Inhibition Of Notch Signaling Research Articles

DLK1 and DLK2, two non-canonical ligands of NOTCH receptors, differentially modulate the osteogenic differentiation of mesenchymal C3H10T1/2 cells

BackgroundC3H10T1/2 is a mesenchymal cell line capable of differentiating into osteoblasts, adipocytes and chondrocytes. The differentiation of these cells into osteoblasts is modulated by various transcription factors, such as RUNX2. Additionally, several interconnected signaling pathways, including the NOTCH pathway, play a crucial role in modulating their differentiation into mature bone cells. We have investigated the roles of DLK1 and DLK2, two non-canonical inhibitory ligands of NOTCH receptors, in the osteogenic differentiation of C3H10T1/2 cells.ResultsOur results corroborate existing evidence that DLK1 acts as an inhibitor of osteogenesis. In contrast, we demonstrate for the first time that DLK2 enhances this differentiation process. Additionally, our data suggest that NOTCH2, 3 and 4 receptors may promote osteogenesis, as indicated by their increased expression during this process, whereas NOTCH1 expression, which decreases during cell differentiation, might inhibit osteogenesis. Moreover, treatment with DAPT, a NOTCH signaling inhibitor, impeded osteogenic differentiation. We have confirmed the increase in ERK1/2 MAPK and p38 MAPK phosphorylation in C3H10T1/2 cells induced to differentiate to osteoblasts. Our new findings reveal increased ERK1/2 MAPK phosphorylation in differentiated C3H10T1/2 cells with a decrease in DLK1 expression or an overexpression of DLK2, which is coincident with the behavior of those transfectants where we have detected an increase in osteogenic differentiation. Additionally, p38 MAPK phosphorylation increases in differentiated C3H10T1/2 cells with reduced DLK1 levels.ConclusionsOur results suggest that DLK1 may inhibit osteogenesis, while DLK2 may promote it, by modulating NOTCH signaling and the phosphorylation of ERK1/2 and p38 MAPK pathways. Given the established inhibitory effect of DLK proteins on NOTCH signaling, these new insights could pave the way for developing future therapeutic strategies aimed at treating bone diseases.

Reciprocal inhibition of NOTCH and SOX2 shapes tumor cell plasticity and therapeutic escape in triple-negative breast cancer.

Cancer cell plasticity contributes significantly to the failure of chemo- and targeted therapies in triple-negative breast cancer (TNBC). Molecular mechanisms of therapy-induced tumor cell plasticity and associated resistance are largely unknown. Using a genome-wide CRISPR-Cas9 screen, we investigated escape mechanisms of NOTCH-driven TNBC treated with a gamma-secretase inhibitor (GSI) and identified SOX2 as a target of resistance to Notch inhibition. We describe a novel reciprocal inhibitory feedback mechanism between Notch signaling and SOX2. Specifically, Notch signaling inhibits SOX2 expression through its target genes of the HEY family, and SOX2 inhibits Notch signaling through direct interaction with RBPJ. This mechanism shapes divergent cell states with NOTCH positive TNBC being more epithelial-like, while SOX2 expression correlates with epithelial-mesenchymal transition, induces cancer stem cell features and GSI resistance. To counteract monotherapy-induced tumor relapse, we assessed GSI-paclitaxel and dasatinib-paclitaxel combination treatments in NOTCH inhibitor-sensitive and -resistant TNBC xenotransplants, respectively. These distinct preventive combinations and second-line treatment option dependent on NOTCH1 and SOX2 expression in TNBC are able to induce tumor growth control and reduce metastatic burden.

Modulation of Notch signaling pathway in activated hepatic stellate cells does not ameliorate the outcome of liver fibrosis in carbon tetrachloride and DDC-feeding models

