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B-dependent Gene Expression (b-dependent + gene_expression)
Selected AbstractsSuppression of NF-,B-dependent gene expression by a hexamethylene bisacetamide-inducible protein HEXIM1 in human vascular smooth muscle cellsGENES TO CELLS, Issue 2 2003Rika Ouchida Background: Neointima formation is a characteristic feature of atherosclerosis and post-angioplasty restenosis, in which various soluble factors and mechanical injury stimulate signalling pathways in vascular smooth muscle cells (VSMC), promoting their migration and proliferation, and the eventual formation of the neointima. The transcription factor NF-,B has been shown to play a pivotal role in this process. Hexamethylene bisacetamide, an inhibitor of VSMC proliferation, induces the mRNA expression of HEXIM1 (hexamethylene bisacetamide-inducible protein 1). However, the protein expression and function of HEXIM1 remain unknown. Results: In the present study, we demonstrated that HEXIM1 localizes in the cytoplasm and nucleus, and its nuclear expression is restricted to discrete speckled areas. Treatment of VSMC with hexamethylene bisacetamide up-regulated HEXIM1 expression, not only in mRNA but also protein levels. Moreover, HEXIM1 is shown to suppress the transcriptional activity of NF-,B via its C-terminal leucine-rich domain. A glutathione-S-transferase pull down assay indicated that HEXIM1 interacts with the p65 subunit of NF-,B. In VSMC, treatment with hexamethylene bisacetamide resulted in a down-modulation of the transcription of NF-,B target genes. Conclusion: We may therefore conclude that HEXIM1 plays an inhibitory role in NF-,B-dependent gene expression in VSMC and is the candidate of a novel therapeutic target for inhibition of VSMC proliferation. [source] Manganese potentiates nuclear factor-,B-dependent expression of nitric oxide synthase 2 in astrocytes by activating soluble guanylate cyclase and extracellular responsive kinase signaling pathwaysJOURNAL OF NEUROSCIENCE RESEARCH, Issue 9 2008Julie A. Moreno Abstract Inflammatory activation of glial cells is associated with neuronal injury in several degenerative movement disorders of the basal ganglia, including manganese neurotoxicity. Manganese (Mn) potentiates the effects of inflammatory cytokines on nuclear factor-,B (NF-,B)-dependent expression of nitric oxide synthase 2 (NOS2) in astrocytes, but the signaling mechanisms underlying this effect have remained elusive. It was postulated in the present studies that direct stimulation of cGMP synthesis and activation of mitogen-activated protein (MAP) kinase signaling pathways underlies the capacity of Mn to augment NF-,B-dependent gene expression in astrocytes. Exposure of primary cortical astrocytes to a low concentration of Mn (10 ,M) potentiated expression of NOS2 mRNA and protein along with production of NO in response to interferon-, (IFN,) and tumor necrosis factor-, (TNF,), which was prevented by overexpression of dominant negative I,B,. Mn also potentiated IFN,- and TNF,-induced phosphorylation of extracellular response kinase (ERK), p38, and JNK, as well as cytokine-induced activation of a fluorescent NF-,B reporter construct in transgenic astrocytes. Activation of ERK preceded that of NF-,B and was required for maximal activation of NO synthesis. Independently of IFN,/TNF,, Mn-stimulated synthesis of cGMP in astrocytes and inhibition of soluble guanylate cyclase (sGC) abolished the potentiating effect of Mn on MAP kinase phosphorylation, NF-,B activation, and production of NO. These data indicate that near-physiological concentrations of Mn potentiate cytokine-induced expression of NOS2 and production of NO in astrocytes via activation of sGC, which promotes ERK-dependent enhancement of NF-,B signaling. © 2008 Wiley-Liss, Inc. [source] Melatonin decreases TLR3-mediated inflammatory factor expression via inhibition of NF-,B activation in respiratory syncytial virus-infected RAW264.7 macrophagesJOURNAL OF PINEAL RESEARCH, Issue 1 2008Sheng-Hai Huang Abstract:, Double-stranded (ds) RNA has been identified as a ligand for Toll-like receptor 3 (TLR3). Respiratory syncytial virus (RSV), a single-stranded RNA virus and a major respiratory pathogen and pneumovirus in human infants pathogenesis of which relies on early inflammatory and immune events of the host in response to RSV, could be recognized by TLR3 sensing viral dsRNA produced during replication. The downstream signaling pathway from TLR3 leads to activation of IFN regulatory factor (IRF)-3 and/or NF-,B and subsequent expression of numerous proinflammatory factors. Melatonin (MT) is an effective regulator of the immune system. To determine the molecular mechanisms responsible for the suppressive effect of MT on RSV infection, we analyzed signaling molecules involved in the TLR3-mediated activation of inflammatory factors in macrophages infected with RSV and the modulatory role of MT on these mediators. We report that RSV infection of RAW264.7 macrophages time-dependently stimulate the rapid activation of TLR3 and NF-,B, as well as subsequent NF-,B-dependent gene expression such as those encoding TNF-, and inducible nitric oxide synthase. Moreover, we demonstrate that MT decreased TLR3-mediated downstream gene expression in RSV-infected macrophages in a dose- and time-dependent manner, and that MT inhibition of NF-,B activity seemed to be the key event required to explain the reduction in inflammatory gene expression caused by MT. But MT did not influence TLR3 at either the protein or mRNA level or MyD88 transcription. These results could be related to the beneficial immunoregulatory role of MT in RSV-infected macrophages and address the possible therapeutic potential of this indoleamine in human RSV diseases. [source] A Salmonella type III secretion effector interacts with the mammalian serine/threonine protein kinase PKN1CELLULAR MICROBIOLOGY, Issue 5 2006Andrea Haraga Summary Essential to salmonellae pathogenesis is an export device called the type III secretion system (TTSS), which mediates the transfer of bacterial effector proteins from the bacterial cell into the host cell cytoplasm. Once inside the host cell, these effectors are then capable of altering a variety of host cellular functions in order to promote bacterial survival and colonization. SspH1 is a Salmonella enterica serovar Typhimurium TTSS effector that localizes to the mammalian nucleus and down-modulates production of proinflammatory cytokines by inhibiting nuclear factor (NF)-,B-dependent gene expression. To identify mammalian binding partners of SspH1 a yeast two-hybrid screen against a human spleen cDNA library was performed. It yielded a serine/threonine protein kinase called protein kinase N 1 (PKN1). The leucine-rich repeat domain of SspH1 was demonstrated to mediate this interaction and also inhibition of NF-,B-dependent gene expression. This suggested that PKN1 may play a role in modulation of the NF-,B signalling pathway. Indeed, we found that expression of constitutively active PKN1 in mammalian cells results in a decrease, while depletion of PKN1 by RNA interference causes an increase in NF-,B-dependent reporter gene expression. These data indicate that SspH1 may inhibit the host's inflammatory response by interacting with PKN1. [source] | ||||||||||