Canonical NF-κB Signaling Pathway Research Articles

Literature review: nuclear factor kappa B (NF-κB) regulation in human cancers mediated by ubiquitin-specific proteases (USPs).

The nuclear factor kappa B (NF-κB) consists of a group of transcription factors of which its dysregulation is responsible for diseases such as inflammation and cancer. Ubiquitin-specific proteases (USPs) are the most prominent group among the deubiquitinases (DUBs). Their functions include control of protein stability and regulation of signaling transduction. The association between NF-κB activity and human cancer progression is evident. Still, the role of USPs in the NF-κB regulation in human cancers, especially prostate cancer, is not well understood. This review discusses on the role of USP-mediated regulation of the canonical NF-κB signaling pathway in human cancers and provides a prospect of future studies in prostate cancers. Within the biomedical literature database, PubMed, our review team searched for keywords including USP, NF-κB signaling pathway, cancer, prostate cancer, and specific USPs such as USP1, USP2, USP3, etc. These keywords were used individually or in combinations. After screening, only mechanistic studies and articles reporting the subsequent changes in cellular behaviors were included for full-text review. Most USPs function primarily as DUBs to regulate the canonical NF-κB signaling pathway. The typical K48- and K63-linked DUB activities of USPs are the best understood. These USPs are positive and negative regulators of the NF-κB activity. However, their DUB activities against polyubiquitin chains with atypical linkages have not yet been extensively studied. Furthermore, some USPs can regulate the canonical NF-κB signaling pathway via ubiquitin-independent mechanisms. In the regulation of the canonical NF-κB pathway, the USPs function primarily as DUBs, but they also regulate the p65/p50 by ubiquitin-independent mechanisms. Generally, in human cancer models, USP-mediated elevation and suppression of p65/p50 activity lead to more or less malignant cellular behaviors, respectively. Given the currently unbalanced focus on K48- and K63-linked DUB activities and the context-dependent function of USPs, future research of USP-mediated NF-κB regulation in human cancers should invest more in the DUB activities against the atypical polyubiquitin chains and test known mechanisms in different cancer models.

SHP-1 alleviates acute liver injury caused by Escherichia coli sepsis through negatively regulating the canonical and non-canonical NFκB signaling pathways

SHP-1, as a protein tyrosine phosphatase, plays a key role in inflammation-related diseases. However, its function and regulatory mechanism in the imbalance of inflammatory response and acute liver injury during sepsis are still unknown. Herein, we constructed a murine model of Escherichia coli (E. coli) sepsis and demonstrated the function and novel mechanism of SHP-1 in sepsis. Overexpression of SHP-1 significantly reduced the mortality rate of mice and alleviated the histopathological deterioration of liver. In addition, it inhibited the expression and release of pro-inflammatory mediators in liver tissue and serum, but upregulated the expression of anti-inflammatory molecules. Silencing SHP-1 exhibited the completely opposite effects. Furthermore, the transcriptome data of mice liver showed that SHP-1 suppressed the progression of sepsis by negatively regulating the activation of multiple inflammation-related signaling pathways. More importantly, we fully revealed the regulation mechanism of SHP-1 on both canonical and non-canonical nuclear factor kappa-B (NFκB) signaling pathways during sepsis for the first time. SHP-1 significantly inhibited the phosphorylation and nuclear translocation of p50, while p65 inhibition was mainly achieved by inhibiting its transcription and translation levels. Meanwhile, SHP-1 inhibited the phosphorylation and nuclear translocation of p52, thereby inhibiting the activation of non-canonical NFκB signaling pathways. In summary, SHP-1 negatively regulated canonical and non-canonical NFκB signaling pathways, thereby blocking the occurrence of excessive inflammatory response and acute liver injury caused by E. coli sepsis. Our findings systematically elucidate the role and mechanism of SHP-1 during sepsis, providing new insights into the prevention and treatment of inflammation and immune-related diseases.

Early Socialization Triggered ROS-Mediated Activation of Canonical NF-κB Pathway Leading to Inflammation of Spleen in Suckling Piglets