BackgroundRecent research suggests a possible role of Notch signaling pathway in development of liver fibrosis, but exact cellular and molecular mechanisms are still not well defined. Methods: We modulated Notch signaling in activated hepatic stellate cells/myofibroblasts using the model of inducible activation or inhibition of Notch signaling selective for αSMA positive cells in murine models of toxic fibrosis induced by CCl4 and cholestatic fibrosis induced by DDC supplemented feeding.ResultsOur results confirm that Notch signaling pathway is activated in both CCL4 and DDC model of liver fibrosis and that αSMA positive myofibroblasts are of activated hepatic stellate cells origin. However, neither the inhibition of canonical Notch signaling (in tamoxifen treated αSMACreER/RBP-Jfl/fl mice) nor its overactivation (in tamoxifen treated αSMACreER/NICD1 mice) changed the degree of liver fibrosis in comparison to the control groups in either of the investigated models. Furthermore, after the withdrawal of the fibrogenic treatment the degree of resolution of fibrosis was similar between the animals with Notch overactivation and controls. In addition to genetic manipulation, we investigated the effect of antibodies against NOTCH1 and NOTCH2 on the development of liver fibrosis. Treatment with antibodies had effects on thymus and spleen respectively, but failed to ameliorate liver fibrosis. In conclusion, our data demonstrate that modulation of Notch activity in activated HSC is not sufficient to change the outcome of liver fibrosis. The results obtained with inhibitory antibodies further demonstrate limitations of targeting Notch 1 and 2 receptors as antifibrotic therapy. Notch pathway remains a potential target for the treatment of liver fibrosis, but future studies should be directed to Notch 3 signaling and/or targeting different populations of cells.

Rabex-5 E3 and Rab5 GEF domains differ in their regulation of Ras, Notch, and PI3K signaling in Drosophila wing development.

Rabex-5 (also called RabGEF1), a protein originally characterized for its Rab5 GEF function, also has an A20-like E3 ubiquitin ligase domain. We and others reported that Rabex-5 E3 activity promotes Ras mono- and di-ubiquitination to inhibit Ras signaling in Drosophila and mammals. Subsequently, we reported that Rabex-5 inhibits Notch signaling in the Drosophila hematopoietic system. Here we report genetic interactions using Rabex-5 transgenes encoding domain-specific mutations that show that Rabex-5 requires an intact E3 domain to inhibit Notch signaling in the epithelial tissue of the developing wing. Surprisingly, we discovered that Rabex-5 with an impaired E3 domain but active Rab5 GEF domain suppresses Notch loss-of-function phenotypes and enhances both Notch duplication phenotypes and activated Ras phenotypes consistent with a model that the Rab5 GEF activity of Rabex-5 might positively regulate Ras and Notch. Positive and negative regulation of developmental signaling by its different catalytic domains could allow Rabex-5 to precisely coordinate developmental signaling to fine-tune patterning. Finally, we report that Rabex-5 also inhibits the overgrowth due to loss of PTEN or activation of PI3K but not activation of AKT. Inhibition of Ras, Notch, and PI3K signaling may explain why Rabex-5 is deleted in some cancers. Paradoxically, Rabex-5 is reported to be an oncogene in other cancers. We propose that Rabex-5 acts as a tumor suppressor via its E3 activity to inhibit Ras, Notch, and PI3K signaling and as an oncogene via its Rab5 GEF activity to enhance Ras and Notch signaling.

Single-chain nanobody inhibition of Notch and avidity enhancement utilizing the β-pore forming toxin Aerolysin.

Notch plays critical roles in developmental processes and disease pathogenesis, which has led to numerous efforts to modulate its function with small molecules and antibodies. Here we present a nanobody inhibitor of Notch signaling, derived from a synthetic phage-display library targeting the notch Negative Regulatory Region (NRR). The nanobody inhibits Notch signaling in a luciferase reporter assay and in Notch-dependent hematopoietic progenitor cell differentiation assay, despite a modest 19uM affinity for Notch. We addressed the low affinity by fusion to a membrane-associating domain derived from the β-Pore forming toxin Aerolysin, resulting in a significantly improved IC50 for Notch inhibition. The nanobody-aerolysin fusion inhibits proliferation of T-ALL cell lines with similar efficacy to other Notch pathway inhibitors. Overall, this study reports the development of a Notch inhibitory antibody, and demonstrates a proof-of-concept for a generalizable strategy to increase the efficacy and potency of low-affinity antibody binders.

Targeting the Notch-Furin axis with 2-hydroxyoleic acid: a key mechanism in glioblastoma therapy.

