Rel/NF-kappaB can trigger the Notch signaling pathway by inducing the expression of Jagged1, a ligand for Notch receptors

A water-soluble arabinoxylan from Chinese liquor distillers' grains: Structural characterization and anti-colitic properties

Chinese liquor distillers' grain (CLDG) is a valuable and abundant by-product from traditional Chinese baijiu production, containing a diverse array of bioactive components that have attracted significant interest. Herein, a water-soluble polysaccharide, DGPS-2B, with a weight-average molecular weight of 37.3 kDa, was isolated from the alkali-extract fraction of CLDG. Methylation and NMR analysis identified that the primary constituents of DGPS-2B are arabinoxylans, with an arabinose-to-xylose ratio of 0.66. In an animal model of colitis, DGPS-2B treatment significantly altered the gut microbiota composition by increasing the SCFA-producing bacteria (e.g., Butyricicoccus) and reducing the mucin-degrading bacteria such as Muribaculaceae. This microbial shift resulted in elevated production of butyrate, acetate, and propionate, which subsequently suppressed NF-κB signaling, decreased the levels of IL-1β, IL-6, and TNFα, and potentially inactivated Notch signaling. These multifaceted effects stimulated mucin 2 production, reduced inflammation and apoptosis in the gut epithelium, and ultimately alleviated colitis symptoms. Collectively, this study not only elucidates the purification and characterization of DGPS-2B from CLDG but also illuminates its anti-colitic properties and the underlying molecular mechanisms. These findings underscore the potential of DGPS-2B as a therapeutic intervention for managing inflammatory bowel disease and emphasize CLDG as a promising source for developing value-added products.

The role of NF-κB in breast cancer initiation, growth, metastasis, and resistance to chemotherapy

Breast cancer (BC) is the second most fatal disease and is the prime cause of cancer allied female deaths. BC is caused by aberrant tumor suppressor genes and oncogenes regulated by transcription factors (TFs) like NF-κB. NF-κB is a pro-inflammatory TF that crucially alters the expressions of various genes associated with inflammation, cell progression, metastasis, and apoptosis and modulates a network of genes that underlie tumorigenesis. Herein, we focus on NF-κB signaling pathways, its regulators, and the rationale for targeting NF-κB. This review also includes TFs that maintain NF-κB crosstalk and their roles in promoting angiogenesis and metastasis. In addition, we discuss the importance of combination therapies, resistance to treatment, and potential novel therapeutic strategies including nanomedicine that targets NF-κB.

Migraine as an inflammatory disorder with microglial activation as a prime candidate

BACKGROUND

The lower threshold of neuronal hyperexcitability has been correlated with migraines for decades but as technology has progressed, it has now become conceivable to learn more about the migraine disease. Apart from the "cortical spreading depression" and "activation of the trigeminovascular system", inflammation has been increasingly recognized as a possible pathogenic process that may have the possibility to regulate the disease severity. Microglial cells, the prime candidate of the innate immune cells of central nervous tissue, has been associated with numerous diseases; including cancer, neurodegenerative disorders, and inflammatory disorders.

AIM

In this review, we have attempted to link the dot of various microglial activation signaling pathways to enlighten the correlation between microglial involvement and the progression of migraine conditions.

METHOD

A structured survey of research articles and review of the literature was done in the electronic databases of Google Scholar, PubMed, Springer, and Elsevier until 31 December 2021.

RESULT & CONCLUSION

Of 1136 articles found initially and screening of 1047 records, 47 studies were included for the final review. This review concluded that inflammation and microglial overexpression as the prime candidate, plays an important role in the modulation of migraine and are responsible for the progression toward chronification. Therefore, this increases the possibility of preventing migraine development and chronification by blocking microglia overexpression.

Reduction of lithium induced interstitial fibrosis on co-administration with amiloride

Long-term administration of lithium is associated with chronic interstitial fibrosis that is partially reduced with exposure to amiloride. We examined potential pathways of how amiloride may reduce interstitial fibrosis. Amiloride was administered to a rat model of lithium induced interstitial fibrosis over a long term (6 months), as well as for short terms of 14 and 28 days. Kidney cortical tissue was subjected to RNA sequencing and microRNA expression analysis. Gene expression changes of interest were confirmed using immunohistochemistry on kidney tissue. Pathways identified by RNA sequencing of kidney tissue were related to 'promoting inflammation' for lithium and 'reducing inflammation' for amiloride. Validation of candidate genes found amiloride reduced inflammatory components induced by lithium including NF-κB/p65^Ser536 and activated pAKT^Ser473, and increased p53 mediated regulatory function through increased p21 in damaged tubular epithelial cells. Amiloride also reduced the amount of Notch1 positive PDGFrβ pericytes and infiltrating CD3 cells in the interstitium. Thus, amiloride attenuates a multitude of pro-inflammatory components induced by lithium. This suggests amiloride could be repurposed as a possible anti-inflammatory, anti-fibrotic agent to prevent or reduce the development of chronic interstitial fibrosis.

Multiple Mechanisms of NOTCH1 Activation in Chronic Lymphocytic Leukemia: NOTCH1 Mutations and Beyond

Simple Summary

Mutations of the NOTCH1 gene are a validated prognostic marker in chronic lymphocytic leukemia and a potential predictive marker for anti-CD20-based therapies. At present, the most frequent pathological alteration of the NOTCH1 gene is due to somatic genetic mutations, which have a multifaceted functional impact. However, beside NOTCH1 mutations, other factors may lead to activation of the NOTCH1 pathway, and these include mutations of FBXW7, MED12, SPEN, SF3B1 as well as other B-cell pathways. Understanding the preferential strategies though which CLL cells hijack NOTCH1 signaling may present important clues for designing targeted treatment strategies for the management of CLL.

Abstract

The Notch signaling pathway plays a fundamental role for the terminal differentiation of multiple cell types, including B and T lymphocytes. The Notch receptors are transmembrane proteins that, upon ligand engagement, undergo multiple processing steps that ultimately release their intracytoplasmic portion. The activated protein ultimately operates as a nuclear transcriptional co-factor, whose stability is finely regulated. The Notch pathway has gained growing attention in chronic lymphocytic leukemia (CLL) because of the high rate of somatic mutations of the NOTCH1 gene. In CLL, NOTCH1 mutations represent a validated prognostic marker and a potential predictive marker for anti-CD20-based therapies, as pathological alterations of the Notch pathway can provide significant growth and survival advantage to neoplastic clone. However, beside NOTCH1 mutation, other events have been demonstrated to perturb the Notch pathway, namely somatic mutations of upstream, or even apparently unrelated, proteins such as FBXW7, MED12, SPEN, SF3B1, as well as physiological signals from other pathways such as the B-cell receptor. Here we review these mechanisms of activation of the NOTCH1 pathway in the context of CLL; the resulting picture highlights how multiple different mechanisms, that might occur under specific genomic, phenotypic and microenvironmental contexts, ultimately result in the same search for proliferative and survival advantages (through activation of MYC), as well as immune escape and therapy evasion (from anti-CD20 biological therapies). Understanding the preferential strategies through which CLL cells hijack NOTCH1 signaling may present important clues for designing targeted treatment strategies for the management of CLL.

IL-33 enhances Jagged1 mediated NOTCH1 intracellular domain (NICD) deubiquitination and pathological angiogenesis in proliferative retinopathy

Pathological retinal neovascularization (NV) is a clinical manifestation of various proliferative retinopathies, and treatment of NV using anti-VEGF therapies is not selective, as it also impairs normal retinal vascular growth and function. Here, we show that genetic deletion or siRNA-mediated downregulation of IL-33 reduces pathological NV in a murine model of oxygen-induced retinopathy (OIR) with no effect on the normal retinal repair. Furthermore, our fluorescent activated cell sorting (FACS) data reveals that the increase in IL-33 expression is in endothelial cells (ECs) of the hypoxic retina and conditional genetic deletion of IL-33 in retinal ECs reduces pathological NV. In vitro studies using human retinal microvascular endothelial cells (HRMVECs) show that IL-33 induces sprouting angiogenesis and requires NFkappaB-mediated Jagged1 expression and Notch1 activation. Our data also suggest that IL-33 enhances de-ubiquitination and stabilization of Notch1 intracellular domain via its interaction with BRCA1-associated protein 1 (BAP1) and Numb in HRMVECs and a murine model of OIR.

