"Telomeres"—have you encountered that term yet? It seems that interest in telomere length and how to lengthen telomeres is reaching somewhat of a fever pitch.
Researchers describe telomeres as the cellular equivalent of the plastic tips placed on the ends of shoelaces to prevent fraying. The material telomeres keep intact, however, is your DNA.
When a cell divides and replicates, the replication does not include the full length of the DNA strand—a small section from the ends does not get copied. Telomeres cap the ends, ensuring nothing vital gets left out of the replicated cell. Each time a cell divides, a little bit of the telomeres at its ends gets left behind. So, over time, telomeres become shorter and shorter. When they get too short, the cell they're attached to stops replication and enters senescence. The accumulation of senescent cells in the body is thought to contribute to the development of many age-related health conditions, such as:
A wealth of research indicates linkages between length of telomeres and overall health. While some have interpolated that to mean that short telomeres indicate a short lifespan, others feel it's more complex than that.
Here's what you should know about telomeres, the vital role of an enzyme called telomerase, and how to lengthen telomeres (including a very accessible option).
What Are Telomeres?
The word telomere is derived from Greek (as many medical terms are)—specifically, the word "telos," which means end, and the word "meros," which means part. Scientists suspect that short telomeres may be a contributing factor to the development of many chronic diseases, while geroscientists think it's possible that the shortening of telomeres may drive the entire aging process.
Telomere shortening can be thought of as the lighting of a fuse attached to a cell. With each cell division, telomeres grow shorter until (to continue the metaphor) the flame gets too close to valuable genetic information, triggering cellular senescence or apoptosis (cell death).
Technically speaking, telomeres are repeated sequences of DNA that keep our chromosomes stable during cellular division and protect our genetic information. Thus, shorter telomeres correlate with an increased risk of cancer and other diseases linked to genetic malfunctions. Telomeres also regulate the cellular aging process, dictating how many times a cell can safely divide. Scientists used to believe that cells could replicate indefinitely, and research into telomeres has been a vital component of efforts to better understand cellular replication and its effect on human health.
The Science of Telomeres
Pioneering scientists Hermann Muller (who gave telomeres their name) and Barbara McClintock were the first to recognize that telomeres appeared to have a protective function. After their groundbreaking work in the 1930s, however, it would take several more decades for researchers to comprehend how telomeres functioned in relation to cellular aging.
One reason for that was the persistent assumption that cells could divide endlessly, an incorrect belief that was shattered at last in 1961 when two scientists from the Wistar Institute of Anatomy and Biology in Philadelphia, Pennsylvania discovered that cells can only divide a limited number of times. For the lung cell cultures they observed that limit appeared to be set around 40 or 50 divisions.
The next decade ushered in the work of Elizabeth Blackburn, an icon in the field of human telomere research. At Yale University in the 1970s, she became the first to identify a telomere sequence.
Another major breakthrough took place in 1998 when a research team based in Menlo Park, California found that artificially extending the length of the telomeres attached to cells could allow them to continue dividing indefinitely, thereby officially "establishing a causal relationship between telomere shortening and in vitro cellular senescence."
Then, in 2009, Elizabeth Blackburn, Carol Greider, and Jack Szostak won a Nobel Prize for their discovery of telomerase, an enzyme that lengthens telomeres and which remains shut off in most cells after the early phases of growth.
Since then, telomeres have become a hot topic among those interested in healthy aging. "Once telomeres became popular knowledge, all sorts of people came out of the woodworks selling nutraceuticals, natural products, claiming that it was the fountain of youth,” explained Jerry Shay, a biologist at the University of Texas Southwestern Medical Center who specializes in telomeres, in an interview.
Understanding the Role of Telomerase
As touched on briefly in the preceding section, the enzyme telomerase is responsible for telomere lengthening. When it restores length to telomeres, it bestows the cells those protective caps that are correlated with a longer lifespan. Because of this, some experts in the field of geroscience believe that increasing the body's supply of telomeres can safeguard—and even restore—the length of our telomeres. This, in turn, will help to prevent the development of age-related diseases.
While a number of different proteins contribute to telomere upkeep, telomerase carries out the most important role—it rebuilds the ends that get shortened during cellular division.
