CLK2 mediates IκBα-independent early termination of NF-κB activation by inducing cytoplasmic redistribution and degradation

Activation of the NF-κB pathway is strictly regulated to prevent excessive inflammatory and immune responses. In a well-known negative feedback model, IκBα-dependent NF-κB termination is a delayed response pattern in the later stage of activation, and the mechanisms mediating the rapid termination of active NF-κB remain unclear. Here, we showed IκBα-independent rapid termination of nuclear NF-κB mediated by CLK2, which negatively regulated active NF-κB by phosphorylating the RelA/p65 subunit of NF-κB at Ser180 in the nucleus to limit its transcriptional activation through degradation and nuclear export. Depletion of CLK2 increased the production of inflammatory cytokines, reduced viral replication and increased the survival of the mice. Mechanistically, CLK2 phosphorylated RelA/p65 at Ser180 in the nucleus, leading to ubiquitin‒proteasome-mediated degradation and cytoplasmic redistribution. Importantly, a CLK2 inhibitor promoted cytokine production, reduced viral replication, and accelerated murine psoriasis. This study revealed an IκBα-independent mechanism of early-stage termination of NF-κB in which phosphorylated Ser180 RelA/p65 turned off posttranslational modifications associated with transcriptional activation, ultimately resulting in the degradation and nuclear export of RelA/p65 to inhibit excessive inflammatory activation. Our findings showed that the phosphorylation of RelA/p65 at Ser180 in the nucleus inhibits early-stage NF-κB activation, thereby mediating the negative regulation of NF-κB.

N4BP1 functions as a dimerization-dependent linear ubiquitin reader which regulates TNF signalling

Signalling through TNFR1 modulates proinflammatory gene transcription and programmed cell death, and its impairment causes autoimmune diseases and cancer. NEDD4-binding protein 1 (N4BP1) is a critical suppressor of proinflammatory cytokine production that acts as a regulator of innate immune signalling and inflammation. However, our current understanding about the molecular properties that enable N4BP1 to exert its suppressive potential remain limited. Here, we show that N4BP1 is a novel linear ubiquitin reader that negatively regulates NFκB signalling by its unique dimerization-dependent ubiquitin-binding module that we named LUBIN. Dimeric N4BP1 strategically positions two non-selective ubiquitin-binding domains to ensure preferential recognition of linear ubiquitin. Under proinflammatory conditions, N4BP1 is recruited to the nascent TNFR1 signalling complex, where it regulates duration of proinflammatory signalling in LUBIN-dependent manner. N4BP1 deficiency accelerates TNFα-induced cell death by increasing complex II assembly. Under proapoptotic conditions, caspase-8 mediates proteolytic processing of N4BP1, resulting in rapid degradation of N4BP1 by the 26 S proteasome, and acceleration of apoptosis. In summary, our findings demonstrate that N4BP1 dimerization creates a novel type of ubiquitin reader that selectively recognises linear ubiquitin which enables the timely and coordinated regulation of TNFR1-mediated inflammation and cell death.

Formation of memory assemblies through the DNA-sensing TLR9 pathway

As hippocampal neurons respond to diverse types of information1, a subset assembles into microcircuits representing a memory2. Those neurons typically undergo energy-intensive molecular adaptations, occasionally resulting in transient DNA damage3-5. Here we found discrete clusters of excitatory hippocampal CA1 neurons with persistent double-stranded DNA (dsDNA) breaks, nuclear envelope ruptures and perinuclear release of histone and dsDNA fragments hours after learning. Following these early events, some neurons acquired an inflammatory phenotype involving activation of TLR9 signalling and accumulation of centrosomal DNA damage repair complexes6. Neuron-specific knockdown of Tlr9 impaired memory while blunting contextual fear conditioning-induced changes of gene expression in specific clusters of excitatory CA1 neurons. Notably, TLR9 had an essential role in centrosome function, including DNA damage repair, ciliogenesis and build-up of perineuronal nets. We demonstrate a novel cascade of learning-induced molecular events in discrete neuronal clusters undergoing dsDNA damage and TLR9-mediated repair, resulting in their recruitment to memory circuits. With compromised TLR9 function, this fundamental memory mechanism becomes a gateway to genomic instability and cognitive impairments implicated in accelerated senescence, psychiatric disorders and neurodegenerative disorders. Maintaining the integrity of TLR9 inflammatory signalling thus emerges as a promising preventive strategy for neurocognitive deficits.

Processing stimulus dynamics by the NF-κB network in single cells

Cells at the site of an infection experience numerous biochemical signals that vary in amplitude, space, and time. Despite the diversity of dynamic signals produced by pathogens and sentinel cells, information-processing pathways converge on a limited number of central signaling nodes to ultimately control cellular responses. In particular, the NF-κB pathway responds to dozens of signals from pathogens and self, and plays a vital role in processing proinflammatory inputs. Studies addressing the influence of stimulus dynamics on NF-κB signaling are rare due to technical limitations with live-cell measurements. However, recent advances in microfluidics, automation, and image analysis have enabled investigations that yield high temporal resolution at the single-cell level. Here, we summarize the recent research which measures and models the NF-κB response to pulsatile and fluctuating stimulus concentrations, as well as different combinations and sequences of signaling molecules. Collectively, these studies show that the NF-κB network integrates external inflammatory signals and translates these into downstream transcriptional responses.

Determining zebrafish dorsal organizer size by a negative feedback loop between canonical/non-canonical Wnts and Tlr4/NFκB

In vertebrate embryos, the canonical Wnt ligand primes the formation of dorsal organizers that govern dorsal-ventral patterns by secreting BMP antagonists. In contrast, in Drosophila embryos, Toll-like receptor (Tlr)-mediated NFκB activation initiates dorsal-ventral patterning, wherein Wnt-mediated negative feedback regulation of Tlr/NFκB generates a BMP antagonist-secreting signalling centre to control the dorsal-ventral pattern. Although both Wnt and BMP antagonist are conserved among species, the involvement of Tlr/NFκB and feedback regulation in vertebrate organizer formation remains unclear. By imaging and genetic modification, we reveal that a negative feedback loop between canonical and non-canonical Wnts and Tlr4/NFκB determines the size of zebrafish organizer, and that Tlr/NFκB and Wnts switch initial cue and feedback mediator roles between Drosophila and zebrafish. Here, we show that canonical Wnt signalling stimulates the expression of the non-canonical Wnt5b ligand, activating the Tlr4 receptor to stimulate NFκB-mediated transcription of the Wnt antagonist frzb, restricting Wnt-dependent dorsal organizer formation.

A proteome-scale map of the SARS-CoV-2-human contactome

Understanding the mechanisms of coronavirus disease 2019 (COVID-19) disease severity to efficiently design therapies for emerging virus variants remains an urgent challenge of the ongoing pandemic. Infection and immune reactions are mediated by direct contacts between viral molecules and the host proteome, and the vast majority of these virus-host contacts (the 'contactome') have not been identified. Here, we present a systematic contactome map of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with the human host encompassing more than 200 binary virus-host and intraviral protein-protein interactions. We find that host proteins genetically associated with comorbidities of severe illness and long COVID are enriched in SARS-CoV-2 targeted network communities. Evaluating contactome-derived hypotheses, we demonstrate that viral NSP14 activates nuclear factor κB (NF-κB)-dependent transcription, even in the presence of cytokine signaling. Moreover, for several tested host proteins, genetic knock-down substantially reduces viral replication. Additionally, we show for USP25 that this effect is phenocopied by the small-molecule inhibitor AZ1. Our results connect viral proteins to human genetic architecture for COVID-19 severity and offer potential therapeutic targets.

