate of cell division slows down until this process stops altogether.
It is the cessation of feeding the body with new cells in a variety of tissue types that leads to its aging as a whole. Until now, however, scientists do not know the detailed reasons for slowing down cell division and methods of reversing this process or at least slowing it down. It is believed that telomeres are somehow responsible for aging - the end sections of chromosomes that shorten each time during the act of cell division.
"Before our study, we knew that telomeres get shorter as a cell divides, and when they get too short, cells either stop dividing or die altogether. Thus, something should, in our opinion, transmit a signal from telomeres to the entire cell nucleus, which would trigger some changes in the work of DNA as a whole," said Jan Karlseder, co-author of the publication from the Solkovsky Institute of Biological Research, quoted by the press service of this organization.
Karsender and his colleagues made comparisons in the number of special proteins – histones – between old and young cells grown in artificial conditions. Histones form a complex compound with DNA molecules in the nucleus, help them take a certain form of a three–dimensional packing structure, forming the so-called chromatin - a DNA-based substance that chromosomes consist of.
Very quickly, Karsender's team discovered that old cells that had undergone about 75 acts of division contained noticeably fewer histones in their nucleus compared to young cells that had divided only about 30 times.
"These proteins perform an auxiliary function in all parts of DNA, and therefore its violation due to a lack of histones inevitably affects the work of the entire genome," said co-author of the article Roddy O'Sullivan (Roddy O'Sullivan).
After conducting a more thorough analysis, the scientists found that negative changes in the number and diversity of histones were observed in cells at all stages of their life, depending on the number of division processes carried out.
This work demonstrates that aging, contrary to the widespread belief that age-related diseases occur due to the accumulation of damage in the DNA itself, is a much more complex process. The aging process can be accelerated by shortening telomeres, distorting the interaction of genes with histones and thus disrupting their work.
Scientists have also shown that genetic intervention in a cell in order to restore its ability to produce additional amounts of histones has significantly increased the number and diversity of these proteins, even in old cells. This is how, according to the authors, it is possible to achieve cell life extension.
"If we just artificially lengthen telomeres, we can transfer them to the so–called "immortal" state characteristic of cancer cells," Karlsender explained.
Portal "Eternal youth" http://vechnayamolodost.ru05.10.2010