Directing gene expression to gustducin-positive taste receptor cells.

We have demonstrated that an 8.4 kb segment (GUS(8.4)) from the upstream region of the mouse alpha-gustducin gene acts as a fully functional promoter to target lacZ transgene expression to the gustducin-positive subset of taste receptor cells (TRCs). The GUS(8. 4) promoter drove TRC expression of the beta-galactosidase marker at high levels and in a developmentally appropriate pattern. The gustducin minimal 1.4 kb promoter (GUS(1.4)) by itself was insufficient to specify TRC expression. We also identified an upstream enhancer from the distal portion of the murine gustducin gene that, in combination with the minimal promoter, specified TRC expression of transgenes. Expression of the lacZ transgene from the GUS(8.4) promoter and of endogenous gustducin was coordinately lost after nerve section and simultaneously recovered after reinnervation, confirming the functionality of this promoter. Transgenic expression of rat alpha-gustducin restored responsiveness of gustducin null mice to both bitter and sweet compounds, demonstrating the utility of the gustducin promoter.