As established earlier, the cells of the body can't replicate indefinitely. To be more precise, however, somatic cells can't replicate like that. Stem cells, however, are immortal. To continue dividing without compromising genetic code, stem cells use telomerase to rebuild the ends of their telomeres. With perpetually long telomeres in place, they can carry on dividing, and dividing, and dividing. Telomerase keeps their telomeres at a consistent length regardless of how many times they divide, allowing them to continue with their vital work, which includes tissue growth and regeneration.
It is because ordinary, somatic cells do not use telomerase that they can only divide a limited number of times.
So, you might be thinking that supplementing with telomerase would have to be the most effective anti-aging treatment ever. And in a sense, you'd be right. But scientists worry this approach could come with serious adverse side effects. You see, there's another type of cell that uses telomerase—cancer cells. That's why they're able to replicate so ruthlessly. Experts worry that if telomerase levels rise too high, that could fuel the growth of cancer.
How to Lengthen Telomeres
Because of the potential risks associated with telomerase therapy, research so far has been conducted with rodents. That said, the results have been highly encouraging.
A 2012 study published in EMBO Molecular Medicine found that the use of telomerase gene therapy in adult mice successfully extended lifespans without increasing cancer risk. They found that higher levels of telomerase translated to "remarkable beneficial effects on health and fitness, including insulin sensitivity, osteoporosis, neuromuscular coordination and several molecular biomarkers of aging." Even more impressive, however, were the increases to lifespan—an increase of 13% for 2-year-old mice and 24% for 1-year-old mice.
While this seems to indicate telomerase therapy could be an effective anti-aging tool, allowing us to live longer, healthier lives, it's important to remember more research is needed to corroborate those findings. There are (obviously) many differences between humans and mice, including that mice have longer telomeres than humans at baseline.
That said, the results of in-vitro, test-tube studies have also shown that adding telomerase makes it possible for cells to continue to replicate long past the point at which they would typically undergo senescence or apoptosis.
Another interesting approach to lengthening telomeres is the use of RNA therapy. Dr. John Cooke, department chair of cardiovascular sciences at Houston Methodist Research Institute, led a team in analyzing whether RNA therapy could lengthen the telomeres of human cells, albeit in test tubes.
To do so, Cook and his team harvested cells from children living with progeria, a condition that causes such rapid aging, most who have it die in their teens. Earlier studies had already established that children with progeria have markedly short telomeres.
Before the RNA treatment, the harvested cells multiplied poorly and died quickly. Once the RNA was inserted, “cells proliferated normally," stated Cooke. "It was a dramatic improvement.“ He noted, too, that the RNA treatment rolled back other indicators of aging, like the presence of inflammatory proteins.
A More Accessible Option
While findings on the use of telomerase and RNA are certainly exciting, it's unlikely that most people will have access to these treatments in the near future. Luckily, there's a more accessible way you can directly impact the health of your telomeres.
Vicki Lundblad, a professor in the Molecular and Cell Biology Laboratory at the Salk Institute for Biological Sciences, led a team who identified a key protein group that helps lengthen telomere ends. Through analysis of the structure of human telomerase, Lundblad uncovered three EST proteins—known as Est1, Est2, and Est3—that make major contributions to telomerase activity. Est2, along with RNA, does the cellular heavy lifting necessary for reconstructing telomeres, while Est1 and Est3 ensure that process progresses smoothly. Both Est1 and Est3 make unique contributions. Est 1 transports telomerase to the telomeres. “Without Est1, telomerase cannot get to the ends of chromosomes, and thus telomeres shorten,” Lundblad stated.
Ongoing analysis is centered on clarifying the role of Est3. What the team knows so far is that it uses specific amino acids to interact with telomerase. When the team inactivated those amino, shorter telomeres were produced, indication that telomerase activity had been measurably impaired.
In other words, without amino acids, the body cannot utilize telomerase. Yet another reason to ensure your body always has a ready, more-than-adequate supply of essential amino acids.
Telomeres ensure that the cellular division process does not result in the loss of genetic material. Instead, each time your cells divide, a section of your telomeres gets left behind. When telomeres become too short, cells stop dividing and become inactive.
This has led to intense interest in how to preserve and lengthen telomeres. Research indicates that both telomerase therapy and RNA treatments could possibly be effective interventions. However, it will likely be some time before those treatments become available to the public.
In the meantime, a new study points to amino acids as a possible method for enhancing the health of your telomeres. Given the many benefits associated with amino acids, this seems like a telomere-lengthening strategy worth trying.