Molecular Signature of Neuroinflammation Induced in Cytokine-Stimulated Human Cortical Spheroids

Crucial in the pathogenesis of neurodegenerative diseases is the process of neuroinflammation that is often linked to the pro-inflammatory cytokines Tumor necrosis factor alpha (TNFα) and Interleukin-1beta (IL-1β). Human cortical spheroids (hCSs) constitute a valuable tool to study the molecular mechanisms underlying neurological diseases in a complex three-dimensional context. We recently designed a protocol to generate hCSs comprising all major brain cell types. Here we stimulate these hCSs for three time periods with TNFα and with IL-1β. Transcriptomic analysis reveals that the main process induced in the TNFα- as well as in the IL-1β-stimulated hCSs is neuroinflammation. Central in the neuroinflammatory response are endothelial cells, microglia and astrocytes, and dysregulated genes encoding cytokines, chemokines and their receptors, and downstream NFκB- and STAT-pathway components. Furthermore, we observe sets of neuroinflammation-related genes that are specifically modulated in the TNFα-stimulated and in the IL-1β-stimulated hCSs. Together, our results help to molecularly understand human neuroinflammation and thus a key mechanism of neurodegeneration.

The ameliorative effect of niclosamide on bile duct ligation induced liver fibrosis via suppression of NOTCH and Wnt pathways

Liver fibrosis is the conjoint consequence of almost all chronic liver diseases. Cholestatic liver injury is a significant stimulus for fibrotic liver. This study was conducted to investigate the hepatoprotective effect of niclosamide as a NOTCH inhibitor and on the Wnt pathway against cholestatic liver fibrosis (CLF) which was experimentally induced by bile duct ligation (BDL). Rats were randomly divided into five main groups (6 per group): sham, BDL, BDL/niclosamide 5, BDL/niclosamide 10 and niclosamide 10 only group. Niclosamide was administered intraperitoneally (i.p.) for 4 weeks starting at the same day of surgery at doses 5 and 10 mg/kg. Liver function, cholestasis, oxidative stress, inflammation, liver fibrosis, NOTCH signaling pathway and Wnt pathway markers were assessed. Niclosamide (5 and 10 mg/kg) significantly reduced liver enzymes levels, oxidative stress, inflammation and phosphorylated signal transducer and activator of transcription3 (p-STAT3). Niclosamide (5 and 10 mg/kg) also significantly reduced NOTCH pathway (Jagged1, NOTCH2, NOTCH3, HES1, SOX9), Wnt pathway (Wnt5B, and Wnt10A), and fibrosis (transforming growth factor-beta1 (TGF-β1), alpha smooth muscle actin (α-SMA) and collagen deposition with more prominent effect of the higher dose 10 mg/kg. So, this study presents nicloamide as a promising antifibrotic agent in CLF through inhibition of NOTCH and Wnt pathways.

Divalent Metal Transporter 1 Knock-Down Modulates IL-1β Mediated Pancreatic Beta-Cell Pro-Apoptotic Signaling Pathways through the Autophagic Machinery

Pro-inflammatory cytokines promote cellular iron-import through enhanced divalent metal transporter-1 (DMT1) expression in pancreatic β-cells, consequently cell death. Inhibition of β-cell iron-import by DMT1 silencing protects against apoptosis in animal models of diabetes. However, how alterations of signaling networks contribute to the protective action of DMT1 knock-down is unknown. Here, we performed phosphoproteomics using our sequential enrichment strategy of mRNA, protein, and phosphopeptides, which enabled us to explore the concurrent molecular events in the same set of wildtype and DMT1-silenced β-cells during IL-1β exposure. Our findings reveal new phosphosites in the IL-1β-induced proteins that are clearly reverted by DMT1 silencing towards their steady-state levels. We validated the levels of five novel phosphosites of the potential protective proteins using parallel reaction monitoring. We also confirmed the inactivation of autophagic flux that may be relevant for cell survival induced by DMT1 silencing during IL-1β exposure. Additionally, the potential protective proteins induced by DMT1 silencing were related to insulin secretion that may lead to improving β-cell functions upon exposure to IL-1β. This global profiling has shed light on the signal transduction pathways driving the protection against inflammation-induced cell death in β-cells after DMT1 silencing.

Hepatocyte TLR4 triggers inter-hepatocyte Jagged1/Notch signaling to determine NASH-induced fibrosis

Aberrant hepatocyte Notch activity is critical to the development of nonalcoholic steatohepatitis (NASH)-induced liver fibrosis, but mechanisms underlying Notch reactivation in developed liver are unclear. Here, we identified that increased expression of the Notch ligand Jagged1 (JAG1) tracked with Notch activation and nonalcoholic fatty liver disease (NAFLD) activity score (NAS) in human liver biopsy specimens and mouse NASH models. The increase in Jag1 was mediated by hepatocyte Toll-like receptor 4 (TLR4)-nuclear factor κB (NF-κB) signaling in pericentral hepatocytes. Hepatocyte-specific Jag1 overexpression exacerbated fibrosis in mice fed a high-fat diet or a NASH-provoking diet rich in palmitate, cholesterol, and sucrose and reversed the protection afforded by hepatocyte-specific TLR4 deletion, whereas hepatocyte-specific Jag1 knockout mice were protected from NASH-induced liver fibrosis. To test therapeutic potential of this biology, we designed a Jag1-directed antisense oligonucleotide (ASO) and a hepatocyte-specific N-acetylgalactosamine (GalNAc)-modified siRNA, both of which reduced NASH diet-induced liver fibrosis in mice. Overall, these data demonstrate that increased hepatocyte Jagged1 is the proximal hit for Notch-induced liver fibrosis in mice and suggest translational potential of Jagged1 inhibitors in patients with NASH.

Interleukin-17 activates and synergizes with the notch signaling pathway in the progression of pancreatic ductal adenocarcinoma

Interleukin (IL)-17 is a prominent cytokine that promotes pancreatic intraepithelial neoplasia (PanIN) and pancreatic ductal adenocarcinoma (PDAC) and is associated with the oncogenic pathways in tumor progression. However, the mechanism and therapeutic value of the IL-17 axis remain unclear. In this study, we verified the activation of the IL-17 and Notch pathways in PanIN/PDAC via complementary approaches and validated their pro-tumor effects on tumor progression. Additionally, we found a positive correlation between IL-17 and Notch; the IL-17 axis can upregulate Notch activity via the canonical NF-κB pathway in vitro, thus synergistically promoting PanIN/PDAC. Furthermore, we observed that the co-inhibition of IL-17 and the Notch pathway can enhance the therapeutic effect by restricting tumor growth in vivo. Our study highlights the synergistic effect of the IL-17 axis and Notch pathway in promoting PanIN/PDAC and further suggests that IL-17-Notch co-inhibition is a novel therapeutic strategy with superior potential in treating PDAC.

Curcumin and cardiovascular diseases: Focus on cellular targets and cascades

Cardiovascular diseases (CVDs) are one of the leading causes of the most considerable mortality globally, and it has been tried to find the molecular mechanisms and design new drugs that triggered the molecular target. Curcumin is the main ingredient of Curcuma longa (turmeric) that has been used in traditional medicine for treating several diseases for years. Numerous investigations have indicated the beneficial effect of Curcumin in modulating multiple signaling pathways involved in oxidative stress, inflammation, apoptosis, and proliferation. The cardiovascular protective effects of Curcumin against CVDs have been indicated in several studies. In the current review study, we provided novel information on Curcumin's protective effects against various CVDs and potential molecular signaling targets of Curcumin. Nonetheless, more studies should be performed to discover the exact molecular target of Curcumin against CVDs.

