Explanation of Nobel Prize in Physiology or Medicine 2021. Discovery of TRPV1 receptor for temperature and Piezo for Touch

 Awarded to: Two US based scientists David Julius at the University of California, San Francisco, and Ardem Patapoutian at Scripps Research, La Jolla, California,

Contribution: for discoveries on receptors for temperature & touch (together called as somatosensation)

Explanation of Nobel Prize in Physiology or Medicine 2021

Experiment of David Julius: Discovery of TRPV1 receptor for temperature and pain

Worked on how the chemical compound capsaicin causes the burning sensation we feel when we come into contact with chili peppers? Is there a single capsaicin receptor?

Experiment of David Julius Step by step explanation

1. First created a cDNA library by activating rodent dorsal root ganglia sensory neurons with capsaicin.

2. Expressed genes mRNA is isolated and used to prepare cDNA library. These genes were thought to react to pain, heat, and touch or causing that burning sensation

Experiment of David Julius: Discovery of TRPV1 receptor for temperature and pain


Julius and colleagues hypothesized that the library would include a DNA fragment encoding the protein capable of reacting to capsaicin. 

3. They used capsaicin insensitive cell line to find out this gene reacting to capsaicin if present.

4. A single gene was identified that was able to make cells capsaicin sensitive. This is ‘gain of function experiment’ where the introduced or transfected gene gives the cell with the ability to respond to capsaicin.

5. Further studies revealed that the identified gene encoded a novel ion channel protein and this newly discovered capsaicin receptor was later named TRPV1.

The significance of TRPV1 discovery

On the basis of this discovery, many additional temperature-sensing receptors were identified

TRPM8, a receptor that was shown to be activated by cold. Additional ion channels related to TRPV1 and TRPM8 were identified and found to be activated by a range of different temperatures. 

Many TRPV receptors were identified responding to changes in temperature.

Experiment of Ardem Patapoutian: Discovered PIEZO2 as a mechanosensitive ion channel for touch and proprioception* (*the sense of our body’s movement and position in space)

Experiment of Ardem Patapoutian Step by step explanation

1. First identified a pressure sensitive cell line called Neuro2A that gave off a measurable electric signal when individual cells were poked with a micropipette. 

2. Identified 72 genes by expression studies on this cell line after inducing pressure by poking with a micropipette.

Experiment of Ardem Patapoutian: Discovered PIEZO2


One of the 72 genes might be responsible for responding to mechanical stimuli

3. Each gene, from 1 to 72 silenced by RNA interference one at a time and assessed electric signal generated. He received electric signal from gene 1 to 71 suggesting that that genes are not involved. This is ‘loss of function’ experiment

4. When silenced the candidate gene 72, no electric signal was generated suggesting that gene 72 is responsible for pressure sensitiveness or mechanosensation

Further studies revealed a  new and entirely unknown mechanosensitive ion channel and was given the name Piezo1, after the Greek word for pressure (í; píesi). Later a second gene was discovered and named Piezo2. Sensory neurons were found to express high levels of Piezo2 and further studies firmly established that Piezo1 and Piezo2 are ion channels that are directly activated by the exertion of pressure on cell membranes. In further work, Piezo1 and Piezo2 channels have been shown to regulate additional important physiological processes including blood pressure, respiration and urinary bladder control.

Importance of this work

Explained how heat, cold and mechanical force are sensed and transformed into nervous impulses that enable us to perceive and adapt to the world around us.

This discovery of temperature and touch receptors, help us to develop treatments for a wide range of disease conditions, including chronic pain.
Thank you so much
Reference: https://www.nobelprize.org/prizes/medicine/2021/press-release/
Image credit: www.nobelprize.org

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