title: The molecular basis for water taste in Drosophila.
abstract: The detection of water and the regulation of water intake are essential for animals to maintain proper osmotic homeostasis. Drosophila and other insects have gustatory sensory neurons that mediate the recognition of external water sources, but little is known about the underlying molecular mechanism for water taste detection. Here we identify a member of the degenerin/epithelial sodium channel family, 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.
authors.affiliation: Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, CA, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Cameron
authors.forename: Makoto
authors.initials: M
authors.lastname: Hiroi
authors.forename: John
authors.initials: J
authors.lastname: Ngai
authors.forename: Kristin
authors.initials: K
authors.lastname: Scott
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001522:Behavior, Animal / Q000502:physiology; D002460:Cell Line; D004326:Drinking / Q000502:physiology; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D053503:Epithelial Sodium Channels / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D009994:Osmolar Concentration; D011984:Sensory Receptor Cells / Q000378:metabolism*; D013649:Taste / Q000502:physiology*; D014867:Water
chemical_list: D029721:Drosophila Proteins; D053503:Epithelial Sodium Channels; C549272:PPK28 protein, Drosophila; D014867:Water