Early socialization during lactation is advocated as a feeding strategy to reduce the weaning stress of piglets. However, early socialization has often been accompanied by more frequent aggression between individuals, and its effect on the immune system of piglets has yet to be evaluated. In this study, 89 piglets were raised separately under conventional feeding and early socialization environments. Based on differences in the aggressive behavior of the piglets in different environments during lactation, we further investigated the effects of early socialization on oxidative stress in the spleen of the piglets and the inflammatory responses involved in the canonical nuclear factor kappa-B (NF-κB) signaling pathway. The results revealed that early socialization led to a higher aggression level between individuals (p < 0.01), increased malondialdehyde (MDA) and H2O2 levels and inducible nitric oxide synthase (iNOS) activity, and inhibited glutathione (GSH) levels and the activities of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPX) in the piglet spleens (p < 0.05). The mRNA expression levels of the protein kinase A (PKA), inhibitor of kappa B kinase-α (IKK-α), inhibitor of kappa B kinase-β (IKK-β), inhibitor of NF-κB-α (IκB-α), NF-κB(p65), interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), cyclooxygenase-2 (COX2), iNOS, and heat shock protein (HSP) genes were significantly up-regulated, as well as the protein levels of P-p65, IKK-β, P-IkB-α, pro-IL-1β, and TNF-α. In summary, early socialization caused oxidative stress and inflammatory responses in the spleen of the piglets by inducing ROS production and the activation of the canonical NF-κB pathway. Our study revealed that early socialization significantly increased the ROS level in the piglet spleens and activated the canonical NF-κB signaling pathway, which induced a high expression of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6, and COX2) and HSP genes regulated by NF-κB signaling, leading to oxidative stress and the inflammatory response.

OTULIN-related conditions: Report of a new case and review of the literature using GenIA

OTULIN encodes an eponymous linear deubiquitinase (DUB) essential for controlling inflammation as a negative regulator of the canonical NF-κB signaling pathway via the regulation of M1-Ub dynamics. Biallelic loss-of-function (LOF) mutations in OTULIN cause an autosomal recessive condition named Otulin-Related Autoinflammatory Syndrome (ORAS), also known as Otulipenia or AutoInflammation, Panniculitis, and Dermatosis Syndrome (AIPDS). Monoallelic OTULIN LOF, also known as OTULIN Haploinsufficiency (OHI) or Immunodeficiency 107 (IMD107), has been linked to an incompletely penetrant, dominantly inherited susceptibility to invasive Staphylococcal infections. At the same time, a recent novel ORAS-like inflammatory syndrome was described in association with a heterozygous missense mutation that appears to exert dominant negative (DN) effects. In this manuscript, we report the identification of a novel homozygous missense mutation, c.595 T > A; p.(Trp199Arg), in a Moroccan infant with an ORAS phenotype and provide experimental evidence for its pathogenicity. We go on to systematically review the literature for OTULIN-associated conditions by using the GenIA database (www.geniadb.net) to collect, extract and harmonize all clinical, laboratory and functional data for published patients and variants. Our comprehensive synthesis of genotypic, phenotypic, and mechanistic data enables a more in-depth view of the diverse mechanisms and pathways by which the OTULIN pathogenic variants may lead to human immune disease. This review may help variant classification activities and inform future variant evaluation, as well as the development of diagnostic and management guidelines. It also identifies current knowledge gaps and raises additional questions warranting future investigation.

Mm9_circ_014683 regulates microglia polarization through canonical NFκB signaling pathway in diabetic retinopathy

Diabetic retinopathy (DR) is still the major cause of visual loss in working-aged people, one of the critical pathological processes are retinal microglia-mediated inflammation. Our previous study demonstrated that enhanced M1 microglial polarization was involved in retinal inflammation in DR, but the detailed mechanism needs further investigation. Circular RNAs (circRNAs) are important kind of noncoding RNAs involved in the regulation of various cell biological processes. Herein, the circRNA expression profiles of BV2 mouse microglia treated with or without glucose were detected, and a total of 347 differentially expressed circRNAs were identified in glucose-treated BV2 cells. The key circRNA mm9_circ_014683 increased after glucose stimulation. Inhibiting or overexpressing mm9_circ_014683 showed no effect on the proliferation and apoptosis of microglia. Inhibiting mm9_circ_014683 impeded M1 polarization and promoted M2 polarization, and overexpressing mm9_circ_014683 showed the opposite effect. A total of 216 differentially expressed genes were identified in mm9_circ_014683-knockdown BV2 cells, which were enriched in several signaling pathways, including the NFκB signaling pathway. Moreover, mm9_circ_014683 positively regulated the canonical, NFκB signaling pathway. Besides, mm9_circ_014683 was highly expressed in the retinal microglia of diabetic mice, and intraocular injection of Lv-circRNA inhibited M1 but enhanced M2 retinal microglial polarization. In conclusion, mm9_circ_014683 regulates microglial polarization through the canonical NFκB signaling pathway in diabetic retinopathy. This study may provide insight into the pathogenesis and treatment of DR.

