Junk DNA Gains Respect
John Moran
Photo: Martin Vloet |
Junk DNA is the Rodney Dangerfield of the genetics world. It makes up nearly
half of all human DNA, but since it doesn’t include genes, many scientists
dismiss it as useless gibberish. New U-M research, however, suggests that segments
of junk DNA called LINE-1 or L1 elements deserve more respect.
“L1s have helped build our genome and their movement continues to influence
its evolution,” says John V. Moran, Ph.D., an assistant professor of
human genetics and internal medicine in the U-M Medical School, recruited here
as part of the prestigious Biological Scholars Training Program. Moran is one
of only a few scientists who study L1s in the human genome. “The more
we learn about L1s, the more we’ll learn about the evolution of the human
genome,” he says.
“Some L1 elements are transposable, meaning they make copies of themselves
and then move to new locations in the genome. Although L1s make up 17 percent
of our DNA, very little is known about them,” Moran adds. “Until
now, everyone thought they were just intracellular DNA parasites left over
from the distant evolutionary past.”
Because L1s are so ancient and because they sometimes carry segments of genes
with them when they jump to a new location, Moran believes they have played
an important role in human evolution by increasing genetic diversity.
In recently published research in Nature Genetics and Cell, Moran and his
team found that some human L1 elements can jump to chromosomes with broken
strands of DNA, slip into the break and repair the damage. They also discovered
that L1s can delete DNA when they jump to a new location — possibly knocking
out genes or creating devastating mutations in the process. Jumping elements
may have a significant influence on the human genome.
Collaborators on the two research studies include Nicolas Gilbert, Ph.D.,
a postdoctoral fellow in human genetics; Sheila Lutz-Prigge, U-M research associate;
and Tammy A. Morrish, a U-M graduate student in human genetics.
—SFP
Read the complete stories online at:
www.med.umich.edu/opm/newspage/2002/junkdel.htm
www.med.umich.edu/opm/newspage/2002/junkdna.htm
To learn more about research in the Moran lab, go to: www.med.umich.edu/hg/research/faculty/Moran/moranweb.htm
 
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