The 2019 Nobel Prize in Physiology or Medicine has been awarded to William G. Kaelin Jr. of Harvard University, Sir Peter J. Ratcliffe of Oxford University, and Gregg L. Semenza of Johns Hopkins University for their pioneering work on how cells adapt to varying oxygen levels.
As is tradition, the Nobel announcements begin with Physiology or Medicine. Last year, the prize recognized James P. Allison and Tasuku Honjo for immunotherapy advances. This year, the Karolinska Institute selected these three scientists from 633 nominations for revealing the molecular mechanisms that allow tissues and organs to respond to oxygen availability.
Oxygen is essential for cell survival, yet its supply fluctuates—during exercise, at high altitudes, or due to illness. Gregg L. Semenza at Johns Hopkins University began by studying the erythropoietin (EPO) gene, which triggers red blood cell production under low-oxygen conditions (hypoxia).
Semenza identified two key proteins that regulate EPO expression. Crucially, one protein senses oxygen: it accumulates during hypoxia and degrades when oxygen is plentiful.
Building on this, William G. Kaelin Jr. at Harvard and Peter J. Ratcliffe at Oxford pinpointed the VHL protein, which targets and destroys the oxygen-sensitive protein when oxygen levels normalize.
Their research expanded beyond EPO, uncovering over 300 genes controlled by this oxygen-sensing pathway—a fundamental mechanism now central to biology and medicine.
These insights not only illuminate cellular function but also pave the way for innovative therapies targeting anemia, heart disease, and cancer, where oxygen regulation plays a critical role.
Nobel week continues with Physics on Tuesday, Chemistry on Wednesday, Literature on Thursday, Peace on Friday, and Economics on Monday.
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