Telomeres are repeated DNA sequences which are found at the end of the chromosomes. To explain how important telomeres are, an analogy between telomeres and the tip of a shoe laze, the aglet, can be made. If you remove the aglet, the whole shoe laze basically falls apart. The same with telomeres, as they get shorter after each cell replication, the integrity of the genetic material is in danger.
We do not care about losing telomeric DNA, since it does not code for proteins. Telomeres main function is to protect the important genetic material, whose deletion would be fatal and could give rise to cancers and many malfunctions. Most somatic cells, cells forming the body of an organism, have a life span of 45-50 divisions. This is due to the fact that after each cell division, telomeres get progressively shorter until the point that there is almost no more telomeric DNA to protect the genetic material, and the cell basically kills itself (apoptosis).
However, there are some cells that cannot be allowed to die, like germline cells, which give raise to gametes. If these cells died due to apoptosis, there would be no living things on this planet. So how to overcome this shortening in germline cells?. The answer is telomerase. This enzyme is in charge of adding the telomere repeats at the chromosome ends so this cells do not die. However, there must be a balance in doing so.
Most cancer cells are basically immortal because telomerase is always active. This is the yin and yang that is posed by telomeres and telomerase; they can make you immortal as well as give raise to cancers. There are nonetheless some interesting organisms that are worth studying in the search for immortality, one of them being the naked mole rats.
You might be thinking right now, what is that? And that was my first reaction when I first saw a naked mole rat. Even though it may not be nice looking (I had some lab partners that thought it was cute…) it is an extremely interesting animal.
These creatures they rarely get cancer and they can survive up to 18 minutes without oxygen. And furthermore, they DO NOT AGE. For an animal with a similar physiology, such as common rats, the life expectancy is around 6 years. On the other side, naked mole rats they live past 30, with no apparent signs of aging.
The only reason why scientists know that naked mole rats can live longer past 30 is because a scientist in Calico, Google owned business that is working on aging, has a specimen of over 35 years. I guess at this point is part of the family now.
As a scientist working on a telomere lab, I think this naked mole rat could be a really exiting model organism to study aging. As I talked in previous blogs, shorter telomeres are related to senescence, so what do telomeres look like on naked mole rats? How is telomere biology different from a mouse to a naked mole rat? All of these answers, perhaps provided by Calico within the following years, will give new insights into aging and immortality.
---Borja Barbero Barcenilla
Borja Barbero Barcenilla is a doctoral student in the Department of Biochemistry