A team of investigators from nine institutions discovered how ATP – the body's main fuel source– is released as the neurotransmitter from sweet, bitter, and umami, or savory, taste bud cells. The CALHM1 channel protein, which spans a taste bud cell's outer membrane to allow ions and molecules in and out, releases ATP to make a neural taste connection. The other two taste types, sour and salt, use different mechanisms to send taste information to the brain.
Taste buds in a circumvallate papilla in a mouse tongue with types I, II and III taste cells visualized by cell-type-specific fluorescent antibodies. Type II cells respond to sweet, bitter, and umami tastes by signaling to the central nervous system by non-vesicular ATP release. Taruno and colleagues have identified CALHM1 as a voltage-gated ATP release channel that mediates this response to these taste modalities.
Credit: Aki Taruno, Perelman School of Medicine, University of Pennsylvania; Nature
Kevin Foskett, PhD, professor of Physiology at the Perelman School of Medicine, University of Pennsylvania, and colleagues from the Monell Chemical Senses Center, the Feinstein Institute for Medical Research, and others, describe in Nature how ATP release is key to this sensory information path. They found that the calcium homeostasis modulator 1 (CALHM1) protein, recently identified by the Foskett lab as a novel ion channel, is indispensable for taste via release of ATP."This is an example of a bona fide ATP ion channel with a clear physiological function," says Foskett. "Now we can connect the molecular dots of sweet and other tastes to the brain."
This work was supported in part by the National Institutes of Health (GM56328, MH059937, NS072775, DC10393, EY13624, R03DC011143, P30 EY001583, P30DC011735).Penn Medicine is one of the world's leading academic medical centers, dedicated to the related missions of medical education, biomedical research, and excellence in patient care. Penn Medicine consists of the Raymond and Ruth Perelman School of Medicine at the University of Pennsylvania (founded in 1765 as the nation's first medical school) and the University of Pennsylvania Health System, which together form a $4.3 billion enterprise.
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