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- Title
Two Autocrine Pathways to Regulate Cyclic GMP Synthesis in Cultured Human Retinal Pigment Epithelial Cells.
- Authors
Roselie M.H. Diederen; Ellen C. La Heij; Marianne Markerink-van Ittersum; Fred Hendrikse; Jan de Vente
- Abstract
AbstractAim:To investigate the role of two separate enzymatic pathways [soluble (sGC) vs. particulate (pGC) guanylyl cyclase] in the synthesis of cyclic GMP (cGMP) in cultured human retinal pigment epithelial (RPE) cells. Methods:cGMP accumulation was evaluated by quantitative analysis of cGMP immunoreactivity. RPE cells were also stained for inducible nitric oxide synthase (iNOS), ANP and ?1- and ?2-subunits of sGC. Results:We showed nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase activity and iNOS immunoreactivity in RPE cells. Incubation of the cells in the presence of 1 mMIBMX to inhibit phosphodiesterase activity, and the simultaneous inhibition of NOS activity with L-NAME suggested the involvement of sGC in maintaining a low level of cGMP in the RPE cells. The involvement of sGC was further supported by detection of the ?1- and ?2-subunits of sGC. Incubation of the cells in the presence of atrial natriuretic peptide (ANP) to stimulate pGC strongly increased cGMP immunoreactivity. We also demonstrated the presence of ANP in all RPE cells. Conclusion:Cultured human RPE cells are capable of producing cGMP after stimulation of sGC or pGC. The presence of iNOS and ANP in all cells suggests two different autocrine pathways of stimulating cGMP production in these cells. The possible role of cGMP in the regulation iNOS gene expression and in the regulation of ANP is discussed.Copyright © 2008 S. Karger AG, Basel
- Subjects
CYCLIC nucleotides; AUTOCRINE mechanisms; ENZYMATIC analysis; RHODOPSIN; EPITHELIAL cells; NITRIC oxide; PHOSPHODIESTERASES; GENE expression
- Publication
Ophthalmic Research, 2008, Vol 40, Issue 5, p227
- ISSN
0030-3747
- Publication type
Article
- DOI
10.1159/000127829