Monday, October 8, 2001

3 Biologists Win Nobel for Work on Life Cycles of Cells By LILA GUTERMAN The Karolinska Institute announced today that three biologists -- one from the Fred Hutchinson Cancer Research Center, in Seattle, and two from Britain -- have won the Nobel Prize for Physiology or Medicine for their "seminal discoveries" about how cells control their life cycles. The scientists discovered some of the molecules that determine when cells grow and divide. In the early 1970s, Leland H. Hartwell, now president and director of the Fred Hutchinson center, as well as a professor of genetics at the University of Washington, discovered more than 100 genes involved in controlling cell division by mutating them in baker's yeast. The most important, dubbed "start," begins the cell's process of growth that must occur before the cell can divide. Mr. Hartwell also discovered that cells stop growing and dividing when they detect damaged DNA, allowing time for repair before the cell cycle continues. The other winners are Sir Paul M. Nurse and R. Timothy Hunt, of the Imperial Cancer Research Fund, in London. Mr. Nurse discovered a gene in another type of yeast that determines when a cell moves between phases of its life cycle, such as advancing from the growth phase into a stage when it makes new copies of DNA, or from the next phase, when it checks DNA for damage, into the final stage of division, when the chromosomes divide into two daughter cells. In the 1980s, he discovered the corresponding gene in human beings, demonstrating that the cell-cycle control processes have stayed largely the same throughout billions of years of evolution. The proteins encoded by those genes are called CDK molecules. Mr. Hunt was first to discover proteins that turn on and off the CDK molecules. He found the so-called cyclins in sea urchins and later discovered them in human beings, showing that another cell-cycle control has been conserved during evolution. Together, CDK molecules and cyclins determine when cells move from one life-cycle stage to another. The statement announcing the winners says that "most biomedical research areas will benefit" from the laureates' discoveries. Already, they are being applied to research on cancer; tumors sometimes contain high levels of CDK molecules and cyclins. The text of the Nobel announcement is available on the Nobel Foundation's World Wide Web site. Easy-to-print version E-mail this article

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