Rifampicin is a macrocyclic antibiotic which is used extensively for treatment against Mycobacterium tuberculosis and other mycobacterial infections. Recently, a number of studies have focused on the immune-regulatory effects of rifampicin. Therefore, we hypothesized that rifampicin may influence the TLR2 expression in LPS-activated RAW 264.7 cells. In this study, we determined that rifampicin suppresses LPS-induced TLR2 mRNA expression. The down-regulation of TLR2 expression coincided with decreased production of TNF-alpha. Since NF-kappaB is a major transcription factor that regulates genes for TLR2 and TNF-alpha, we examined the effect of rifampicin on the LPS-induced NF-kappaB activation. Rifampicin inhibited NF-kappaB DNA-binding activity in LPS-activated RAW 264.7 cells, while it did not affect IKKalpha/beta activity. However, rifampicin slightly inhibited the nuclear translocation of NF-kappaB p65. In addition, rifampicin increased physical interaction between pregnane X receptor, a receptor for rifampicin, and NF-kappaB p65, suggesting pregnane X receptor interferes with NF-kappaB binding to DNA. Taken together, our results demonstrate that rifampicin inhibits LPS-induced TLR2 expression, at least in part, via the suppression of NF-kappaB DNA-binding activity in RAW 264.7 cells. Thus, the present results suggest that the rifampicin-mediated inhibition of TLR2 via the suppression of NF-kappaB DNA-binding activity may be a novel mechanism of the immune-suppressive effects of rifampicin.
DNA ; Down-Regulation ; Mycobacterium tuberculosis ; NF-kappa B ; Receptors, Steroid ; Rifampin ; RNA, Messenger ; Toll-Like Receptor 2 ; Toll-Like Receptors ; Transcription Factors ; Tumor Necrosis Factor-alpha

No abstract available.
Acetyltransferases/metabolism ; Animal ; Carrier Proteins/metabolism ; DNA-Binding Proteins/metabolism ; Human ; Nuclear Proteins/metabolism ; Receptors, Cytoplasmic and Nuclear/metabolism* ; Repressor Proteins/metabolism*n ; Trans-Activators/metabolism* ; Transcription Factors/metabolism

Animals ; Cells, Cultured ; Cyclic AMP Response Element-Binding Protein ; metabolism ; Hepatocytes ; drug effects ; metabolism ; Humans ; Kruppel-Like Factor 6 ; Kruppel-Like Transcription Factors ; NF-kappa B ; metabolism ; Proto-Oncogene Proteins ; RNA, Messenger ; metabolism ; Trans-Activators ; genetics ; metabolism ; Transcription Factor AP-1 ; metabolism ; Transcription Factors ; pharmacology

Transcriptional activators are required to turn on the expression of genes in a eukaryotic cell. Activators bound to the enhancer can facilitate either the recruitment of RNA polymerase II to the promoter or its elongation. This article examines a few selected issues in understanding activator functions and activation mechanisms.
Animals ; Humans ; Trans-Activators ; genetics ; metabolism ; Transcription Factors ; genetics ; metabolism ; Transcription, Genetic ; Transcriptional Activation

The NF-kappaB family of transcription factors plays a critical role in many tissues by modulating both inflammation and cell survival, and this primarily comes about through transcriptional regulation of the downstream effecter genes. This central role of coordinating complex programs of gene induction suggests that the NF-kappaB transcription factors and/or the signaling pathways leading to their activation may present a prime opportunity for performing therapeutic intervention. However, the dual role of this pathway in inflammation and survival dictates rigorous and empiric validation of such interventions in realistic models of disease before we can translate research findings to the clinical arena. Interestingly, the precise approach chosen to modulate NF-kappaB activation appears to dramatically alter the balance of the downstream effects on apoptosis and inflammation. Here we provide a brief overview of NF-kappaB signaling and its role in atherogenesis as well as in acute coronary syndromes, while considering the clinical implications for therapeutic strategies.
Acute Coronary Syndrome ; Apoptosis ; Atherosclerosis* ; Cell Survival ; Humans ; Inflammation ; NF-kappa B* ; Transcription Factors

