The origins of NF-κB

NF-kB's contribution to B cell fate decisions

NF-κB signaling is essential to an effective innate and adaptive immune response. Many immune-specific functional and developmental outcomes depend in large on NF-κB. The formidable task of sorting out the mechanisms behind the regulation and outcome of NF-κB signaling remains an important area of immunology research. Here we briefly discuss the role of NF-κB in regulating cell fate decisions at various times in the path of B cell development, activation, and the generation of long-term humoral immunity.

Insight into the pivotal role of signaling pathways in psoriasis pathogenesis, potential therapeutic molecules and drug delivery approaches

Psoriasis is a multifactorial chronic autoimmune skin disorder, the exact cause of which is still under investigation. It is classified into different types displaying various histopathological features such as hyperproliferation, irregular parakeratosis and vascular infiltration of various immune cells with neutrophils in the epidermis. Over the past few decades, psoriasis pathogenesis has been thoroughly researched, leading to several advances in the treatment using small molecules and biologics. This review focuses on describing the role of various signaling pathways, including PDE-4, JAK-STAT, S1P, A₃AR and NF-κB, in psoriasis pathogenesis and associated new molecules that are either recently approved or under clinical trials. This study has also addressed the relevance of employing nanotherapeutics to boost the efficacy of psoriasis treatment.

Electrochemiluminescence platform for transcription factor diagnosis by using CRISPR-Cas12a trans-cleavage activity

Herein, we exploited the double-stranded DNA (dsDNA) binding property of transcription factor (TF), combined with the trans cleavage characteristic of CRISPR-Cas12a, for the detection of NF-κB p50.

Correlation between the expression of IL‑18 and deep venous thrombosis

The present study aimed to investigate the effect of the expression of interleukin (IL)‑18 and related markers on deep venous thrombosis (DVT) to examine their correlation. Sprague‑Dawley rats of different models were established and were randomly assigned into three groups. The expression of IL‑18, nuclear factor (NF)‑κB and von Willebrand factor (vWF) were detected in blood samples. The inferior vena cava (IVC) was ligated to establish the DVT model. Rat IL‑18 overexpression and inhibition vectors were constructed. The expression levels of IL‑18 and related markers in the venous wall were compared between the model group and the control group using reverse transcription‑quantitative polymerase chain reaction and western blot analyses. Following the culture of human umbilical vein endothelial cells (HUVECs), IL‑18 was added to the cells, following which the growth of the HUVECs, and changes in vWF and other endothelial functional markers were analyzed. The IVC model demonstrated complete thrombosis at 8 h and stable thrombosis at 24 h. At 24 h following model establishment, the expression levels of IL‑18, NF‑κB and vWF were high in the blood samples with the occurrence and development of thrombosis (P<0.05). The weight, length and weight/length ratio of thrombi in each model group showed significant differences from those in the control group (P<0.05) with the overexpression of IL‑18, and the expression levels of NF‑κB and vWF in venous tissues were altered with abnormal expression levels of IL‑18. IL‑18 damaged HUVECs and significantly increased viability in early‑stage apoptosis, promoted the upregulation of vWF and P‑selectin, and reduced tissue plasminogen activator. IL‑18 and the related markers were closely associated with the occurrence and development of DVT.

BAG-1M co-activates BACE1 transcription through NF-κB and accelerates Aβ production and memory deficit in Alzheimer's disease mouse model

Accumulation of amyloid β protein (Aβ)-containing neuritic plaques in the brain is a neuropathological feature of Alzheimer's disease (AD). The β-site APP-cleaving enzyme 1 (BACE1) is essential for Aβ generation and dysregulation of BACE1 expression may lead to AD pathogenesis. Bcl-2-associated athanogen 1M (BAG-1M), initially identified as an anti-apoptotic protein, has also been found to be highly expressed in the same neurons that contain intracellular amyloid in the hippocampus of AD patient. In this report, we found that over-expression of BAG-1M enhances BACE1-mediated cleavage of amyloid precursor protein (APP) and Aβ production by up-regulating BACE1 gene transcription. The regulation of BACE1 transcription by BAG-1M was dependent on NF-κB, as BAG-1M complexes NF-κB at the promoter of BACE1 gene and co-activates NF-κB-facilitated BACE1 transcription. Moreover, expression of BAG-1M by lentiviral vector in the hippocampus of AD transgenic model mice promotes Aβ generation and formation of neuritic plaque, and subsequently accelerates memory deficits of the mice. These results provide evidence for an emerging role of BAG-1M in the regulation of BACE1 expression and AD pathogenesis and that targeting the BAG-1M-NF-κB complex may provide a mechanism for inhibiting Aβ production and plaque formation.