Genes and pathways involved in senescence bypass identified by functional genetic screens

Cellular senescence is a state of stable and irreversible cell cycle arrest with active metabolism, that normal cells undergo after a finite number of divisions (Hayflick limit). Senescence can be triggered by intrinsic and/or extrinsic stimuli including telomere shortening at the end of a cell's lifespan (telomere-initiated senescence) and in response to oxidative, genotoxic or oncogenic stresses (stress-induced premature senescence). Several effector mechanisms have been proposed to explain senescence programmes in diploid cells, including the induction of DNA damage responses, a senescence-associated secretory phenotype and epigenetic changes. Senescent cells display senescence-associated-β-galactosidase activity and undergo chromatin remodeling resulting in heterochromatinisation. Senescence is established by the pRb and p53 tumour suppressor networks. Senescence has been detected in in vitro cellular settings and in premalignant, but not malignant lesions in mice and humans expressing mutant oncogenes. Despite oncogene-induced senescence, which is believed to be a cancer initiating barrier and other tumour suppressive mechanisms, benign cancers may still develop into malignancies by bypassing senescence. Here, we summarise the functional genetic screens that have identified genes, uncovered pathways and characterised mechanisms involved in senescence evasion. These include cell cycle regulators and tumour suppressor pathways, DNA damage response pathways, epigenetic regulators, SASP components and noncoding RNAs.

CD28 Signaling Drives Notch Ligand Expression on CD4 T Cells

Notch signaling provides an important cue in the mammalian developmental process. It is a key player in T cell development and function. Notch ligands such as Delta-like ligands (DLL) 1, 3, 4, and JAG1, 2 can impact Notch signaling positively or negatively, by trans-activation or cis-inhibition. Trans and cis interactions are receptor-ligand interaction on two adjacent cells and interaction on the same cell, respectively. The former sends an activation signal and the later, a signal for inhibition of Notch. However, earlier reports suggested that Notch is activated in the absence of Notch ligand-expressing APCs in a purified population of CD4 T cells. Thus, the role of ligands in Notch activation, in a purified population of CD4 T cells, remains obscure. In this study, we demonstrate that mature CD4 T cells are capable of expressing Notch ligands on their surface very early upon activation with soluble antibodies against CD3 and CD28. Moreover, signaling solely through CD28 induces Notch ligand expression and CD3 signaling inhibits ligand expression, in contrast to Notch which is induced by CD3 signaling. Additionally, by using decoys, mimicking the Notch extracellular domain, we demonstrated that DLL1, DLL4, and JAG1, expressed on the T cells, can cis-interact with the Notch receptor and inhibit activation of Notch. Thus, our data indicate a novel mechanism of the regulation of Notch ligand expression on CD4 T cells and its impact on activated Notch.

Dlk1-Mediated Temporal Regulation of Notch Signaling Is Required for Differentiation of Alveolar Type II to Type I Cells during Repair

Lung alveolar type I cells (AT1) and alveolar type II cells (AT2) regulate the structural integrity and function of alveoli. AT1, covering ∼95% of the surface area, are responsible for gas exchange, whereas AT2 serve multiple functions, including alveolar repair through proliferation and differentiation into AT1. However, the signaling mechanisms for alveolar repair remain unclear. Here, we demonstrate, in Pseudomonas aeruginosa-induced acute lung injury in mice, that non-canonical Notch ligand Dlk1 (delta-like 1 homolog) is essential for AT2-to-AT1 differentiation. Notch signaling was activated in AT2 at the onset of repair but later suppressed by Dlk1. Deletion of Dlk1 in AT2 induced persistent Notch activation, resulting in stalled transition to AT1 and accumulation of an intermediate cell population that expressed low levels of both AT1 and AT2 markers. Thus, Dlk1 expression leads to precisely timed inhibition of Notch signaling and activates AT2-to-AT1 differentiation, leading to alveolar repair.

Notch signaling: Its essential roles in bone and craniofacial development

Notch is a cell–cell signaling pathway that is involved in a host of activities including development, oncogenesis, skeletal homeostasis, and much more. More specifically, recent research has demonstrated the importance of Notch signaling in osteogenic differentiation, bone healing, and in the development of the skeleton. The craniofacial skeleton is complex and understanding its development has remained an important focus in biology. In this review we briefly summarize what recent research has revealed about Notch signaling and the current understanding of how the skeleton, skull, and face develop. We then discuss the crucial role that Notch plays in both craniofacial development and the skeletal system, and what importance it may play in the future.

Bone marrow-derived mesenchymal stem cells utilize the notch signaling pathway to induce apoptosis of hepatic stellate cells via NF-κB sensor

The present study aimed at evaluating the mechanism by which functionality of hepatic stellate cells (HSCs) is modulated by bone marrow stromal cells (BMSCs). Induction of apoptosis in HSCs was found to be caused by directly co-culturing HSCs with BMSCs, where the expression of α-smooth muscle actin (α-SMA) increased significantly in HSCs, along with an increase in their proliferation rate. Additionally, expression of Hes1 and Notch1 in HSCs co-cultured with BMSCs increased significantly at both protein and mRNA levels. Blocking of the notch signaling pathway (NSP) either by Notch1 siRNA or by DAPT treatment increased the proliferation rate while decreasing apoptosis and led to activation of the NF-κB signaling pathway in HSCs co-cultured with BMSCs. These effects were found to be reversed in HSCs overexpressing IκB S32/S36 mutants. The Notch signaling-mediated cell-cell contact was partially involved in the significant inhibition of proliferation of HSCs by BMSCs. Additionally, the NF-κB pathway was found to be responsible for NSP-mediated inhibition of growth of HSCs in the co-culture system. Thus, BMSCs might have a potential therapeutic significance in treating hepatic fibrosis.

Molecular Mechanisms of Notch Signaling in Lymphoid Cell Lineages Development: NF-κB and Beyond

Notch is a ligand-receptor interaction-triggered signaling cascade highly conserved, that influences multiple lineage decisions within the hematopoietic and the immune system. It is a recognized model of intercellular communication that plays an essential role in embryonic as well as in adult immune cell development and homeostasis. Four members belong to the family of Notch receptors (Notch1-4), and each of them plays nonredundant functions at several developmental stages. Canonical and noncanonical pathways of Notch signaling are multifaceted drivers of immune cells biology. In fact, increasing evidence highlighted Notch as an important modulator of immune responses, also in cancer microenvironment. In these contexts, multiple transduction signals, including canonical and alternative NF-κB pathways, play a relevant role. In this chapter, we will first describe the critical role of Notch and NF-κB signals in lymphoid lineages developing in thymus: natural killer T cells, thymocytes, and thymic T regulatory cells. We will address also the role played by ligand expressing cells. Given the importance of Notch/NF-κB cross talk, its role in T-cell leukemia development and progression will be discussed.