CXCL4 synergizes with TLR8 for TBK1-IRF5 activation, epigenomic remodeling and inflammatory response in human monocytes

Regulation of endosomal Toll-like receptor (TLR) responses by the chemokine CXCL4 is implicated in inflammatory and fibrotic diseases, with CXCL4 proposed to potentiate TLR responses by binding to nucleic acid TLR ligands and facilitating their endosomal delivery. Here we report that in human monocytes/macrophages, CXCL4 initiates signaling cascades and downstream epigenomic reprogramming that change the profile of the TLR8 response by selectively amplifying inflammatory gene transcription and interleukin (IL)-1β production, while partially attenuating the interferon response. Mechanistically, costimulation by CXCL4 and TLR8 synergistically activates TBK1 and IKKε, repurposes these kinases towards an inflammatory response via coupling with IRF5, and activates the NLRP3 inflammasome. CXCL4 signaling, in a cooperative and synergistic manner with TLR8, induces chromatin remodeling and activates de novo enhancers associated with inflammatory genes. Our findings thus identify new regulatory mechanisms of TLR responses relevant for cytokine storm, and suggest targeting the TBK1-IKKε-IRF5 axis may be beneficial in inflammatory diseases.

Supraphysiologic Testosterone Induces Ferroptosis and Activates Immune Pathways through Nucleophagy in Prostate Cancer

The discovery that androgens play an important role in the progression of prostate cancer led to the development of androgen deprivation therapy (ADT) as a first line of treatment. However, paradoxical growth inhibition has been observed in a subset of prostate cancer upon administration of supraphysiologic levels of testosterone (SupraT), both experimentally and clinically. Here we report that SupraT activates cytoplasmic nucleic acid sensors and induces growth inhibition of SupraT-sensitive prostate cancer cells. This was initiated by the induction of two parallel autophagy-mediated processes, namely, ferritinophagy and nucleophagy. Consequently, autophagosomal DNA activated nucleic acid sensors converge on NFκB to drive immune signaling pathways. Chemokines and cytokines secreted by the tumor cells in response to SupraT resulted in increased migration of cytotoxic immune cells to tumor beds in xenograft models and patient tumors. Collectively, these findings indicate that SupraT may inhibit a subset of prostate cancer by activating nucleic acid sensors and downstream immune signaling. SIGNIFICANCE: This study demonstrates that supraphysiologic testosterone induces two parallel autophagy-mediated processes, ferritinophagy and nucleophagy, which then activate nucleic acid sensors to drive immune signaling pathways in prostate cancer.

Revisiting steroidogenesis and its role in immune regulation with the advanced tools and technologies

Historically tools and technologies facilitated scientific discoveries. Steroid hormone research is not an exception. Unfortunately, the dramatic advancement of the field faded this research area and flagged it as a solved topic. However, it should have been the opposite. The area should glitter with its strong foundation and attract next-generation scientists. Over the past century, a myriad of new facts on biochemistry, molecular biology, cell biology, physiology and pathology of the steroid hormones was discovered. Several innovations were made and translated into life-saving treatment strategies such as synthetic steroids, and inhibitors of steroidogenesis and steroid signaling. Steroid molecules exhibit their diverse effects on cell metabolism, salt and water balance, development and function of the reproductive system, pregnancy, and immune-cell function. Despite vigorous research, the molecular basis of the immunomodulatory effect of steroids is still mysterious. The recent excitement on local extra-glandular steroidogenesis in regulating inflammation and immunity is revitalizing the topic with a new perspective. Therefore, here we review the role of steroidogenesis in regulating inflammation and immunity, discuss the unresolved questions, and how this area can bring another golden age of steroid hormone research with the development of new tools and technologies and advancement of the scientific methods.

N4BP1 negatively regulates NF-κB by binding and inhibiting NEMO oligomerization

Many immune responses depend upon activation of NF-κB, an important transcription factor in the elicitation of a cytokine response. Here we show that N4BP1 inhibits TLR-dependent activation of NF-κB by interacting with the NF-κB signaling essential modulator (NEMO, also known as IκB kinase γ) to attenuate NEMO-NEMO dimerization or oligomerization. The UBA-like (ubiquitin associated-like) and CUE-like (ubiquitin conjugation to ER degradation-like) domains in N4BP1 mediate interaction with the NEMO COZI domain. Both in vitro and in mice, N4bp1 deficiency specifically enhances TRIF-independent (TLR2, TLR7, or TLR9-mediated) but not TRIF-dependent (TLR3 or TLR4-mediated) NF-κB activation, leading to increased production of proinflammatory cytokines. In response to TLR4 or TLR3 activation, TRIF causes activation of caspase-8, which cleaves N4BP1 distal to residues D424 and D490 and abolishes its inhibitory effect. N4bp1-/- mice also have diminished numbers of T cells in the peripheral blood. Our work identifies N4BP1 as an inhibitory checkpoint protein that must be overcome to activate NF-κB, and a TRIF-initiated caspase-8-dependent mechanism by which this is accomplished.

Quantifying information accumulation encoded in the dynamics of biochemical signaling

Cellular responses to environmental changes are encoded in the complex temporal patterns of signaling proteins. However, quantifying the accumulation of information over time to direct cellular decision-making remains an unsolved challenge. This is, in part, due to the combinatorial explosion of possible configurations that need to be evaluated for information in time-course measurements. Here, we develop a quantitative framework, based on inferred trajectory probabilities, to calculate the mutual information encoded in signaling dynamics while accounting for cell-cell variability. We use it to understand NFκB transcriptional dynamics in response to different immune threats, and reveal that some threats are distinguished faster than others. Our analyses also suggest specific temporal phases during which information distinguishing threats becomes available to immune response genes; one specific phase could be mapped to the functionality of the IκBα negative feedback circuit. The framework is generally applicable to single-cell time series measurements, and enables understanding how temporal regulatory codes transmit information over time.

IRAK3 modulates downstream innate immune signalling through its guanylate cyclase activity

Interleukin-1 receptor associated kinase 3 (IRAK3) is a cytoplasmic homeostatic mediator of inflammatory responses and is potentially useful as a prognostic marker in inflammation. IRAK3 inhibits signalling cascades downstream of myddosome complexes associated with toll like receptors. IRAK3 contains a death domain that interacts with other IRAK family members, a pseudokinase domain and a C-terminus domain involved with tumour necrosis factor receptor associated factor 6 (TRAF6). Previous bioinformatic studies revealed that IRAK3 contained a guanylate cyclase centre in its pseudokinase domain but its role in IRAK3 action is unresolved. We demonstrate that wildtype IRAK3 is capable of producing cGMP. Furthermore, we show that a specific point mutation in the guanylate cyclase centre reduced cGMP production. Cells containing toll like receptor 4 and a nuclear factor kappa-light-chain-enhancer of activated B cells (NFĸB) reporter system were transfected with IRAK3 or mutant IRAK3 proteins. Cell-permeable cGMP treatment of untransfected control cells suppresses downstream signalling through modulation of the NFĸB in the presence of lipopolysaccharides. Cells transfected with wildtype IRAK3 also suppress lipopolysaccharide induced NFĸB activity in the absence of exogenous cGMP. Lipopolysaccharide induced NFĸB activity was not suppressed in cells transfected with the IRAK3 mutant with reduced cGMP-generating capacity. Whereas in the presence of exogenously applied cell-permeable cGMP the IRAK3 mutant was able to retain its function by suppressing lipopolysaccharide induced NFĸB activity. Furthermore, increasing the amount of membrane permeable cGMP did not affect IRAK3's ability to reduce NFĸB activity. These results suggest that cGMP generated by IRAK3 may be involved in regulatory function of the protein where the presence of cGMP may selectively affect downstream signalling pathway(s) by modulating binding and/or activity of nearby proteins that interact in the inflammatory signalling cascade.

