165,919 research outputs found

    A novel technique for selective NF-kappa B inhibition in Kupffer cells: contrary effects in fulminant hepatitis and ischaemia-reperfusion.

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    Background and aims: The transcription factor nuclear factor kappa B (NF-kB) has risen as a promising target for anti-inflammatory therapeutics. In the liver, however, NFkB inhibition mediates both damaging and protective effects. The outcome is deemed to depend on the liver cell type addressed. Recent gene knock-out studies focused on the role of NF-kB in hepatocytes, whereas the role of NF-kB in Kupffer cells has not yet been investigated in vivo. Here we present a novel approach, which may be suitable for clinical application, to selectively target NF-kB in Kupffer cells and analyse the effects in experimental models of liver injury. Methods: NF-kB inhibiting decoy oligodeoxynucleotides were loaded upon gelatin nanoparticles (D-NPs) and their in vivo distribution was determined by confocal microscopy. Liver damage, NF-kB activity, cytokine levels and apoptotic protein expression were evaluated after lipopolysaccharide (LPS), D-galactosamine (GalN)/LPS, or concanavalin A (ConA) challenge and partial warm ischaemia and subsequent reperfusion, respectively. Results: D-NPs were selectively taken up by Kupffer cells and inhibited NF-kB activation. Inhibition of NF-kB in Kupffer cells improved survival and reduced liver injury after GalN/LPS as well as after ConA challenge. While anti-apoptotic protein expression in liver tissue was not reduced, pro-apoptotic players such as cJun N-terminal kinase (JNK) were inhibited. In contrast, selective inhibition of NF-kB augmented reperfusion injury. Conclusions: NF-kB inhibiting decoy oligodeoxynucleotide- loaded gelatin nanoparticles is a novel tool to selectively inhibit NF-kB activation in Kupffer cells in vivo. Thus, liver injury can be reduced in experimental fulminant hepatitis, but increased at ischaemia–reperfusion

    Opposite effects of two zinc(II) dithiocarbamates on NF-kB pathway

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    Inhibiting nuclear factor-kappaB (NF-kB) activation in anticancer and antiinflammatory therapy is of topical interest. Current research in molecular biology has dramatically advanced in the understanding of the cellular events involved in NF-kB induction. Dithiocarbamates, in particular diethyldithiocarbamate and pyrrolidinedithiocarbamate, have been known and widely used as strong inhibitors of NF-kB signaling pathway for more than ten years. Their activity is frequently thought to be due to chelating of zinc or copper present in serum supplemented in the culture medium. Zinc(II) diethyldithiocarbamate (Et2Zn) and zinc(II) dibenzyldithiocarbamate (Bz2Zn) were prepared by direct synthesis in aqueous millieu. They were structurally characterized by X-ray analysis (solid phase) and mass spectrometry (aqueous conditions). Et2Zn and Bz2Zn both in 20 micromolar concentration were applied to HeLa cells. The status of NF-kB signaling was assessed as nuclear translocation of p65 subunit. Surprisingly, Et2Zn activated NF-kB pathway, while TNF-dependent activation of NF-kB was inhibited by Bz2Zn. Our results are preliminary

    Spiky oscillations in NF-kB signalling

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    The NF-kB signalling system is involved in a variety of cellular processes including immune response, inflammation, and apoptosis. Recent experiments have found oscillations in the nuclear-cytoplasmic translocation of the NF-kB transcription factor. How the cell uses the oscillations to differentiate input conditions and send specific signals to downstream genes is an open problem. We shed light on this issue by examining the small core network driving the oscillations, which, we show, is designed to produce periodic spikes in nuclear NF-kB concentration. The oscillations can be used to regulate downstream genes in a variety of ways. In particular, we show that genes to whose operator sites NF-kB binds and dissociates fast can respond very sensitively to changes in the input signal, with effective Hill coefficients in excess of 20.Comment: 11 pages, 13 figure

