The Fountain of Youth is a famous legend, a supposed wellspring of eternal life that was discovered by Ponce de Leon. Unfortunately, the Fountain of Youth and the immortality elixir don't actually exist. However, telomeres might be the closest thing we’ve got to a magical cure for eternal life!
So what is a telomere, what does it do, and why are they important? Essentially, telomeres are little caps that go on the ends of chromosomes. In fact, the word telomere literally comes from the Greek words, telos ‘end’ and meros ‘part’. Telomeres are composed of many repeating sequences of TTAGGG/AATCCC. They protect the DNA within, which is made of base pairs that code for genes. Chromosomes need to replicate to produce new chromosomes to be in the daughter cells when the cell divides. This is called DNA replication which is when one original DNA molecule creates two replicas! Each time DNA replication occurs, some important DNA base pairs could be lost because of the way primers, which help DNA replicate, miss some DNA bases. Luckily, telomeres help prevent that.
Telomeres “sacrifice” themselves so their base pairs are lost instead of the actual genes. Telomeres “die”, instead of the important DNA. Unfortunately, every time a chromosome undergoes replication, the protective telomere shortens and becomes less effective, eventually triggering cell death. Under the Hayflick limit, a normal human cell can only divide about sixty times before dying since the telomeres get shorter. In white blood cells, telomeres are around 8,000 base pairs long in babies, but as little as 1,500 in the elderly, for example.
As people age, they often get many severe health complications that decrease lifespan and make life more difficult. Research has shown that some of these diseases like diabetes and cancer could be linked to rapidly shortening telomeres!
One study by Munoz-Lorente et al. found that mice with longer telomeres lived an average of 24 percent longer! That’s the equivalent of about 20 years longer for humans! They also found that signs of aging and the chances of developing cancer were less.
Meanwhile, in humans, Richard Cawthorn and his team found that in people over 60, shorter telomeres were associated with a 3X greater chance of dying from heart disease and 8X greater chance of dying from infection. This shows that telomeres play an important role in disease and aging.
If we can find a way to control telomeres safely, then this can have revolutionary impacts on humans. We could have longer, healthier, happier lives. One idea is to harness the telomerase enzyme that makes telomerase, to restore telomeres! Another idea plans to treat cancer by inhibiting the telomerase enzymes that restore the telomeres in cancer cells.
This picture shows a detailed guide for how telomeres protect chromosomes. Credit to Learn Genetics Utah.
Extension Questions:
What is a possible medical application of telomere restoration?Research Online: Do animal species with longer telomeres live longer than species with shorter telomeres? Why? Are there exceptions?What other factors go into aging, besides telomeres? Which do you think is most important?Besides replication, what other things can shorten telomeres?Who first discovered the function of telomeres? (Hint: Three scientists)How many base pairs is one telomere repeating sequence?More information about telomeres and citations:
Image credit:
by Sarah Gao and Andrew Gao