At this point, scientists in Dr. Julius’ lab knew that the receptor they had identified – TRPV1, a channel on the surface of cells activated by capsaicin – must have evolved primarily for a more common stimulus, beyond the rare case someone might encounter chili peppers. That other stimulus turned out to be heat, said Dr Michael Caterina, professor of neurosurgery at Johns Hopkins University School of Medicine who helped conduct a 1997 critical study on the subject in Dr’s lab. Julius. The acid also activated the channel.
Tobias Rosen, an undergraduate student at the lab, “intelligently discovered that what we had cloned was essentially a sweet and sour soup receptor,” said Dr Caterina. “It’s got acid, it’s hot, and it’s spicy.”
In search of the molecular basis of touch, Dr Patapoutian also had to sift through a number of possible genes. One by one, he and his colleagues knocked out genes until they identified the one that, when turned off, made cells unresponsive to a tiny pipette.
The channel integrated with the sense of touch became Piezo1, after the Greek word for pressure. This channel and a similar one, both described in a 2010 article, are now known to regulate a number of stretch-sensitive bodily functions, said Dr. Walter Koroshetz, director of the NIH National Institute on Neurological Disorders and Stroke. , which funded the laboratories of Dr Julius and Dr Patapoutian.
These functions include functioning of blood vessels, breathing, and sensitivity to a full bladder.
Why is work important?
There has been a lot of interest in identifying pain receptors from drug companies: if you could block the channel Dr Julius identified, they thought, you could treat chronic pain.
But there were several major issues. The first is that some sensitivity to pain is helpful; otherwise, people risk taking a hot bath or burning their hands on a stove. “Pain serves a purpose,” said Dr. Caterina.
Another is that the same heat-sensitive channels have also been shown to help control body temperature. Their blockage turned out to cause a slight fever – a potentially major handicap.