    Effect of Energy Metabolism on NF-kB activity in Ovarian Cancer

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    NF-kB is a transcription factor involved in cancer cell growth and survival. The activation of NF-kB can be assessed by monitoring phosphorylation of RelA p65 at Ser-536, which is a surrogate of the NF-kB transcription factor activation. The objective of this study was to determine if the loss of ATP leads to NF-kB deficiency and thus, apoptotic cell death of “bad” cells in ovarian cancer cells. The independent variables were metformin (Met), an anti-diabetic medicine, another compound MinB functionally similar to Met and a glucose transporter inhibitor BAY-876. The dependent variables were the resulting effect of Met and MinB on phosphorylated AMPK at Thr-172 (marker of ATP loss) and RelA p65 at Ser-536 (marker of NF-kB activation). In each experiment, AMPK and RelA phosphorylation were tested by treatment of ovarian cancer cell lines with Met, MinB, BAY-876, Met+BAY-876, MinB+BAY-876. Western blotting was performed to determine the phosphorylation levels of AMPK and RelA p65. For two gels, the process was repeated. In each gel, Met or MinB treatment leads to thicker bands of AMPK-p, indicating decrease in cellular ATP levels following treatments. The effect of Met, MinB, or BAY-876 on RelA p65 was limited. However, co-treatment of Met or MinB with BAY-876 caused strong inhibition of NF-kB, as reflected by reduction in RelA p65-p. These results suggested that ATP deficiency together with inhibition of glucose transport cause inactivation of NK-kB. Future research will be conducted to study the effects of these compounds or their combinations on ovarian cancer cell growth and survival against from apoptosis.https://scholarscompass.vcu.edu/uresposters/1267/thumbnail.jp

    The IkB kinase inhibitor nuclear factor-kB essential modulator–binding domain peptide for inhibition of balloon injury-induced neointimal formation

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    Objective—The activation of nuclear factor-kB (NF-kB) is a crucial step in the arterial wall’s response to injury. The identification and characterization of the NF-kB essential modulator– binding domain (NBD) peptide, which can block the activation of the IkB kinase complex, have provided an opportunity to selectively abrogate the inflammation-induced activation of NF-kB. The aim of the present study was to evaluate the effect of the NBD peptide on neointimal formation.<br></br> Methods and Results—In the rat carotid artery balloon angioplasty model, local treatment with the NBD peptide (300 microg/site) significantly reduced the number of proliferating cells at day 7 (by 40%; P<0.01) and reduced injury-induced neointimal formation (by 50%; P<0.001) at day 14. These effects were associated with a significant reduction of NF-kB activation and monocyte chemotactic protein-1 expression in the carotid arteries of rats treated with the peptide. In addition, the NBD peptide (0.01 to 1 micromol/L) reduced rat smooth muscle cell proliferation, migration, and invasion in vitro. Similar results were observed in apolipoprotein E-/-, mice in which the NBD peptide (150 microg/site) reduced wire-induced neointimal formation at day 28 (by 47%; P<0.01).<br></br> Conclusion—The NBD peptide reduces neointimal formation and smooth muscle cell proliferation/migration, both effects associated with the inhibition of NF-kB activation

    Inducing phase-locking and chaos in cellular oscillators by modulating the driving stimuli

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    Inflammatory responses in eucaryotic cells are often associated with oscillations in the nuclear-cytoplasmic translocation of the transcription factor NF-kB. In most laboratory realizations, the oscillations are triggered by a cytokine stimulus, like the tumor necrosis factor alpha, applied as a step change to a steady level. Here we use a mathematical model to show that an oscillatory external stimulus can synchronize the NF-kB oscillations into states where the ratios of the internal to external frequency are close to rational numbers. We predict a specific response diagram of the TNF-driven NF-kB system which exhibits bands of synchronization known as "Arnold tongues". Our model also suggests that when the amplitude of the external stimulus exceeds a certain threshold there is the possibility of coexistence of multiple different synchronized states and eventually chaotic dynamics of the nuclear NF-kB concentration. This could be used as a way of externally controlling immune response, DNA repair and apoptotic pathways.Comment: 12 pages, 3 figure