Immune adaptor SKAP1 acts a scaffold for Polo-like kinase 1 (PLK1) for the optimal cell cycling of T-cells

While the immune cell adaptor protein SKAP1 mediates LFA-1 activation induced by antigen-receptor (TCR/CD3) ligation on T-cells, it is unclear whether the adaptor interacts with other mediators of T-cell function. In this context, the serine/threonine kinase, polo-like kinase (PLK1) regulates multiple steps in the mitotic and cell cycle progression of mammalian cells. Here, we show that SKAP1 is phosphorylated by and binds to PLK1 for the optimal cycling of T-cells. PLK1 binds to the N-terminal residue serine 31 (S31) of SKAP1 and the interaction is needed for optimal PLK1 kinase activity. Further, siRNA knock-down of SKAP1 reduced the rate of T-cell division concurrent with a delay in the expression of PLK1, Cyclin A and pH3. Reconstitution of these KD cells with WT SKAP1, but not the SKAP1 S31 mutant, restored normal cell division. SKAP1-PLK1 binding is dynamically regulated during the cell cycle of T-cells. Our findings identify a novel role for SKAP1 in the regulation of PLK1 and optimal cell cycling needed for T-cell clonal expansion in response to antigenic activation.

Doxorubicin-Hyaluronan Conjugated Super-Paramagnetic Iron Oxide Nanoparticles (DOX-HA-SPION) Enhanced Cytoplasmic Uptake of Doxorubicin and Modulated Apoptosis, IL-6 Release and NF-kappaB Activity in Human MDA-MB-231 Breast Cancer Cells

Triple negative breast cancer exhibit increased IL-6 expression compared with matched healthy breast tissue and a strong link between inflammation and cancer progression and metastasis has been reported. We investigated whether doxorubicin-hyaluronan-super-paramagnetic iron oxide nanoparticles (DOX-HA-SPION) would show greater therapeutic efficacy in human triple negative breast cancer cells (TNBC) MDA-MB-231, as was recently shown in drug-sensitive and multi-drug-resistant ovarian cancer cells. Therefore, we measured cellular DOX uptake via confocal microscopy; observed morphologic changes: mitochondrial and nuclear changes with electron microscopy, and quantitated apoptosis using FACS analysis after Annexin V and PI staining in MDA-MB-231 cells treated with either DOX alone or DOX-HA-SPION. We also measured both proinflammatory and anti-inflammatory cytokines; IL-6, IL-10 respectively and also measured nitrate levels in the conditioned medium by ELISA. Inaddition, NF-κB activity was measured by luciferase assay. Confocal microscopy demonstrated greater cytoplasmic uptake of DOX-HA-SPION than free DOX. We also demonstrated reduction of Vimentin with DOX-HA-SPION which is significantly less than both control and DOX. DOX-HA-SPION enhanced apoptosis and significantly down regulated both pro-inflammatory mediators IL-6 and NF-κB in comparison to DOX alone. The secretion levels of anti-inflammatory mediators IL-10 and nitrate was not decreased in the DOX or DOX-HA-SPION treatment groups. Our data suggest that DOX-HA-SPION nanomedicine-based drug delivery could have promising potential in treating metastasized and chemoresistant breast cancer by enhancing the drug efficacy and minimizing off-target effects.

Liver X receptor-dependent inhibition of microglial nitric oxide synthase 2

BACKGROUND

The nuclear receptor liver X receptor (LXR) exerts transcriptional control over lipid metabolism and inflammatory response in cells of the myeloid lineage, suggesting that LXR may be a potential target in a number of chronic neuroinflammatory and neurodegenerative diseases where persistent microglial activation has been implicated in the pathogenesis.

METHODS

The effect of LXR activation on microglia and central nervous system (CNS) inflammation was studied using a synthetic LXR agonist in cultured microglia, a microglial cell line and experimental allergic encephalomyelitis (EAE), an animal model of CNS inflammation.

RESULTS

LXR activation inhibited nitric oxide synthase 2, inducible (Nos2) expression and nitric oxide production in lipopolysaccharide (LPS)-stimulated microglia. Inhibition of microglial activation in response to interferon-γ was less reliable. In LPS-stimulated cells, LXR activation did not inhibit nuclear translocation of NF-kappaB1 p50. Instead, LXR-dependent Nos2 repression was associated with inhibition of histone 4 acetylation and inhibition of NF-kappaB1 p50 binding at the Nos2 promoter. Histone acetylation and NF-kappaB1 p50 binding were mechanistically linked, and histone deacetylase (HDAC) activity appeared to be important for LXR-dependent transcriptional repression of Nos2. Analysis of CNS gene expression in animals undergoing EAE showed that the expressions of Lxr and LXR-dependent genes were downregulated during CNS inflammation. Nevertheless, administration of LXR agonist GW3965 during the effector phase of EAE delayed the onset of clinical disease and reversed the diminished expression of LXR-dependent reverse cholesterol transport genes. However, the CNS expressions of Nos2 and other inflammatory genes were not significantly inhibited by LXR activation in EAE, and clinical disease severity was comparable to vehicle controls at later time points in LXR agonist treated animals.

CONCLUSIONS

LXR can be targeted to modulate microglial activation. LXR-dependent repression of inflammatory genes may be stimulus-dependent and impaired by HDAC inhibition. Endogenous LXR activity does not appear to modulate CNS inflammation, but LXR activity can be partially restored in the CNS by administration of exogenous LXR agonist with an impact on clinical disease severity at early, but not late, time points in EAE.

Glucocorticoids increase excitotoxic injury and inflammation in the hippocampus of adult male rats

BACKGROUND/AIMS

Stress exacerbates neuron loss in many CNS injuries via the actions of adrenal glucocorticoid (GC) hormones. For some injuries, this GC endangerment of neurons is accompanied by greater immune cell activation in the CNS, a surprising outcome given the potent immunosuppressive properties of GCs.

METHODS

To determine whether the effects of GCs on inflammation contribute to neuron death or result from it, we tested whether nonsteroidal anti-inflammatory drugs could protect neurons from GCs during kainic acid excitotoxicity in adrenalectomized male rats. We next measured GC effects on (1) chemokine production (CCL2 and CINC-1), (2) signals that suppress immune activation (CX3CL1, CD22, CD200, and TGF-β), and (3) NF-κB activity.

RESULTS

Concurrent treatment with minocycline, but not indomethacin, prevented GC endangerment. GCs did not substantially affect CCL2, CINC-1, or baseline NF-κB activity, but they did suppress CX3CL1, CX3CR1, and CD22 expression in the hippocampus - factors that normally restrain inflammatory responses.

CONCLUSIONS

These findings demonstrate that cellular inflammation is not necessarily suppressed by GCs in the injured hippocampus; instead, GCs may worsen hippocampal neuron death, at least in part by increasing the neurotoxicity of CNS inflammation.

Upregulation of mGlu2 receptors via NF-κB p65 acetylation is involved in the Proneurogenic and antidepressant effects of acetyl-L-carnitine

Acetyl-L-carnitine (ALC) is a naturally occurring molecule with an important role in cellular bioenergetics and as donor of acetyl groups to proteins, including NF-κB p65. In humans, exogenously administered ALC has been shown to be effective in mood disturbances, with a good tolerability profile. No current information is available on the antidepressant effect of ALC in animal models of depression and on the putative mechanism involved in such effect. Here we report that ALC is a proneurogenic molecule, whose effect on neuronal differentiation of adult hippocampal neural progenitors is independent of its neuroprotective activity. The in vitro proneurogenic effects of ALC appear to be mediated by activation of the NF-κB pathway, and in particular by p65 acetylation, and subsequent NF-κB-mediated upregulation of metabotropic glutamate receptor 2 (mGlu2) expression. When tested in vivo, chronic ALC treatment could revert depressive-like behavior caused by unpredictable chronic mild stress, a rodent model of depression with high face validity and predictivity, and its behavioral effect correlated with upregulated expression of mGlu2 receptor in hippocampi of stressed mice. Moreover, chronic, but not acute or subchronic, drug treatment significantly increased adult born neurons in hippocampi of stressed and unstressed mice. We now propose that this mechanism could be potentially involved in the antidepressant effect of ALC in humans. These results are potentially relevant from a clinical perspective, as for its high tolerability profile ALC may be ideally employed in patient subpopulations who are sensitive to the side effects associated with classical antidepressants.

Effects of low-dose aspirin and fish oil on platelet function and NF-kappaB in adults with diabetes mellitus

INTRODUCTION

Many diabetics are insensitive to aspirin's platelet anti-aggregation effects. The possible modulating effects of co-administration of aspirin and fish oil in subjects with diabetes are poorly characterized.