Mass cytometry revealed the circulating immune cell landscape across different Suzuki stages of Moyamoya disease

Moyamoya disease (MMD) is a cerebrovascular disorder marked by progressive arterial narrowing, categorized into six stages known as Suzuki stages based on angiographic features. Growing evidence indicates a pivotal role of systemic immune and inflammatory responses in the initiation and advancement of MMD. This study employs high-dimensional mass cytometry to reveal the immunophenotypic characteristics of peripheral blood immune cells (PBMCs) at various Suzuki stages, offering insights into the progression of MMD. PBMC samples from eight patients with early-stage MMD (Suzuki stages II and III) and eight patients with later-stage MMD (Suzuki stages IV, V, and VI) were analyzed using high-dimensional mass cytometry to evaluate the frequency and phenotype of immune cell subtypes. We identified 15 cell clusters and found that the immunological features of early-stage MMD and later-stage MMD are composed of cluster variations. In this study, we confirmed that, compared to later-stage MMD, the early-stage MMD group exhibits an increase in non-classical monocytes. As the Suzuki stage level increases, the proportions of plasmacytoid DCs and monocyte-derived DCs decrease. Furthermore, T cells, monocytes, DCs, and PMN-MDSCs in the early-stage MMD group show activation of the canonical NF-κB signaling pathway. We summarized and compared the similarities and differences between early-stage MMD patients and later-stage MMD patients. There is a potential role of circulating immune dysfunction and inflammatory responses in the onset and development of MMD.

Intravenous Injection of PEI-Decorated Iron Oxide Nanoparticles Impacts NF-kappaB Protein Expression in Immunologically Stressed Mice.

Nanoparticle-based formulations are considered valuable tools for diagnostic and treatment purposes. The surface decoration of nanoparticles with polyethyleneimine (PEI) is often used to enhance their targeting and functional properties. Here, we aimed at addressing the long-term fate in vivo and the potential "off-target" effects of PEI decorated iron oxide nanoparticles (PEI-MNPs) in individuals with low-grade and persistent systemic inflammation. For this purpose, we synthesized PEI-MNPs (core-shell method, PEI coating under high pressure homogenization). Further on, we induced a low-grade and persistent inflammation in mice through regular subcutaneous injection of pathogen-associated molecular patterns (PAMPs, from zymosan). PEI-MNPs were injected intravenously. Up to 7 weeks thereafter, the blood parameters were determined via automated fluorescence flow cytometry, animals were euthanized, and the organs analyzed for iron contents (atomic absorption spectrometry) and for expression of NF-κB associated proteins (p65, IκBα, p105/50, p100/52, COX-2, Bcl-2, SDS-PAGE and Western blotting). We observed that the PEI-MNPs had a diameter of 136 nm and a zeta-potential 56.9 mV. After injection in mice, the blood parameters were modified and the iron levels were increased in different organs. Moreover, the liver of animals showed an increased protein expression of canonical NF-κB signaling pathway members early after PEI-MNP application, whereas at the later post-observation time, members of the non-canonical signaling pathway were prominent. We conclude that the synergistic effect between PEI-MNPs and the low-grade and persistent inflammatory state is mainly due to the hepatocytes sensing infection (PAMPs), to immune responses resulting from the intracellular metabolism of the uptaken PEI-MNPs, or to hepatocyte and immune cell communications. Therefore, we suggest a careful assessment of the safety and toxicity of PEI-MNP-based carriers for gene therapy, chemotherapy, and other medical applications not only in healthy individuals but also in those suffering from chronic inflammation.

Dysregulation of Immune Regulators in AML Bone Marrow Promotes Dysfunction of CD8 + T Cells