Aromadendrin, a flavonol, has been reported to possess a variety of pharmacological activities such as anti-inflammatory, antioxidant, and anti-diabetic properties. However, the underlying mechanism by which aromadendrin exerts its biological activity has not been extensively demonstrated. The objective of this study is to elucidate the anti-inflammatory mechanism of aromadedrin in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells. Aromadendrin significantly suppressed LPS-induced excessive production of pro-inflammatory mediators such as nitric oxide (NO) and PGE2. In accordance, aromadendrin attenuated LPS-induced overexpression iNOS and COX-2. In addition, aromadendrin significantly suppressed LPS-induced degradation of IkappaB, which sequesters NF-kappaB in cytoplasm, consequently inhibiting the nuclear translocation of pro-inflammatory transcription factor NF-kappaB. To elucidate the underlying signaling mechanism of anti-inflammatory activity of aromadendrin, MAPK signaling pathway was examined. Aromadendrin significantly attenuated LPS-induced activation of JNK, but not ERK and p38, in a concentration-dependent manner. Taken together, the present study clearly demonstrates that aromadendrin exhibits anti-inflammatory activity through the suppression of nuclear translocation of NF-kappaB and phosphorylation of JNK in LPS-stimulated RAW 264.7 macrophage cells.
Cytoplasm ; Dinoprostone ; Macrophages* ; NF-kappa B* ; Nitric Oxide ; Phosphorylation* ; Transcription Factors

5-Lipoxygenase (5-LO) plays a pivotal role in the progression of atherosclerosis. Therefore, this study investigated the molecular mechanisms involved in 5-LO expression on monocytes induced by LPS. Stimulation of THP-1 monocytes with LPS (0~3 microg/ml) increased 5-LO promoter activity and 5-LO protein expression in a concentration-dependent manner. LPS-induced 5-LO expression was blocked by pharmacological inhibition of the Akt pathway, but not by inhibitors of MAPK pathways including the ERK, JNK, and p38 MAPK pathways. In line with these results, LPS increased the phosphorylation of Akt, suggesting a role for the Akt pathway in LPS-induced 5-LO expression. In a promoter activity assay conducted to identify transcription factors, both Sp1 and NF-kappaB were found to play central roles in 5-LO expression in LPS-treated monocytes. The LPS-enhanced activities of Sp1 and NF-kappaB were attenuated by an Akt inhibitor. Moreover, the LPS-enhanced phosphorylation of Akt was significantly attenuated in cells pretreated with an anti-TLR4 antibody. Taken together, 5-LO expression in LPS-stimulated monocytes is regulated at the transcriptional level via TLR4/Akt-mediated activations of Sp1 and NF-kappaB pathways in monocytes.
Arachidonate 5-Lipoxygenase ; Atherosclerosis ; Monocytes* ; NF-kappa B ; p38 Mitogen-Activated Protein Kinases ; Phosphorylation ; Transcription Factors

Humans ; Hemangioendothelioma, Epithelioid/pathology* ; Trans-Activators ; Transcription Factors ; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors ; Hemangioendothelioma

This study examined the anti-osteoclastogenic effects of baicalin on receptor activator of NF-kB ligand (RANKL)-induced RAW264.7 cells. Baicalin is a flavonoid that is produced by Scutellaria baicalensis and is known to have multiple biological properties, including antibacterial, anti-inflammatory and analgesic effects. The effects of baicalin on osteoclasts were examined by measuring 1) cell viability; 2) the formation of tartrate-resistant acid phosphatase (TRAP) (+) multinucleated cells; 3) RANK/RANKL signaling pathways and 4) mRNA levels of osteoclast-associated genes. Baicalin inhibited the formation of RANKL-stimulated TRAP (+) multinucleated cells and also suppressed the RANKL-stimulated activation of p-38, ERK, cSrc and AKT signaling. Baicalin also inhibited the RANKL-stimulated degradation of IkappaB in RAW264.7 cells. In addition, the RANKL-stimulated induction of NFATc1 transcription factors was found to be abrogated by this flavonoid. Baicalin was further found to decrease the mRNA expression of osteoclast-associated genes, including carbonic anhydrase II, TRAP and cathepsin K in the RAW264.7 cells. Our data thus demonstrate that baicalin inhibits osteoclastogenesis by inhibiting the RANKL-induced activation of signaling molecules and transcription factors in osteoclast precursors.
Acid Phosphatase ; Carbonic Anhydrase II ; Cathepsin K ; Flavonoids ; Isoenzymes ; NF-kappa B ; NFATC Transcription Factors ; Osteoclasts ; RNA, Messenger ; Scutellaria baicalensis ; Transcription Factors

No abstract available.
Transcription Factors*