Effects of Different Ligands in the Notch Signaling Pathway on the Proliferation and Transdifferentiation of Primary Type II Alveolar Epithelial Cells

Background: Transdifferentiation of type II alveolar epithelial cells (AECII) into type I alveolar epithelial cells (AECI) is involved in neonatal respiratory distress syndrome (NRDS). Different ligands of the Notch pathway could have different effects on AECII transdifferentiation. Objective: To investigate the effects of Dlk1 and Jagged1 on the proliferation and transdifferentiation of AECII. Methods: Fetal AECIIs (19 days of gestation) were divided: control group, Dlk1 group, rhNF-κB group. Proliferation was tested using the MTT assay. Expression of surfactant protein C (SP-C) and aquaporin 5 (AQP5) was examined by immunofluorescence. mRNA and protein levels of SP-C, AQP5, Nortch1, Dlk1, Jagged1, and Hes1 were examined by RT-PCR and western blot. Results: In response to Dlk1, cell number and proliferation were increased (P < 0.05), and mRNA and protein levels of SP-C, Dlk1, Notch1, and Hes1 were up-regulated, while AQP and Jagged1 were decreased. In response to rhNF-κB, the cell number and proliferation were reduced, and mRNA and protein levels of Jagged1 and Notch1 were up-regulated, while Dlk1, and SP-C were downregulated. In the Dlk1 group, SP-C, and AQP5 expression patterns suggested that the cells were still transdifferentiating by 96 h, while in the rhNF-κB group, most cells had transdifferentiated by 72 h and were close to apoptosis by 96 h. Conclusion: These results suggest that Dlk1 promoted proliferation of AECIIs and inhibited cell transdifferentiation, while Jagged1 treatment inhibited proliferation of AECIIs and promoted transdifferentiation to AECIs. These results provide some clue for the eventual management of NDRS.

Notch pathway: a bistable inducer of biological noise?

Notch signalling pathway is central to development of metazoans. The pathway codes a binary fate switch. Upon activation, downstream signals contribute to resolution of fate dichotomies such as proliferation/differentiation or sub-lineage differentiation outcome. There is, however, an interesting paradox in the Notch signalling pathway. Despite remarkable predictability of fate outcomes instructed by the Notch pathway, the associated transcriptome is versatile and plastic. This inconsistency suggests the presence of an interface that compiles input from the plastic transcriptome of the Notch pathway but communicates only a binary output in biological decisions. Herein, we address the interface that determines fate outcomes. We provide an alternative hypothesis for the Notch pathway as a biological master switch that operates by induction of genetic noise and bistability in order to facilitate resolution of dichotomous fate outcomes in development.

Preactivation of Notch1 in remote ischemic preconditioning reduces cerebral ischemia-reperfusion injury through crosstalk with the NF-κB pathway

Background

Remote ischemic preconditioning (RIPC) initiates endogenous protective pathways in the brain from a distance and represents a new, promising paradigm in neuroprotection against cerebral ischemia-reperfusion (I/R) injury. However, the underlying mechanism of RIPC-mediated cerebral ischemia tolerance is complicated and not well understood. We reported previously that preactivation of Notch1 mediated the neuroprotective effects of cerebral ischemic preconditioning in rats subjected to cerebral I/R injury. The present study seeks to further explore the role of crosstalk between the Notch1 and NF-κB signaling pathways in the process of RIPC-induced neuroprotection.

Methods

Middle cerebral artery occlusion and reperfusion (MCAO/R) in adult male rats and oxygen-glucose deprivation and reoxygenation (OGD/R) in primary hippocampal neurons were used as models of I/R injury in vivo and in vitro, respectively. RIPC was induced by a 3-day procedure with 4 cycles of 5 min of left hind limb ischemia followed by 5 min of reperfusion each day before MCAO/R. Intracerebroventricular DAPT injection and sh-Notch1 lentivirus interference were used to inhibit the Notch1 signaling pathway in vivo and in vitro, respectively. After 24 h of reperfusion, neurological deficit scores, infarct volume, neuronal apoptosis, and cell viability were assessed. The protein expression levels of NICD, Hes1, Phospho-IKKα/β (p-IKK α/β), Phospho-NF-κB p65 (p-NF-κB p65), Bcl-2, and Bax were assessed by Western blotting.

Results

RIPC significantly improved neurological scores and reduced infarct volume and neuronal apoptosis in rats subjected to I/R injury. OGD preconditioning significantly reduced neuronal apoptosis and improved cell viability after I/R injury on days 3 and 7 after OGD/R. However, the neuroprotective effect was reversed by DAPT in vivo and attenuated by Notch1-RNAi in vitro. RIPC significantly upregulated the expression of proteins related to the Notch1 and NF-κB pathways. NF-κB signaling pathway activity was suppressed by a Notch1 signaling pathway inhibitor and Notch1-RNAi.

Conclusions

The neuroprotective effect of RIPC against cerebral I/R injury was associated with preactivation of the Notch1 and NF-κB pathways in neurons. The NF-κB pathway is a downstream target of the Notch1 pathway in RIPC and helps protect focal cerebral I/R injury.

Curcumin attenuates hypoxia/reoxygenation‑induced cardiomyocyte injury by downregulating Notch signaling

Recovery of the blood supply is the most effective treatment against ischemic heart disease; however, it is also a major cause of myocardial ischemia/reperfusion injury in clinical therapy. Curcumin has been reported to possess beneficial effects against hypoxia/reoxygenation (H/R)-induced cardiomyocyte injury by regulating cell proliferation, apoptosis and antioxidant enzyme activity. The aim of the present study was to investigate the molecular mechanisms underlying the effects of curcumin on H/R-injured cardiomyocytes. H9C2 cardiomyocytes were pretreated with curcumin, and then cultured under H/R conditions. The viability of H9C2 cells was measured using a Cell Counting kit-8 assay, and the levels of intracellular lactate dehydrogenase (LDH), malondialdehyde (MDA) and superoxide dismutase (SOD) were measured to assess cell injury. Levels of reactive oxygen species (ROS) and apoptosis were evaluated by flow cytometry. The expression levels of Notch intracellular domain (NICD) and numerous downstream genes were analyzed via reverse transcription-quantitative polymerase chain reaction and western blotting. The results revealed that curcumin protected H9C2 cells against H/R-induced injury, reversing the H/R-induced increases in LDH and MDA levels, and decreases in SOD levels. ROS levels in H/R-induced cells were also significantly downregulated by curcumin treatment (P<0.01), and the apoptotic rate was significantly decreased from 15.13% in the H/R group to 7.7% in the H/R + curcumin group (P<0.01). The expression levels of NICD, hairy and enhancer of split (Hes)-1, Hes-5 and hairy/enhancer-of-split related with YRPW motif protein 1 (Hey-1) were significantly decreased in H/R-treated cells following curcumin treatment. Treatment with Jagged1 attenuated the effects of curcumin on cell viability, ROS levels and apoptosis; the Notch pathway was also reactivated. The present study indicated that there was a role for the Notch pathway in the protective effects of curcumin against H/R-induced cardiomyocyte injury, suggesting that downregulation of the Notch pathway may alleviate H/R-induced injury in H9C2 cells.

Notch signaling in astrocytes mediates their morphological response to an inflammatory challenge

In the nervous system, Notch pathway has a prominent role in the control of neuronal morphology and in the determination of the astrocyte fate. However, the role of Notch in morphological astrocyte plasticity is unknown. Here, we have explored the role of Notch activity on the morphological reactivity of primary astrocytes in response to LPS, an inflammatory stimulus. We found that LPS induces reactive astrocyte morphology by the inhibition of Notch signaling via NFκB activation and Jagged upregulation. In contrast, IGF-1, an anti-inflammatory molecule, inhibits LPS-induced reactive astrocyte morphological phenotype by enhancing Notch signaling through the inhibition of NFκB and the activation of MAPK. Therefore, Notch signaling pathway emerges as a mediator of the regulation of astrocyte morphology by inflammatory and anti-inflammatory stimuli.

The dynamic nature of senescence in cancer

Cellular senescence is implicated in physiological and pathological processes spanning development, wound healing, age-related decline in organ functions and cancer. Here, we discuss cell-autonomous and non-cell-autonomous properties of senescence in the context of tumour formation and anticancer therapy, and characterize these properties, such as reprogramming into stemness, tissue remodelling and immune crosstalk, as far more dynamic than suggested by the common view of senescence as an irreversible, static condition.

