Telomeres: What They Are, Characteristics And How They Are Linked To Age
Time passes for everyone, and that is an undeniable reality. Conceiving life without death is impossible, since all organic matter degrades, loses shape and transforms. Without going any further, the most appropriate definition that comes to mind to define life from a biological point of view is the following: the intermediate state between birth and death.
Time passes inalienably, yes, but you will be surprised to know that it does not do so in the same way for everyone. Chronological (chronometric) age indicates the movement of the clock hands, but this physical magnitude has nothing to do with what happens inside our bodies. The phases of a biological process do not have the same quality or nature as those of a physical process as they are merely successive.
In the physiological study of living beings, the phases of a process are determined by the dynamics “of the intrinsic process”, and not by the impositions of a physical element, such as a clock. Thus, a 40-year-old alcoholic person may have the liver of an 80-year-old, for example, while an octogenarian athlete may have the lower body muscles typical of a sedentary 60-year-old person. Time passes, yes, but biological age may be different from what the calendar indicates
Many of the parameters that modify the biological age of living tissues are completely linked to the individual’s lifestyle, but there are other complex and fascinating concepts that explain, in part, why the cellular aging process is unique and interchangeable. We explain the secret of life and death with a term as exciting as it is useful: know everything about telomeres
How are chromosomes organized and where are the telomeres?
Let’s start from the beginning, like life itself. Human beings present, in each of our cells, DNA enclosed in a nucleus. Through a series of processes that do not concern us here, the DNA information is transported from the nucleus to the ribosomes of the cell cytoplasm, so that they can synthesize proteins. Protein synthesis is the basis of the metabolism of living beings, so it could be said that DNA contains all the information necessary for life to be such
In humans, DNA condenses into chromatin, forming chromosomes. Each non-sexual cell in our body (generally) has 23 pairs of chromosomes (46 total), of which 23 come from the female gamete (n) and 23 from the male gamete (n), which when put together form a zygote (2n) . The parts of a chromosome are the following:
We have left some specific sections in the pipeline in order not to get lost in technicalities, but we have already encountered the term that concerns us here for the first time. It’s time to explore it thoroughly.
What are telomeres?
Based on what we have seen so far, the telomere defines itself almost by itself: is the tip of the chromosome Telomeres are highly repetitive regions of non-coding DNA (they do not have information necessary for protein synthesis), whose function is to provide stability to chromosomes in eukaryotic cells throughout their life. Based on the existence of these structures, we can partially explain two phenomena that take the breath away from every human being: aging and cancer. Let’s see how.
1. During DNA replication, telomeres do not replicate in their entirety
Somatic cells divide by mitosis and, for this to be possible, the DNA of the original cell must be duplicated, which will give rise to the lineage of descendants. With each replication process, and due to certain characteristics of the enzymes that make it possible, telomeres shorten
Telomere length in humans decreases at a rate of 24.8-27.7 base pairs per year. With time and cell division, the telomeres of the chromosomes of the descendant cells become so short that the cell can no longer divide, and therefore, with the death of the last cellular entities, tissue death occurs. Making a parallel of “walking around the house”, it is as if we remove a little water every time we pass it from one glass to another. At first it may not be noticed, but after repeating the process X times, the transfer can no longer be done, since there is no water left to transfer.
For this reason, Telomeres are said to be an excellent marker of biological age: Based on its length, scientists can estimate how far a cell group and, therefore, the entire organism has to go. Telomere shortening is part of the normal aging process, but certain agents associated with a specific lifestyle can promote chromosomal DNA damage and, therefore, more rapid telomere shortening.
2. The importance of telomerase
We have explained the mechanism of old age, but things get even more interesting if we know that, as incredible as it may seem, the body itself has the solution for immortality on a theoretical level, at least in the first stages of life.
Telomerase is an enzyme responsible for maintaining telomere length by adding repeated genetic sequences This biological process has a “trick”: the activity is present in germline cells and certain hematopoietic cells, but mature somatic cells inhibit their functionality after birth. Thus, it is the organism itself that encodes its programmed degradation.
3. Telomeres and cancer
Current studies suggest that humans could reverse the process of cellular senescence if we artificially increased telomerase activity in the somatic cells that make up the tissues of our body. Unfortunately, this could have a double effect: in experimental settings, if telomerase activity is stimulated and certain tumor suppression genes are inactivated, a cellular immortalization that significantly promotes the appearance of a tumor
We go further in this line of thought, since 75-80% of cancers arising from somatic cells present telomerase activity. This does not necessarily mean that telomerase causes cancer, but everything seems to indicate that high levels of this enzyme are a clear indication of the possible malignancy of a tumor. If a cell is immortal, it can replicate indefinitely: we are explaining almost word by word the formation of cancer.
Based on this premise, various anti-telomerase treatments are being developed experimentally. In cell cultures, the results are promising to say the least: In some cancer cell lines, by inhibiting the activity of telomerase, a spontaneous death of the line occurs after about 25 divisions since the telomeres shorten and cannot be replaced in any way.
Summary
After the exposure of data like this, it is impossible not to feel hopeful. Cancer is one of the most important and tragic health problems today, because behind each death and each figure there is a story of struggle, sadness and hope. A neoplastic tumor is not just a group of cells growing uncontrollably: it is fear, a battle of science against physiology, acceptance or denial and, in the worst case, the early loss of a life.
The mechanisms of cellular senescence help us understand the aging of tissues and the process that leads us to death, but the ultimate goal is not to find immortality. The real challenge, today, is to save all those lives that are hanging by a thread by a group of rebel cells that mutated to turn against their host.
