This year’s Nobel Prize in Physiology or Medicine was awarded to David Julius and Ardem Patapoudian for their discoveries of receptors for temperature and touch, marking a key breakthrough in our understanding of how mechanical stimuli are converted into electrical impulses in the nervous system.
Sight, hearing, touch, smell, and taste, our five major senses, connect our bodies and brains to the world. A sixth sense, proprioception, which helps our body know where it is in space, involves receptors that process sensory information. “Your sensory neurons innervate all the muscles in your body, and from how much your muscles are stretched, you have a very visual — without actually looking — image of where your limbs are,” says Patapoudian in an interview with Scientific American earlier this month. “This is how I can close my eyes and touch my nose. This is proprioception.” These senses have many different mechanisms — chemical, hormonal — but the mechanism for touch is not completely understood.
In the 1990s, David Julius, working at the University of San Francisco, had discovered a single gene responsible for sensitivity to capsaicin, a chili pepper extract that induces that burning/painful sensation you feel when eating spicy food. Through years of research and millions of gene sequences, Julius and his team were able to identify the gene that encoded a heat-sensing ion channel protein and named it TRPV1.
Ion channels in nerve cells allow ions to flow into the cell and activate an electrical signal. This signal gets passed between other cells and eventually arrives at the central nervous system, where the signal is interpreted as a sensory perception. The ion channel that Julius discovered, TRPV1, only opens at a certain threshold temperature level considered to be “painful.”
Ardem Patapoudian’s team at Scripps Research in La Jolla, CA identified two genes responsible for mechanosensitivity (sense of touch and proprioception) by using a micropipette to poke variants of a specific line of cells that give off electric signals when poked. The encoded ion channels were named Piezo1 and Piezo2. Although there still remains much research to be done, Piezo2 seems to be involved in a number of functions, including bladder fullness. Additionally, people who lack Piezo2 lack coordination and have limited proprioception, making Piezo2 an exciting possible target for future drugs.
Additionally, both Julius and Patapoudian independently discovered another gene that encodes a protein receptor activated by the cold, which was named TRPM8.
For their years-long work and groundbreaking research on TRPV1, TRPM8, and Piezo receptors, Julius and Patapoudian have been awarded this year’s nobel prize in Physiology or Medicine. In order to reach these discoveries, the research teams meticulously deactivated numerous other genes one at a time and noted the functional outcomes of each deactivation. For example, Julius and Patapoudian deleted the TRPM8 gene in mice, and found that those mice couldn’t sense cold very well. The process of identifying these genes was painstaking and arduous — it took days to test just one gene candidate, and years to reach a discovery. Additionally, by taking non mechanosensitive cells and inserting the identified genes, researchers could further analyze the role of those genes in mechanosensitivity. Their work has allowed us to better understand how we process temperature and mechanical force information. Future research needs to be done to study the mechanisms of these receptors in a more physiological context so that novel therapies to treat symptoms such as chronic pain can be discovered.
Diversity and the Nobel Prize
The Nobel Prizes in STEM fields have historically represented the benchmark for scientific discoveries around the world. For their groundbreaking contributions to humankind, Nobel Prize Laureates receive over a million dollars in research funding as well as international recognition.
However, it is no secret to most that it has a major diversity problem. This year, all eight Nobel Prize Laureates in Medicine, Physics, Chemistry, and Literature are men. There has never been a Black recipient for Medicine, Physics, or Chemistry. Only 25% of the Nobel Prize in Medicine Selection Committee are women.
A recent episode of Vox’s Unexplainable podcast series, “Nobel Prize 2.0,” delves into some flaws of the Nobel Prize and how it is awarded. Check it out on Spotify.
This article was edited by Kate Braverman and Sooyeon Jung.