Faithful Expression of GFP from the PLCβ2 Promoter in a Functional Class of Taste Receptor Cells

Phospholipase C–type b2 (PLCb2) is expressed in a subset of cells within mammalian taste buds. This enzyme is involved in the transduction of sweet, bitter, and umami stimuli and thus is believed to be a marker for gustatory sensory receptor cells. We have developed transgenic mice expressing green fluorescent protein (GFP) under the control of the PLCb2 promoter to enable one to identify these cells and record their physiological activity in living preparations. Expression of GFP (especially in lines with more than one copy integrated) is strong enough to be detected in intact tissue preparations using epifluorescence microscopy. By immunohistochemistry, we confirmed that the overwhelming majority of cells expressing GFP are those that endogenously express PLCb2. Expression of the GFP transgene in circumvallate papillae occurs at about the same time during development as endogenous PLCb2 expression. When loaded with a calcium-sensitive dye in situ, GFP-positive taste cells produce typical Ca 2+ responses to a taste stimulus, the bitter compound cycloheximide. These PLCb2 promoter–GFP transgenic lines promise to be useful for studying taste transduction, sensory signal processing, and taste bud development.