Glioblastomas (GBMs) are highly treatment-resistant and aggressive brain tumors. 2OHOA, which is currently running a phase IIB/III clinical trial for newly diagnosed GBM patients, was developed in the context of melitherapy. This therapy focuses on the regulation of the membrane's structure and organization with the consequent modulation of certain cell signals to revert the pathological state in several disorders. Notch signaling has been associated with tumorigenesis and cell survival, potentially driving the pathogenesis of GBM. The current study aims to determine whether 2OHOA modulates the Notch pathway as part of its antitumoral mechanism. 2OHOA's effect was evaluated on different components of the pathway by Western blot, Q-PCR, and confocal microscopy. Notch receptor processing was analyzed by subcellular fractionation and colocalization studies. Furin activity was evaluated under cleavage of its substrate by fluorescence assays and its binding affinity to 2OHOA was determined by surface plasmon resonance. We found that 2OHOA inhibits Notch2 and Notch3 signaling by dual mechanism. Notch2 inhibition is unleashed by impairment of its processing through the inactivation of furin activity by physical association. Instead, Notch3 is transcriptionally downregulated leading to a lower activation of the pathway. Moreover, we also found that HES1 overexpression highlighted the relevance of this pathway in the 2OHOA pharmacological efficacy. These findings report that the inhibition of Notch signaling by 2OHOA plays a role in its anti-tumoral activity, an effect that may be driven through direct inhibition of furin, characterizing a novel target of this bioactive lipid to treat GBM.

Therapeutic Suppression of Atherosclerotic Burden and Vulnerability via Dll4 Inhibition in Plaque Macrophages Using Dual-Targeted Liposomes.

Atherosclerosis, characterized by chronic inflammation within the arterial wall, remains a pivotal concern in cardiovascular health. We developed a dual-targeted liposomal system encapsulating Dll4-targeting siRNA, designed to selectively bind to pro-inflammatory M1 macrophages through surface conjugation with anti-F4/80 and anti-CD68 antibodies. The Dll4-targeting siRNA is then delivered to the macrophages, where it silences Dll4 expression, inhibiting Notch signaling and reducing plaque vulnerability. Emphasizing accuracy in targeting, the system demonstrates effective suppression of Dll4, a key modulator of atherosclerotic progression, and vulnerability via VSMCs phenotypic conversion and senescence. By employing liposomes for siRNA delivery, we observed enhanced stability and specificity of the siRNA. Alongside the therapeutic efficacy, our study also evaluated the safety profile and pharmacokinetics of the dual-targeted liposomal system, revealing favorable outcomes with minimal off-target effects and optimal biodistribution. The integration of RNA interference techniques with advanced nanotechnological methodologies signifies the importance of targeted delivery in this therapeutic approach. Preliminary findings suggest a potential attenuation in plaque development and vulnerability, indicating the therapeutic promise of this approach. This research emphasizes the potential of nanocarrier-mediated precision targeting combined with a reassuring safety and pharmacokinetic profile for advancing atherosclerosis therapeutic strategies.

Notch-Driven Cholangiocarcinogenesis Involves the Hippo Pathway Effector TAZ via METTL3-m6A-YTHDF1

Background and AimsNotch and TAZ are implicated in cholangiocarcinogenesis, but whether and how these oncogenic molecules interact remain unknown. MethodsThe development of CCA was induced by hydrodynamic tail vein (HDTV) injection of oncogenes (NICD/AKT) to the FVB/NJ mice. CCA xenograft was developed by inoculation of human CCA cells into the livers of SCID mice. Tissues and cells were analyzed using qRT-PCR, Western blotting analyses, Immunohistochemistry, ChIP-qPCR and WST-1 cell proliferation Assay. ResultsOur experimental findings show that TAZ is indispensable in NICD-driven cholangiocarcinogenesis. Notch activation induces the expression of METTL3 (Methyltransferase like-3) which catalyzes N6-methyladenosine (m6A) modification of TAZ mRNA and that this mechanism plays a central role in the crosstalk between Notch and TAZ in CCA cells. Mechanistically, Notch regulates the expression of METTL3 through the binding of NICD to its downstream transcription factor CSL in the promoter region of METTL3. METTL3 in turn mediates m6A modification of TAZ mRNA which is recognized by the m6A reader YTHDF1 to enhance TAZ protein translation. We observed that inhibition of Notch signaling decreased the protein levels of both MELLT3 and TAZ. Depletion of METTL3 by shRNAs or by the next generation GapmeR antisense oligonucleotides (ASOs) decreased the level of TAZ protein and inhibited the growth of human CCA cells in vitro and in mice. ConclusionThis study describes a novel Notch-METTL3-TAZ signaling cascade which is important in CCA development and progression. Our experimental results provide new insight into how the Notch pathway cooperates with TAZ signaling in CCA, and the findings may have important therapeutic implications.

