The 2021 Nobel prize in physiology or medicine has been awarded to two U.S. scientists who discovered the microscopic secrets behind the human sense of touch.
David Julius, of the University of California San Francisco, received half of the prize for using "capsaicin, a pungent compound from chili peppers that induces a burning sensation, to identify a sensor in the nerve endings of the skin that responds to heat," while Ardem Patapoutian, of the Scripps Research Institute in La Jolla, California, received the other half for using "pressure-sensitive cells to discover a novel class of sensors that respond to mechanical stimuli in the skin and internal organs," the Royal Swedish Academy of Sciences announced Monday (Oct. 4).
Their discoveries "have allowed us to understand how heat, cold and mechanical force can initiate the nerve impulses that allow us to perceive and adapt to the world around us," the Nobel Committee said in a statement. "This knowledge is being used to develop treatments for a wide range of disease conditions, including chronic pain."
The award comes with a prize of 10 million Swedish kronor ($1.15 million) to be shared equally between the two winners.
Beginning in the 1990s, the scientists pieced together the molecular pathways that translate heat and pressure detected on the skin into nerve impulses perceived by the brain. Julius and his colleagues started the work by creating a library of millions of DNA segments containing genes found in sensory nerve cells. By adding the genes one by one to cells that did not normally react to capsaicin, they eventually found that a single gene was responsible for the burning sensation associated with capsaicin. The gene they had discovered gave cells the ability to build a protein called TRPV1, which was activated at temperatures hot enough to be considered painful.
Both Julius and Patapoutian independently went on to use menthol to discover another protein, TPRM8, which was activated by cold temperatures, as well as a number of other proteins that detected a range of different temperatures.
Building on this work, Patapoutian and his colleagues created a library of 72 genes that they suspected encoded blueprints to make receptors for mechanical pressure. By painstakingly deactivating these genes one by one in cells, they discovered that one of the genes produced a protein that spurred cells to produce a tiny electrical signal each time they were prodded. The receptor they had discovered was not only vital for sensing mechanical force, but was also used in various ways to maintain blood vessels, alongside having a proposed role in adjusting the body’s blood pressure.
Soon after that, they found a second protein receptor that was vital in sensing body position and motion, a sense known as proprioception. They named the two receptors Piezo1 and Piezo2, after the Greek word for pressure.
Not only did the discoveries help explain the mechanisms behind sensory experiences like temperature and pressure, but they also opened up a world of possibilities for new drugs targeting the receptors — from painkillers to drugs that could alleviate blood pressure across blood vessels and organs.
"While we understood the physiology of the senses, what we didn't understand was how we sensed differences in temperature or pressure," Oscar Marin, director of the MRC Centre for Neurodevelopmental Disorders at King’s College London told The Associated Press. "Knowing how our body senses these changes is fundamental because once we know those molecules, they can be targeted. It's like finding a lock and now we know the precise keys that will be necessary to unlock it."
Joseph Erlanger and Herbert Gasser, who shared the Nobel prize in physiology or medicine in 1944, first discovered specialized nerve cells responsive to both painful and non-painful touch.
Last year's prize went to three scientists for their discovery of hepatitis C, a blood-borne virus that causes chronic liver inflammation. The deadly disease's discovery was a breakthrough that enabled doctors to identify the virus in patients' blood and develop a cure, Live Science previously reported.
Originally published on Live Science.
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Ben Turner is a U.K. based staff writer at Live Science. He covers physics and astronomy, among other topics like tech and climate change. He graduated from University College London with a degree in particle physics before training as a journalist. When he's not writing, Ben enjoys reading literature, playing the guitar and embarrassing himself with chess.