Notch Signaling Regulates Mitochondrial Metabolism and NF-κB Activity in Triple-Negative Breast Cancer Cells via IKKα-Dependent Non-canonical Pathways

Triple negative breast cancer (TNBC) patients have high risk of recurrence and metastasis, and current treatment options remain limited. Cancer stem-like cells (CSCs) have been linked to cancer initiation, progression and chemotherapy resistance. Notch signaling is a key pathway regulating TNBC CSC survival. Treatment of TNBC with PI3K or mTORC1/2 inhibitors results in drug-resistant, Notch-dependent CSC. However, downstream mechanisms and potentially druggable Notch effectors in TNBC CSCs are largely unknown. We studied the role of the AKT pathway and mitochondrial metabolism downstream of Notch signaling in TNBC CSC from cell lines representative of different TNBC molecular subtypes as well as a novel patient-derived model. We demonstrate that exposure of TNBC cells to recombinant Notch ligand Jagged1 leads to rapid AKT phosphorylation in a Notch1-dependent but RBP-Jκ independent fashion. This requires mTOR and IKKα. Jagged1 also stimulates mitochondrial respiration and fermentation in an AKT- and IKK-dependent fashion. Notch1 co-localizes with mitochondria in TNBC cells. Pharmacological inhibition of Notch cleavage by gamma secretase inhibitor PF-03084014 in combination with AKT inhibitor MK-2206 or IKK-targeted NF-κB inhibitor Bay11-7082 blocks secondary mammosphere formation from sorted CD90^hi or CD44⁺CD24^low (CSCs) cells. A TNBC patient-derived model gave comparable results. Besides mitochondrial oxidative metabolism, Jagged1 also triggers nuclear, NF-κB-dependent transcription of anti-apoptotic gene cIAP-2. This requires recruitment of Notch1, IKKα and NF-κB to the cIAP-2 promoter. Our observations support a model where Jagged1 triggers IKKα-dependent, mitochondrial and nuclear Notch1 signals that stimulate AKT phosphorylation, oxidative metabolism and transcription of survival genes in PTEN wild-type TNBC cells. These data suggest that combination treatments targeting the intersection of the Notch, AKT and NF-κB pathways have potential therapeutic applications against CSCs in TNBC cases with Notch1 and wild-type PTEN expression.

Notch and NF-κB: Coach and Players of Regulatory T-Cell Response in Cancer

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

NOTCH1 Aberrations in Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL) is an incurable B-cell neoplasm characterized by highly variable clinical outcomes. In recent years, genomic and molecular studies revealed a remarkable heterogeneity in CLL, which mirrored the clinical diversity of this disease. These studies profoundly enhanced our understanding of leukemia cell biology and led to the identification of new biomarkers with potential prognostic and therapeutic significance. Accumulating evidence indicates a key role of deregulated NOTCH1 signaling and NOTCH1 mutations in CLL. This review highlights recent discoveries that improve our understanding of the pathophysiological NOTCH1 signaling in CLL and the clinical impact of NOTCH1 mutations in retrospective and prospective trials. In addition, we discuss the rationale for a therapeutic strategy aiming at inhibiting NOTCH1 signaling in CLL, along with an overview on the currently available NOTCH1-directed approaches.

Notch Signaling Regulates Microglial Activation and Inflammatory Reactions in a Rat Model of Temporal Lobe Epilepsy

The inflammatory response mediated by microglia in the central nervous system is closely related to epilepsy. Notch signaling plays an important role in the microglial activation during hypoxia. This study aimed to investigate whether Notch signaling is involved in microglial activation and subsequent inflammation-related neuronal injury during the process of epileptogenesis in a rat model of temporal lobe epilepsy. By using western blotting, real-time quantitative PCR, immunohistochemistry and immunofluorescence labeling, we found that the expression of Notch signaling increased after status epilepticus and that a γ-secretase inhibitor could significantly inhibit the upregulation of Notch signaling, the activation of microglia, and the release of proinflammatory cytokines. Likewise, the neuronal apoptosis and loss in the hippocampus after SE were attenuated by the γ-secretase inhibitor. These results suggest that Notch signaling plays a key role in neuroinflammation and inflammation-related neuronal damage in epilepsy, and γ-secretase inhibitors may become a novel prospective therapeutic agent for epilepsy.

Interleukin-1beta (IL-1β)-induced Notch ligand Jagged1 suppresses mitogenic action of IL-1β on human dystrophic myogenic cells

Duchenne muscular dystrophy (DMD) is a severe X-linked recessive muscle disorder caused by mutations in the dystrophin gene. Nonetheless, secondary processes involving perturbation of muscle regeneration probably exacerbate disease progression, resulting in the fatal loss of muscle in DMD patients. A dysfunction of undifferentiated myogenic cells is the most likely cause for the reduction of regenerative capacity of muscle. To clarify molecular mechanisms in perturbation of the regenerative capacity of DMD muscle, we have established several NCAM (CD56)-positive immortalized human dystrophic and non-dystrophic myogenic cell lines from DMD and healthy muscles. A pro-inflammatory cytokine, IL-1β, promoted cell cycle progression of non-dystrophic myogenic cells but not DMD myogenic cells. In contrast, IL-1β upregulated the Notch ligand Jagged1 gene in DMD myogenic cells but not in non-dystrophic myogenic cells. Knockdown of Jagged1 in DMD myogenic cells restored the IL-1β-promoted cell cycle progression. Conversely, enforced expression of Jagged1-blocked IL-1β promoted proliferation of non-dystrophic myogenic cells. In addition, IL-1β prevented myogenic differentiation of DMD myogenic cells depending on Jagged1 but not of non-dystrophic myogenic cells. These results demonstrate that Jagged1 induced by IL-1β in DMD myogenic cells modified the action of IL-1β and reduced the ability to proliferate and differentiate. IL-1β induced Jagged1 gene expression may be a feedback response to excess stimulation with this cytokine because high IL-1β (200-1000 pg/ml) induced Jagged1 gene expression even in non-dystrophic myogenic cells. DMD myogenic cells are likely to acquire the susceptibility of the Jagged1 gene to IL-1β under the microcircumstances in DMD muscles. The present results suggest that Jagged1 induced by IL-1β plays a crucial role in the loss of muscle regeneration capacity of DMD muscles. The IL-1β/Jagged1 pathway may be a new therapeutic target to ameliorate exacerbation of muscular dystrophy in a dystrophin-independent manner.

The persistent dynamic secrets of senescence

While the beneficial versus detrimental implications of the senescence-associated secretome remain an issue of debate, time-resolved analyses of its composition, regulatory mechanisms and functional consequences have been largely missing. The dynamic activity of NOTCH is now shown to direct two distinct senescence phenotypes, by first promoting a pro-senescent TGF-β1-dependent secretome, followed by a second wave of pro-inflammatory, senescence-clearing cytokines.