Toe1 promotes proliferation and differentiation of neural progenitor cells

Toe1 (target of EGR1, member 1) is a 3′- exonuclease in the deadenylase family, essential for the maturation of small nuclear RNAs. Mutations in Toe1 are linked to pontocerebellar hypoplasia 7 (PCH7), a severe neurodegenerative syndrome affecting infants, characterized by progressive neurodegeneration, developmental delay, and genital abnormalities. The pathogenic mechanisms of PCH7 are unclear but are thought to involve abnormal neural stem cell (NSC) development during embryogenesis. This study investigates Toe1's role in NSC development using the C17.2 NSC line. Colony formation, EdU incorporation, and CFSE staining assays showed that Toe1 knockout inhibited C17.2 cell proliferation. Upon inducing differentiation, Toe1 knockout significantly reduced cell dendrites. Immunofluorescence, qPCR, and Western blot analyses indicated that Toe1 knockout suppressed the expression of neuronal marker βIII-tubulin and glial cell marker Gfap, thereby inhibiting C17.2 cell differentiation. Additionally, Toe1 knockout reduced the expression of Dll1 and Jag1, suggesting an inhibition of Notch signaling. High-throughput transcriptome sequencing revealed that Toe1 influenced calcium ion binding, ECM, and amino acid catabolism in undifferentiated C17.2 cells, and peptidase activity, chemotactic factors, ECM, and TNF signaling in differentiated cells. These findings underscore Toe1's critical regulatory role in NSC proliferation and differentiation, with significant implications for developing therapeutic targets for neurodegenerative diseases such as PCH7.

PLGA-Loaded Nedaplatin (PLGA-NDP) Inhibits 7,12-Dimethylbenz[a]anthracene (DMBA) Induced Oral Carcinogenesis via Modulating Notch Signaling Pathway and Induces Apoptosis in Experimental Hamster Model.

The present study is designed to evaluate the nanotherapeutic efficacy of prepared PLGA-loaded Nedaplatin (PLGA-NDP) against 7,12-dimethyl benz(a)anthracene (DMBA)-induced experimental oral carcinogenesis in hamster buccal pouch (HBP) model. The buccal pouch of golden Syrian hamsters was painted with 0.5% DMBA in liquid paraffin three times a week for 14 weeks, ultimately leading to the development of oral squamous cell carcinoma (OSCC). Oral administration of PLGA-NDP (preinitiation) and Cisplatin delivery (5 mg/kg b.wt) started 1 week before the carcinogen exposure and continued on alternative days. Post-administration of PLGA-NDP (5 mg/kg b.wt) started 2 days after carcinogen (DMBA) induction until the end of the experiment. After the 14th week, we observed that DMBA-painted hamsters exhibited tumor formation, morphological alterations, and well-differentiated OSSC in addition to the responsive molecular proteins during oral carcinogenesis. Furthermore, immunoblotting analysis demonstrated that PLGA-NDP inhibits Notch signaling, as evidenced by downregulation of Bcl-Xl, Bcl-2, p21, PGE2, HGF, and CXCL12 proteins, and upregulation of p53 and Bax. This apoptotic response is crucial for PLGA-NDP to induce apoptosis. In addition, RT-PCR results showed that PLGA-NDP nanoparticles play a downregulatory role in the therapeutic action of the notch signaling gene (Notch1, Notch 2, Hes1, Hey1, and Jagged1) at the mRNA transcription level in HBP carcinoma. Taken together, these data indicate that PLGA-NDP is a potent inhibitor of oral carcinogenesis and the expansion of cells that specifically target the Notch signaling pathway indicates that obstructing Notch signaling could potentially serve as a new and innovative therapeutic approach for oral squamous cell carcinoma (OSCC).

