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NF-kappaB controls the global pro-inflammatory response in endothelial cells: evidence for the regulation of a pro-atherogenic program.

ABSTRACT: Activation of the transcription factor NF-kappaB is critical for the tumor necrosis factor-alpha (TNF-alpha)-induced inflammatory response. Here we report the complete gene expression profile from activated microvascular endothelial cells emphasizing the direct contribution of the NF-kappaB pathway. Human microvascular endothelial cell line-1 (HMEC-1) cells were modified to express dominant interfering mutants of the IKK/NF-kappaB signaling module and expression profiles were determined. Our results provide compelling evidence for the virtually absolute dependence of TNF-alpha-regulated genes on NF-kappaB. A constitutively active IKK2 was sufficient for maximal induction of most target genes, whereas a transdominant IkappaBalpha suppressed gene expression. Several genes with a critical role in atherogenesis were identified. The endothelial lipase (EL) gene, a key enzyme involved in lipoprotein metabolism, was investigated more in detail. Binding sites interacting with NF-kappaB in vitro and in vivo were identified and co-transfection experiments demonstrated the direct regulation of the EL promoter by NF-kappaB. We conclude that targeting the IKK/NF-kappaB pathway or specific genes downstream may be effective for the control or prevention of chronic inflammatory diseases such as atherosclerosis.

SUBMITTER: Kempe S

PROVIDER: S-EPMC1226313 | biostudies-literature | 2005

REPOSITORIES: biostudies-literature

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NF-kappaB controls the global pro-inflammatory response in endothelial cells: evidence for the regulation of a pro-atherogenic program.

Kempe Sybille S Kestler Hans H Lasar Andrea A Wirth Thomas T

Nucleic acids research 20050921 16

Activation of the transcription factor NF-kappaB is critical for the tumor necrosis factor-alpha (TNF-alpha)-induced inflammatory response. Here we report the complete gene expression profile from activated microvascular endothelial cells emphasizing the direct contribution of the NF-kappaB pathway. Human microvascular endothelial cell line-1 (HMEC-1) cells were modified to express dominant interfering mutants of the IKK/NF-kappaB signaling module and expression profiles were determined. Our res ...[more]

PMID: 16177180

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Project description:The ability of the transcription factor NF-kappaB to upregulate anti-apoptotic proteins has been linked to the chemoresistance of solid tumors to standard chemotherapy. In contrast, recent studies have proposed that, in response to doxorubicin, NF-kappaB can be pro-apoptotic through repression of anti-apoptotic target genes. However, there is little evidence analyzing the outcome of NF-kappaB inhibition on the cytotoxicity of doxorubicin in studies describing pro-apoptotic NF-kappaB activity. In this study, we further characterize the activation of NF-kappaB in response to doxorubicin and evaluate its role in chemotherapy-induced cell death in sarcoma cells where NF-kappaB is reported to be pro-apoptotic. Doxorubicin treatment in U2OS cells induced canonical NF-kappaB activity as evidenced by increased nuclear accumulation of phosphorylated p65 at serine 536 and increased DNA-binding activity. Co-treatment with a small molecule IKKbeta inhibitor, Compound A, abrogated this response. RT-PCR evaluation of anti-apoptotic gene expression revealed that doxorubicin-induced transcription of cIAP2 was inhibited by Compound A, while doxorubicin-induced repression of other anti-apoptotic genes was unaffected by Compound A or siRNA to p65. Furthermore, the combination of doxorubicin and canonical NF-kappaB inhibition with Compound A or siRNA to p65 resulted in decreased cell viability measured by trypan blue staining and MTS assay and increased apoptosis measured by cleaved poly (ADP-ribose) polymerase and cleaved caspase 3 when compared to doxorubicin alone. Our results demonstrate that doxorubicin-induced canonical NF-kappaB activity associated with phosphorylated p65 is anti-apoptotic in its function and that doxorubicin-induced repression of anti-apoptotic genes occurs independent of p65. Therefore, combination therapies incorporating NF-kappaB inhibitors together with standard chemotherapies remains a viable method to improve the clinical outcomes in patients with advanced stage malignancies.