Bortezomib augments lymphocyte stimulatory cytokine signaling in the tumor microenvironment to sustain CD8+T cell antitumor function

Tumor-induced immune tolerance poses a major challenge for therapeutic interventions aimed to manage cancer. We explored approaches to overcome T-cell suppression in murine breast and kidney adenocarcinomas, and lung fibrosarcoma expressing immunogenic antigens. We observed that treatment with a reversible proteasome inhibitor bortezomib (1 mg/kg body weight) in tumor-bearing mice significantly enhanced the expression of lymphocyte-stimulatory cytokines IL-2, IL-12, and IL-15. Notably, bortezomib administration reduced pulmonary nodules of mammary adenocarcinoma 4T1.2 expressing hemagglutinin (HA) model antigen (4T1HA) in mice. Neutralization of IL-12 and IL-15 cytokines with a regimen of blocking antibodies pre- and post-adoptive transfer of low-avidity HA518-526-specific CD8+T-cells following intravenous injection of 4T1HA cells increased the number of pulmonary tumor nodules. This neutralization effect was counteracted by the tumor metastasis-suppressing action of bortezomib treatments. In bortezomib-treated 4T1HA tumor-bearing mice, CD4+T-cells showed increased IL-2 production, CD11c+ dendritic cells showed increased IL-12 and IL-15 production, and HA-specific activated CD8+T-cells showed enhanced expression of IFNγ, granzyme-B and transcription factor eomesodermin. We also noted a trend of increased expression of IL-2, IL-12 and IL-15 receptors as well as increased phosphorylation of STAT5 in tumor-infiltrating CD8+T-cells following bortezomib treatment. Furthermore, bortezomib-treated CD8+T-cells showed increased phosphorylation of mitogen-activated protein kinase p38, and Akt, which was abrogated by phosphatidylinositide 3-kinase (PI3K) inhibitor. These data support the therapeutic potential of bortezomib in conjunction with other immunotherapies to augment the strength of convergent signals from CD8+T-cell signaling molecules including TCR, cytokine receptors and downstream PI3K/Akt/STAT5 pathways to sustain CD8+T-cell effector function in the tumor microenvironment.

Fine-Tuning of the Kaposi's Sarcoma-Associated Herpesvirus Life Cycle in Neighboring Cells through the RTA-JAG1-Notch Pathway

Kaposi’s sarcoma (KS)-associated herpesvirus (KSHV) is an oncogenic pathogen that displays latent and lytic life cycles. In KS lesions, infiltrated immune cells, secreted viral and/or cellular cytokines, and hypoxia orchestrate a chronic pro-lytic microenvironment that can promote KSHV reactivation. However, only a small subset of viruses spontaneously undergoes lytic replication in this pro-lytic microenvironment while the majority remains in latency. Here, we show that the expression of the Notch ligand JAG1 is induced by KSHV-encoded replication and transcription activator (RTA) during reactivation. JAG1 up-regulation activates Notch signaling in neighboring cells and prevents viral lytic replication. The suppression of JAG1 and Notch1 with inhibitors or small interfering RNA promotes lytic replication in the presence of RTA induction or under conditions of hypoxia. The underlying mechanism involves the Notch downstream effector hairy and enhancer of split 1 (Hes1), which directly binds lytic gene promoters and attenuates viral lytic gene expression. RTA interacts with lymphoid enhancer-binding factor 1 (LEF1), disrupts LEF1/Groucho/TLE suppressive complexes and releases LEF1 to activate JAG1 expression. Taken together, our results suggest that cells with viral lytic replication can inhibit KSHV reactivation in neighboring cells through an RTA-JAG1-Notch pathway. These data provide insight into the mechanism by which the virus maintains the balance between lytic and latent infection in the pro-lytic tumor microenvironment.

KSHV infected cells display significant heterogeneity in viral lytic replication within the universal pro-lytic inflammatory milieu, suggesting that the balance between latency and reactivation is carefully regulated. This fine-tuned regulatory mechanism is essential for KSHV to persist in the host and drive cells to malignancy. In the present study, we show that KSHV can usurp the Notch signaling pathway to inhibit the viral lytic life cycle in neighboring cells. Notch signaling in surrounding cells can be activated through an RTA-JAG1-Notch pathway initiated by cells in which KSHV is reactivated. Activated Notch inhibits KSHV reactivation through its downstream effector Hes1. These findings suggest that the ability of Notch to determine the fate of adjacent cells is hijacked by KSHV to maintain its life cycle, providing a mechanistic explanation for the phenomenon by which only a small fraction of viruses enters lytic replication in the common pro-lytic microenvironment.

Activation of an endothelial Notch1-Jagged1 circuit induces VCAM1 expression, an effect amplified by interleukin-1β

The Notch1 and Notch4 signaling pathways regulate endothelial cell homeostasis. Inflammatory cytokines induce the expression of endothelial adhesion molecules, including VCAM1, partly by downregulating Notch4 signaling. We investigated the role of endothelial Notch1 in this IL-1β-mediated process. Brief treatment with IL-1β upregulated endothelial VCAM1 and Notch ligand Jagged1. IL-1β decreased Notch1 mRNA levels, but levels of the active Notch1ICD protein remained constant. IL-1β-mediated VCAM1 induction was downregulated in endothelial cells subjected to pretreatment with a pharmacological inhibitor of the γ-secretase, which activates Notch receptors, producing NotchICD. It was also downregulated in cells in which Notch1 and/or Jagged1 were silenced.Conversely, the forced expression of Notch1ICD in naïve endothelial cells upregulated VCAM1 per se and amplified IL-1β-mediated VCAM1 induction. Jagged1 levels increased and Notch4 signaling was downregulated in parallel. Finally, Notch1ICD and Jagged1 expression was upregulated in the endothelium of the liver in a model of chronic liver inflammation.In conclusion, we describe here a cell-autonomous, pro-inflammatory endothelial Notch1-Jagged1 circuit (i) triggering the expression of VCAM1 even in the absence of inflammatory cytokines and (ii) enhancing the effects of IL-1β. Thus, IL-1β regulates Notch1 and Notch4 activity in opposite directions, consistent with a selective targeting of Notch1 in inflamed endothelium.

Endothelial Jag1-RBPJ signalling promotes inflammatory leucocyte recruitment and atherosclerosis

Aim

To determine the role of NOTCH during the arterial injury response and the subsequent chronic arterial-wall inflammation underlying atherosclerosis.

Methods and results

We have generated a mouse model of endothelial-specific (Cdh5-driven) depletion of the Notch effector recombination signal binding protein for immunoglobulin kappa J region (RBPJ) [(ApoE-/-); homozygous RBPJk conditional mice (RBPJflox/flox); Cadherin 5-CreERT, tamoxifen inducible driver mice (Cdh5-CreERT)]. Endothelial-specific deletion of RBPJ or systemic deletion of Notch1 in athero-susceptible ApoE-/- mice fed a high-cholesterol diet for 6 weeks resulted in reduced atherosclerosis in the aortic arch and sinus. Intravital microscopy revealed decreased leucocyte rolling on the endothelium of ApoE-/-; RBPJflox/flox; Cdh5-CreERT mice, correlating with a lowered content of leucocytes and macrophages in the vascular wall. Transcriptome analysis revealed down-regulation of proinflammatory and endothelial activation pathways in atherosclerotic tissue of RBPJ-mutant mice. During normal Notch activation, Jagged1 signalling up-regulation in endothelial cells promotes nuclear translocation of the Notch1 intracellular domain (N1ICD) and its physical interaction with nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). This N1ICD-NF-κB interaction is required for reciprocal transactivation of target genes, including vascular cell adhesion molecule-1.

Conclusions

Notch signalling pathway inactivation decreases leucocyte rolling, thereby preventing endothelial dysfunction and vascular inflammation. Attenuation of Notch signalling might provide a treatment strategy for atherosclerosis.

Notch Signaling Mediates Skeletal Muscle Atrophy in Cancer Cachexia Caused by Osteosarcoma

Skeletal muscle atrophy in cancer cachexia is mediated by the interaction between muscle stem cells and various tumor factors. Although Notch signaling has been known as a key regulator of both cancer development and muscle stem cell activity, the potential involvement of Notch signaling in cancer cachexia and concomitant muscle atrophy has yet to be elucidated. The murine K7M2 osteosarcoma cell line was used to generate an orthotopic model of sarcoma-associated cachexia, and the role of Notch signaling was evaluated. Skeletal muscle atrophy was observed in the sarcoma-bearing mice, and Notch signaling was highly active in both tumor tissues and the atrophic skeletal muscles. Systemic inhibition of Notch signaling reduced muscle atrophy. In vitro coculture of osteosarcoma cells with muscle-derived stem cells (MDSCs) isolated from normal mice resulted in decreased myogenic potential of MDSCs, while the application of Notch inhibitor was able to rescue this repressed myogenic potential. We further observed that Notch-activating factors reside in the exosomes of osteosarcoma cells, which activate Notch signaling in MDSCs and subsequently repress myogenesis. Our results revealed that signaling between tumor and muscle via the Notch pathway may play an important role in mediating the skeletal muscle atrophy seen in cancer cachexia.

