Issue Date: October 12, 2009
Nobel Prize In Physiology Or Medicine
This year’s Nobel Prize in Physiology or Medicine goes to three U.S.-based researchers who illuminated the fundamental biochemistry that takes place at the ends of chromosomes. The work has stimulated the development of new therapeutic strategies for cancer.
The winners are Elizabeth H. Blackburn, 60, a professor of biology and physiology at the University of California, San Francisco; Carol W. Greider, 48, a professor of molecular biology and genetics at Johns Hopkins University School of Medicine; and Jack W. Szostak, 56, a professor of molecular biology at Massachusetts General Hospital and a professor of genetics at Harvard Medical School. Each has been awarded one-third of the $1.4 million prize. Theirs is the first Nobel science prize to be shared by two women.
The prizewinners have demonstrated that chromosome ends, called telomeres, and the enzyme that makes them, known as telomerase, protect chromosomes and ensure that they’re faithfully copied each time a cell divides. The discovery has launched major research efforts in areas where cell division takes center stage, including aging and cancer.
Blackburn, Greider, and Szostak carried out their seminal work in the late 1970s and early 1980s. Studying a single-celled pond-dweller called Tetrahymena thermophila, Blackburn showed that simple repeating DNA sequences make up chromosome ends. She and Szostak joined forces to establish that the T. thermophila repeats could protect chromosomes from degradation in a different organism, a yeast. Telomeres were later found to protect the genetic code throughout biology, from paramecia to people. Blackburn likens telomeres to the plastic caps that prevent the ends of shoelaces from fraying.
Blackburn and Szostak’s work suggested that a then-unknown enzyme capped chromosomes with telomere DNA. On Christmas Day 1984, Greider, then a first-year graduate student in the Blackburn group, found the first hints of that enzyme, which she and Blackburn dubbed telomerase. “It was a thrilling moment,” Greider said at a press conference last week. The protective DNA repeats serve as a molecular buttress for DNA polymerases as they copy an entire chromosome, ensuring that those polymerases don’t miss the chromosome’s ends.
Telomerase is “an intimate collaboration between protein and RNA,” and it continues to spark the interest of researchers seeking to understand the capabilities of such molecular partnerships, says Thomas R. Cech, a Nobel Laureate who studies telomere structure and function at the University of Colorado, Boulder.
Szostak, Blackburn, and Greider went on to lay the foundations for work that links telomeres to cancer and age-related diseases. The shortening of telomeres contributes to the complex biology of aging. In contrast, cancer cells have long telomeres that lend them a sinister immortality. Clinical trials of vaccine and small-molecule cancer treatments inspired by these insights are under way. “What we really have now is a better level of understanding of certain aspects of aging and cancer,” but real therapeutic benefits remain to be seen, Szostak tells C&EN.
The excitement surrounding the prize may stem from medical implications, but the original driver was a biomolecular question, notes chemist Jeremy M. Berg, director of the National Institute of General Medical Sciences at NIH. “There are frequent criticisms that the chemistry prize is too biological; this is a case where the medicine and physiology prize is actually pretty chemical.
- Chemical & Engineering News
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