The 2021 Nobel Prize in Physiology or Medicine was recently awarded to David Julius (University of California, San Francisco, USA) and Ardem Patapoutian (Scripps Research, La Jolla, California, USA) for their discoveries of receptors for temperature and touch.
Touch is a crucial sense that is involved in a great many functions of daily life, including our ability to interact with our environment and perceive threats from hot or cold substances. However, the underlying mechanisms of touch have remained poorly understood at the molecular level. The discoveries made by these Nobel laureates have led to a substantial breakthrough in our understanding of how the human nervous system senses heat, cold, and mechanical stimuli in our environment.
An overview of the discoveries:
Using the chemical capsaicin, which is responsible for inducing the burning sensation we feel when we come into contact with chilli peppers, Julius was able to discover a sensor in the skin’s nerve endings that responds to heat. To do this, a library of millions of DNA fragments corresponding to the genes expressed in the sensory neurons which react to pain, heat, and touch, was used and fragments were expressed individually in cultured cells that do not normally react to capsaicin. This onerous process was repeated until the team was able to identify the single fragment which encodes the protein capable of reacting to capsaicin. Further experiments were conducted, and it was discovered that this gene is responsible for encoding a novel ion channel protein which was later named TRPV1. Subsequently, both Julius and Patapoutian independently identified another new receptor, TRPV8, which is activated by cold.
Using pressure-sensitive cells, Patapoutian identified a new class of sensors which are sensitive to mechanical stimuli in the skin and internal organs. The first step in this discovery was the identification of pressure-sensitive cells which gave off an electric signal when poked with a micropipette. The researchers assumed that the receptor that was being activated by the mechanical stimuli was an ion channel and began searching for the gene which encoded it. After individually expressing 72 candidate genes, Patapoutian and his team were able to isolate the single gene which was responsible for the mechanosensitivity in the cells being studied. This novel ion channel was named Piezo1 and subsequent studies led to the discovery of another new sensory ion channel, Piezo2.
These new discoveries of TRPV1, TRPV8, Piezo1, and Piezo2 have led to significant advances in our understanding of how the human body interacts with, and interprets, the world around us with respect to heat, cold, and mechanical stimuli.
For more information on the Nobel Prize laureates and their achievements, please visit https://www.nobelprize.org/prizes/medicine/2021/press-release/
The Nobel Prize in Physiology or Medicine 2021. NobelPrize.org. Nobel Prize Outreach AB 2021. Accessed: Mon. 15 Nov 2021. Available at: https://www.nobelprize.org/prizes/medicine/2021/summary/.