DNA
strands on the end of our chromosomes hint when
Brigham Young University, Science
Daily
BYU biologist Jonathan Alder has a startling secret he doesn't
freely share: he knows when most of us are going to die.
OK, he doesn't know exactly the day or time, but he has a pretty
good idea, thanks to his research on tiny biological clocks attached to our
chromosomes. These DNA end caps, called telomeres, are the great predictors of
life expectancy: the shorter your telomeres, the shorter your lifespan.
But that's not the only thing these fascinating strands of DNA
predict. Shorter telomeres also indicate a greater chance for bone marrow
failure, liver disease, skin disease and lung disease.
"When we are born, our telomeres are longer. As you get
older, they shorten," said Alder, an assistant professor of physiology and
developmental biology at BYU. "What we have found is that if you look at
individuals with lung disease, they have shorter telomeres than the rest of
us."
Alder is currently studying the gene mutations that cause people
to have unnaturally short telomeres. Recent research he coauthored with
collaborators at Johns Hopkins University, published in the Journal of
Clinical Investigation and Chest, finds those mutations
are connected to both pulmonary fibrosis and emphysema.
Telomeres are the protective tip of our chromosomes, kind of
like the plastic cap on the end of a shoelace. Each time a cell divides and
replicates, the DNA at the end of telomeres shorten. Since cell division
happens throughout life, telomeres get shorter and shorter as we age.
When the telomeres run out, the cell becomes inactive or dies,
which leads to disease. Some scientists have figured out ways to lengthen
telomeres, but that isn't the magic bullet either: telomeres that keep their
length can lead to other complications like cancer.
"This is a definite Goldilocks situation," Alder said.
"Too little, you age prematurely; too much, you could get more serious
diseases. You need to be just right."
The findings from the research team on emphysema -- one of the
leading causes of death in the U.S. -- are particularly important.
The
researchers found that a fraction of individuals who develop sever emphysema
have mutations in one of the genes responsible for maintaining telomeres. Since
mutations in telomere genes are known to cause pulmonary fibrosis, these
findings link two diseases that were previously thought to be unrelated. These
mutations have implications for future generations too.
"Families with telomere mutations pass those down the line,
meaning offspring start off with shorter telomeres," he said. "With
each passing generation the disease gets worse and they get it at an earlier
age."
While only people with very short telomere length are at greater
risk for lung diseases, finding the connection was unexpected. Alder's research
on the matter, which started at Johns Hopkins and has continued here at BYU,
will now focus on why it is happening.
"Most people don't realize that lung disease is the third
most common cause of death in the United States," said lead researcher
Mary Armanios, associate professor of oncology at John Hopkins University
School of Medicine. "Telomere research has its most significant direct
public health benefit in the area of lung disease."
Research has already shown that smokers are at a great risk for
lung disease. This new research could mean those with telomere mutations who
smoke -- even for a brief part of life -- could be at an even greater risk.
Story Source:
The above story is based on materials provided
by Brigham Young University. Note:
Materials may be edited for content and length.
Journal References:
Jonathan K. Alder, Susan E. Stanley, Christa L. Wagner, Makenzie
Hamilton, Vidya Sagar Hanumanthu, Mary Armanios. Exome sequencing
identifies mutantTINF2in a family with pulmonary fibrosis. CHEST
Journal, 2014; DOI:10.1378/chest.14-1947
Susan E. Stanley, Julian J.L. Chen, Joshua D. Podlevsky,
Jonathan K. Alder, Nadia N. Hansel, Rasika A. Mathias, Xiaodong Qi, Nicholas M.
Rafaels, Robert A. Wise, Edwin K. Silverman, Kathleen C. Barnes, Mary Armanios. Telomerase
mutations in smokers with severe emphysema. Journal of Clinical
Investigation, 2014; 125 (2): 563 DOI: 10.1172/JCI78554
Cite This Page:
Brigham Young University. "We're all going to die; DNA
strands on the end of our chromosomes hint when." Science Daily,
6 February 2015.
<www.sciencedaily.com/releases/2015/02/150206125342.htm>.