Background: Acute myeloid leukemia (AML) originates in the bone marrow, evading immune recognition and destruction. The bone marrow microenvironment (BME), comprising diverse immune cells and regulators, profoundly influences AML development. However, the impact of immune regulators in the BME, particularly on T-cell anti-AML immunity, remains inadequately understood. Therefore, evaluating the impact of immune regulators in the AML bone marrow microenvironment on T cell dysfunction is of paramount importance and necessity. M ethod : Bone marrow blood samples were obtained from pediatric AML patients at diagnosis and age-matched healthy individuals considered as hematopoietic stem cell transplantation (HSCT) donors after written informed consent. By centrifuging at 2000-3000rpm for 10min, we obtained the supernatant as plasma and stored it in a -80°C refrigerator. After using proteomics to identify the expression of 180 immune regulatory factors in plasma samples, we performed GO and KEGG functional enrichment analysis. After density gradient centrifugation, we isolated bone marrow mononuclear cells (BMMNCs) and immediately identified frequencies of T cell populations and expression levels of functional markers by flow cytometry when they were fresh. Moreover, the co-culture model of CD8 +T cells and THP-1 cell line was used to evaluate the anti-AML effector function of T cells. CD8 +T cells in BMMNCs were sorted by FACS and then subjected to whole transcriptome sequencing and in vitro experiments. After using the TRRUST and KnockTF databases for transcription factor prediction analysis, we selected phospho-flow cytometry to detect and verify the association between the level of phosphorylation of transcription factors and the function of CD8 +T cells. The data were analyzed using R software. Results: Using proteomics techniques, we uncovered a substantial presence of immune-suppressive regulatory factors in AML bone marrow plasma. Interestingly, the canonical NF-κB pathway, mediated by immune regulators and vital for immune regulation in BME, displayed significant downregulation, implying T-cell dysfunction. In our investigation, we identified dysfunctional CD8 +T cells in the primary AML bone marrow, characterized by heightened expression of co-inhibitory receptors and pro-dysfunctional transcription factors, as well as significantly decreased anti-AML effector function. Transcriptome sequencing further linked AML CD8 +T cell dysfunction to reduced transcriptional activity of NF-κB p65 in the canonical NF-κB signaling pathway. Intriguingly, in vitro inhibition of NF-κB p65 and its phosphorylation led to elevated expression of exhaustion markers, such as PD-1, LAG-3, and TIM-3 on primary CD8 +T cells. Most notably, the stimulation of the canonical NF-κB signaling pathway effectively restored activation and effector function-related pathways in dysfunctional AML CD8 +T cells. Conclusion: Immune regulators in the bone marrow microenvironment play a vital role in maintaining dysfunctional AML CD8 +T cells. These findings provide a novel strategy to investigate the potential mechanisms and interventions for T-cell dysfunction.

Modified Curcuminoid-Rich Extract Liposomal CRE-SDInhibits Osteoclastogenesis via the Canonical NF-κB Signaling Pathway.

Curcuminoids, namely curcumin, demethoxycurcumin, and bisdemethoxycurcumin, are the major active compounds found in Curcuma longa L. (turmeric). Although their suppressive effects on bone resorption have been demonstrated, their pharmacokinetic disadvantages remain a concern. Herein, we utilized solid dispersion of a curcuminoid-rich extract (CRE), comprising such curcuminoids, to prepare CRE-SD; subsequently, we performed liposome encapsulation of the CRE-SD to yield liposomal CRE-SD. In vitro release assessment revealed that a lower cumulative mass percentage of CRE-SD was released from liposomal CRE-SD than from CRE-SD samples. After culture of murine RANKL-stimulated RAW 264.7 macrophages, our in vitro examinations confirmed that liposomal CRE-SD may impede osteoclastogenesis by suppressing p65 and IκBα phosphorylation, together with nuclear translocation and transcriptional activity of phosphorylated p65. Blind docking simulations showed the high binding affinity between curcuminoids and the IκBα/p50/p65 protein complex, along with many intermolecular interactions, which corroborated our in vitro findings. Therefore, liposomal CRE-SD can inhibit osteoclastogenesis via the canonical NF-κB signaling pathway, suggesting its pharmacological potential for treating bone diseases with excessive osteoclastogenesis.

Interleukin-34-NF-κB signaling aggravates myocardial ischemic/reperfusion injury by facilitating macrophage recruitment and polarization

Macrophage infiltration and polarization are integral to the progression of heart failure and cardiac fibrosis after ischemia/reperfusion (IR). Interleukin 34 (IL-34) is an inflammatory regulator related to a series of autoimmune diseases. Whether IL-34 mediates inflammatory responses and contributes to cardiac remodeling and heart failure post-IR remains unclear. IL-34 knock-out mice were used to determine the role of IL-34 on cardiac remodeling after IR surgery. Then, immunofluorescence, flow cytometry assays, and RNA-seq analysis were performed to explore the underlying mechanisms of IL-34-induced macrophage recruitment and polarization, and further heart failure after IR. By re-analyzing single-cell RNA-seq and single-nucleus RNA-seq data of murine and human ischemic hearts, we showed that IL-34 expression was upregulated after IR. IL-34 knockout mitigated cardiac remodeling, cardiac dysfunction, and fibrosis after IR and vice versa. RNA-seq analysis revealed that IL-34 deletion correlated negatively with immune responses and chemotaxis after IR injury. Consistently, immunofluorescence and flow cytometry assays demonstrated that IL-34 deletion attenuated macrophage recruitment and CCR2+ macrophage polarization. Mechanistically, IL-34 deficiency repressed both the canonical and noncanonical NF-κB signaling pathway, leading to marked reduction of P-IKKβ and P-IκBα kinase levels; downregulation of NF-κB p65, RelB, and p52 expression, which drove the decline in chemokine CCL2 expression. Finally, IL-34 and CCL2 levels were increased in the serum of acute coronary syndrome patients, with a positive correlation between circulating IL-34 and CCL2 levels in clinical patients. In conclusion, IL-34 sustains NF-κB pathway activation to elicit increased CCL2 expression, which contributes to macrophage recruitment and polarization, and subsequently exacerbates cardiac remodeling and heart failure post-IR. Strategies targeting IL-34-centered immunomodulation may provide new therapeutic approaches to prevent and reverse cardiac remodeling and heart failure in clinical MI patients after percutaneous coronary intervention. This study was supported by the National Nature Science Foundation of China (81670352 and 81970327 to R T, 82000368 to Q F).