Single-cell transcriptomics reveals e-cigarette vapor-induced airway epithelial remodeling and injury

BackgroundIn recent years, e-cigarettes have been used as alternatives among adult smokers. However, the impact of e-cigarette use on human bronchial epithelial (HBE) cells remains controversial.MethodsWe collected primary HBE cells of healthy nonsmokers and chronic obstructive pulmonary disease (COPD) smokers, and analyzed the impact of e- cigarette vapor extract (ECE) or cigarette smoke extract (CSE) on HBE cell differentiation and injury by single-cell RNA sequencing, immunostaining, HE staining, qPCR and ELISA. We obtained serum and sputum from healthy non- smokers, smokers and e-cigarette users, and analyzed cell injury markers and mucin proteins.ResultsECE treatment led to a distinct differentiation program of ciliated cells and unique patterns of their cell–cell communications compared with CSE. ECE treatment caused increased Notch signaling strength in a ciliated cell subpopulation, and HBE cell remodeling and injury including hypoplasia of ciliated cells and club cells, and shorter cilia. ECE-induced hypoplasia of ciliated cells and shorter cilia were ameliorated by the Notch signaling inhibition.ConclusionsThis study reveals distinct characteristics in e-cigarette vapor-induced airway epithelial remodeling, pointing to Notch signaling pathway as a potential targeted intervention for e-cigarette vapor-caused ciliated cell differentiation defects and cilia injury. In addition, a decrease in SCGB1A1 proteins is associated with e- cigarette users, indicating a potential lung injury marker for e-cigarette users.

Viral-mediated Oct4 overexpression and inhibition of Notch signaling synergistically induce neurogenic competence in mammalian Müller glia.

Retinal Müller glia in cold-blooded vertebrates can reprogram into neurogenic progenitors to replace neurons lost to injury, but mammals lack this ability. While recent studies have shown that transgenic overexpression of neurogenic bHLH factors and glial-specific disruption of NFI family transcription factors and Notch signaling induce neurogenic competence in mammalian Müller glia, induction of neurogenesis in wildtype glia has thus far proven elusive. Here we report that viral-mediated overexpression of the pluripotency factor Oct4 ( Pou5f1 ) induces transdifferentiation of wildtype mouse Müller glia into bipolar neurons and stimulates this process synergistically in parallel with Notch loss of function. Single cell multiomic analysis shows that Oct4 overexpression leads to widespread changes in gene expression and chromatin accessibility, inducing activity of both the neurogenic transcription factor Rfx4 and the Yamanaka factors Sox2 and Klf4. This study demonstrates that viral-mediated overexpression of Oct4 induces neurogenic competence in wildtype retinal Müller glia, identifying mechanisms that could be used in cell-based therapies for treating retinal dystrophies.

Beauvericin Reverses Epithelial-to-Mesenchymal Transition in Triple-Negative Breast Cancer Cells through Regulation of Notch Signaling and Autophagy.

Metastasis stands as a prime contributor to triple-negative breast cancer (TNBC) associated mortality worldwide, presenting heightened severity and significant challenges due to limited treatment options. Addressing TNBC metastasis necessitates innovative approaches and novel therapeutics to specifically target its propensity for dissemination to distant organs. Targeted therapies capable of reversing epithelial-to-mesenchymal transition (EMT) play a crucial role in suppressing metastasis and enhancing the treatment response. Beauvericin, a promising fungal secondary metabolite, exhibits significant potential in diminishing the viability of EMT-induced TNBC cells by triggering intracellular oxidative stress, as evidenced by an enhanced reactive oxygen species level and reduced mitochondrial transmembrane potential. In monolayer cultures, it has exhibited an IC50 of 2.3 μM in both MDA-MB-468 and MDA-MB-231 cells, while in 3D spheroids, the IC50 values are 9.7 and 7.1 μM, respectively. Beauvericin has also reduced the migratory capability of MDA-MB-468 and MDA-MB-231 cells by 1.5- and 1.7-fold, respectively. Both qRT-PCR and Western blot analysis have shown significant upregulation in the expression of epithelial marker (E-cadherin) and downregulation in the expression of mesenchymal markers (N-cadherin, vimentin, Snail, Slug, and β-catenin), following treatment, indicating reversal of EMT. Furthermore, beauvericin has suppressed the Notch signaling pathway by substantially downregulating Notch-1, Notch-3, Hes-1, and cyclinD3 expression and induced autophagy as observed by elevated expression of autophagy markers LC3 and Beclin-1. In conclusion, beauvericin has successfully downregulated TNBC cell survival by inducing oxidative stress and suppressed their migratory potential by reversing EMT through the inhibition of Notch signaling and activation of autophagy.

