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You're listening to ALL THINGS CONSIDERED from NPR News.
Now, time to hear from three scientists who discovered this morning they had won the Nobel Prize in Physiology or Medicine.
As NPR's Jon Hamilton reports, they won for explaining a biological process that seems to play an important role in cancer and aging.
JON HAMILTON: When cells divide, they lose a tiny bit of genetic information at the end of each chromosome.
Dr. ELIZABETH BLACKBURN (University of California, San Francisco): The ends of chromosomes are always wearing down.
HAMILTON: Elizabeth Blackburn from the University of California, San Francisco, is one of the scientists who became a Nobel winner today. Blackburn says the ends of chromosomes would eventually get worn away if they weren't protected by something called a telomere. She says it acts like the plastic tip on a shoelace, which prevents the lace ends from fraying.
But where do telomeres come from? That's what Blackburn was trying to figure out in the 1980s when she was at UC Berkeley. She figured there must be an enzyme responsible for making and maintaining these genetic shoelace tips.
Dr. BLACKBURN: There were some hints. And then I think there was a particular time when we really saw a particular piece of evidence there, which said very strongly to us, ah, this thing really does exist.
HAMILTON: The discovery was made by Carol Greider, who was a graduate student back then. These days, Greider is a professor at Johns Hopkins University in Baltimore. She also will receive a share of the Nobel Prize.
Dr. CAROL GREIDER (Johns Hopkins University) We were studying these single-celled pond animals called Tetrahymena, that happen to have 40,000 chromosomes. And we figured if you want to understand how chromosomes are replicated and how telomeres work, go to the organism that has 40,000 of them.
HAMILTON: What Greider found in those organisms was an enzyme that was able to keep the ends of chromosomes in good shape. She says at first they called the enzyme telomere terminal transferase.
Dr. GREIDER: But we realized, especially because we were working with this organism that was called Tetrahymena thermophila, that if you want to say Tetrahymena thermophila telomere terminal transferase, that gets to be a mouthful.
HAMILTON: So Greider took a friend's suggestion and renamed the enzyme telomerase. At the time, it wasn't clear whether the system worked the same way in other species. That question was answered by Jack Szostak, a geneticist at Harvard Medical School and Massachusetts General Hospital. He's the third recipient of today's Nobel Prize.
Szostak took the telomere DNA from the organism Blackburn and Greider were studying and inserted it into yeast cells. He then used X-ray images to see whether the DNA was protecting yeast chromosomes during cell division.
Dr. JACK SZOSTAK (Geneticist, Harvard Medical School, Massachusetts General Hospital): There was a moment where, you know, in sort of developing the X-ray film where, you know, just by looking at it, it was obvious that the experiment had worked and that, therefore, the telomere machinery was working in yeast.
HAMILTON: That suggested the machinery would be present in all species, including humans. More recent research has confirmed that. Szostak says that when he and other scientists made those early discoveries, they were just trying to understand how cells work. But since then, it's become clear that the process they uncovered offers a new way to understand a wide range of diseases, including cancer. Szostak says cancer cells depend on telomerase. He says it seems to allow them to divide like crazy without dying the way normal cells would.
Dr. SZOSTAK: The hope is that by interfering with the enzyme, maybe there will be a therapeutically useful benefit.
HAMILTON: Elizabeth Blackburn from UC San Francisco says telomeres also seem to have a role in things like heart disease, diabetes and perhaps even the aging process itself. Blackburn's recent work suggests that chronic psychological stress can actually damage telomeres.
Jon Hamilton, NPR News.
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