Food-Experience Induced Taste Desensitization Modulated by the Drosophila TRPL Channel

Animals tend to reject bitter foods. However, long-term exposure to some unpalatable tastants increases acceptance of the foods. Here, we showed that dietary exposure to the unappealing food but safe additive, camphor, caused the fruit fly, Drosophila melanogaster, to decrease camphor rejection. The TRPL cation channel was a direct target for camphor in gustatory receptor neurons (GRNs), and long-term feeding on a camphor diet led to reversible down-regulation of TRPL protein levels. The turnover of TRPL was controlled by an E3 ubiquitin ligase, Ube3a. The decline in TRPL levels and increased acceptance of camphor reversed after returning the flies long-term to a camphor-free diet. We propose that dynamic regulation of taste receptor levels by ubiquitin-mediated protein degradation comprises an important molecular mechanism that allows an animal to alter taste behavior in response to a changing food environment.