Brain rejuvenation
Scientists have restored youth to stem cells of nervous tissue
Sergey Vasiliev, Naked Science
One of the main factors of aging is the loss of stem cells and regenerative abilities of the body. This is especially evident in the nervous system, which is unable to fully restore the functions of many "retiring" neurons. In the neuronal stem cells of mice, scientists found clusters of proteins awaiting processing in special organelles – lysosomes.
As the cell ages, its ability to utilize these proteins decreases, the lysosomes filled with them grow and multiply, reducing its functionality. Anne Brunet and her colleagues from Stanford University managed to "purify" stem cells from old proteins and thereby restore their ability to grow and divide. They talk about this in an article published by the magazine Science.
The discovery of protein aggregates in young stem cells was unexpected for scientists themselves: it is believed that their accumulation is associated with senile neurodegenerative processes. However, the finding once again highlighted the importance of "intracellular hygiene" and effective protein metabolism for the health and functionality of neurons. "We were surprised because dormant, passive neuronal stem cells are thought to be such 'untouched' cells just waiting for activation," says Anne Brunet.
Protein aggregates accumulate in them even faster than in actively working stem cells, since their ability to utilize these molecules is lower. Proteins are enclosed in lysosomes – scientists have shown that the corresponding genes continue to work in "sleeping" stem cells, but they are not processed: the genes of the proteases necessary for this remain switched off. So, despite the slower metabolism of proteins, the resting cell accumulates them much more, and its lysosomes grow.
"Sleeping" neural stem cells (nuclei are colored blue) accumulate large protein aggregates (pink) inside and around lysosomes (green). Xiaoai Zhao, Stanford University School of Medicine.
Over time, this process only accelerates, and the stem cell loses its ability to respond normally to activation signals; the body loses another opportunity to recover. However, scientists have shown that if you force an old resting cell to activate protein processing, it "rejuvenates" and returns functionality. To do this, the authors started the work of proteases directly, or placed the cell in conditions of resource scarcity, in which it almost completely stopped the synthesis of new proteins and gradually "purified" itself. Perhaps in the future, drugs will be found that perform such a "cleansing" in the human brain, restoring its invaluable resource of regeneration.
Portal "Eternal youth" http://vechnayamolodost.ru