PARTICIPANTS AND METHODS

Thirty adults with type 2 diabetes mellitus were treated with aspirin 81 mg/d for 7 days, then with fish oil 4 g/day for 28 days, then the combination of fish oil and aspirin for another 7 days.

RESULTS

Aspirin alone and in combination with fish oil reduced platelet aggregation in most participants. Five of 7 participants classified as aspirin insensitive 1 week after daily aspirin ingestion were sensitive after the combination. Although some platelet aggregation measures correlated positively after aspirin and fish oil ingestion alone and (in combination) in all individuals, correlation was only observed in those who were aspirin insensitive after ingestion of the combination.

CONCLUSIONS

Co-administration of aspirin and fish oil may reduce platelet aggregation more than aspirin alone in adults with diabetes mellitus.

Lack of Cyp1b1 promotes the proliferative and migratory phenotype of perivascular supporting cells

Perivascular supporting cells, including pericytes and smooth muscle cells (PC/SMC), have an integral role during angiogenesis and control vascular remodeling, maturation, and stabilization of neoteric vessels. We recently showed that a Cyp1B1 deficiency in mice results in the attenuation of angiogenesis in vivo and the pro-angiogenic activity of endothelial cells in vitro. However, the contribution of PC/SMC, and more specifically the cell autonomous effects of Cyp1B1 in these processes, needs further investigation. Here we demonstrate that PC constitutively expressed Cyp1B1, and that a deficiency in Cyp1B1 was associated with enhanced proliferation, and decreased apoptosis. Mechanistically, the lack of Cyp1B1 was associated with increased oxidative stress and sustained NF-κB activation, which was reversed by the antioxidant N-acetylcysteine. These changes were also concomitant with alterations in PC migration, adhesion, and expression of various extracellular matrix proteins, including thrombospondin-2. Cyp1B1-deficient PC also expressed decreased levels of vascular endothelial growth factor. Together, our results suggest an important role for Cyp1B1 expression in the regulation of PC proliferation, migration, and survival through modulation of the intracellular oxidative state and NF-κB expression and/or activity. Thus, a lack of Cyp1B1 in PC may have a significant role in vascular dysfunction and integrity, contributing to the attenuation of angiogenesis.

NF-kB overexpression and decreased immunoexpression of AR in the muscular layer is related to structural damages and apoptosis in cimetidine-treated rat vas deferens

BACKGROUND

Cimetidine, histamine H2 receptors antagonist, has caused adverse effects on the male hormones and reproductive tract due to its antiandrogenic effect. In the testes, peritubular myoid cells and muscle vascular cells death has been associated to seminiferous tubules and testicular microvascularization damages, respectively. Either androgen or histamine H2 receptors have been detected in the mucosa and smooth muscular layer of vas deferens. Thus, the effect of cimetidine on this androgen and histamine-dependent muscular duct was morphologically evaluated.

METHODS

The animals from cimetidine group (CMTG; n=5) received intraperitoneal injections of 100 mg/kg b.w. of cimetidine for 50 days; the control group (CG) received saline solution. The distal portions of vas deferens were fixed in formaldehyde and embedded in paraffin. Masson´s trichrome-stained sections were subjected to morphological and the following morphometrical analyzes: epithelial perimeter and area of the smooth muscular layer. TUNEL (Terminal deoxynucleotidyl-transferase mediated dUTP Nick End Labeling) method, NF-kB (nuclear factor kappa B) and AR (androgen receptors) immunohistochemical detection were also carried out. The birefringent collagen of the muscular layer was quantified in picrosirius red-stained sections under polarized light. The muscular layer was also evaluated under Transmission Electron Microscopy (TEM).

RESULTS

In CMTG, the mucosa of vas deferens was intensely folded; the epithelial cells showed numerous pyknotic nuclei and the epithelial perimeter and the area of the muscular layer decreased significantly. Numerous TUNEL-labeled nuclei were found either in the epithelial cells, mainly basal cells, or in the smooth muscle cells which also showed typical features of apoptosis under TEM. While an enhanced NF-kB immunoexpression was found in the cytoplasm of muscle cells, a weak AR immunolabeling was detected in these cells. In CMTG, no significant difference was observed in the birefringent collagen content of the muscular layer in comparison to CG.

CONCLUSIONS

Cimetidine induces significant damages in the epithelium; a possible antiandrogenic effect on the basal cells turnover should be considered. The cimetidine-induced muscle cells apoptosis confirms the susceptibility of these cells to this drug. The parallelism between enhanced cytoplasmic NF-kB immunolabeling in the damaged muscular tissue and muscle cell apoptosis suggests that this drug may avoid the translocation of NF-kB to the nucleus and interfere in the control of NF-kB-mediated smooth muscle cell apoptosis. The decreased immunoexpression of ARs verified in the damaged muscular tissue reinforces this possibility.

A functional genomics screen for microRNA regulators of NF-kappaB signaling

BACKGROUND

The nuclear factor-KappaB (NF-κB) pathway is conserved from fruit flies to humans and is a key mediator of inflammatory signaling. Aberrant regulation of NF-κB is associated with several disorders including autoimmune disease, chronic inflammation, and cancer, making the NF-κB pathway an attractive therapeutic target. Many regulatory components of the NF-κB pathway have been identified, including microRNAs (miRNAs). miRNAs are small non-coding RNAs and are common components of signal transduction pathways. Here we present a cell-based functional genomics screen to systematically identify miRNAs that regulate NF-κB signaling.

RESULTS

We screened a library of miRNA mimics using a NF-κB reporter cell line in the presence and absence of tumor necrosis factor (+/- TNF). There were 9 and 15 hits in the -TNF and +TNF screens, respectively. We identified putative functional targets of these hits by integrating computational predictions with NF-κB modulators identified in a previous genome-wide cDNA screen. miR-517a and miR-517c were the top hits, activating the reporter 86- and 126-fold, respectively. Consistent with these results, miR-517a/c induced the expression of endogenous NF-κB targets and promoted the nuclear localization of p65 and the degradation of IκB. We identified TNFAIP3 interacting protein1 (TNIP1) as a target and characterized a functional SNP in the miR-517a/c binding site. Lastly, miR-517a/c induced apoptosis in vitro, which was phenocopied by knockdown of TNIP1.

CONCLUSIONS

Our study suggests that miRNAs are common components of NF-κB signaling and miR-517a/c may play an important role in linking NF-κB signaling with cell survival through TNIP1.

Interleukin-1 antagonists and other cytokine blockade strategies for type 1 diabetes

Proinflammatory cytokines stimulate adaptive immunity and attenuate T cell regulation and tolerance induction. They also profoundly impair β-cell function, proliferation, and viability, activities of similar importance in the context of type 1 diabetes (T1D). Detailed knowledge of the molecular mechanisms of β-cell toxicity has been gathered within the last 2-3 decades. However, the efficacy of individual proinflammatory cytokine blockade in animal models of T1D has been inconsistent and generally modest, except in the context of islet transplantation. This suggests that the timing of the cytokine blockade relative to anti-β-cell immune activation is critical, and that combination therapy may be required. In randomized, placebo-controlled, clinical trials of limited power, TNF-α (but not IL-1) blockade has yielded moderate but significant improvements in glycemia, insulin requirement, and β-cell function. The safety experience with anti-cytokine biologics is still very limited in T1D. However, combinations with other biologics, at doses of adaptive and innate immune inhibitors/modulators that are suboptimal or ineffective in themselves, may generate synergies of true therapeutic benefit and safety in T1D. Critical and balanced appraisal of the preclinical and clinical evidence of efficacy and safety of anti-immune, anti-inflammatory, and anti-dysmetabolic therapeutics should thus guide future studies to move closer to novel treatments, targeting the underlying causes of β-cell failure and destruction in T1D.

