A novel role for a Drosophila homologue of cGMP-specific phosphodiesterase in the active transport of cGMP

Day, J.P., Houslay, M.D. and Davies, S.-A. (2006) A novel role for a Drosophila homologue of cGMP-specific phosphodiesterase in the active transport of cGMP. Biochemical Journal, 393(2), pp. 481-488.

Abstract

cGMP was first discovered in urine, demonstrating that kidney cells extrude this cyclic nucleotide. Drosophila Malpighian tubules provide a model renal system in which a homologue of mammalian PDE (phosphodiesterase) 6 is expressed. In humans, this cG-PDE (cGMP-specific PDE) is specifically expressed in the retinal system, where it controls visual signal transduction. In order to gain insight into the functional role of DmPDE6 (Drosophila PDE6-like enzyme) in epithelial function, we generated transgenic animals with targeted expression of DmPDE6 to tubule Type I (principal) cells. This revealed localization of DmPDE6 primarily at the apical membranes. As expected, overexpression of DmPDE6 resulted in elevated cG-PDE activity and decreased tubule cGMP content. However, such targeted overexpression of DmPDE6 creates a novel phenotype that manifests itself in inhibition of the active transport and efflux of cGMP by tubules. This effect is specific to DmPDE6 action, as no effect on cGMP transport is observed in tubules from a bovine PDE5 transgenic line which display reduced rates of fluid secretion, an effect not seen in DmPDE6 transgenic animals. Specific ablation of DmPDE6 in tubule principal cells, via expression of a targeted DmPDE6 RNAi (RNA interference) transgene, conferred increased active transport of cGMP, confirming a direct role for DmPDE6 in regulating cGMP transport in tubule principal cells. Pharmacological inhibition of DmPDE6 in wild-type tubules using the cG-PDE inhibitor, zaprinast, similarly results in stimulated cGMP transport. We provide the first demonstration of a novel role for a cG-PDE in modulating cGMP transport and efflux.

• Item Type: Articles
• Keywords: cGMP, Drosophila, phosphodiesterase 6 (PDE6), renal epithelium, RNA interference (RNAi)
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Houslay, Professor Miles
• Authors: Day, J.P., Houslay, M.D., and Davies, S.-A.
• Subjects: Q Science > QR Microbiology
• College/School: College of Medical Veterinary and Life Sciences > School of Psychology & Neuroscience
• Journal Name: Biochemical Journal
• Publisher: Portland Press Ltd.
• ISSN: 0264-6021
• ISSN (Online): 1470-8728

Project Code	Award No	Project Name	Principal Investigator	Funder's Name	Funder Ref	Lead Dept
20836	1	PDE4 cAMP phosphodiesterses: intracellular targeting, SH3 domain interaction and phosphorylation by stress kinases	Miles Houslay	Medical Research Council (MRC)	G8604010	Institute of Neuroscience and Psychology
29408	1	PDE4 Cyclic AMP phosphodiesterases	Miles Houslay	Medical Research Council (MRC)	G8604010	Institute of Neuroscience and Psychology
3069	2	Molecular interaction between receptor signal transduction systems involving guanine nucleotide regulatory proteins	Miles Houslay	Medical Research Council (MRC)	G8604010	Institute of Neuroscience and Psychology
34364	1	PDE4 cAMP phosphodiesterases - intracellular targeting, SH3 Domain Interaction & phosphorylation by stress kinases	Miles Houslay	Medical Research Council (MRC)	G8604010	Institute of Neuroscience and Psychology
9737	1	Programme Grant (PG 8604010) Supplementation (Equipment). Molecular interaction between receptor transduction systems involving guanine nucl	Miles Houslay	Medical Research Council (MRC)	G8604010	Institute of Neuroscience and Psychology