O96 NICD LACTYLATION OF NOTCH SIGNALING IMPROVES MICROVASCULATION RAREFACTION IN HYPERTENSION

Background and Objective: Microvascular rarefaction is a key pathophysiologic basis of hypertension-related cardiovascular disease. Exercise decreases blood pressure and promotes angiogenesis related to inhibition of NOTCH signaling. The activation of the NOTCH pathway depends on the transcriptional regulation of its intracellular active fragment NICD after nuclear translocation. The post-translational modification status of proteins plays a crucial role in the nuclear translocation effect of transcription factors. Lactylation is influenced by the level of lactate in the body. Exercise can promote glycolysis in endothelial cells, and increase intracellular lactate levels. Therefore, we explored whether the beneficial effects of Exercise were mediated by promoting NICD lactylation, inhibiting the NOTCH signaling, and promoting angiogenesis. Methods: To test our hypotheses, WKYs (normotensive rats) and SHRs (spontaneously hypertensive rats) were given exercise for 12 weeks. Blood pressure was determined by the tail-cuff method, and cardiac function was assessed by echocardiography. Using rats’ retina, gastrocnemius, and myocardium detected microvascular density. The expression levels of NOTCH signaling pathway related proteins and angiogenesis related factors were measured by Western Blotting. The level of lactate was measured by using a lactate assay kit. Protein modification omics was used to detect the modification types and levels of NICD in microvascular endothelial cells, followed by liquid chromatography tandem mass spectrometry (LC-MS/MS) to detect the lactylation sites of NICD in microvascular endothelial cells. Results: Exercise in SHRs resulted in reduced blood pressure and concentric hypertrophy. Exercise promoted angiogenesis and improved microcirculation rarefaction. Exercise also reduced the production of NOTCH pathway related proteins and increased the expression level of angiogenesis related factors. The lactate level increased after exercise, and the lactylation level of NICD increased. Conclusions: In summary, Exercise decreases hypertension and improves cardiac function in SHRs. Our research results indicated that exercise increases lactate production and induces NICD lactylation, thereby inhibiting the NOTCH signaling, upregulating the expression of angiogenic factors, promoting angiogenesis, and lowering blood pressure.

Numb Suppresses Notch-Dependent Activation of Enhancer of split during Lateral Inhibition in the Drosophila Embryonic Nervous System.

The role of Drosophila numb in regulating Notch signaling and neurogenesis has been extensively studied, with a particular focus on its effects on the peripheral nervous system (PNS). Previous studies based on a single loss-of-function allele of numb, numb1, showed an antineurogenic effect on the peripheral nervous system (PNS), which revealed that the wild-type numb suppresses Notch signaling. In the current study, we examined whether this phenotype is consistently observed in loss-of-function mutations of numb. Two more numb alleles, numbEY03840 and numbEY03852, were shown to have an antineurogenic phenotype in the PNS. We also found that introducing a wild-type numb genomic fragment into numb1 homozygotes rescued their antineurogenic phenotype. These results demonstrated that loss-of-function mutations of numb universally induce this phenotype. Many components of Notch signaling are encoded by maternal effect genes, but no maternal effect of numb was observed in this study. The antineurogenic phenotype of numb was found to be dependent on the Enhancer of split (E(spl)), a downstream gene of Notch signaling. We found that the combination of E(spl) homozygous and numb1 homozygous suppressed the neurogenic phenotype of the embryonic central nervous system (CNS) associated with the E(spl) mutation. In the E(spl) allele, genes encoding basic helix-loop-helix proteins, such as m5, m6, m7, and m8, remain. Thus, in the E(spl) allele, derepression of Notch activity by numb mutation can rescue the neurogenic phenotype by increasing the expression of the remaining genes in the E(spl) complex. We also uncovered a role for numb in regulating neuronal projections. Our results further support an important role for numb in the suppression of Notch signaling during embryonic nervous system development.

Robust reprogramming of glia into neurons by inhibition of Notch signaling and nuclear factor I (NFI) factors in adult mammalian retina.

