title: The putative Na⁺/Cl⁻-dependent neurotransmitter/osmolyte transporter inebriated in the Drosophila hindgut is essential for the maintenance of systemic water homeostasis.
abstract: Most organisms are able to maintain systemic water homeostasis over a wide range of external or dietary osmolarities. The excretory system, composed of the kidneys in mammals and the Malpighian tubules and hindgut in insects, can increase water conservation and absorption to maintain systemic water homeostasis, which enables organisms to tolerate external hypertonicity or desiccation. However, the mechanisms underlying the maintenance of systemic water homeostasis by the excretory system have not been fully characterized. In the present study, we found that the putative Na(+)/Cl(-)-dependent neurotransmitter/osmolyte transporter inebriated (ine) is expressed in the basolateral membrane of anterior hindgut epithelial cells. This was confirmed by comparison with a known basolateral localized protein, the α subunit of Na(+)-K(+) ATPase (ATPα). Under external hypertonicity, loss of ine in the hindgut epithelium results in severe dehydration without damage to the hindgut epithelial cells, implicating a physiological failure of water conservation/absorption. We also found that hindgut expression of ine is required for water conservation under desiccating conditions. Importantly, specific expression of ine in the hindgut epithelium can completely restore disrupted systemic water homeostasis in ine mutants under both conditions. Therefore, ine in the Drosophila hindgut is essential for the maintenance of systemic water homeostasis.
authors.affiliation: Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
authors.forename: Zhuo
authors.initials: Z
authors.lastname: Luan
authors.affiliation: Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
authors.forename: Caitlin
authors.initials: C
authors.lastname: Quigley
authors.affiliation: Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
authors.forename: Hong-Sheng
authors.initials: HS
authors.lastname: Li
mesh_terms: D000818:Animals; D004330:Drosophila / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D006706:Homeostasis / Q000235:genetics; D007413:Intestinal Mucosa / Q000378:metabolism; D050479:Neurotransmitter Transport Proteins / Q000235:genetics / Q000378:metabolism*; D009997:Osmotic Pressure; D050480:Plasma Membrane Neurotransmitter Transport Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D021381:Protein Transport; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D014882:Water-Electrolyte Balance / Q000235:genetics
chemical_list: D029721:Drosophila Proteins; C102353:INE protein, Drosophila; D050479:Neurotransmitter Transport Proteins; D050480:Plasma Membrane Neurotransmitter Transport Proteins; D000254:Sodium-Potassium-Exchanging ATPase