Issue 11, 2012

Nitric oxide promotes recycling of 8-nitro-cGMP, a cytoprotective mediator, into intact cGMP in cells

Abstract

8-Nitro-cGMP is an endogenous nucleotide discovered under inflammation conditions as an important mediator of nitric oxide (NO) signaling. Besides cGMP-like behaviour, 8-nitro-cGMP exerts unique cytoprotective effects against oxidative stress. Although the formation of 8-nitro-cGMP from 8-nitro-GTP has previously been proposed, the mechanism by which excess or unused 8-nitro-cGMP is removed from cells remains unknown. In this study, we report a nitric oxide-dependent cellular conversion of 8-nitro-cGMP to intact cGMP in RAW 264.7 macrophage cells. In our experiments, we synthesized isotopically labeled 8-nitro-cGMP as a tool for metabolites analysis and identified 8-amino-cGMP as an initial metabolite of 8-nitro-cGMP using a LC-MS/MS technique. We also proved that endogenous 8-nitro-cGMP can be converted into 8-amino-cGMP by immunocytochemical staining with an antibody that specifically recognizes 8-amino-cGMP. Moreover, we showed that isotopically labeled 8-amino-cGMP is metabolized into cGMP under inflammation conditions. We propose that nitrosylation of 8-amino-cGMP occurs by NO formation under stress conditions and gives putative 8-diazonium-cGMP, which subsequently decomposes into cGMP. To the best of our knowledge, this study is the first to report reductive deamination of aminoguanine nucleotide at the C-8 position. The findings of this study collectively indicate that NO plays a crucial role not only in the production of 8-nitro-cGMP but also in its elimination under oxidative stress or inflammation.

Graphical abstract: Nitric oxide promotes recycling of 8-nitro-cGMP, a cytoprotective mediator, into intact cGMP in cells

Supplementary files

Article information

Article type
Paper
Submitted
15 May 2012
Accepted
26 Jul 2012
First published
27 Jul 2012

Mol. BioSyst., 2012,8, 2909-2915

Nitric oxide promotes recycling of 8-nitro-cGMP, a cytoprotective mediator, into intact cGMP in cells

Y. Saito, T. Sawa, J. Yoshitake, C. Ito, S. Fujii, T. Akaike and H. Arimoto, Mol. BioSyst., 2012, 8, 2909 DOI: 10.1039/C2MB25189B

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