Project description:BackgroundMicroglia, the resident macrophage-like cells in the brain, regulate innate immune responses in the CNS to protect neurons. However, excessive activation of microglia contributes to neurodegenerative diseases. Corticosteroids are potent modulators of inflammation and mediate their effects by binding to mineralocorticoid receptors (MR) and glucocorticoid receptors (GR). Here, the coordinated activities of GR and MR on the modulation of the nuclear factor-?B (NF-?B) pathway in murine BV-2 microglial cells were studied.MethodsBV-2 cells were treated with different corticosteroids in the presence or absence of MR and GR antagonists. The impact of the glucocorticoid-activating enzyme 11?-hydroxysteroid dehydrogenase type 1 (11?-HSD1) was determined by incubating cells with 11-dehydrocorticosterone, with or without selective inhibitors. Expression of interleukin-6 (IL-6), tumor necrosis factor receptor 2 (TNFR2), and 11?-HSD1 mRNA was analyzed by RT-PCR and IL-6 protein expression by ELISA. NF-?B activation and translocation upon treatment with various corticosteroids were visualized by western blotting, immunofluorescence microscopy, and translocation assays.ResultsGR and MR differentially regulate NF-?B activation and neuroinflammatory parameters in BV-2 cells. By converting inactive 11-dehydrocorticosterone to active corticosterone, 11?-HSD1 essentially modulates the coordinated action of GR and MR. Biphasic effects were observed for 11-dehydrocorticosterone and corticosterone, with an MR-dependent potentiation of IL-6 and tumor necrosis factor-? (TNF-?) expression and NF-?B activation at low/moderate concentrations and a GR-dependent suppression at high concentrations. The respective effects were confirmed using the MR ligand aldosterone and the antagonist spironolactone as well as the GR ligand dexamethasone and the antagonist RU-486. NF-?B activation could be blocked by spironolactone and the inhibitor of NF-?B translocation Cay-10512. Moreover, an increased expression of TNFR2 was observed upon treatment with 11-dehydrocorticosterone and aldosterone, which was reversed by 11?-HSD1 inhibitors and/or spironolactone and Cay-10512.ConclusionsA tightly coordinated GR and MR activity regulates the NF-?B pathway and the control of inflammatory mediators in microglia cells. The balance of GR and MR activity is locally modulated by the action of 11?-HSD1, which is upregulated by pro-inflammatory mediators and may represent an important feedback mechanism involved in resolution of inflammation.

Project description:The cytokine tumor necrosis factor (TNF) initiates tissue inflammation, a process mediated by the NF-kappaB transcription factor. In response to TNF, latent cytoplasmic NF-kappaB is activated, enters the nucleus, and induces expression of inflammatory and anti-apoptotic gene expression programs. Recently it has been shown that NF-kappaB displays two distinct activation modes, monophasic and oscillatory, depending on stimulus duration. Characterization of temporal expression patterns for the NF-kappaB network and determination of those genes under monophasic- or oscillatory control has not been experimentally addressed.To identify the kinetics of NF-kappaB-dependent gene expression and determine whether these two types of NF-kappaB translocation modes control distinct gene programs, a detailed kinetic analysis of a validated microarray data set was performed on 74 unique NF-kappaB-dependent genes in response to TNF. Hierarchical clustering identified distinct expression profiles termed the "Early", "Middle", "Late" response groups, peaking 1, 3, and 6 h after stimulation, respectively. These expression patterns were validated by Quantitative Real Time PCR (Q-RT-PCR) and NF-kappaB binding was demonstrated by chromatin immunoprecipitation (ChIP) assays. Each response group was mapped to its molecular function; this analysis indicated that the Early group encodes cytokines or negative regulators of the IKK-NF-kappaB pathway, and the Late group encodes cell surface receptors, adhesion molecules and signal adapters. That similar coordinated sequential cascades of gene expression were also seen in response to stimulation by the cytokine IL-1, and expression patterns observed in MRC-5 fibroblasts indicated that the epithelial NF-kappaB program is relatively stimulus- and cell type-independent. Bioinformatic analysis of the Early and Late gene promoters indicates that although both groups contain similar patterns of NF-kappaB-binding sites, only the Early gene promoters contain NF-kappaB-binding sites located in phylogenetically conserved domains. Stimulation protocols designed to produce either monophasic or oscillatory NF-kappaB activation modes showed that the oscillatory mode is required only for expression of the Late genes.This analysis provides important insights into the TNF-regulated genetic response program in epithelial cells, where NF-kappaB controls sequential expression patterns of functionally distinct genes that depend on its oscillatory activation mode.

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NF-kappaB controls the global pro-inflammatory response in endothelial cells: evidence for the regulation of a pro-atherogenic program.

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NF-kappaB controls the global pro-inflammatory response in endothelial cells: evidence for the regulation of a pro-atherogenic program.

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