NF-κB dysregulation in multiple myeloma

The nuclear factor-κB (NF-κB) transcription factor family plays critical roles in the pathophysiology of hematologic neoplasias, including multiple myeloma. The current review examines the roles that this transcription factor system plays in multiple myeloma cells and the nonmalignant accessory cells of the local microenvironment; as well as the evidence indicating that a large proportion of myeloma patients harbor genomic lesions which perturb diverse genes regulating the activity of NF-κB. This article also discusses the therapeutic targeting of the NF-κB pathway using proteasome inhibitors, a pharmacological class that has become a cornerstone in the therapeutic management of myeloma; and reviews some of the future challenges and opportunities for NF-κB-related research in myeloma.

The Immune Adaptor SLP-76 Binds to SUMO-RANGAP1 at Nuclear Pore Complex Filaments to Regulate Nuclear Import of Transcription Factors in T Cells

While immune cell adaptors regulate proximal T cell signaling, direct regulation of the nuclear pore complex (NPC) has not been reported. NPC has cytoplasmic filaments composed of RanGAP1 and RanBP2 with the potential to interact with cytoplasmic mediators. Here, we show that the immune cell adaptor SLP-76 binds directly to SUMO-RanGAP1 of cytoplasmic fibrils of the NPC, and that this interaction is needed for optimal NFATc1 and NF-κB p65 nuclear entry in T cells. Transmission electron microscopy showed anti-SLP-76 cytoplasmic labeling of the majority of NPCs in anti-CD3 activated T cells. Further, SUMO-RanGAP1 bound to the N-terminal lysine 56 of SLP-76 where the interaction was needed for optimal RanGAP1-NPC localization and GAP exchange activity. While the SLP-76-RanGAP1 (K56E) mutant had no effect on proximal signaling, it impaired NF-ATc1 and p65/RelA nuclear entry and in vivo responses to OVA peptide. Overall, we have identified SLP-76 as a direct regulator of nuclear pore function in T cells.

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Immune adaptor SLP-76 binds to SUMO-RanGAP1 of cytoplasmic fibrils of the NPC

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SLP-76 K-56 binding needed for optimal RanGAP1 localization and exchange activity

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SLP-76 K56E mutant impaired NF-ATc1 and NFκB p65 (RelA) nuclear entry

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Immune adaptors directly regulate nuclear entry of transcription factors in T cells

The endoplasmic reticulum adaptor protein ERAdP initiates NK cell activation via the Ubc13-mediated NF-κB pathway

NK cells play a pivotal role in innate immune responses against pathogenic infections. However, the underlying mechanisms driving defined NK functions remain largely elusive. In this study, we identified a novel endoplasmic reticulum (ER) membrane protein, ER adaptor protein (ERAdP), which is constitutively expressed in human and mouse NK cells. ERAdP is expressed at low levels in peripheral NK cells of hepatitis B virus-associated hepatocellular carcinoma patients. We show that ERAdP initiates NK cell activation through the NF-κB pathway. Notably, ERAdP interacts with ubiquitin-conjugating enzyme 13 (Ubc13) to potentiate its charging activity. Thus, ERAdP augments Ubc13-mediated NF-κB essential modulator ubiquitination to trigger the Ubc13-mediated NF-κB pathway, leading to NK cell activation. Finally, ERAdP transgenic mice display hyperactivated NK cells that are more resistant to pathogenic infections. Therefore, understanding the mechanism of ERAdP-mediated NK cell activation will provide strategies for treatment of infectious diseases.

