Nordic Life Science 1
n 7 October 2019, Sir Peter Ratcliffe was having
a typical scientist’s day, writing a grant proposal. Then, Ratcliffe, who is Director of Clinical Research at the Francis Crick Institute and Director of the Target Discovery Institute at the University of Oxford, got a call. The Nobel Committee told him that he, William Kaelin of Harvard University, and Gregg Semenza of Johns Hopkins University were awarded the Physiology or Medicine prize for “discoveries of how cells sense and adapt to oxygen availability.” We still have much to learn in this area, Ratcliffe says: “Maintaining oxygen homeostasis across the 40 trillion cells in the body requires great precision and accuracy. Even a short lapse in oxygen causes trouble.” Fortunately for the field, he finished the grant proposal, with his coapplicants Drs. Peppi Karppinen and Johanna Myllyharju from University of Oulu in Finland taking over writing while he handled the Nobel publicity. The Oulu scientists took time to celebrate, though. They learned of the award during a campus event to watch the Nobel announcement live. “We guessed as soon as they said ‘William’,” Myllyharju says. The event was chaired by Karppinen, who did postdoctoral work with Kaelin. “Johanna and I quickly organized a celebration for our research groups,” she says. “We toasted the Nobels and sent photos to Bill [Kaelin] and Peter.” The details of how cells sense and respond to lack of oxygen, or hypoxia, were a mystery before the Nobel-winning work. The Ratcliffe, Semenza, and other groups studied how hypoxia increases transcription of the gene for erythropoietin (EPO), a kidney hormone that signals for more red blood cells. The Ratcliffe lab showed that cells that do not produce EPO use the same mechanism, operating on different genes, to respond to hypoxia. “The discovery that this system operates in a widespread fashion,” Ratcliffe says, “meant it doesn’t just regulate EPO but does countless other things. This implied physiological importance in all sorts of cells and potential importance in medicine.” That impact is seen today in drugs targeting the Peter Ratcliffe at the Nobel Prize Museum in Stockholm 2019 hypoxia-response system that are in use or development for anemia, cardiovascular disease, cancer, and more. The hypoxia system is complex. The Semenza lab found the crucial transcription regulator: hypoxia-inducible factor (HIF). The Kaelin lab discovered that the ubiquitin ligase VHL (linked to von Hippel-Lindau disease, which increases cancer risk), tags proteins for proteosomal degradation. Then the Ratcliffe and Kaelin groups copublished the mech-anism. They showed that HIF is usually modified by prolyl hydroxylation that allows interaction with VHL, which marks HIF for degradation. In hypoxia, HIF is not hydroxylated or degraded so it activates hypoxia-related genes. NORDICLIFESCIENCE.ORG 57 © NOBEL MEDIA AB PHOTO ALEXANDER MAHMOUD