Bioactive silica nanoparticles target autophagy, NF-κB, and MAPK pathways to inhibit osteoclastogenesis

Spherical 50 nm silica-based nanoparticles (SiNPs) promote healthy bone homeostasis and maintenance by supporting bone forming osteoblast lineage cells while simultaneously inhibiting the differentiation of bone resorbing osteoclasts. Previous work demonstrated that an intraperitoneal injection of SiNPs in healthy mice - both young and old - increased bone density and quality, suggesting the possibility that SiNPs represent a dual action therapeutic. However, the underlying mechanisms governing the osteoclast response to SiNPs have yet to be fully explored and defined. Therefore, the goals of this study were to investigate the cellular and molecular mechanisms by which SiNPs inhibit osteoclastogenesis. SiNPs strongly inhibited RANKL-induced osteoclast differentiation within the first hours and concomitantly inhibited early transcriptional regulators such as Nfatc1. SiNPs simultaneously stimulated expression of autophagy related genes p62 and LC3β dependent on ERK1/2 signaling pathway. Intriguingly, SiNPs were found to stimulate autophagosome formation while inhibiting the autophagic flux necessary for RANKL-stimulated osteoclast differentiation, resulting in the inhibition of both the canonical and non-canonical NF-κB signaling pathways and stabilizing TRAF3. These results suggest a model in which SiNPs inhibit osteoclastogenesis by inhibiting the autophagic machinery and RANKL-dependent functionality. This mechanism of action defines a novel therapeutic strategy for inhibiting osteoclastogenesis.

A plausible identifiable model of the canonical NF-κB signaling pathway.

An overwhelming majority of mathematical models of regulatory pathways, including the intensively studied NF-κB pathway, remains non-identifiable, meaning that their parameters may not be determined by existing data. The existing NF-κB models that are capable of reproducing experimental data contain non-identifiable parameters, whereas simplified models with a smaller number of parameters exhibit dynamics that differs from that observed in experiments. Here, we reduced an existing model of the canonical NF-κB pathway by decreasing the number of equations from 15 to 6. The reduced model retains two negative feedback loops mediated by IκBα and A20, and in response to both tonic and pulsatile TNF stimulation exhibits dynamics that closely follow that of the original model. We carried out the sensitivity-based linear analysis and Monte Carlo-based analysis to demonstrate that the resulting model is both structurally and practically identifiable given measurements of 5 model variables from a simple TNF stimulation protocol. The reduced model is capable of reproducing different types of responses that are characteristic to regulatory motifs controlled by negative feedback loops: nearly-perfect adaptation as well as damped and sustained oscillations. It can serve as a building block of more comprehensive models of the immune response and cancer, where NF-κB plays a decisive role. Our approach, although may not be automatically generalized, suggests that models of other regulatory pathways can be transformed to identifiable, while retaining their dynamical features.

A novel 2-iminobenzimidazole compound, XYA1353, displays in vitro and in vivo anti-myeloma activity via targeting NF-κB signaling.

Multiple myeloma (MM) is an accumulated disease of malignant plasma cells, which is still incurably owing to therapeutic resistance and disease relapse. Herein, we synthesized a novel 2-iminobenzimidazole compound, XYA1353, showing a potent anti-myeloma activity both in vitro and in vivo. Compound XYA1353 dose-dependently promoted MM cell apoptosis via activating caspase-dependent endogenous pathways. Moreover, compound XYA1353 could enhance bortezomib (BTZ)-mediated DNA damage via elevating γH2AX expression levels. Notably, compound XYA1353 interacted synergistically with BTZ and overcame drug resistance. RNA sequencing analysis and experiments confirmed that compound XYA1353 inhibited primary tumor growth and myeloma distal infiltration by disturbing canonical NF-κB signaling pathway via decreasing expression of P65/P50 and p-IκBα phosphorylation level. Due to its importance in regulating MM progression, compound XYA1353 alone or combined with BTZ may potentially exert therapeutic effects on multiple myeloma by suppressing canonical NF-κB signaling.

