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IN RESEARCH: Body’s temperature sensing system starts with 6 ion channels, adds on
Scientists have long known the molecular mechanisms behind most of the body's sensing capabilities. Vision, for example, is made possible in part by rhodopsin, a pigment molecule that is extremely sensitive to light. It is involved in turning photons into electrical signals that can be decoded by the brain into visual information. But how the human body is able to sense a one-degree change in temperature has remained a mystery.
Huge progress was made in the last decade when scientists discovered four ion channels sensitive to heat and two cold-sensitive ones, said Jie Zheng, assistant professor in the Department of Physiology and Membrane Biology at the UC Davis School of Medicine.
"But it was still unclear how only six temperature-sensor channels could cover wide ranges of temperature and still discriminate subtle differences," Zheng said.
Using a novel method based on a technique first used by physicists, Zheng and his colleagues have shown that the subunits of one channel can come together with subunits from another channel, or coassemble, in laboratory cell cultures to form new functioning channels. Assuming this process also happens in normal cells, it suggests a likely mechanism for the thermosensitivity seen in all animal cells, Zheng explained.
"We found that, by reassembling subunits we potentially have a lot more than six channel types responsible for the sensing of temperature," he said.
The findings, subject of March 2007's cover story in the Journal of General Physiology, promise to help solve the mystery of temperature sensitivity in animals once and for all. And, because the cells with these ion channels in their membranes are also the cells that sense pain, the basic knowledge they have provided may one day prove useful to scientists looking for novel remedies for pain.
Zheng wrote the paper with visiting scientist Wei Cheng from China, graduate student Fan Yang and former lab technician Christina L. Takanishi.
- Carol Gan, UC Davis Health System