Dual-specificity phosphatase 5 acts as an anti-inflammatory regulator by inhibiting the ERK and NF-κB signaling pathways

Abstract

Although dual-specificity phosphatase 5 (DUSP5), which inactivates extracellular signal-regulated kinase (ERK), suppresses tumors in several types of cancer, its functional roles remain largely unknown. Here, we show that DUSP5 is induced during lipopolysaccharide (LPS)-mediated inflammation and inhibits nuclear factor-κB (NF-κB) activity. DUSP5 mRNA and protein expression increased transiently in LPS-stimulated RAW 264.7 cells and then returned to basal levels. DUSP5 overexpression in RAW 264.7 cells suppressed the production of pro-inflammatory tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6), whereas knockdown of DUSP5 increased their expression. Investigation of two major inflammatory signaling pathways, mitogen-activated protein kinase (MAPK) and NF-κB, using activator protein-1 (AP-1) and NF-κB reporter plasmids, respectively, showed that NF-κB transcription activity was downregulated by DUSP5 in a phosphatase activity-independent manner whereas AP-1 activity was inhibited by DUSP5 phosphatase activity towards ERK,. Further investigation showed that DUSP5 directly interacts with transforming growth factor beta-activated kinase 1 (TAK1) and inhibitor of κB (IκB) kinases (IKKs) but not with IκBα. DUSP5 binding to IKKs interfered with the association of TAK1 with IKKs, suggesting that DUSP5 might act as a competitive inhibitor of TAK1-IKKs association. Therefore, we propose that DUSP5 negatively regulates ERK and NF-κB in a phosphatase activity-dependent and -independent manner, respectively.

Dual-Specificity Phosphatases in Immunity and Infection: An Update

“…In macrophages, DUSP5 expression was induced by the LPS stimulation of TLR4 and reduced cytokine production in RAW264.7 macrophages at the level of ERK1/2-dependent AP1 activation [72]. The stimulation of macrophages with the mycobacterial cord factor trehalose-6,6-dimycolate also upregulated DUSP5 expression, independent of the cord factor receptor Mincle (9).…”

Thioredoxin-1 Protects Spinal Cord from Demyelination Induced by Methamphetamine through Suppressing Endoplasmic Reticulum Stress and Inflammation

“…Several lines of evidence have shown that ERK activation might activate NF-κB ( 42 , 43 ). Inactivation of both ERK1/2 and NF-κB pathways inhibits the level of TNF-α ( 44 ) and inflammation ( 45 , 46 ). Overproduction of TNF-α and IL-1β results in the injury in spinal cord and finally causes demyelination ( 47 ).…”

Growth suppression by dual BRAF(V600E) and NRAS(Q61) oncogene expression is mediated by SPRY4 in melanoma

“…Following assays were conducted as previously described by our laboratory [27, 28]. Lentiviral particles were used to deliver tetracycline-inducible recombinant DNA constructs.…”

“…The protein concentrations of the lysates were measured by BCA protein assay kit (Bio-Rad, Hercules, CA). The lysates (10–20 µg protein) were separated on 4–20% SDS polyacrylamide mini-gels (Bio-Rad, Hercules, CA) and transferred to PVDF or nitrocellulose membrane followed by western blot analysis as described previously [27]. The antibodies used were as follows: mouse monoclonal anti-BRAF(V600E) (1:4000, Spring Bioscience, Pleasanton, CA), NRAS(Q61R) (1:2000, Abnova, Atlanta, GA), (SPRY4) anti-Sprouty4, NRAS, BRAF (1:1000, Santa Cruz Biotechnology, Dallas, TX), and mouse monoclonal anti-GAPDH (1:40,000, Abcam, Cambridge, MA) for 2 h, and horseradish peroxidase-conjugated secondary antibody (1:4000) for 1 h. Antigen–antibody complexes were detected by ECL enhanced chemiluminescence solution (Bio-Rad, Hercules, CA).…”