title: Cell-type specific calcium signalling in a Drosophila epithelium.
abstract: Calcium is a ubiquitous second messenger that plays a critical role in both excitable and non-excitable cells. Calcium mobilisation in identified cell types within an intact renal epithelium, the Drosophila melanogaster Malpighian tubule, was studied by GAL4-directed expression of an aequorin transgene. CAP2b, a cardioactive neuropeptide that stimulates fluid secretion by a mechanism involving nitric oxide, causes a rapid, dose-dependent rise in cytosolic calcium in only a single, genetically-defined, set of 77 principal cells in the main (secretory) segment of the tubule. In the absence of external calcium, the CAP2b-induced calcium response is abolished. In Ca2+-free medium, the endoplasmic reticulum Ca2+-ATPase inhibitor, thapsigargin, elevates [Ca2+]i only in the smaller stellate cells, suggesting that principal cells do not contain a thapsigargin-sensitive intracellular pool. Assays for epithelial function confirm that calcium entry is essential for CAP2b to induce a physiological response in the whole organ. Furthermore, the data suggest a role for calcium signalling in the modulation of the nitric oxide signalling pathway in this epithelium. The GAL4-targeting system allows general application to studies of cell-signalling and pharmacology that does not rely on invasive or cytotoxic techniques.
authors.affiliation: Division of Molecular Genetics, Institute of Biomedical and Life Sciences, University of Glasgow, UK.
authors.forename: P
authors.initials: P
authors.lastname: Rosay
authors.forename: S A
authors.initials: SA
authors.lastname: Davies
authors.forename: Y
authors.initials: Y
authors.lastname: Yu
authors.forename: M A
authors.initials: MA
authors.lastname: Sözen
authors.forename: K
authors.initials: K
authors.lastname: Kaiser
authors.forename: J A
authors.initials: JA
authors.lastname: Dow
mesh_terms: D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors; D000331:Aequorin / Q000235:genetics / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004268:DNA-Binding Proteins; D004331:Drosophila melanogaster / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells; D004848:Epithelium / Q000378:metabolism; D008317:Malpighian Tubules / Q000166:cytology / Q000378:metabolism*; D008954:Models, Biological; D009479:Neuropeptides / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives; D029701:Saccharomyces cerevisiae Proteins; D015398:Signal Transduction; D019284:Thapsigargin / Q000494:pharmacology; D014157:Transcription Factors / Q000235:genetics; D019076:Transgenes
chemical_list: D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; C052130:GAL4 protein, S cerevisiae; D009479:Neuropeptides; D009842:Oligopeptides; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C095817:cardioacceleratory peptide 2b; D000331:Aequorin; D019284:Thapsigargin; D000251:Adenosine Triphosphatases; D002118:Calcium; D011761:Pyrrolidonecarboxylic Acid