IKBA phosphorylation governs human sperm motility through ACC-mediated fatty acid beta-oxidation

The nuclear factor-κB (NF-κB) signaling pathway regulates specific immunological responses and controls a wide range of physiological processes. NF-κB inhibitor alpha (IKBA) is an NF-κB inhibitory mediator in the cytoplasm that modulates the nuclear translocation and DNA binding activities of NF-κB proteins. However, whether the upstream cascade of the canonical NF-κB signaling pathway has physiological roles independent of IKBA-mediated transcriptional activation remains unclear. Herein we investigated the function of IKBA in mature sperm in which transcriptional and translational events do not occur. IKBA was highly expressed in human sperm. The repression of IKBA phosphorylation by its inhibitor Bay117082 markedly enhanced sperm motility. On the contrary, lipopolysaccharide-stimulated IKBA phosphorylation significantly decreased sperm motility. Nevertheless, Bay117082 treatment did not affect the motility of IKBA-knockout sperm. Further, untargeted metabolomic analysis and pharmacological blocking assays revealed that the Bay117082-induced increase in sperm motility was attributable to fatty acid β-oxidation (FAO) enhancement. In addition, we found that IKBA phosphorylation inhibition resulted in a significant reduction of acetyl-CoA carboxylase levels in the FAO metabolic pathway. Our findings indicate that IKBA-mediated signaling orchestrates sperm motility program and improves our understanding of transcription-independent NF-κB signaling pathway in cells.

Absorption and Transport Mechanism of Red Meat-Derived N-glycolylneuraminic Acid and Its Damage to Intestinal Barrier Function through the NF-κB Signaling Pathway.

N-glycolylneuraminic acid (Neu5Gc) is a specific factor in red meat that induces intestinal disease. Our aim was to investigate the effect of Neu5Gc on the intestinal barrier as well as its mechanism of endocytosis and exocytosis. Ten specific inhibitors were used to explore the mechanism of Neu5Gc endocytosis and exocytosis by Caco-2 cells. Amiloride hydrochloride and cytochalasin D had the strongest inhibitory effect on the endocytosis of Neu5Gc. Sodium azide, dynasore, chlorpromazine hydrochloride, and nystatin also inhibited Neu5Gc endocytosis. Dynasore exhibited a stronger inhibitory effect than that of chlorpromazine hydrochloride or nystatin alone. Exocytosis inhibitors, including nocodazole, brefeldin A, monensin, and bafilomycin A, inhibited the transmembrane transport of Neu5Gc. Monensin promoted the exocytosis of Neu5Gc from Caco-2 cells. In another experiment, we observed no significant inhibitory effects of monensin and brefeldin A. Dietary concentrations of Neu5Gc induced prominent damage to intestinal tight junction proteins zonula occludens-1 (ZO-1), occludin, and claudin-1 and promoted the phosphorylation of IκB-α and P65 to activate the canonical Nuclear Factor kappa-B (NF-κB) pathway. Neu5Gc increased the RNA levels of pro-inflammatory factors IL-1β, IL-6, and TNF-α and inhibited those of anti-inflammatory factors TGF-β and IL-10. BAY, an NF-κB signaling pathway inhibitor, attenuated these changes. Reductions in the levels of ZO-1, occludin, and claudin-1 were recovered in response to BAY. Our data reveal the endocytosis and exocytosis mechanism of Neu5Gc and prove that Neu5Gc can activate the canonical NF-κB signaling pathway, regulate the transcription of inflammatory factors, thereby damaging intestinal barrier function.

The role of the canonical nf-κb signaling pathway in the development of acute liver failure

ABSTRACT As a clinical emergency with a high mortality rate, the treatment of acute liver failure has been paid attention to by society. At present, liver transplantation is the most effective treatment for acute liver failure, but there is still an insufficient supply of liver sources and a poor prognosis. In view of the current therapeutic development of this disease, more researchers have turned their attention to the research of drugs related to the NF-κB pathway. The NF-κB canonical pathway has been proven to play a role in a variety of diseases, regulating inflammation, apoptosis, and other physiological processes. More and more evidence shows that the NF-κB canonical pathway regulates the pathogenesis of acute liver failure. In this review, we will summarize the regulation process of the NF-κB canonical pathway on acute liver failure, and develop a new way to treat acute liver failure by targeting the components of the pathway.