Generation of neurons through direct reprogramming has emerged as a promising therapeutic approach for treating neurodegenerative diseases. In this study, we present an efficient method for reprogramming retinal glial cells into neurons. By suppressing Notch signaling by disrupting either Rbpj or Notch1/2, we induced mature Müller glial cells to reprogram into bipolar- and amacrine-like neurons. We demonstrate that Rbpj directly activates both Notch effector genes and genes specific to mature Müller glia while indirectly repressing expression of neurogenic basic helix-loop-helix (bHLH) factors. Combined loss of function of Rbpj and Nfia/b/x resulted in conversion of nearly all Müller glia to neurons. Last, inducing Müller glial proliferation by overexpression of dominant-active Yap promotes neurogenesis in both Rbpj- and Nfia/b/x/Rbpj-deficient Müller glia. These findings demonstrate that Notch signaling and NFI factors act in parallel to inhibit neurogenic competence in mammalian Müller glia and help clarify potential strategies for regenerative therapies aimed at treating retinal dystrophies.

The Notch inhibitor, FLI-06, increases the chemosensitivity of head and neck Squamous cell carcinoma cells to taxanes-based treatment

Aberration of Notch signaling is one of the key events involved in the development and progression of head and neck squamous cell carcinoma (HNSCC). The Notch pathway controls the tissue-specific differentiation of normal squamous epithelial cells and is frequently altered in squamous carcinomas, thus affecting their proliferation, growth, survival, and chemosensitivity or resistance against anti-cancer agents. In this study, we show that the use of novel, small-molecule inhibitors of Notch signaling, such as FLI-06, can have a beneficial effect on increasing the chemosensitivity of HNSCC to taxane-based chemotherapy. Inhibition of Notch signaling by FLI-06 alone virtually blocks the proliferation and growth of HNSCC cells in both 2D and 3D cultures and the zebrafish model, which is accompanied by down-regulation of key Notch target genes and proteins. Mechanistically, FLI-06 treatment causes cell cycle arrest in the G1-phase and induction of apoptosis in HNSCC, which is accompanied by increased c-JunS63 phosphorylation. Combining FLI-06 with Docetaxel shows a synergistic effect and partially blocks the cell growth of aggressive HNSCC cells via enhanced apoptosis and modification of c-JunS243 phosphorylation via GSK-3β inhibition. In conclusion, inhibition of Notch signaling in HNSCC cells that retain active Notch signaling significantly supports taxane-based anticancer activities via modulation of both the GSK-3β and the c-Jun.

Tanshinol ameliorates imiquimod-induced psoriasis by inhibiting M1 macrophage polarization through suppression of the notch signaling pathway

BackgroundPsoriasis is a common immune-related chronic inflammatory skin disease, often accompanied by significant itching, and once diseased, the course of the disease lasts for most of the lifetime. Tanshinol (TAN) is an active ingredient of Salvia miltiorrhiza, which possesses pharmacological effects such as anti-inflammatory and antioxidant properties. However, the effects of TAN on psoriasis have not been widely reported. Therefore, the aim of this study was to investigate the therapeutic effects and mechanisms of TAN in psoriasis.MethodsAn imiquimod (IMQ)-induced psoriasis mouse model was constructed and treated with different doses of TAN to observe the changes in skin lesion phenotype, macrophage polarization, inflammation and Notch signaling pathway in mice. Further removal of macrophages or inhibition or activation of Notch signaling pathway was performed to examine the changes in skin lesion phenotype, macrophage polarization, inflammation and Notch signaling pathway in mice. In addition, in vitro experiments verified that TAN regulates RAW264.7 macrophage polarization and cytokine secretion through the Notch pathway.ResultsThe results showed that TAN alleviated IMQ-induced skin lesions and pathological phenotypes in psoriasis mice and inhibited Notch signaling pathway and M1-type macrophage polarization. Moreover, macrophage clearance and Notch signaling pathway activation inhibited the effect of TAN on psoriasis. Further in vitro experiments showed that Notch agonists reversed the effects of TAN on macrophage polarization and inflammatory cytokines.ConclusionsCollectively, these findings suggest that TAN may exert a therapeutic effect on psoriasis by inhibiting the Notch signaling pathway and thus M1-type macrophage polarization.