Tumor necrosis factor-alpha up-regulates expression of Jagged-1 and induces epithelial-mesenchymal transition in rat cholangiocytes in vitro

AIM: To investigate the role of tumor necrosis factor-alpha (TNF-α) in the epithelial-mesenchymal transition (EMT) process in rat cholangiocytes in vitro.

METHODS: Primary rat cholangiocytes were treated with TNF-α (10 ng/mL) alone, TNF-α plus nuclear factor kappa B (NF-κB) inhibitor PDTC (50 µmol/L), or PDTC alone for 72 h. The expression of Jagged-1, mesenchymal markers [fibroblast-specific protein-1 (FSP-1), Vimentin and α-SMA] as well as epithelial marker CK19 was detected by Western blot. NF-κB binding activity was measured by EMSA. Migration ability and morphological changes of cholangiocytes were also examined.

RESULTS: In the TNF-α alone group, the protein levels of Jagged-1, FSP-1, Vimentin and α-SMA were up-regulated compared to control cells, whereas the expression of CK19 was down-regulated. The migration ability of cholangiocytes was increased and their shape changed from stone-like to fiber-like. For the TNF-α plus PTCD group and the PTCD alone group, no significant changes in EMT markers as well as migration ability were observed compared to control cells.

CONCLUSION: TNF-α is able to increase the expression of Jagged-1 and induce EMT in rat cholangiocytes in vitro possibly through activation of NF-κB signaling.

Bortezomib enhances expression of effector molecules in anti-tumor CD8+ T lymphocytes by promoting Notch-nuclear factor-κB crosstalk

The immunosuppressive tumor microenvironment usurps host antitumor immunity by multiple mechanisms including interference with the Notch system, which is important for various metazoan cell fate decisions and hematopoietic cell differentiation and function. We observed that treatment with the proteasome inhibitor bortezomib in mice bearing various solid tumors resulted in an upregulated expression of various Notch signaling components in lymphoid tissues, thereby increasing CD8+T-lymphocyte IFNγ secretion and expression of effector molecules, perforin and granzyme B, as well as the T-box transcription factor eomesodermin. Bortezomib also neutralized TGFβ-mediated suppression of IFNγ and granzyme B expression in activated CD8+T-cells. Of note, bortezomib reversed tumor-induced downregulation of Notch receptors, Notch1 and Notch2, as well as increased the levels of cleaved Notch intracellular domain (NICD) and downstream targets Hes1 and Hey1 in tumor-draining CD8+T-cells. Moreover, bortezomib promoted CD8+T-cell nuclear factor-κB (NFκB) activity by increasing the total and phosphorylated levels of the IκB kinase and IκBα as well as the cytoplasmic and nuclear levels of phosphorylated p65. Even when we blocked NFκB activity by Bay-11-7082, or NICD cleavage by γ-secretase inhibitor, bortezomib significantly increased expression of Notch Hes1 and Hey1 genes as well as perforin, granzyme B and eomesodermin in activated CD8+T-cells. Data suggest that bortezomib can rescue tumor-induced dysfunction of CD8+T-cells by its intrinsic stimulatory effects promoting NICD-NFκB crosstalk. These findings provide novel insights on using bortezomib not only as an agent to sensitize tumors to cell death but also to provide lymphocyte-stimulatory effects, thereby overcoming immunosuppressive actions of tumor on anti-tumor T-cell functions.

CD163 interacts with TWEAK to regulate tissue regeneration after ischaemic injury

Macrophages are an essential component of the immune response to ischaemic injury and play an important role in promoting inflammation and its resolution, which is necessary for tissue repair. The type I transmembrane glycoprotein CD163 is exclusively expressed on macrophages, where it acts as a receptor for haemoglobin:haptoglobin complexes. An extracellular portion of CD163 circulates in the blood as a soluble protein, for which no physiological function has so far been described. Here we show that during ischaemia, soluble CD163 functions as a decoy receptor for TWEAK, a secreted pro-inflammatory cytokine of the tumour necrosis factor family, to regulate TWEAK-induced activation of canonical nuclear factor-κB (NF-κB) and Notch signalling necessary for myogenic progenitor cell proliferation. Mice with deletion of CD163 have transiently elevated levels of TWEAK, which stimulate muscle satellite cell proliferation and tissue regeneration in their ischaemic and non-ischaemic limbs. These results reveal a role for soluble CD163 in regulating muscle regeneration after ischaemic injury.

CD163 is a glycoprotein receptor expressed on the surface of macrophages. Here, the authors demonstrate that a soluble form of CD163 can act as a decoy receptor for the pro inflammatory cytokine TWEAK, thereby revealing a new mechanism for the regulation of tissue repair after ischaemic injury.

Wnt and Notch signaling pathway involved in wound healing by targeting c-Myc and Hes1 separately

Introduction

Wnt and Notch signaling pathways are critically involved in relative cell fate decisions within the development of cutaneous tissues. Moreover, several studies identified the above two pathways as having a significant role during wound healing. However, their biological effects during cutaneous tissues repair are unclear.

Methods

We employed a self-controlled model (Sprague–Dawley rats with full-thickness skin wounds) to observe the action and effect of Wnt/β-catenin and Notch signalings in vivo. The quality of wound repair relevant to the gain/loss-of-function Wnt/β-catenin and Notch activation was estimated by hematoxylin-and-eosin and Masson staining. Immunofluorescence analysis and Western blot analysis were used to elucidate the underlying mechanism of the regulation of Wnt and Notch signaling pathways in wound healing. Meanwhile, epidermal stem cells (ESCs) were cultured in keratinocyte serum-free medium with Jaggedl or in DAPT (N-[(3,5-difluorophenyl)acetyl]-L-alanyl-2-phenyl]glycine-1,1-dimethylethyl) to investigate whether the interruption of Notch signaling contributes to the expression of Wnt/β-catenin signaling.

Results

The results showed that in vivo the gain-of-function Wnt/β-catenin and Notch activation extended the ability to promote wound closure. We further determined that activation or inhibition of Wnt signaling and Notch signaling can affect the proliferation of ESCs, the differentiation and migration of keratinocytes, and follicle regeneration by targeting c-Myc and Hes1, which ultimately lead to enhanced or delayed wound healing. Furthermore, Western blot analysis suggested that the two pathways might interact in vivo and in vitro.

Conclusion

These results suggest that Wnt and Notch signalings play important roles in cutaneous repair by targeting c-Myc and Hes1 separately. What’s more, interaction between the above two pathways might act as a vital role in regulation of wound healing.

Visfatin promotes cell and tumor growth by upregulating Notch1 in breast cancer

Overexpression of Notch1 has been associated with breast cancer. We recently showed that visfatin stimulates breast cancer cell proliferation and invasion. The present study was undertaken to determine whether Notch1 signaling is affected by visfatin and to characterize the functional role of the visfatin-Notch1 axis in breast cancer. Visfatin and Notch1 were expressed at higher levels in breast tumors than in matched control tissues. Visfatin induced Notch1 expression in MDA-MB-231 breast cancer cell line and in nontransformed MCF10A mammary epithelial cells, whereas visfatin depletion reduced Notch1 mRNA and protein levels. Depletion of Notch1 in MDA-MB-231 cells attenuated cell growth in vitro and in vivo; visfatin depletion produced similar effects, but was less potent. Additionally, Notch1 depletion inhibited cell proliferation induced by visfatin. Analysis of the signaling pathways underlying visfatin-mediated Notch1 upregulation revealed that visfatin activated NF-κB p65. Blockade of NF-κB signaling suppressed the effects of visfatin on Notch1 upregulation and breast cancer cell proliferation. Breast tumors expressing high levels of NF-κB p65 exhibited increased expression of Notch1. Our results demonstrate that the visfatin-Notch1 axis contributes to breast tumor growth through the activation of the NF-κB pathway. Study of the visfatin-Notch1 axis may offer new therapeutic directions for breast cancer.

