Telomeres, the protective cap at the ends of your chromosomes that get a little shorter with every cell division, are clearly an important aspect in cellular aging; allowing immortal cell lines when prevented from shortening. Telomere biology is somewhat controversial however and has been the subject of great debate since their discovery, one camp believing they shorten for a good reason and prevent cancer occurring more frequently. As more evidence has emerged however, the picture has become much more complex, with shortened telomeres themselves paradoxically increasing cancer risk in some cases.
Although animals have very different telomere lengths and rates of attrition, when mice underwent gene therapy in a study to increase their levels of telomerase (an enzyme that repairs and lengthens telomeres), this delayed many aspects of aging and unexpectedly didn't increase cancer rates. Although evolution has generally conserved this telomere shortening process, it may be for a different reason than a brake on cancer. In recent modelling, animals that live in a plentiful environment seem to develop longer lifespans, while those with sparse food tend to develop shorter ones, suggesting there is some evolutionary pressure on various mechanisms to cap lifespans when resources are limited. Whilst telomere attrition is certainly not the sole cause of aging and may indeed play a protective role to a point, the picture is looking increasingly complicated; they might well help get rid of some damaged cells, but they also create genomic instability which can lead to all sorts of problems. Any theories are all rather speculative at this point, but ever more research is linking defective telomeres to a big range of diseases and cancers.
'Telomere syndromes, or telomeropathies, have been identified in patients with mutations of the telomerase enzyme. This group includes, for example, pulmonary fibrosis and problems related to the malfunction of the bone marrow. A direct relationship between telomere dysfunctions and many types of cancer has also been found. More recently, we have also discovered that mutations of the proteins that protect telomeric DNA, the shelterins, and those that interact with the telomeres, are linked to various diseases, such as dyskeratosis congenita, Hoyeraal-Hreidarsson syndrome or Revesz syndrome'
It's too early to jump to conclusions and it may be some time before the overall picture is clarified, but telomere biology is clearly an important area to study further and may yield some promising treatments for disease in the future.
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