Coding of sweet, bitter, and umami tastes: different receptor cells sharing similar signaling pathways.
Mammals can taste a wide repertoire of chemosensory stimuli. Two unrelated families of receptors (T1Rs and T2Rs) mediate responses to sweet, amino acids, and bitter compounds. Here, we demonstrate that knockouts of TRPM5, a taste TRP ion channel, or PLCbeta2, a phospholipase C selectively expressed in taste tissue, abolish sweet, amino acid, and bitter taste reception, but do not impact sour or salty tastes. Therefore, despite relying on different receptors, sweet, amino acid, and bitter transduction converge on common signaling molecules. Using PLCbeta2 taste-blind animals, we then examined a fundamental question in taste perception: how taste modalities are encoded at the cellular level. Mice engineered to rescue PLCbeta2 function exclusively in bitter-receptor expressing cells respond normally to bitter tastants but do not taste sweet or amino acid stimuli. Thus, bitter is encoded independently of sweet and amino acids, and taste receptor cells are not broadly tuned across these modalities.
Zhang
Yifeng
Y
Howard Hughes Medical Institute, Department of Biology, University of California, San Diego, La Jolla, CA 92093, USA.
Hoon
Mark A
MA
Chandrashekar
Jayaram
J
Mueller
Ken L
KL
Cook
Boaz
B
Wu
Dianqing
D
Zuker
Charles S
CS
Ryba
Nicholas J P
NJ
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D019343:Citric Acid / Q000494:pharmacology; D005260:Female; D019204:GTP-Binding Proteins / Q000187:drug effects / Q000378:metabolism; D018698:Glutamic Acid / Q000494:pharmacology; D007527:Isoenzymes / Q000172:deficiency* / Q000235:genetics; D008297:Male; D008565:Membrane Proteins / Q000172:deficiency* / Q000235:genetics; D051379:Mice; D018345:Mice, Knockout; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology; D054799:Phospholipase C beta; D011803:Quinine / Q000494:pharmacology; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism*; D011984:Sensory Receptor Cells / Q000187:drug effects / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013395:Sucrose / Q000494:pharmacology; D050053:TRPM Cation Channels; D013649:Taste / Q000187:drug effects / Q000235:genetics*; D013650:Taste Buds / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010738:Type C Phospholipases / Q000172:deficiency* / Q000235:genetics
D007527:Isoenzymes; D008565:Membrane Proteins; D011956:Receptors, Cell Surface; D050053:TRPM Cation Channels; C498617:Trpm5 protein, mouse; D019343:Citric Acid; D018698:Glutamic Acid; D013395:Sucrose; D011803:Quinine; D010738:Type C Phospholipases; D054799:Phospholipase C beta; D019204:GTP-Binding Proteins