The Nobel Prize in Physiology or Medicine this year goes to the American physiologist David Julius and the Lebanese-American molecular biologist Ardem Patapoutian for their discovery of temperature and tactile sensors in the skin. Her work laid the molecular basis for understanding how humans perceive and interpret the environment.
The decision was announced by the Nobel Assembly of the Karolinska Institute on Monday. The prize is endowed with ten million Swedish kronor, which corresponds to almost one million euros.
Julius, born in 1955, used the hot substance capsaicin, which is found in chilli pods, to identify molecular sensors at the nerve endings of the skin that react to heat, for example. He researches and teaches at the University of California, San Francisco. Ardem Patapoutian, born in Lebanon in 1967, used pressure-sensitive cells to detect the molecular sensors that respond to mechanical stimuli from the skin and internal organs. Patapoutian is a professor at the Scripps Research Institute in La Jolla, California. The Nobel Assembly recognized the work of the two scientists as the “missing link” for understanding the interaction between human senses and the environment.
Until the discovery, it was completely unclear how temperature or tactile stimuli are transformed into electrical impulses in such a way that the human nervous system can process them. In the second half of the 1990s, Julius began to investigate the molecular processes that make you feel a burning sensation when you eat or even just handle chili peppers. At that time, the pungent substance capsaicin was already known, as was its stimulating effect on nerve cells. But what exactly was going on was still unclear.
Sensors that enable walking and standing
Julius and colleagues first looked for genes that are particularly active in sensory nerve cells. They suspected that there would also be a genetic blueprint for a receptor that reacts to the substance capsaicin. They smuggled these genes one after the other into cells that normally do not respond to the hot substance. Eventually they found the gene for the capsaicin receptor, which was later named TRPV1. Julius studied this protein further and discovered that the receptor also triggers nerve signals when exposed to heat. The discovery enables the development of new pain therapies, according to a message from the Nobel Assembly.
As a result, Julius also found the cold receptor TRPM8, which Ardem Patapoutian had also come across independently of him. However, it remained unclear which receptors the body uses to receive mechanical stimuli. To find this sensory molecule, Patapoutian and his colleagues used cells that respond to pressure with an electrical signal. They assumed that the receptor they were looking for had to be able to send electrical impulses to nerves. This usually happens when a stimulus opens a molecular channel in a cell wall, through which electrically charged ions can then flow in or out. This is how a nerve impulse is started.
In the genes of the pressure-sensitive cells, Patapoutian looked for those that presumably contain the blueprint for such channel proteins. He switched off these candidates one by one and thus identified the gene that is responsible for responding to pressure. The corresponding sensor was named Piezo1 and, as a result, another pressure-sensitive ion channel was found with Piezo2.
The pressure sensors are not only central to the tactile sensation, but also for the processing of so-called proprioceptive stimuli. So the body knows at all times in which positions all limbs are, whether the head is straight or crooked, at what speed an arm is moving and whether the finger will hit the nose in order to dig into it. Without this form of self-awareness, walking and standing would be impossible.
So far, mRNA researchers have come away empty-handed
Even if the award is well deserved, the decision of the Nobel Assembly came as a surprise at this point. Much had been speculated beforehand that the prize could be awarded this year for the development of new mRNA vaccines against the coronavirus. The immunologist Drew Weissman or the biochemist Katalin Karikó, who works for Biontech, would have come into consideration for this purpose.
A spokesman for the assembly did not justify the decision against pandemic vaccines, just explained how the voting process works. The Assembly chooses from a number of proposals, and this year the choice has been made for the discovery of these important ion channels. But there is still the possibility that vaccine researchers will be awarded the Nobel Prize in Chemistry on Wednesday – or in the coming years.
The announcement of the Nobel Prize winners in medicine traditionally marks the start of the Nobel Prize series. The prizes in the physics and chemistry categories follow on Tuesday and Wednesday. On Thursday it is the turn of the Nobel Prize for Literature, on Friday the Nobel Peace Prize, which is the only one to be awarded in Oslo.
The prizes will be awarded together on December 10th, the anniversary of the death of Alfred Nobel. The chosen ones also receive their prestigious Nobel medals and diplomas. The Nobel Foundation has already announced that at least at the award ceremony in Stockholm, as in the previous year, there will be no award winners in the Swedish capital. Instead, they are honored in their home countries. According to the Nobel Foundation, this is due to uncertainties about the further course of the corona pandemic. Only the Norwegian Nobel Committee left the opportunity to bring award winners to Oslo for the award ceremony.