Aggregated alpha-synuclein transcriptionally activates pro-inflammatory canonical and non-canonical NF-κB signaling pathways in peripheral monocytic cells

Parkinson’s disease (PD) is a neurodegenerative disorder characterized by chronic neuroinflammation, loss of dopaminergic neurons in the substantia nigra, and in several cases accumulation of alpha-synuclein fibril (α-syn) containing Lewy-bodies (LBs). Peripheral inflammation may play a causal role in inducing and perpetuating neuroinflammation in PD and accumulation of fibrillar α-syn has been reported at several peripheral sites including the gut and liver. Peripheral fibrillar α-syn may induce activation of monocytes via recognition by toll-like receptors (TLRs) and stimulation of downstream NF-κB signaling; however, the specific mechanism by which this occurs is not defined. In this study we utilized the THP-1 monocytic cell line to model the peripheral transcriptional response to preformed fibrillar (PFF) α-syn. Compared to monomeric α-syn, PFF α-syn displays overt inflammatory gene upregulation and pathway activation including broad pan-TLR signaling pathway activation and increases in TNF and IL1B gene expression. Notably, the non-canonical NF-κB signaling pathway gene and PD genome wide association study (GWAS) candidate NFKB2 was upregulated. Additionally, non-canonical NF-κB activation-associated RANK and CD40 pathways were also upregulated. Transcriptional-phenotype analysis suggests PFFs induce transcriptional programs associated with differentiation of monocytes towards macrophages and osteoclasts via non-canonical NF-κB signaling as a potential mechanism in which myeloid/monocyte cells may contribute to peripheral inflammation and pathogenesis in PD.

Cell-Penetrating Peptide Conjugated Au Nanoclusters Selectively Suppress Refractory Lymphoma Cells via Targeting Both Canonical and Noncanonical NF-κB Signaling Pathways.

Activated B cell-like diffuse large B-cell lymphoma (ABC-DLBCL) is the most aggressive form of DLBCL, with a significantly inferior prognosis due to resistance to the standard R-CHOP immunochemotherapy. Survival of ABC-DLBCL cells addicted to the constitutive activations of both canonical and noncanonical NF-κB signaling makes them attractive therapeutic targets. However, a pharmaceutical approach simultaneously targeting the canonical and noncanonical NF-κB pathway in the ABC-DLBCL cell is still lacking. Peptide-conjugated gold nanoclusters (AuNCs) have emerged unique intrinsic biomedical activities and possess a great potential in cancer theranostics. Here, we demonstrated a Au25 nanocluster conjugated by cell-penetrating peptides that can selectively repress the growth of ABC-DLBCL cells by inducing efficient apoptosis, more efficiently than glutathione (GSH)-conjugated AuNCs. The mechanism study showed that the cell-penetrating peptides enhanced the cellular internalization efficiency of AuNCs, and the selective repression in ABC-DLBCL cells is due to the inhibition of inherent constitutive canonical and noncanonical NF-κB activities by AuNCs. Several NF-κB target genes involved in chemotherapy resistance in ABC-DLBCL cells, including anti-apoptotic Bcl-2 family members and DNA damage repair proteins, were effectively down-regulated by the AuNC. The emerged novel activity of AuNCs in targeting both arms of NF-κB signaling in ABC-DLBCL cells may provide a promising candidate and a new insight into the rational design of peptide-conjugated Au nanomedicine for molecular targeting treatment of refractory lymphomas.

Canonical NF-κB signaling pathway and GRO-α/CXCR2 axis are activated in unruptured intracranial aneurysm patients.

Activation of the nuclear factor kappa-B (NF-κB) stimulates the production of pro-inflammatory molecules involved in the formation of intracranial aneurysms (IA). The study aimed to assess the NF-κB p65 subunit and the GRO-α chemokine and its receptor CXCR2 concentrations in unruptured intracranial aneurysm patients (UIA, n = 25) compared to individuals without vascular changes in the brain (n = 10). It was also analyzed whether tested proteins are related to the size and number of aneurysms. Cerebrospinal fluid (CSF) and serum protein levels were measured using the ELISA method. Median CSF and serum NF-κB p65 concentrations were significantly lower, while median CSF GRO-α and CXCR2 concentrations were significantly higher in UIA patients compared to the control group. CSF and serum NF-κB p65 concentrations negatively correlated with the number of aneurysms. In UIA patients the median GRO-α concentration was two-fold and CXCR2 almost four-fold higher in CSF compared to the serum value. CSF GRO-α concentration positively correlated with the size of aneurysms.Significantly decreased CSF NF-κB p65 and significantly increased CSF GRO-α and its CXCR2 receptor concentrations in UIA patients compared to the control group may altogether suggest that the canonical NF-κB signaling pathway is activated and its target pro-inflammatory genes are highly expressed in UIA patients. However, to unequivocally assess the involvement of the classical NF-κB pathway with the participation of the NF-κB p65 subunit and the GRO-α/CXCR2 axis in the formation of IA, further in vivo model studies are needed.