Microencapsulated drug delivery: a new approach to pro-inflammatory cytokine inhibition

CONTEXT

This article reviews the use of albumin microcapsules 3-4 µm in size containing cytokine inhibiting drugs which include neutralizing antibodies to TNF and IL1, CNI-1493, antisense oligonucleotides to TNF and NF-kappaB, and the antioxidant catalase.

OBJECTIVE

Describe the effects, cellular uptake and distribution of microencapsulated drugs and the effect in both a peritonitis model of infection and a model of adjuvant-induced arthritis.

METHODS

The studies performed by our group are reviewed, the only such studies available.

RESULTS

Microencapsulation of these compounds produced high intracellular drug concentrations due to rapid uptake by phagocytic cells, including endothelial cells, without toxicity. All compounds produced excellent inhibition of TNF and IL1 resulting in improved animal survival in a peritonitis model of septic shock and inflammation in an arthritis model.

CONCLUSION

Albumin microencapsulated pro-inflammatory cytokine inhibiting compounds are superior to equivalent concentration of these compounds administered in solution form.

Crucial role of CD40 signaling in vascular wall cells in neointimal formation and vascular remodeling after vascular interventions

OBJECTIVE

It has been shown that CD40-TRAF6 axis in leukocytes plays a significant role in neointimal formation after carotid ligation. Because CD40 and TRAF6 are expressed not only in leukocytes but also in vascular cells, we examined the role of CD40 contributed by vascular wall cells in neointimal formation after carotid ligation in an atherogenic environment.

METHODS AND RESULTS

Both CD40 and TRAF6 in medial smooth muscle cells (SMCs) was upregulated significantly at 3 days and more prominently at 7 days after injury in wildtype mice, but the TRAF6 upregulation was abolished in CD40(-/-) mice. In vitro, TRAF6 expression was induced by cytokines (tumor necrosis factor -α, interleukin-1β) via a NF-κB-dependent manner in wildtype SMCs, but this induction was blocked in CD40-deficient SMCs. Bone marrow chimeras revealed a comparable reduction in neointimal formation and lumen stenosis in mice lacking either vascular wall- or bone marrow-associated CD40. Lacking vascular wall-associated CD40 resulted in a significant reduction in monocyte/macrophage accumulation, NF-κB activation, and multiple proinflammatory mediators (ICAM-1, VCAM-1, MCP-1, MMP-9, tissue factor). In vitro data confirmed that CD40 deficiency or TRAF6 knockdown suppressed CD40L-induced proinflammatory phenotype of SMCs by inhibition of NF-κB activation. Moreover, both in vivo and in vitro data showed that CD40 deficiency prevented injury-induced SMC apoptosis but did not affect SMC proliferation and migration.

CONCLUSIONS

CD40 signaling through TRAF6 in vascular SMCs seems to be centrally involved in neointimal formation in a NF-κB-dependent manner. Modulating CD40 signaling on local vascular wall may become a new therapeutic target against vascular restenosis.

Molecular imaging of nuclear factor-κB in bladder as a primary regulator of inflammatory response

PURPOSE

Nuclear factor-κB activation is implicated in chronic inflammatory disorders and it is a key regulator of genes involved in the response to infection, inflammation and stress. Interstitial cystitis and painful bladder syndrome are common inflammatory disorders of the bladder characterized by frequent urination and bladder pain. The role of nuclear factor-κB activation in bladder inflammation is not well defined.

MATERIALS AND METHODS

Female transgenic nuclear factor-κB-luciferase Tag mice (The Jackson Laboratory, Bar Harbor, Maine) were used to perform serial, noninvasive in vivo and ex vivo molecular imaging of nuclear factor-κB activation in the whole body after administering arsenic trioxide (5 mg/kg), lipopolysaccharide (2 mg/kg) or cyclophosphamide (Sigma®) (200 mg/kg) to initiate acute transient bladder inflammation. Pretreatment with dexamethasone (Sigma) (10 mg/kg) was used to modulate cyclophosphamide induced nuclear factor-κB dependent luminescence in vivo.

RESULTS

Treatment of nuclear factor-κB-luciferase Tag mice with chemicals increased luminescence in a time and organ specific manner in vivo and ex vivo. The highest levels of bladder nuclear factor-κB dependent luminescence were observed 4 hours after cyclophosphamide administration. Pretreatment with dexamethasone 1 hour before cyclophosphamide injection significantly down-regulated cyclophosphamide induced bladder nuclear factor-κB dependent luminescence, ameliorated the grossly evident pathological features of acute inflammation and decreased cellular immunostaining for nuclear factor-κB in the bladder.

CONCLUSIONS

Nuclear factor-κB activity may have an important role in the pathophysiology of bladder inflammation. Nuclear factor-κB-luciferase mice can serve as a useful model in which to screen potential candidate drugs for cystitis associated with aberrant nuclear factor-κB activity. Such screening may significantly aid the development of therapeutic strategies to manage inflammatory bladder disorders.

Mapping the IkappaB kinase beta (IKKbeta)-binding interface of the B14 protein, a vaccinia virus inhibitor of IKKbeta-mediated activation of nuclear factor kappaB

The IκB kinase (IKK) complex regulates activation of NF-κB, a critical transcription factor in mediating inflammatory and immune responses. Not surprisingly, therefore, many viruses seek to inhibit NF-κB activation. The vaccinia virus B14 protein contributes to virus virulence by binding to the IKKβ subunit of the IKK complex and preventing NF-κB activation in response to pro-inflammatory stimuli. Previous crystallographic studies showed that the B14 protein has a Bcl-2-like fold and forms homodimers in the crystal. However, multi-angle light scattering indicated that B14 is in monomer-dimer equilibrium in solution. This transient self-association suggested that the hydrophobic dimerization interface of B14 might also mediate its interaction with IKKβ, and this was investigated by introducing amino acid substitutions on the dimer interface. One mutant (Y35E) was entirely monomeric but still co-immunoprecipitated with IKKβ and blocked both NF-κB nuclear translocation and NF-κB-dependent gene expression. Therefore, B14 homodimerization is nonessential for binding and inhibition of IKKβ. In contrast, a second monomeric mutant (F130K) neither bound IKKβ nor inhibited NF-κB-dependent gene expression, demonstrating that this residue is required for the B14-IKKβ interaction. Thus, the dimerization and IKKβ-binding interfaces overlap and lie on a surface used for protein-protein interactions in many viral and cellular Bcl-2-like proteins.

Neuropeptide Y modulation of interleukin-1{beta} (IL-1{beta})-induced nitric oxide production in microglia

Given the modulatory role of neuropeptide Y (NPY) in the immune system, we investigated the effect of NPY on the production of NO and IL-1β in microglia. Upon LPS stimulation, NPY treatment inhibited NO production as well as the expression of inducible nitric-oxide synthase (iNOS). Pharmacological studies with a selective Y(1) receptor agonist and selective antagonists for Y(1), Y(2), and Y(5) receptors demonstrated that inhibition of NO production and iNOS expression was mediated exclusively through Y(1) receptor activation. Microglial cells stimulated with LPS and ATP responded with a massive release of IL-1β, as measured by ELISA. NPY inhibited this effect, suggesting that it can strongly impair the release of IL-1β. Furthermore, we observed that IL-1β stimulation induced NO production and that the use of a selective IL-1 receptor antagonist prevented NO production upon LPS stimulation. Moreover, NPY acting through Y(1) receptor inhibited LPS-stimulated release of IL-1β, inhibiting NO synthesis. IL-1β activation of NF-κB was inhibited by NPY treatment, as observed by confocal microscopy and Western blotting analysis of nuclear translocation of NF-κB p65 subunit, leading to the decrease of NO synthesis. Our results showed that upon LPS challenge, microglial cells release IL-1β, promoting the production of NO through a NF-κB-dependent pathway. Also, NPY was able to strongly inhibit NO synthesis through Y(1) receptor activation, which prevents IL-1β release and thus inhibits nuclear translocation of NF-κB. The role of NPY in key inflammatory events may contribute to unravel novel gateways to modulate inflammation associated with brain pathology.

