title: A fructose receptor functions as a nutrient sensor in the Drosophila brain.
abstract: Internal nutrient sensors play important roles in feeding behavior, yet their molecular structure and mechanism of action are poorly understood. Using Ca(2+) imaging and behavioral assays, we show that the gustatory receptor 43a (Gr43a) functions as a narrowly tuned fructose receptor in taste neurons. Remarkably, Gr43a also functions as a fructose receptor in the brain. Interestingly, hemolymph fructose levels are tightly linked to feeding status: after nutritious carbohydrate consumption, fructose levels rise several fold and reach a concentration sufficient to activate Gr43a in the brain. By using different feeding paradigms and artificial activation of Gr43a-expressing brain neurons, we show that Gr43a is both necessary and sufficient to sense hemolymph fructose and promote feeding in hungry flies but suppress feeding in satiated flies. Thus, our studies indicate that the Gr43a-expressing brain neurons function as a nutrient sensor for hemolymph fructose and assign opposing valence to feeding experiences in a satiation-dependent manner.
authors.affiliation: Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, TX 77845, USA.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Miyamoto
authors.forename: Jesse
authors.initials: J
authors.lastname: Slone
authors.forename: Xiangyu
authors.initials: X
authors.lastname: Song
authors.forename: Hubert
authors.initials: H
authors.lastname: Amrein
mesh_terms: D000818:Animals; D001921:Brain / Q000502:physiology; D004330:Drosophila / Q000502:physiology*; D029721:Drosophila Proteins / Q000378:metabolism*; D005502:Food; D005632:Fructose / Q000378:metabolism*; D041981:Gastrointestinal Tract / Q000502:physiology; D006458:Hemolymph / Q000378:metabolism; D006815:Hunger; D009474:Neurons / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism*; D012528:Satiety Response
chemical_list: D029721:Drosophila Proteins; C577647:Gr43a protein, Drosophila; D011956:Receptors, Cell Surface; D005632:Fructose