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

Pollock, Valerie P and Radford, Jonathan C and Pyne, Susan and Hasan, Gaiti and Dow, Julian A T and Davies, Shireen-A (2003) NorpA and itpr mutants reveal roles for phospholipase C and inositol (1,4,5)- trisphosphate receptor in Drosophila melanogaster renal function. Journal of Experimental Biology, 206 (5). pp. 901-911. ISSN 0022-0949 (https://doi.org/10.1242/​jeb.00189)

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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.

ORCID iDs

Pollock, Valerie P, Radford, Jonathan C, Pyne, Susan ORCID logoORCID: https://orcid.org/0000-0002-6608-9584, Hasan, Gaiti, Dow, Julian A T and Davies, Shireen-A;
CORE (COnnecting REpositories)