The Role of Notch Signaling Pathway in Adult Patients with Epstein-Barr Virus-induced Infectious Mononucleosis

To investigate the changes of Notch signaling molecules and Th22 cells in adult patients with infectious mononucleosis (IM), and assess the regulatory function of Notch signaling inhibition to Th22 cells. Forty-two IM patients and twenty-one healthy controls were enrolled in this study. Their peripheral blood was collected, from which plasma and peripheral blood mononuclear cells (PBMCs) were isolated. Plasma interleukin (IL)-17 and IL-22 were measured by enzyme-linked immunosorbent assay. The percentages of CD3+ CD4+ IL-17+ Th17 cells and CD3+ CD4+ IL-22+ Th22 cells were investigated by flow cytometry. The mRNA relative levels corresponding to Th17 transcription factor retinoic acid related orphan receptor γt (RORγt), Th22 transcription factor aryl hydrocarbon receptor (AhR), and Notch signaling pathway molecules (including Notch receptors, Notch ligands, Notch downstream molecules) were semi-quantified by real-time PCR. CD4+ T cells were purified and stimulated with γ-secretase inhibitor (GSI). Cellular proliferation, Th17 and Th22 percentage, IL-17 and IL-22 secretion, transcription factor mRNA were measured in response to GSI stimulation. The relative expression levels of Notch1 and Notch2 mRNA in PBMCs of IM group were 13.58±3.18 and 4.73±1.16, respectively, which were significantly higher than 1.09±0.12 and 1.07±0.15 in PBMCs of control group (both P < 0.001). However, there were no significant differences in relative expression levels of Notch3 and Notch4 mRNA between IM group and control group (P >0.05). The relative expression levels of Notch ligands (including DLL1 and Jagged1 ) mRNA and Notch downstream molecules (including Hes1, Hes5, and Hey1 ) were increased in IM group compared with control group (all P < 0.001). In IM group, the Th17 and Th22 percentage were 5.03%±1.15% and 4.48%±1.29%, respectively, which were both higher than 4.36%±0.82% and 3.83%±0.55% in control group (both P < 0.05). In IM group, the IL-17 and IL-22 level were (301.1±53.82) and (101.2±16.45) pg/ml, respectively, which were both higher than (237.2±72.18) and (84.75±11.83) pg/ml in control group (both P < 0.001). In IM group, the relative expression levels of RORγt and AhR mRNA were 1.25±0.22 and 1.21±0.12, respectively, which were both higher than 0.99±0.15 and 1.04±0.11 in control group (both P < 0.001). There were no remarkable differences in CD4+ T cell proliferation, Th17 percentage, IL-17 secretion, and relative expression level of RORγt mRNA between cells with GSI stimulation and without GSI stimulation (P >0.05). GSI stimulation reduced Th22 percentage, IL-22 secretion, and relative expression level of AhR mRNA compared with non-stimulation (all P < 0.05). Notch signaling pathway regulates IL-22 secretion by CD4+ T cells via AhR in IM patients. Notch-AhR-Th22 pathway may take part in the pathogenesis of IM.

Reduction of specific enterocytes from loss of intestinal LGR4 improves lipid metabolism in mice

Whether intestinal Leucine-rich repeat containing G-protein-coupled receptor 4 (LGR4) impacts nutrition absorption and energy homeostasis remains unknown. Here, we report that deficiency of Lgr4 (Lgr4iKO) in intestinal epithelium decreased the proportion of enterocytes selective for long-chain fatty acid absorption, leading to reduction in lipid absorption and subsequent improvement in lipid and glucose metabolism. Single-cell RNA sequencing demonstrates the heterogeneity of absorptive enterocytes, with a decrease in enterocytes selective for long-chain fatty acid-absorption and an increase in enterocytes selective for carbohydrate absorption in Lgr4iKO mice. Activation of Notch signaling and concurrent inhibition of Wnt signaling are observed in the transgenes. Associated with these alterations is the substantial reduction in lipid absorption. Decrement in lipid absorption renders Lgr4iKO mice resistant to high fat diet-induced obesity relevant to wild type littermates. Our study thus suggests that targeting intestinal LGR4 is a potential strategy for the intervention of obesity and liver steatosis.