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How cells get younger again

How cells get younger again

Researchers discover fountain of youth for cells

Scientists from Ulm have tracked down a fountain of youth for cells. As they report in the research magazine of the German Research Foundation (DFG), the protein "RhoGTPase Cdc42" is responsible for the aging process of stem cells. As stem cells age, they are no longer able to produce blood properly, so the body's immune system is weakened and less red blood cells are produced. This leads to age-related anemia, which leads to a weakening of the body. In experiments with genetically modified mice, the scientists recently succeeded in reversing this process by inhibiting protein activity and rejuvenating the cells.

Aging of the blood stem cells leads to weakening of the body Hartmut Geiger, professor of dermatology and allergology at the Ulm University Hospital, and his team investigated the aging process of blood stem cells in mice. Blood-forming stem cells are mainly found in the bone marrow, where they form countless new blood cells every day. They produce the red blood cells responsible for oxygen transport and the white blood cells, which play an important role in the immune system. They also form platelets, which are responsible for the blood's clotting. While blood cells have a limited lifespan and do not divide, blood stem cells can be divided almost indefinitely. Only the aging process means that the stem cells can no longer form blood properly.

Geiger and his colleagues succeeded in reversing this phenomenon in mice after they first demonstrated that blood stem cells age faster due to an increased activity of the protein RhoGTPase Cdc42. The researchers observed that the inhibition of the protein in the mice led to a reorganization of the stem cells, which rejuvenated them sustainably. “So the aging process could be reversed at this point. This approach could initially help in the mouse to ensure that its immune system still functions well in old age and that age-related anemia is slowed down, "writes Geiger in the specialist magazine Find out research in the next few years, but it is clear that aging at the molecular and cellular level does not have to be a one-way street. ”

Can aging be stopped in the future? In the future, it could therefore be possible not only to stop the aging process, but also to reverse it. But until then it is still a long way. Because not only the blood stem cells but also all other cells of the body age. The function of the organs also deteriorates with age. If research succeeds in deciphering this process, the lungs, heart, kidneys and liver could also function longer and better. This could make an important contribution to health in old age, which would ultimately enable a longer, healthier life. At the moment, however, the aging researchers are not yet concerned with concrete measures, but rather with deciphering the molecular mechanisms of cell aging.

"Above all, model organisms such as yeast, roundworms, fruit flies and mice help the scientists to get to the bottom of the aging process," says Geiger. Their main advantage is that they age very quickly compared to humans. With a yeast cell it was a few days, with a mouse three years. Meanwhile, it is also known that some mechanisms of aging in yeast, worms and mice function very similarly, explains the scientist. This could suggest that the results can at least partially be transferred to the human organism.

Telomeres have an influence on the aging of the cells. Regardless of these mechanisms, each organism also ages individually, because each cell contains individual DNA, genetic material that, among other things, codes the blueprints for the cell proteins. These proteins and protein compounds supply the cell with everything it needs. Since cell aging is associated with reduced cell function, researchers suspect that both damaged DNA and damaged proteins are responsible for the aging process.

In this context, research also focuses on so-called telomeres, which were discovered by the American cell biologists Elizabeth Blackburn, Carol Greider and Jack Szostak. The researchers received the Nobel Prize in Medicine for this. Telomores are the end pieces of chromosomes, the carriers of the genetic material of the cells. They sit like protective caps at the end of the chromosomes and ensure that they do not fray. In this way, the telomeres prevent the ends from not being recognized as damaged genetic material and from being fought by the immune system. “However, the telomeres shorten with each cell division. If they fall below a critical length, the cell stops dividing or dies. The older a person, the shorter the telomeres of their chromosomes are, therefore, “reports Geiger. “The protein telomerase is a kind of antagonist that slows down the aging process by ensuring that these protective caps are not too short. But not all cells have enough of this life-extending enzyme. One theory assumes that the length of the telomeres is an indicator of the life expectancy of the cell. ”Nevertheless, therapy with telomerase drugs would not be a solution, since not only stem cells but also cancer cells contain telomerase. Thus, telomerase drugs would slow down the aging process, but at the same time they also promote cancer. (ag)

Image: Jens Goetzke / pixelio.de

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