Aging is inevitable no matter how much you exercise, sleep or eat healthy. There is no magic pill or supplement that can thwart growing older. However, preventing certain age-related diseases is a different story. Genetic mutations can raise the risk of acquiring age-related diseases like heart disease, diabetes, cancer and dementia. And scientists are on the hunt for treatments that target these mutations in hopes of preventing these diseases from happening.
Another genetic component that can accelerate diseases of aging are telomeres. These are caps made up of repeat sequences of DNA that sit at the ends of chromosomes and prevent the loss of important genetic material housed within chromosomes. Healthy cells have long telomeres, and ascells divide these telomeres begin to shorten. If telomere shortening is left unchecked, cells become unhealthy and either stop growing or self-destruct.
Cells have machinery to regrow their telomeres, but in most cases, the machinery isn’t activated and over time, the resulting shortened telomeres can lead to problems like an impaired immune system and organ degeneration. Shortened telomeres are associated with age-related diseases, but the reasons why have remained elusive until recently.
Scientists from the Gladstone Institutes have found a clue to this telomere puzzle that they shared in a study published yesterday in the Journal of Clinical Investigation. This research was funded in part by a CIRM Discovery stage award.
In their study, the team found that mice with a mutation that causes a heart condition known as calcific aortic valve disease (CAVD) were more likely to get the disease if they had short telomeres. CAVD causes the heart valves and vessels to turn hard as rock due to a buildup of calcium. It’s the third leading cause of heart disease and the only effective treatment requires surgery to replace the calcified parts of the heart.
Old age and mutations in one of the copies of the NOTCH1 gene can cause CAVD in humans. However, attempts to model CAVD in mice using the same NOTCH1 mutation have failed to produce symptoms of the disease. The team at Gladstone knew that mice inherently have longer telomeres than humans and hypothesized that these longer telomeres could protect mice with the NOTCH1 mutation from getting CAVD.
They decided to study NOTCH1 mutant mice that had short telomeres and found that these mice had symptoms of CAVD including hardened arteries. Furthermore, mice that had the shortest telomeres had the most severe heart-related symptoms.
First author on the study Christina Theodoris, explained in a Gladstone news release how telomere length matters in animal models of age-related diseases:
“Our findings reveal a critical role for telomere length in a mouse model of age-dependent human disease. This model provides a unique opportunity to dissect the mechanisms by which telomeres affect age-dependent disease and also a system to test novel therapeutics for aortic valve disease.”
The team believes that there is a direct relationship between short telomeres and CAVD, likely through alterations in the activity of gene networks related to CAVD. They also propose that telomere length could influence how severe the symptoms of this disease manifest in humans.
This study is important to the field because it offers a new strategy to study age-related diseases in animal models. Senior author on the study, Dr. Deepak Srivastava, elaborated on this concept:
“Historically, we have had trouble modeling human diseases caused by mutation of just one copy of a gene in mice, which impedes research on complex conditions and limits our discovery of therapeutics. Progressive shortening of longer telomeres that are protective in mice not only reproduced the clinical disease caused by NOTCH1 mutation, it also recapitulated the spectrum of disease severity we see in humans.”
Going forward, the Gladstone team will use their new mouse model of CAVD to test drug candidates that have the potential to treat CAVD in humans. If you want to learn more about this study, watch this Gladstone video featuring an interview of Dr. Srivastava about this publication.