Tumor necrosis factor alpha-induced inflammation is increased but apoptosis is inhibited by common food additive carrageenan

Tumor necrosis factor (TNF)-α, a homotrimeric, pleiotropic cytokine, is secreted in response to inflammatory stimuli in diseases such as rheumatoid arthritis and inflammatory bowel disease. TNF-α mediates both apoptosis and inflammation, stimulating an inflammatory cascade through the non-canonical pathway of NF-κB activation, leading to increased nuclear RelB and p52. In contrast, the common food additive carrageenan (CGN) stimulates inflammation through both the canonical and non-canonical pathways of NF-κB activation and utilizes the adaptor molecule BCL10 (B-cell leukemia/lymphoma 10). In a series of experiments, colonic epithelial cells and mouse embryonic fibroblasts were treated with TNF-α and carrageenan in order to simulate the possible effects of exposure to dietary CGN in the setting of a TNF-α-mediated inflammatory disease process. A marked increase in secretion of IL-8 occurred, attributable to synergistic effects on phosphorylated NF-κB-inducing kinase (NIK) in the non-canonical pathway. TNF-α induced the ubiquitination of TRAF2 (TNF receptor-associated factor 2), which interacts with NIK, and CGN induced phosphorylation of BCL10, leading to increased NIK phosphorylation. These results suggest that TNF-α and CGN in combination act to increase NIK phosphorylation, thereby increasing activation of the non-canonical pathway of NF-κB activation. In contrast, the apoptotic effects of TNF-α, including activation of caspase-8 and PARP-1 (poly(ADP-ribose) polymerase 1) fragmentation, were markedly reduced in the presence of CGN, and CGN caused reduced expression of Fas. These findings demonstrate that exposure to CGN drives TNF-α-stimulated cells toward inflammation rather than toward apoptotic cell death and suggest that CGN exposure may compromise the effectiveness of anti-TNF-α therapy.

Cactin targets the MHC class III protein IkappaB-like (IkappaBL) and inhibits NF-kappaB and interferon-regulatory factor signaling pathways

Toll-like receptors (TLRs) act as primary sensors of the immune system by recognizing specific microbial motifs and inducing proinflammatory genes that facilitate innate and adaptive immunity. TLRs regulate gene expression by activating transcription factors, such as NF-κB and interferon-regulatory factors. Dysregulation of these pathways can lead to inflammatory diseases, and thus they are subject to stringent control by negative regulators of innate immune signaling. Cactin (Cactus interactor) was initially discovered as a novel interactor of Drosophila Cactus, a regulator of Drosophila Toll signaling. We now describe the first functional characterization of the human ortholog of Cactin (hCactin) and show that it acts as a negative regulator of TLRs. Overexpression of hCactin suppresses TLR-induced activation of NF-κB and interferon-regulatory factor transcription factors and induction of TLR-responsive genes, whereas knockdown of endogenous hCactin augments TLR induction of these responses. hCactin also interacts with IκB-like protein and targets other proteins that are encoded by genes in the MHC Class III region of chromosome 6. We demonstrate that hCactin localizes to the nucleus, and this nuclear localization is critical for manifesting its inhibitory effects on TLR signaling. This study thus defines hCactin as a novel negative regulator of TLR signaling and reveals its capacity to target MHC Class III genes at the molecular and functional level.

Cigarette smoke extract promotes human vascular smooth muscle cell proliferation and survival through ERK1/2- and NF-κB-dependent pathways

Tobacco use is one of the major risk factors of cardiovascular disease. The underlying molecular mechanisms that link cigarette smoke to cardiovascular disease remain unclear. The present study was designed to examine the effects of dimethyl sulfoxide (DMSO)-soluble smoke particles (DSPs) on human aortic smooth muscle cell (HASMC) cultures, and to explore the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated protein kinase 1 and 2 (ERK1/2) and nuclear factor-kappaB (NF-κB) signal mechanisms involved. Serum-starved HASMCs were treated with DSPs for up to 48 h. DSPs promoted cell proliferation in a concentration-dependent manner from 0.05 to 0.2 μl/ml. Activation of ERK1/2 and NF-κB was seen after exposure to DSPs. This occurred in parallel with the increase in cell population, bromodeoxyuridine incorporation, and cyclinD1/cyclin-dependent kinase 4 expression. Blocking phosphorylation of ERK1/2 by MAPK inhibitors U0126 and PD98059, and inhibiting activation of NF-κB by IkappaB (IκB) kinase inhibitors wedelolactone or IMD-0354, abolished the DSP effects. However, either a p38 inhibitor (SB203580) or an inhibitor of lipopolysaccharide (polymyxin B), or nicotinic receptor blockers (mecamylamine and alpha-bungarotoxin), did not inhibit a DSP-induced increase in the cell population. DSPs increased the expression of intercellular adhesion molecule 1 and the release of interleukin-6 in HASMCs, both of which were inhibited by ERK1/2 or NF-κB pathway inhibitors. Furthermore, cell apoptosis and necrosis were found in serum-starved HASMCs. DSPs decreased cell death and increased B-cell leukemia/lymphoma 2 expression. Blocking phosphorylation of ERK1/2 or NF-κB attenuated DSP-induced cell death inhibition. Cigarette smoke particles stimulate HASMC proliferation and inhibit cell death. The intracellular signal mechanisms behind this involve activation of ERK1/2 and NF-κB pathways.

CCAAT/enhancer-binding protein β and NF-κB mediate high level expression of chemokine genes CCL3 and CCL4 by human chondrocytes in response to IL-1β

A large set of chemokines is highly up-regulated in human chondrocytes in response to IL-1β (Sandell, L. J., Xing, X., Franz, C., Davies, S., Chang, L. W., and Patra, D. (2008) Osteoarthr. Cartil. 16, 1560-1571). To investigate the mechanism of transcriptional regulation, deletion constructs of selected chemokine gene promoters, the human CCL3 (MIP-1α) and CCL4 (MIP-1β), were transfected into human chondrocytes with or without IL-1β. The results show that an IL-1β-responsive element is located between bp -300 and -140 of the CCL3 promoter and between bp -222 and -100 of the CCL4 promoter. Because both of these elements contain CCAAT/enhancer-binding protein β (C/EBPβ) motifs, the function of C/EBPβ was examined. IL-1β stimulated the expression of C/EBPβ, and the direct binding of C/EBPβ to the C/EBPβ motif was confirmed by EMSA and ChIP analyses. The -300 bp CCL3 promoter and -222 bp CCL4 promoter were strongly up-regulated by co-transfection with the C/EBPβ expression vector. Mutation of the C/EBPβ motif and reduction of C/EBPβ expression by siRNA decreased the up-regulation. Additionally, another cytokine-related transcription factor, NF-κB, was also shown to be involved in the up-regulation of chemokines in response to IL-1β, and the binding site was identified. The regulation of C/EBPβ and NF-κB was confirmed by the inhibition by C/EBPβ and NF-κB and by transfection with C/EBPβ and NF-κB expression vectors in the presence or absence of IL-1β. Taken together, our results suggest that C/EBPβ and NF-κB are both involved in the IL-1β-responsive up-regulation of chemokine genes in human chondrocytes. Time course experiments indicated that C/EBPβ gradually and steadily induces chemokine up-regulation, whereas NF-κB activity was highest at the early stage of chemokine up-regulation.

Reactive oxygen species in TNFalpha-induced signaling and cell death

TNFalpha is a pleotropic cytokine that initiates many downstream signaling pathways, including NF-kappaB activation, MAP kinase activation and the induction of both apoptosis and necrosis. TNFalpha has shown to lead to reactive oxygen species generation through activation of NADPH oxidase, through mitochondrial pathways, or other enzymes. As discussed, ROS play a role in potentiation or inhibition of many of these signaling pathways. We particularly discuss the role of sustained JNK activation potentiated by ROS, which generally is supportive of apoptosis and "necrotic cell death" through various mechanisms, while ROS could have inhibitory or stimulatory roles in NF-kappaB signaling.

