The p38 Mitogen-activated Protein Kinase Is Required for NF-κB-dependent Gene Expression

Abstract

Endotoxin-induced cytokine gene transcription in monocytes and macrophages is regulated in part by NF-B. We have previously shown that the p38 mitogenactivated protein (MAP) kinase is necessary for endotoxin-induced cytokine gene transcription. Due to the fact that most cytokine promoter sequences have active NF-B sites, we hypothesized that the p38 MAP kinase was necessary for NF-B-dependent gene expression. We found that NF-B-dependent gene expression was reduced to near control levels with either SB 203580 or a dominant-negative p38 MAP kinase expression vector. Inhibition of the p38 MAP kinase did not alter NF-B activation at any level, but it significantly reduced the DNA binding of TATA-binding protein (TBP) to the TATA box. The dominant-negative p38 MAP kinase expression vector interfered with the direct interaction of native TFIID (TBP) with a co-transfected p65 fusion protein. Likewise, this dominant-negative plasmid also interfered with the direct interaction of a co-transfected TBP fusion protein with the native p65 subunit. The p38 kinase also phosphorylated TFIID (TBP) in vitro, and SB 203580 inhibited phosphorylation of TFIID (TBP) in vivo. Thus, the p38 MAP kinase regulates NF-B-dependent gene transcription, in part, by modulating activation of TFIID (TBP). Cytokine gene expression in endotoxin (LPS)1 -stimulated macrophages is regulated, at least in part, at the level of transcription. A transcription factor that is necessary for the transcription of many cytokine genes is nuclear factor B (NF-B) (1-4). In addition to others, we have previously shown that NF-B binds to specific cytokine promoter sequences (1-8). NF-B is composed of heterodimers (most commonly p50 and p65) of members of the Rel family of transcription factors. In quiescent cells the heterodimers are kept in the cytoplasm by an inhibitor protein, IB (9 -11). NF-B translocation and DNA binding is dependent on IB kinase (IKK), which phosphorylates IB on serines within the amino-terminal domain (12)(13)(14)(15)(16)(17). This phosphorylation results in IB degradation, thus allowing NF-B translocation to the nucleus. Other factors, however, have been shown to be essential for NF-B transcriptional activation, especially phosphorylation of the p65 subunit of NF-B in one of two of its transactivation domains (18). In addition, the association of the carboxyl terminus of p65 with basal transcription factors, such as transcription factor IIB (TFIIB) and TATA-binding protein (TBP), is known to be important for transcriptional regulation of .One family of kinases that is essential for transferring signals from the cell surface to the nucleus is the mitogen-activated protein (MAP) kinases. We and others have shown that the p38 MAP kinase is critical for LPS-induced cytokine gene expression (23)(24)(25)(26).Some of these studies showed that LPS, interleukin 1, and osmotic stress activate p38 MAP kinases, and inhibition with SB 203580, a competitive inhibitor of the p38 MAP kinases, reduced cytokine release but did not affect cytokine mRNA accumu...

Anthocyanin‐ and hydrolyzable tannin‐rich pomegranate fruit extract modulates MAPK and NF‐κB pathways and inhibits skin tumorigenesis in CD‐1 mice

“…65 Studies have shown that ERK1/2 and p38 are involved in the transcriptional activation of NF-B. 66,67 In the present study, we further investigated the effect of PFE on the pattern of NF-B activation and its nuclear translocation by TPA in CD-1 mouse skin. NF-B has emerged as one of the most promising molecular targets in the prevention of cancer.…”

Cymbopogon citratus as source of new and safe anti-inflammatory drugs: Bio-guided assay using lipopolysaccharide-stimulated macrophages

“…Accordingly, previous studies demonstrated that JNK 1/2 (Zhou et al, 2008) and p38 MAPK, but not ERK 1/2 (Chen and Wang, 1999), modulated iNOS expression and NO production in LPSstimulated Raw 264.7 macrophages. In addition, activated MAPKs and PI3K/Akt were also implicated in NF-κB activation (Carter et al, 1999;Nakano et al, 1998), being NF-κB one of the critical transcription factors that controls iNOS gene expression in macrophages (Geller and Billiar, 1998). Cy extract also inhibited p38 MAPK, JNK 1/2 and NF-κB signaling pathways.…”

“…Besides, the iNOS expression could also be modulated by phosphatidylinositol-3-kinase (PI3K)/Akt pathway (Salh et al, 1998), a serine/threonine kinase activated in response to certain growth factors and cytokines that provides a strong cell survival signal (Crawley et al, 1996;Gold et al, 1994). MAPKs and Akt also play A c c e p t e d M a n u s c r i p t 5 a critical role in the activation of nuclear factor (NF)-κB (Carter et al, 1999;Nakano et al, 1998). The NF-κB transcription factor regulates the expression of many genes involved in immune and inflammatory responses, including iNOS and COX-2 (Geller and Billiar, 1998).…”

17β-Estradiol downregulates Kupffer cell TLR4-dependent p38 MAPK pathway and normalizes inflammatory cytokine production following trauma-hemorrhage

“…p38 MAPK has been implicated in the activation of NF-κB (Carter et al, 1999). Other investigators have demonstrated that p38 MAPK-specific inhibitor SB203580 markedly attenuated NF-κB-dependent transcription (Conejo et al, 2001;Thirunavukkarasu et al, 2006).…”

“…Both p38 MAPK and NF-κB are crucial to the signaling pathway that leads to the proinflammatory cytokine production (Baldwin, 1996;Raingeaud et al, 1995). P38 MAPK is a key mediator in organ dysfunction relating to inflammatory states, and acts as an important regulator of cell proliferation, differentiation, and production of proinflammatory cytokines (Carter et al, 1999;Thobe et al, 2006). NF-κB plays a key role in the transcriptional regulation of adhesion molecules, chemokines and cytokines involved in acute inflammatory responses (Baldwin, 1996).…”