Télomères & Télomérase

Light is gradually being shed on the ageing mechanisms as science advances. The most recent discoveries, rewarded with a Nobel Prize, pinpoint cells, their DNA and more particularly telomeres as being at the heart of the ageing process. The double-helix structure of DNA, which is present in all living cells, contains all the information required for the development and satisfactory functioning of living organisms. At the ends of these structures, like breakable plugs, there are the precious telomeres, which are greatly implicated in the ageing process as they get shorter under the affect of age, pollution, stress and an unhealthy lifestyle. It is the telomerase enzyme that is responsible for cell renewal, through until the complete depletion of our youthfulness.


Three Nobel Price

In 1971, the Russian biologist Alexey Olovnikov put forward the hypothesis that the maximum lifetime of cells is correlated with the gradual loss of telomeric sequences, because at the time of each cell division the telomeres are eroded until they reach a critical size which causes the cell to enter a state of senescence (with the telomeres acting like a biological clock that governs the length of cells’ life).

 

This is known as the Telomere Theory of Ageing. This biologist predicted the existence of an enzyme capable of reversing this process by synthesizing new sequences of telomere DNA: telomerase. Telomerase was officially identified in 1985 by Elizabeth Blackburn, Carol Greider and Jack Szostak, whose work was rewarded with the Nobel Prize in Physiology or Medicine in 2009.

 

 

 

 


Telomeres explained by Dr. Christophe BENETTON, researcher and physician

 

Telomerase reactivation halts and reverses the ageing process in telomerase-deficient mice.

 

 

Summary:

The losses of information from DNA linked to its gradual deterioration over time have been clearly associated with the ageing process. In particular, the loss of the DNA protection function owing to telomeres causes ageing, and cell death in animal models. In humans, studies have shown that people whose telomeres are bigger generally enjoy better health and live longer. Maintaining the integrity of telomeres would therefore appear to be a priority goal in the struggle against ageing. The length and integrity of telomeres depends on an enzyme, telomerase. Promoting the activity of this telomerase would therefore seem to be an effective anti-ageing strategy.

This study on mice, published in the renowned journal Nature, not only confirms that the alteration of telomeres is linked to ageing but also and above all demonstrates that the restoration of telomeres halts and even reverses cell and tissue ageing mechanisms.

This is a crucial study because it is the first to have shown it is possible to reverse the ageing process of genetic origin. The technique used in this study consists of incorporating genetic material which, in practical terms, is still impossible. However, on the basis of this study, the development of active substances that have a protective effect on telomeres, in particular by acting on the telomerase, offers extremely promising perspectives in the struggle against ageing.

 

The study:

Telomerase is one of our cells’ enzymes whose role is to reconstitute the telomeres at the time of each cell division. When there is a telomerase deficiency, a shortening of the telomeres can be observed, and the signs of ageing start to appear. In this study, a particular gene was introduced into mice embryos by replacing the normal telomerase-coding gene. This artificial gene has the information required for producing telomerase but it is inactive. It can only be activated and produce telomerase in the presence of an appropriate substance. This manipulation has therefore made it possible to obtain telomerase-deficient mice that could recover this function.

 

Results:

The deficient mice obtained presented all the signs of premature ageing:

  • Senescent cells, in particular fibroblasts (cells responsible for the volume, firmness and smoothness of tissues),
  • Atrophy of tissues and organs (spleen, liver, testicles, intestines, brain),
  • Brain ageing: lowering of the number of brain cells and reduced neurogenesis (development of new neurons),
  • Halving of the median survival rate: 43.5 weeks instead of 86.6 weeks.

These results confirm the effects of the loss of telomerase activity on the ageing process.

 

In the second phase of the study, a group of deficient mice benefitted from the treatment for four weeks. As expected, these mice recovered their telomerase activity and saw a lengthening of their telomeres. More surprising, however, were the effects on their organs and tissues whose appearance after four weeks was identical to that of the control mice: volumes and architecture returned to normal in the spleen, liver, testicles (with restored fertility) and intestines, not to mention the brain. Likewise, survival was significantly improved thanks to these four weeks’ “treatment”. Analysis of brain tissue has shown the partial recovery of the capacity to renew neurons and other brain cells. The researchers used the mice’s reaction to odours to assess part of their brain function. There again, the capacity to distinguish between smells – altered in the deficient mice – was restored in the treated mice.

 

Conclusion:

This study demonstrates in an animal model that the ageing processes can be reversed and that the restoration of a declining telomerase activity seems crucial. These results cannot, however, be transposed without reservation to human ageing: in particular because “sick” animals were used for this experiment and not normally ageing animals. By showing for the first time it is possible to reverse the ageing processes, this study nonetheless remains extremely encouraging and justifies the interest shown in developing human therapies aiming to stimulate or restore telomerase activity.


DNA & Europe’s scientific backing


Telomeres shorten with age, inflammation and stress. Studies have shown that short telomeres are associated with a greater risk of age-related diseases. Certain assets contained in DNA Telomeractives,benefit of allegations proven health or under consideration by EFSA as Astragalus, "traditionally used against free radicals that cause damage to cells and tissues; antioxidant activity and anti-aging"(from two tablets - 100 mg of extracts corresponding to 2880 mg of dry roots), or even the zinc, which contributes to the normal DNA synthesis.

 

Lead more about the health claims confirmed by the EFSA group of scientific experts relative to DNA protection, by clicking on the following link:  

 

acces tothe list of vitamins and minirals and access to the lists of plants

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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