Bacteria-free solution derived from Lactobacillus plantarum inhibits multiple NF-kappaB pathways and inhibits proteasome function

BACKGROUND

Bacteria play a role in inflammatory bowel disease and other forms of intestinal inflammation. Although much attention has focused on the search for a pathogen or inciting inflammatory bacteria, another possibility is a lack of beneficial bacteria that normally confer anti-inflammatory properties in the gut. The purpose of this study was to determine whether normal commensal bacteria could inhibit inflammatory pathways important in intestinal inflammation.

METHODS

Conditioned media from Lactobacillus plantarum (Lp-CM) and other gut bacteria was used to treat intestinal epithelial cell (YAMC) and macrophage (RAW 264.7) or primary culture murine dendritic cells. NF-kappaB was activated through TNF-Receptor, MyD88-dependent and -independent pathways and effects of Lp-CM on the NF-kappaB pathway were assessed. NF-kappaB binding activity was measured using ELISA and EMSA. 1kappaB expression was assessed by Western blot analysis, and proteasome activity determined using fluorescence-based proteasome assays. MCP-1 release was determined by ELISA.

RESULTS

Lp-CM inhibited NF-kappaB binding activity, degradation of IkappaBalpha and the chymotrypsin-like activity of the proteasome. Moreover, Lp-CM directly inhibited the activity of purified mouse proteasomes. This effect was specific, since conditioned media from other bacteria had no inhibitory effect. Unlike other proteasome inhibitors, Lp-CM was not toxic in cell death assays. Lp-CM inhibited MCP-1 release in all cell types tested.

CONCLUSIONS

These studies confirm, and provide a mechanism for, the anti-inflammatory effects of the probiotic and commensal bacterium Lactobacillus plantarum. The use of bacteria-free Lp-CM provides a novel strategy for treatment of intestinal inflammation which would eliminate the risk of bacteremia reported with conventional probiotics.

Discovery and development of the G-rich oligonucleotide AS1411 as a novel treatment for cancer

Certain guanine-rich (G-rich) DNA and RNA molecules can associate intermolecularly or intramolecularly to form four stranded or "quadruplex" structures, which have unusual biophysical and biological properties. Several synthetic G-rich quadruplex-forming oligodeoxynucleotides have recently been investigated as therapeutic agents for various human diseases. We refer to these biologically active G-rich oligonucleotides as aptamers because their activities arise from binding to protein targets via shape-specific recognition (analogous to antibody-antigen binding). As therapeutic agents, the G-rich aptamers may have some advantages over monoclonal antibodies and other oligonucleotide-based approaches. For example, quadruplex oligonucleotides are non-immunogenic, heat stable and they have increased resistance to serum nucleases and enhanced cellular uptake compared to unstructured sequences. In this review, we describe the characteristics and activities of G-rich oligonucleotides. We also give a personal perspective on the discovery and development of AS1411, an antiproliferative G-rich phosphodiester oligonucleotide that is currently being tested as an anticancer agent in Phase II clinical trials. This molecule functions as an aptamer to nucleolin, a multifunctional protein that is highly expressed by cancer cells, both intracellularly and on the cell surface. Thus, the serendipitous discovery of the G-rich oligonucleotides also led to the identification of nucleolin as a new molecular target for cancer therapy.

NF-kappaB-YY1-miR-29 regulatory circuitry in skeletal myogenesis and rhabdomyosarcoma

Studies support the importance of microRNAs in physiological and pathological processes. Here we describe the regulation and function of miR-29 in myogenesis and rhabdomyosarcoma (RMS). Results demonstrate that in myoblasts, miR-29 is repressed by NF-kappaB acting through YY1 and the Polycomb group. During myogenesis, NF-kappaB and YY1 downregulation causes derepression of miR-29, which in turn accelerates differentiation by targeting its repressor YY1. However, in RMS cells and primary tumors that possess impaired differentiation, miR-29 is epigenetically silenced by an activated NF-kappaB-YY1 pathway. Reconstitution of miR-29 in RMS in mice inhibits tumor growth and stimulates differentiation, suggesting that miR-29 acts as a tumor suppressor through its promyogenic function. Together, these results identify a NF-kappaB-YY1-miR-29 regulatory circuit whose disruption may contribute to RMS.

NF-kappaB in carcinoma therapy and prevention

BACKGROUND

NF-kappaB includes a family of signal-activated transcription factors that normally regulate responses to injury and infection but which are aberrantly activated in many carcinomas.

OBJECTIVE

To review the activation and role of NF-kappaB in pathogenesis and as a target for treatment and prevention in carcinoma.

METHODS

Evidence from experimental, epidemiological, preclinical studies and clinical trials cited in the literature are reviewed.

RESULTS/CONCLUSION

Cumulative evidence implicates NF-kappaB in cell survival, inflammation, angiogenesis, spread and therapeutic resistance during tumor development, progression and metastasis of carcinomas. Non-specific natural and synthetic agents that inhibit NF-kappaB have demonstrated activity and safety in prevention or therapy. NF-kappaB-activating kinases and the proteasome are under investigation for targeted prevention and therapy of carcinoma.

Cigarette smoke activates NF kappa B and induces Muc5b expression in mouse middle ear cells

OBJECTIVES

Cigarette smoke exposure is a significant risk factor in the development of otitis media (OM). Nuclear factor kappa B (NF-kappa B) is a ubiquitous transcription factor known to mediate cigarette smoke effects on gene regulation in multiple cell types. The MUC5B mucin gene contains several putative NF-kappa B sites in its promoter and is the predominant mucin expressed in human OM. We hypothesized that in vitro stimulation of a recently developed model system, murine middle ear epithelial cells (MEEC), with cigarette smoke condensate (CSC) activates NF-kappa B and subsequently induces Muc5b gene expression.

METHODS

Luciferase reporter assays, electromobility shift assays (EMSA), and quantitative microplate transcription factor assays (TFA) were performed to evaluate NF-kappaB activation with CSC in immortalized murine MEEC (mMEEC). Reverse transcriptase polymerase chain reaction (RT-PCR) assays and quantitative real time RT-PCR were performed to determine whether time course CSC stimulation upregulates Muc5b mRNA levels in differentiated mMEEC. Luciferase reporter assays were performed to determine whether CSC activates the Muc5b promoter.

RESULTS

Reporter assays, EMSA, and TFA demonstrated three- to five-fold dose-dependent activation of NF-kappa B with CSC in mMEEC. CSC stimulation likewise increased Muc5b mRNA abundance and induced reporter activity 1.8- to 4.8-fold in plasmids containing -556 and -255 base pairs upstream of the Muc5b transcriptional start site in mMEEC.

CONCLUSIONS

CSC activates NF-kappaB in immortalized MEEC. Furthermore, this activation correlates with CSC-induced Muc5b promoter activation and gene expression. Taken together, these results hint that much as in lung cells, the activation of mucins by cigarette smoke is mediated in part by NF-kappa B.

House dust mite induces expression of intercellular adhesion molecule-1 in EoL-1 human eosinophilic leukemic cells

The house dust mite (HDM) is considered to be the most common indoor allergen associated with bronchial asthma. In this study, we investigated whether crude extract of the HDM Dermatophagoides farinae could activate human eosinophilic leukemic cells (EoL-1) to induce upregulation of cell-surface adhesion molecules. When EoL-1 cells were incubated with D. farinae extract, expression of intercellular adhesion molecule-1 (ICAM-1) significantly increased on the cell surfaces compared to cells incubated with medium alone. In contrast, surface expression of CD11b and CD49d in EoL-1 cells was not affected by D. farinae extract. In addition, pretreatment of cells with NF-kappaB inhibitor (MG-132) or JNK inhibitor (SP600125) significantly inhibited ICAM-1 expression promoted by HDM extract. However, neither p38 MAP kinase inhibitor nor MEK inhibitor prevented HDM-induced ICAM-1 expression in EoL-1 cells. These results suggest that crude extract of D. farinae induces ICAM-1 expression in EoL-1 cells through signaling pathways involving both NF-kappaB and JNK.

