Dual Specificity Phosphatase 1 Regulates Human Inducible Nitric Oxide Synthase Expression by p38 MAP Kinase

Tuija Turpeinen,Riku Korhonen,Ville Taimi,Taina Heittola,Eeva Moilanen,Outi Sareila,Andrew R Clark,Riina Nieminen

doi:10.1155/2011/127587

Abstract

The role of dual specificity phosphatase 1 (DUSP1) in inducible nitric oxide synthase (iNOS) expression in A549 human pulmonary epithelial cells, J774 mouse macrophages and primary mouse bone marrow-derived macrophages (BMMs) was investigated. iNOS expression was induced by a cytokine mixture (TNF, IFNγ and IL-1β) in A549 cells and by LPS in J774 cells, and it was inhibited by p38 MAPK inhibitors SB202190 and BIRB 796. Stimulation with cytokine mixture or LPS enhanced also DUSP1 expression. Down-regulation of DUSP1 by siRNA increased p38 MAPK phosphorylation and iNOS expression in A549 and J774 cells. In addition, LPS-induced iNOS expression was enhanced in BMMs from DUSP1(−/−) mice as compared to that in BMMs from wild-type mice. The results indicate that DUSP1 suppresses iNOS expression by limiting p38 MAPK activity in human and mouse cells. Compounds that enhance DUSP1 expression or modulate its function may be beneficial in diseases complicated with increased iNOS-mediated NO production.

Highlights

Nitric oxide (NO) is a gaseous signaling molecule that regulates various physiological and pathophysiological processes in many tissues and organ systems
The role of dual specificity phosphatase 1 (DUSP1) in inducible nitric oxide synthase expression in A549 human pulmonary epithelial cells, J774 mouse macrophages and primary mouse bone marrow-derived macrophages (BMMs) was investigated. iNOS expression was induced by a cytokine mixture (TNF, IFNγ and IL-1β) in A549 cells and by LPS in J774 cells, and it was inhibited by p38 Mitogen-activated protein kinases (MAPKs) inhibitors SB202190 and BIRB 796
We investigated the effect of DUSP1 on the expression of iNOS and production of NO in response to stimulation with cytokines (TNF, IFNγ, and IL-1β) in human A549 lung epithelial cells and with LPS in murine J774 macrophages and primary mouse BMMs

Summary

Introduction

Nitric oxide (NO) is a gaseous signaling molecule that regulates various physiological and pathophysiological processes in many tissues and organ systems. Three NOS enzyme isoforms exist: neuronal NOS (nNOS), inducible NOS (iNOS), and endothelial NOS (eNOS). There are considerable differences in the transcriptional regulation of mouse and human iNOS expression. Mouse iNOS promoter activity is substantially induced by interferon (IFN)γ and bacteria-derived substances, such as lipopolysaccharide (LPS). INOS promoter contains two regions responsive to LPS and IFNs. The proximal region is located between −48 and −209 bp upstream of transcriptional start site and contains binding site for nuclear factor κB (NK-κB) and is essential for NF-κB-dependent inducible iNOS promoter activity. Interferon-stimulated gene factor 3 (ISGF3; a heterotrimer of signal transducer and activator of transcription (STAT), STAT2, and interferon regulatory factor (IRF)9) bound to the distal responsive element and NF-κB bound to the proximal responsive element have been shown to cooperate to induce iNOS expression [6]. Several other transcription factors have been shown to regulate mouse iNOS transcription including

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