CCN1 induces hepatic ductular reaction through integrin αvβ₅-mediated activation of NF-κB

Liver cholestatic diseases, which stem from diverse etiologies, result in liver toxicity and fibrosis and may progress to cirrhosis and liver failure. We show that CCN1 (also known as CYR61), a matricellular protein that dampens and resolves liver fibrosis, also mediates cholangiocyte proliferation and ductular reaction, which are repair responses to cholestatic injury. In cholangiocytes, CCN1 activated NF-κB through integrin αvβ5/αvβ3, leading to Jag1 expression, JAG1/NOTCH signaling, and cholangiocyte proliferation. CCN1 also induced Jag1 expression in hepatic stellate cells, whereupon they interacted with hepatic progenitor cells to promote their differentiation into cholangiocytes. Administration of CCN1 protein or soluble JAG1 induced cholangiocyte proliferation in mice, which was blocked by inhibitors of NF-κB or NOTCH signaling. Knock-in mice expressing a CCN1 mutant that is unable to bind αvβ5/αvβ3 were impaired in ductular reaction, leading to massive hepatic necrosis and mortality after bile duct ligation (BDL), whereas treatment of these mice with soluble JAG1 rescued ductular reaction and reduced hepatic necrosis and mortality. Blockade of integrin αvβ5/αvβ3, NF-κB, or NOTCH signaling in WT mice also resulted in defective ductular reaction after BDL. These findings demonstrate that CCN1 induces cholangiocyte proliferation and ductular reaction and identify CCN1/αvβ5/NF-κB/JAG1 as a critical axis for biliary injury repair.

The role of Notch signaling in muscle progenitor cell depletion and the rapid onset of histopathology in muscular dystrophy

Although it has been speculated that stem cell depletion plays a role in the rapid progression of the muscle histopathology associated with Duchenne Muscular Dystrophy (DMD), the molecular and cellular mechanisms responsible for stem cell depletion remain poorly understood. The rapid depletion of muscle stem cells has not been observed in the dystrophin-deficient model of DMD (mdx mouse), which may explain the relatively mild dystrophic phenotype observed in this animal model. In contrast, we have observed a rapid occurrence of stem cell depletion in the dystrophin/utrophin double knockout (dKO) mouse model, which exhibits histopathological features that more closely recapitulate the phenotype observed in DMD patients compared with the mdx mouse. Notch signaling has been found to be a key regulator of stem cell self-renewal and myogenesis in normal skeletal muscle; however, little is known about the role that Notch plays in the development of the dystrophic histopathology associated with DMD. Our results revealed an over-activation of Notch in the skeletal muscles of dKO mice, which correlated with sustained inflammation, impaired muscle regeneration and the rapid depletion and senescence of the muscle progenitor cells (MPCs, i.e. Pax7+ cells). Consequently, the repression of Notch in the skeletal muscle of dKO mice delayed/reduced the depletion and senescence of MPCs, and restored the myogenesis capacity while reducing inflammation and fibrosis. We suggest that the down-regulation of Notch could represent a viable approach to reduce the dystrophic histopathologies associated with DMD.

Inflammatory signaling regulates hematopoietic stem and progenitor cell emergence in vertebrates

TLR4–MyD88–NF-κB is required for HSPC emergence in zebrafish and mouse embryos. Notch functions downstream of inflammatory signaling to regulate HSPC emergence.

Control of hair cell development by molecular pathways involving Atoh1, Hes1 and Hes5

Atoh1, Hes1 and Hes5 are crucial for normal inner ear hair cell development. They regulate the expression of each other in a complex network, while they also interact with many other genes and pathways, such as Notch, FGF, SHH, WNT, BMP and RA. This paper summarized molecular pathways that involve Atoh1, Hes1, and Hes5. Some of the pathways and gene regulation mechanisms discussed here were studied in other tissues, yet they might inspire studies in inner ear hair cell development. Thereby, we presented a complex regulatory network involving these three genes, which might be crucial for proliferation and differentiation of inner ear hair cells.

The truncate mutation of Notch2 enhances cell proliferation through activating the NF-κB signal pathway in the diffuse large B-cell lymphomas

The Notch2 is a critical membrane receptor for B-cell functions, and also displays various biological roles in lymphoma pathogenesis. In this article, we reported that 3 of 69 (4.3%) diffuse large B-cell lymphomas (DLBCLs) exhibited a truncate NOTCH2 mutation at the nucleotide 7605 (G/A) in the cDNA sequence, which led to partial deletion of the C-terminal of PEST (proline-, glutamic acid-, serine- and threonine-rich) domain. The truncate Notch2 activated both the Notch2 and the NF-κB signals and promoted the proliferation of B-cell lymphoma cell lines, including DLBCL and Burkitt's lymphoma cell lines. Moreover, the ectopic proliferation was completely inhibited by ammonium pyrrolidinedithiocarbamate (PDTC), an NF-κB inhibitor. Simultaneously, PDTC also reduced the expression level of Notch2. Based on these results, we conclude that the Notch2 receptor with PEST domain truncation enhances cell proliferation which may be associated with the activation of the Notch2 and the NF-κB signaling. Our results are expected to provide a possible target for new DLBCL therapies by suppressing the Notch2 and the NF-κB signaling.

Top Notch cancer stem cells by paracrine NF-κB signaling in breast cancer

Cancer stem cells are likely to play critical roles in metastasis, therapy resistance, and recurrence of hematological and solid malignancies. It is well known that the stem cell niche plays a key role for asymmetric division and homeostasis of normal stem cells, whereas cancer stem cells seem to use these niches. Among many pathways involved in self-renewal of cancer stem cells, nuclear factor-kappa B (NF-κB) signaling has been documented to promote their expansion in a cell-autonomous fashion. A recent study, however, suggests that paracrine NF-κB activation promotes the expansion of cancer stem cells through the activation of Notch in basal-type breast cancer cells.

Role of notch signaling in the maintenance of human mesenchymal stem cells under hypoxic conditions

Human adipose tissue-derived multilineage progenitor cells (hADMPCs) are attractive for cell therapy and tissue engineering because of their multipotency and ease of isolation without serial ethical issues. However, their limited in vitro lifespan in culture systems hinders their therapeutic application. Some somatic stem cells, including hADMPCs, are known to be localized in hypoxic regions; thus, hypoxia may be beneficial for ex vivo culture of these stem cells. These cells exhibit a high level of glycolytic metabolism in the presence of high oxygen levels and further increase their glycolysis rate under hypoxia. However, the physiological role of glycolytic activation and its regulatory mechanisms are still incompletely understood. Here, we show that Notch signaling is required for glycolysis regulation under hypoxic conditions. Our results demonstrate that 5% O2 dramatically increased the glycolysis rate, improved the proliferation efficiency, prevented senescence, and maintained the multipotency of hADMPCs. Intriguingly, these effects were not mediated by hypoxia-inducible factor (HIF), but rather by the Notch signaling pathway. Five percent O2 significantly increased the level of activated Notch1 and expression of its downstream gene, HES1. Furthermore, 5% O2 markedly increased glucose consumption and lactate production of hADMPCs, which decreased back to normoxic levels on treatment with a γ-secretase inhibitor. We also found that HES1 was involved in induction of GLUT3, TPI, and PGK1 in addition to reduction of TIGAR and SCO2 expression. These results clearly suggest that Notch signaling regulates glycolysis under hypoxic conditions and, thus, likely affects the cell lifespan via glycolysis.