Manipulation of the nuclear factor-kappaB pathway and the innate immune response by viruses

Viral and microbial constituents contain specific motifs or pathogen-associated molecular patterns (PAMPs) that are recognized by cell surface- and endosome-associated Toll-like receptors (TLRs). In addition, intracellular viral double-stranded RNA is detected by two recently characterized DExD/H box RNA helicases, RIG-I and Mda-5. Both TLR-dependent and -independent pathways engage the IkappaB kinase (IKK) complex and related kinases TBK-1 and IKKvarepsilon. Activation of the nuclear factor kappaB (NF-kappaB) and interferon regulatory factor (IRF) transcription factor pathways are essential immediate early steps of immune activation; as a result, both pathways represent prime candidates for viral interference. Many viruses have developed strategies to manipulate NF-kappaB signaling through the use of multifunctional viral proteins that target the host innate immune response pathways. This review discusses three rapidly evolving areas of research on viral pathogenesis: the recognition and signaling in response to virus infection through TLR-dependent and -independent mechanisms, the involvement of NF-kappaB in the host innate immune response and the multitude of strategies used by different viruses to short circuit the NF-kappaB pathway.

Neutrophil elastase causes MUC5AC mucin synthesis via EGF receptor, ERK and NF-kB pathways in A549 cells

BACKGROUND

Neutrophil elastase (NE) was found to increase the respiratory mucin gene, MUC5AC, although the molecular mechanisms of this process remain unknown. We attempted to determine the signal transduction pathway through which NE induces MUC5AC gene expression in bronchial epithelial cells.

METHODS

A fragment of 1.3 Kb MUC5AC promoter which had been cloned into the pGL3-Basic luciferase vector was transfected to the A549 cells. By measuring the luciferase activity, we were able to evaluate the MUC5AC promoter activity in A549 cells. The involvement of mitogen-activated protein kinases (MAPK) was confirmed by Western blotting. To confirm the involvement of nuclear factorkappaB (NF-kB), we used site-directed mutagenesis and electrophoretic mobility shift assay (EMSA) autoradiogram. The MUC5AC mRNA expression was confirmed by RT-PCR.

RESULTS

NE increased the transcriptional activity of the MUC5AC promoter in A549 cells. The increased transcriptional activity of the MUC5AC promoter by NE was found to be associated with increased NF-kB activity. Site-directed mutagenesis showed that the transfection of the mutated NF-kB binding sites from the PGL3-MUC5AC-3752 promoter luciferase reporter plasmid decreased the luciferase activity after NE stimulation. Among the MAPKs, only extracellular signal-regulated kinases (ERK) were involved in this NE-induced MUC5AC mucin expression. RT-PCR also showed that NE increased MUC5AC mRNA. An EMSA autoradiogram revealed that NE induced NF-kB:DNA binding.

CONCLUSIONS

These results indicate that human NE induces MUC5AC mucin through the epidermal growth factor receptor (EGF-R), ERK, and NF-kB pathways in A549 cells.

Methylglyoxal induces apoptosis mediated by reactive oxygen species in bovine retinal pericytes

One of the histopathologic hallmarks of early diabetic retinopathy is the loss of pericytes. Evidences suggest that the pericyte loss in vivo is mediated by apoptosis. However, the underlying cause of pericyte apoptosis is not fully understood. This study investigated the influence of methylglyoxal (MGO), a reactive alpha-dicarbonyl compound of glucose metabolism, on apoptotic cell death in bovine retinal pericytes. Analysis of internucleosomal DNA fragmentation by ELISA showed that MGO (200 to 800 microM) induced apoptosis in a concentration-dependent manner. Intracellular reactive oxygen species were generated earlier and the antioxidant, N-acetyl cysteine, inhibited the MGO-induced apoptosis. NF-kappaB activation and increased caspase-3 activity were detected. Apoptosis was also inhibited by the caspase-3 inhibitor, Z-DEVD-fmk, or the NF-kappaB inhibitor, pyrrolidine dithiocarbamate. These data suggest that elevated MGO levels observed in diabetes may cause apoptosis in bovine retinal pericytes through an oxidative stress mechanism and suggests that the nuclear activation of NF-kappaB are involved in the apoptotic process.

Mechanism of cigarette smoke condensate-induced acute inflammatory response in human bronchial epithelial cells

BACKGROUND

To demonstrate the involvement of tobacco smoking in the pathophysiology of lung disease, the responses of pulmonary epithelial cells to cigarette smoke condensate (CSC) - the particulate fraction of tobacco smoke - were examined.

METHODS

The human alveolar epithelial cell line A549 and normal human bronchial epithelial cells (NHBEs) were exposed to 0.4 microg/ml CSC, a concentration that resulted in >90% cell survival and <5% apoptosis. Changes in gene expression and signaling responses were determined by RT-PCR, western blotting and immunocytofluorescence.

RESULTS

NHBEs exposed to CSC showed increased expression of the inflammatory mediators sICAM-1, IL-1beta, IL-8 and GM-CSF, as determined by RT-PCR. CSC-induced IL-1beta expression was reduced by PD98059, a blocker of mitogen-actived protein kinase (MAPK) kinase (MEK), and by PDTC, a NFkappaB inhibitor. Analysis of intracellular signaling pathways, using antibodies specific for phosphorylated MAPKs (extracellular signal-regulated kinase [ERK]-1/2), demonstrated an increased level of phosphorylated ERK1/2 with increasing CSC concentration. Nuclear localization of phosphorylated ERK1/2 was seen within 30 min of CSC exposure and was inhibited by PD98059. Increased phosphorylation and nuclear translocation of IkappaB was also seen after CSC exposure. A549 cells transfected with a luciferase reporter plasmid containing a NFkappaB-inducible promoter sequence and exposed to CSC (0.4 microg/ml) or TNF-alpha (50 ng/ml) had an increased reporter activity of approximately 2-fold for CSC and 3.5-fold for TNF-alpha relative to untreated controls.

CONCLUSION

The acute phase response of NHBEs to cigarette smoke involves activation of both MAPK and NFkappaB.

Differential clinical efficacy of anti-CD4 monoclonal antibodies in rat adjuvant arthritis is paralleled by differential influence on NF-kappaB binding activity and TNF-alpha secretion of T cells

The aim of this study was to analyze the differential effects of three anti-CD4 monoclonal antibodies (mAbs) (with distinct epitope specifities) in the treatment of rat adjuvant arthritis (AA) and on T-cell function and signal transduction. Rat AA was preventively treated by intraperitoneal injection of the anti-CD4 mAbs W3/25, OX35, and RIB5/2 (on days -1, 0, 3, and 6, i.e. 1 day before AA induction, on the day of induction [day 0], and thereafter). The effects on T-cell reactivity in vivo (delayed-type hypersensitivity), ex vivo (ConA-induced proliferation), and in vitro (mixed lymphocyte culture) were assessed. The in vitro effects of anti-CD4 preincubation on T-cell receptor (TCR)/CD3-induced cytokine production and signal transduction were also analyzed. While preventive treatment with OX35 and W3/25 significantly ameliorated AA from the onset, treatment with RIB5/2 even accelerated the onset of AA by approximately 2 days (day 10), and ameliorated the arthritis only in the late phase (day 27). Differential clinical effects at the onset of AA were paralleled by a differential influence of the mAbs on T-cell functions, i.e. in comparison with OX35 and W3/25, the 'accelerating' mAb RIB5/2 failed to increase the delayed-type hypersentivity (DTH) to Mycobacterium tuberculosis, increased the in vitro tumor necrosis factor (TNF)-alpha secretion, and more strongly induced NF-kappaB binding activity after anti-CD4 preincubation and subsequent TCR/CD3-stimulation. Depending on their epitope specificity, different anti-CD4 mAbs differentially influence individual proinflammatory functions of T cells. This fine regulation may explain the differential efficacy in the treatment of AA and may contribute to the understanding of such treatments in other immunopathologies.