Inhibition of Both IRAK1 and IRAK4 Is Required for Complete Suppression of NF-Kb Signaling across Multiple Receptor-Mediated Pathways in MDS and AML

There is increasing interest in the role of the IRAK kinases as targets in the treatment of MDS and AML (reviewed in J Bennett and DT Starczynowski, Curr Opin Hematol 2022). IRAK1 and IRAK4 lie downstream of multiple receptors that stimulate the canonical NF-κB signaling pathway upstream of TRAF6 via the myddosome complex. While TRAF6 is necessary to preserve the tonic NF-κB signaling that is required for hematopoietic stem cell (HSC) homeostasis (J Fang et. al. Cell Reports 2018), overactivity of the NF-κB signaling pathway has been implicated in both MDS and AML (reviewed in MCJ Bosman et. al., Crit Rev Oncol/Hematol 2016; JJ Trowbridge and DT Starczynowski, J Exp Med 2021). The requirement for both IRAK1 and IRAK4 in this pathway has been explored using both genetic and pharmacologic technologies. The use of genetic loss-of-function approaches revealed that deletion and/or inhibition of IRAK4 results in a compensatory increase in IRAK1 protein and activation (data unpublished), suggesting that high potency antagonism of both kinases will be required for optimal inhibition of NF-κB-mediated transcriptional responses in disease-propagating MDS and AML cells. In this report, we use a pharmacological approach in which a series of IRAK inhibitors of varying relative potency at IRAK1:IRAK4 were examined for both inhibition of NF-κB activation in AML cells and inhibition of leukemic progenitor cell function in vitro. We find that potency and efficacy for antagonism at NF-κB requires effective inhibition of both IRAK1 and IRAK4. We also find that the relative potency of NF-κB inhibition correlates with suppression of leukemic progenitor cell function in vitro, providing pharmacological validation that inhibition of both IRAK1 and IRAK4 are necessary for optimal inhibition of NF-κB and effect on leukemia progenitor cell function. We utilized an NF-κB reporter system expressed in human AML cells (THP1) to measure NF-κB dependent activation in response to a variety of IRAK4, IRAK1, or IRAK1/4 antagonists. The cells are highly responsive to both TLR agonists as well as to IL-1b, which allows for measurement of IRAK-mediated antagonism of multiple receptor-mediated pathways. Using the IRAK4-selective antagonists PF-06650833 and BAY 1834845 we find that both compounds fully suppress signaling through TLR2 (IC50vs. Pam3CSK4 = 7.2 and 150 nM, respectively). The IRAK4 antagonists inhibit signaling through the IL-1R with similar relative potency (IC50vs. IL-1b = 5.7 and 81 nM), but do not fully suppress signaling through this receptor (Span = 75% and 59%, respectively). Interestingly, the IRAK1 selective covalent inhibitor JH-X-119-01 does not inhibit signaling against either the TLR or the IL-1 receptor agonist. Together these data imply that neither IRAK4 nor IRAK1 inhibition alone is sufficient to fully inhibit NF-κB-mediated signaling through multiple receptor mediated pathways. For this reason, we then examined the activity of a series of IRAK4/IRAK1 inhibitors in AML cells. This allowed us to study the effect of adding in additional inhibitory activity at IRAK1 on the background of high potency IRAK4 inhibitors. Using two reference compounds with varying IRAK1:IRAK4 potency, we then compared the relative ability to inhibit TLR-agonist or IL-1b-agonist stimulated NF-κB activity in AML. KME-2780 has an IRAK1:IRAK4 potency ratio of 36 whereas KME-3859 has an IRAK1:IRAK4 potency ratio of 100. Unlike what we observed with the IRAK4-selective antagonists, both compounds can completely suppress NF-κB signaling through IL-1b, with relative potencies apparently determined by their activity at IRAK1: (IC50vs. Pam3CSK4 = 6.3 and 73.8 nM for KME- 2780 and KME-3859, respectively); (IC50vs. IL-1b = 9.3 and 227 nM for KME- 2780 and KME-3859, respectively). Finally, we examined the correlation between potency in the biochemical kinase assay at IRAK1 or IRAK4, activity in the NF-κB reporter assay, and leukemic progenitor cell activity in the colony forming assay for a series of KME compounds in AML and MDS cells. We find a correlation between kinase activity for both IRAK1 and IRAK4 and NF-κB activity that extends to the leukemia colony forming assays. This suggests that NF-κB signaling contributes to leukemia progenitor cell function and that optimal inhibition requires potent antagonism of both IRAK1 and IRAK4 in the setting of MDS and AML.