Downregulation of RelA (p65) by Rapamycin Inhibits Murine Adipocyte Differentiation and Reduces Fat Mass of C57BL/6J Mice despite High Fat Diet

Rapamycin (RAPA) is a clinical immunosuppressive agent first reported in the literature in 1975 after its discovery in a soil sample from the island of Rapa Nui. Aside from the well-documented effects of RAPA on cell division and immunologic response, the literature reveals it to have negative effects on adipocyte and osteocyte differentiation as well. Understanding of the molecular effects of RAPA on cell differentiation is fragmentary in regard to these cell lineages. In this paper, we examined a potential mechanism for RAPA's effects on adipocyte differentiation in vitro and in vivo. The data point to a unique role of Rel A (p65)—a component of the NF-κB system—in mediating this event. In murine adipose derived stem cell cultures (muADSCs) from C57BL/6J mice, RAPA was found to selectively downregulate RelA/p65, mammalian target of rapamycin (mTOR), and do so in a dose-dependent manner. This implies a novel role for RelA in adipocyte biology. Intracellular lipid accumulation—as subjectively observed—was also decreased in muADSCs treated with RAPA. Mice treated with RAPA had reduced overall body weight and reduced size of both intraabdominal and subcutaneous fat pads. When treated with RAPA, mice fed a high fat diet did not develop obesity and were not different from their regular diet controls in terms of body weight. These results suggested that RAPA inhibits adipogenesis and lipogenesis of muADSCs resulting in a prevention of obesity in C57BL/6J mice. This inhibition is strong enough to negate the effects of a high fat diet and seems to act by downregulating the RelA/p65 mTOR signaling pathway—a key component of the NF-κB family.

Sufficient production of geranylgeraniol is required to maintain endotoxin tolerance in macrophages

Endotoxin tolerance allows macrophages to produce large quantities of proinflammatory cytokines immediately after their contact with lipopolysaccharides (LPSs), but prevents their further production after repeated exposure to LPSs. While this response is known to prevent overproduction of proinflammatory cytokines, the mechanism through which endotoxin tolerance is established has not been identified. In the current study, we demonstrate that sufficient production of geranylgeraniol (GGOH) in macrophages is required to maintain endotoxin tolerance. We show that increased synthesis of 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCR) protein following LPS treatment is required to produce enough GGOH to inhibit expression of Malt1, a protein known to stimulate expression of proinflammatory cytokines, in macrophages repeatedly exposed to LPSs. Depletion of GGOH caused by inhibition of HMGCR led to increased Malt1 expression in macrophages subjected to repeated exposure to LPSs. Consequently, endotoxin tolerance was impaired, and production of interleukin 1-β and other proinflammatory cytokines was markedly elevated in these cells. These results suggest that insufficient production of GGOH in macrophages may cause autoinflammatory diseases.

UAS domain of Ubxd8 and FAF1 polymerizes upon interaction with long-chain unsaturated fatty acids

Ubxd8, a multidomain protein sensor for long-chain unsaturated fatty acids (FAs), plays a crucial role to maintain cellular homeostasis of FAs. Ubxd8 polymerizes upon interaction with long-chain unsaturated FAs, but the molecular mechanism involved in this polymerization remains unclear. Here we report that the UAS domain of Ubxd8 mediates this polymerization. We show that a positively charged surface area in the domain is required for the reaction. Mutations changing the positively charged residues in this area to glutamates prevented long-chain unsaturated FAs from inducing oligomerization of Ubxd8. Consequently, the mutant protein no longer responded to regulation by long-chain unsaturated FAs in cultured cells. Long-chain unsaturated FAs also induced polymerization of Fas-associated factor 1 (FAF1), the only other mammalian protein that contains a UAS domain homologous to that of Ubxd8. These results provide further insights into protein-FA interactions by identifying the UAS domain as a motif interacting with long-chain unsaturated FAs.