    Subunit-Specific Role of NF-ÎşB in Cancer

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    Kaltschmidt B, Greiner J, Kadhim H, Kaltschmidt C. Subunit-Specific Role of NF-ÎşB in Cancer. Biomedicines. 2018;6(2): 44.The transcription factor NF-kB is a key player in inflammation, cancer development, and progression. NF-kB stimulates cell proliferation, prevents apoptosis, and could promote tumor angiogenesis as well as metastasis. Extending the commonly accepted role of NF-kB in cancer formation and progression, different NF-kB subunits have been shown to be active and of particular importance in distinct types of cancer. Here, we summarize overexpression data of the NF-kB subunits RELA, RELB, and c-REL (referring to the v-REL, which is the oncogene of Reticuloendotheliosis virus strain T) as well as of their upstream kinase inhibitor, namely inhibitor of kB kinases (IKK), in different human cancers, assessed by database mining. These data argue against a universal mechanism of cancer-mediated activation of NF-kB, and suggest a much more elaborated mode of NF-kB regulation, indicating a tumor type-specific upregulation of the NF-kB subunits. We further discuss recent findings showing the diverse roles of NF-kB signaling in cancer development and metastasis in a subunit-specific manner, emphasizing their specific transcriptional activity and the role of autoregulation. While non-canonical NF-kB RELB signaling is described to be mostly present in hematological cancers, solid cancers reveal constitutive canonical NF-kB RELA or c-REL activity. Providing a linkage to cancer therapy, we discuss the recently described pivotal role of NF-kB c-REL in regulating cancer-targeting immune responses. In addition, current strategies and ongoing clinical trials are summarized, which utilize genome editing or drugs to inhibit the NF-kB subunits for cancer treatment

    Nuclear Factor-Kappa B Inhibition Can Enhance Apoptosis of Differentiated Thyroid Cancer Cells Induced by 131I

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    Objective: To evaluate changes of nuclear factor-kappa B (NF-kB) during radioiodine 131 ( 131 I) therapy and whether NF-kB inhibition could enhance 131 I-induced apoptosis in differentiated thyroid cancer (DTC) cells in a synergistic manner. Methods: Three human DTC cell lines were used. NF-kB inhibition was achieved by using a NF-kB inhibitor (Bay 11-7082) or by p65 siRNA transfection. Methyl-thiazolyl-tetrazolium assay was performed for cell viability assessment. DNA-binding assay, luciferase reporter assay, and Western blot were adopted to determine function and expression changes of NF-kB. Then NF-kB regulated anti-apoptotic factors XIAP, cIAP1, and Bcl-xL were measured. Apoptosis was analyzed by Western blot for caspase 3 and PARP, and by flow cytometry as well. An iodide uptake assay was performed to determine whether NF-kB inhibition could influence radioactive iodide uptake. Results: The methyl-thiazolyl-tetrazolium assay showed significant decrease of viable cells by combination therapy than by mono-therapies. The DNA-binding assay and luciferase reporter assay showed enhanced NF-kB function and reporter gene activities due to 131 I, yet significant suppression was achieved by NF-kB inhibition. Western blot proved 131 I could increase nuclear NF-kB concentration, while NF-kB inhibition reduced NF-kB concentration. Western blot also demonstrated significant up-regulation of XIAP, cIAP1, and Bcl-xL after 131 I therapy. And inhibition of NF-kB could significantly downregulate these factors. Finally, synergism induced by combined therapy was displayed by significant enhancements o

    Notch and NF-kB: Coach and Players of Regulatory T-Cell Resposnse in Cancer

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    The Notch signaling pathway plays multiple roles in driving T-cell fate decisions, proliferation, and aberrant growth. NF-kB is a cell-context key player interconnected with Notch signaling either in physiological or in pathological conditions. This review focuses on how themultilayered crosstalk between different Notches and NF-kB subunits may converge on Foxp3 gene regulation and orchestrate CD4+ regulatory T (Treg) cell function, particularly in a tumor microenvironment. Notably, Treg cells may play a pivotal role in the inhibition of antitumor immune responses, possibly promoting tumor growth. A future challenge is represented by further dissection of both Notch and NF-kB pathways and consequences of their intersection in tumor-associated Treg biology. This may shed light on themolecularmechanisms regulating Treg cell expansion andmigration to peripheral lymphoid organs thought to facilitate tumor development and still to be explored. In so doing, new opportunities for combined and/or more selective therapeutic Q25 approaches to improve anticancer immunity may be found
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