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The molecular basis for water taste in Drosophila

2010; Nature Portfolio; Volume: 465; Issue: 7294 Linguagem: Inglês

10.1038/nature09011

1476-4687

Peter Cameron, Makoto Hiroi, John Ngai, Kristin Scott,

Physiological and biochemical adaptations

Animals must detect water in their environment to stay alive, but how they do it has remained unclear. Now PPK28, a member of the degenerin/epithelial sodium channel family, has been identified as the water taste receptor in Drosophila melanogaster. Other proteins of this family have been implicated in the detection of mechanical and salt stimuli. Animals must detect water in their environment to stay alive, but the molecular basis for water detection has been unclear. Here the essential mediators of water-sensing and drinking in fruitflies have been identified: an ion channel of the degenerin/epithelial sodium channel family, and the sensory neurons that make it. The detection of water and the regulation of water intake are essential for animals to maintain proper osmotic homeostasis1. Drosophila and other insects have gustatory sensory neurons that mediate the recognition of external water sources2,3,4, but little is known about the underlying molecular mechanism for water taste detection. Here we identify a member of the degenerin/epithelial sodium channel family5, PPK28, as an osmosensitive ion channel that mediates the cellular and behavioural response to water. We use molecular, cellular, calcium imaging and electrophysiological approaches to show that ppk28 is expressed in water-sensing neurons, and that loss of ppk28 abolishes water sensitivity. Moreover, ectopic expression of ppk28 confers water sensitivity to bitter-sensing gustatory neurons in the fly and sensitivity to hypo-osmotic solutions when expressed in heterologous cells. These studies link an osmosensitive ion channel to water taste detection and drinking behaviour, providing the framework for examining the molecular basis for water detection in other animals.