NF-κB-regulated, proinflammatory miRNAs in Alzheimer's disease

Abundant neurochemical, neuropathological, and genetic evidence suggests that a critical number of proinflammatory and innate immune system-associated factors are involved in the underlying pathological pathways that drive the sporadic Alzheimer's disease (AD) process. Most recently, a series of epigenetic factors - including a select family of inducible, proinflammatory, NF-κB-regulated small noncoding RNAs called miRNAs - have been shown to be significantly elevated in abundance in AD brain. These upregulated miRNAs appear to be instrumental in reshaping the human brain transcriptome. This reorganization of mRNA speciation and complexity in turn drives proinflammatory and pathogenic gene expression programs. The ensuing, progressively altered immune and inflammatory signaling patterns in AD brain support immunopathogenetic events and proinflammatory features of the AD phenotype. This report will briefly review what is known concerning NF-κB-inducible miRNAs that are significantly upregulated in AD-targeted anatomical regions of degenerating human brain cells and tissues. Quenching of NF-κB-sensitive inflammatory miRNA signaling using NF-κB-inhibitors such as the polyphenolic resveratrol analog trans-3,5,4'-trihydroxystilbene (CAY10512) may have some therapeutic value in reducing inflammatory neurodegeneration. Antagonism of NF-κB-inducing, and hence proinflammatory, epigenetic and environmental factors, such as the neurotrophic herpes simplex virus-1 and exposure to the potent neurotoxin aluminum, are briefly discussed. Early reports further indicate that miRNA neutralization employing anti-miRNA (antagomir) strategies may hold future promise in the clinical management of this insidious neurological disorder and expanding healthcare concern.

NF-κB: an essential transcription factor in psoriasis

Nuclear factor kappa B (NF-κB) is a protein transcription factor that orchestrates inflammation and other complex biological processes. It is a key regulatory element in a variety of immune and inflammatory pathways, in cellular proliferation and differentiation and in apoptosis. Therefore NF-κB is a crucial mediator involved in the pathogenesis of psoriasis. Psoriasis, an inflammatory dermatosis, is marked by elevated levels of active, phosphorylated NF-κB. Genomic studies have also linked psoriasis with mediators in the NF-κB pathway. NF-κB has been hypothesized to connect the altered keratinocyte and immune cell behavior that characterizes the psoriatic milieu. Several anti-psoriatic therapies, including tumor necrosis factor-α blockers and glucocorticoids, reduce active NF-κB levels and related down-stream elements, and other biologics currently in development, including interleukin-17 blockers, may also target this pathway. Compounds that specifically target NF-κB signaling may be developed as novel therapeutics for chronic inflammatory disorders including psoriasis. However, chronic NF-κB inhibition could also result in immunodeficiencies. Therefore, a delicate balance must be found that maximizes therapeutic potential while limiting harmful effects, and may be achieved through several possible approaches, including localized therapy, selective inhibition of NF-κB signaling in pathologic cells, incomplete pathway inhibition or short treatment durations.

MicroRNAs, new effectors and regulators of NF-κB

Since its discovery 25 years ago, nuclear factor-κB (NF-κB) has emerged as a transcription factor that controls diverse biological functions, ranging from inflammation to learning and memory. Activation of NF-κB initiates an elaborate genetic program. Some of the NF-κB-driven genes do not encode proteins but rather are precursors to microRNAs. These microRNAs play important roles in the regulation of the inflammatory process, some being inhibitory and others activating. Here, we discuss both the regulation of their expression and the function of some of these non-coding RNA genes. We also include a personal discussion of how NF-κB was first discovered.

NF-кB-regulated micro RNAs (miRNAs) in primary human brain cells

Micro RNAs (miRNAs), small and labile ~22 nucleotide-sized fragments of single stranded RNA, are important regulators of messenger (mRNA) complexity and in shaping the transcriptome of a cell. In this communication, we utilized amyloid beta 42 (Aβ42) peptides and interleukin-1beta (IL-1β) as a combinatorial, physiologically-relevant stress to induce miRNAs in human primary neural (HNG) cells (a co-culture of neurons and astroglia). Specific miRNA up-regulation was monitored using miRNA arrays, Northern micro-dot blots and RT-PCR. Selective NF-кB translocation and DNA binding inhibitors, including the chelator and anti-oxidant pyrollidine dithiocarbamate (PDTC) and the polyphenolic resveratrol analog CAY10512 (trans-3,5,4'-trihydroxystilbene), indicated the NF-кB sensitivity of several brain miRNAs, including miRNA-9, miRNA-125b and miRNA-146a. The inducible miRNA-125b and miRNA-146a, and their verified mRNA targets, including 15-lipoxygenase (15-LOX), synapsin-2 (SYN-2), complement factor H (CFH) and tetraspanin-12 (TSPAN12), suggests complex and highly interactive roles for NF-кB, miRNA-125b and miRNA-146a. These data further indicate that just two NF-кB-mediated miRNAs have tremendous potential to contribute to the regulation of neurotrophic support, synaptogenesis, neuroinflammation, innate immune signaling and amyloidogenesis in stressed primary neural cells of the human brain.