NorpA and itpr mutants reveal roles for phospholipase C and inositol (1,4,5)- trisphosphate receptor in Drosophila melanogaster renal function

Valerie P Pollock, Jonathan C Radford, Susan Pyne, Gaiti Hasan, Julian A T Dow, Shireen-A Davies

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38 Citations (Scopus)

Abstract

Mutants of norpA, encoding phospholipase C beta (PLC beta), and itpr, encoding inositol (1,4,5)-trisphosphate receptor (IP(3)R), both attenuate response to diuretic peptides of Drosophila melanogaster renal (Malpighian) tubules. Intact tubules from norpA mutants severely reduced diuresis stimulated by the principal cell- and stellate cell-specific neuropeptides, CAP(2b) and Drosophila leucokinin (Drosokinin), respectively, suggesting a role for PLC beta in both these cell types. Measurement of IP(3) production in wild-type tubules and in Drosokinin-receptor-transfected S2 cells stimulated with CAP(2b) and Drosokinin, respectively, confirmed that both neuropeptides elevate IP(3) levels. In itpr hypomorphs, basal IP(3) levels are lower, although CAP(2b)-stimulated IP(3) levels are not significantly reduced compared with wild type. However, CAP(2b)-stimulated fluid transport is significantly reduced in itpr alleles. Rescue of the itpr(90B.0) allele with wild-type itpr restores CAP(2b)-stimulated fluid transport levels to wild type. Drosokinin-stimulated fluid transport is also reduced in homozygous and heteroallelic itpr mutants. Measurements of cytosolic calcium levels in intact tubules of wild-type and itpr mutants using targeted expression of the calcium reporter, aequorin, show that mutations in itpr attenuated both CAP(2b)- and Drosokinin-stimulated calcium responses. The reductions in calcium signals are associated with corresponding reductions in fluid transport rates. Thus, we describe a role for norpA and itpr in renal epithelia and show that both CAP(2b) and Drosokinin are PLC beta-dependent, IP(3)-mobilising neuropeptides in Drosophila. IP(3)R contributes to the calcium signalling cascades initiated by these peptides in both principal and stellate cells.

Original languageEnglish
Pages (from-to)901-911
Number of pages11
JournalJournal of Experimental Biology
Volume206
Issue number5
DOIs
Publication statusPublished - 1 Mar 2003

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Keywords

  • aequorin
  • alleles
  • animals
  • calcium channels
  • calcium signaling
  • DNA primers
  • diuresis
  • drosophila proteins
  • drosophila melanogaster
  • gene expression profiling
  • inositol 1,4,5-trisphosphate
  • inositol 1,4,5-trisphosphate receptors
  • isoenzymes
  • malpighian tubules
  • mutation
  • neuropeptides
  • phospholipase C beta
  • receptors, cytoplasmic and nuclear
  • type C phospholipases

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