How Hot Peppers Helped David Julius Make the TRP Channel Connection

Michael Caterina recalls a graduate student in David Julius' University of California, San Francisco lab who often brought his collection of bottled hot sauces to lab parties, for tasting with guacamole and chips. But the lab's interest in capsaicin goes beyond social gatherings.

Julius started out in yeast genetics, but decided as a postdoc to switch to neuroscience. "I started reading and becoming more and more interested in the biology of the sensory neurons involved in pain," he says. He also became interested in the idea of using natural products, such as capsaicin, to identify molecular components of the pain pathway.

At the time, the defining hallmark of these neurons was sensitivity to capsaicin and other vanilloid compounds. So he decided to take a pharmacological approach and identify the capsaicin receptor by expression cloning. "But what really made it happen," says Julius, was the development of a calcium imaging system by Caterina. This system was used to detect capsaicin-sensitive channels expressed in mammalian cells from a dorsal root ganglion cDNA library. Later, a similar approach was taken using mustard oil, an isothiocyanate compound similar to those found in wasabi, horseradish, and mustard. Menthol was used to identify a TRP channel that responds to cold.

Julius attributes his lab's successes to "good people," but Caterina suggests that it's more than that. "He has created a very scientifically creative and stimulating environment." And capsaicin still shows up at lab festivities, says Julius, "also menthol now, and wasabi, of course."