scholarly journals Structural and functional analysis of the repressor complex in the Notch signaling pathway ofDrosophila melanogaster

2011 ◽  
Vol 22 (17) ◽  
pp. 3242-3252 ◽  
Author(s):  
Dieter Maier ◽  
Patricia Kurth ◽  
Adriana Schulz ◽  
Andrew Russell ◽  
Zhenyu Yuan ◽  
...  
Keyword(s):  
Cell Culture ◽  
Notch Signaling ◽  
Target Genes ◽  
Notch Pathway ◽  
Structural Similarity ◽  
Receptor Activation ◽  
Notch Signaling Pathway ◽  
Repressor Complex

In metazoans, the highly conserved Notch pathway drives cellular specification. On receptor activation, the intracellular domain of Notch assembles a transcriptional activator complex that includes the DNA-binding protein CSL, a composite of human C-promoter binding factor 1, Suppressor of Hairless of Drosophila melanogaster [Su(H)], and lin-12 and Glp-1 phenotype of Caenorhabditis elegans. In the absence of ligand, CSL represses Notch target genes. However, despite the structural similarity of CSL orthologues, repression appears largely diverse between organisms. Here we analyze the Notch repressor complex in Drosophila, consisting of the fly CSL protein, Su(H), and the corepressor Hairless, which recruits general repressor proteins. We show that the C-terminal domain of Su(H) is necessary and sufficient for forming a high-affinity complex with Hairless. Mutations in Su(H) that affect interactions with Notch and Mastermind have no effect on Hairless binding. Nonetheless, we demonstrate that Notch and Hairless compete for CSL in vitro and in cell culture. In addition, we identify a site in Hairless that is crucial for binding Su(H) and subsequently show that this Hairless mutant is strongly impaired, failing to properly assemble the repressor complex in vivo. Finally, we demonstrate Hairless-mediated inhibition of Notch signaling in a cell culture assay, which hints at a potentially similar repression mechanism in mammals that might be exploited for therapeutic purposes.

scholarly journals Notch pathway activation targets AML-initiating cell homeostasis and differentiation

2013 ◽  
Vol 210 (2) ◽  
pp. 301-319 ◽  
Author(s):  
Camille Lobry ◽  
Panagiotis Ntziachristos ◽  
Delphine Ndiaye-Lobry ◽  
Philmo Oh ◽  
Luisa Cimmino ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Notch Signaling ◽  
Myeloproliferative Neoplasms ◽  
Notch Pathway ◽  
Notch Signaling Pathway ◽  
Notch Receptor ◽  
Pathway Activation ◽  
Function Models

Notch signaling pathway activation is known to contribute to the pathogenesis of a spectrum of human malignancies, including T cell leukemia. However, recent studies have implicated the Notch pathway as a tumor suppressor in myeloproliferative neoplasms and several solid tumors. Here we report a novel tumor suppressor role for Notch signaling in acute myeloid leukemia (AML) and demonstrate that Notch pathway activation could represent a therapeutic strategy in this disease. We show that Notch signaling is silenced in human AML samples, as well as in AML-initiating cells in an animal model of the disease. In vivo activation of Notch signaling using genetic Notch gain of function models or in vitro using synthetic Notch ligand induces rapid cell cycle arrest, differentiation, and apoptosis of AML-initiating cells. Moreover, we demonstrate that Notch inactivation cooperates in vivo with loss of the myeloid tumor suppressor Tet2 to induce AML-like disease. These data demonstrate a novel tumor suppressor role for Notch signaling in AML and elucidate the potential therapeutic use of Notch receptor agonists in the treatment of this devastating leukemia.

scholarly journals Loss of PLK2 induces acquired resistance to temozolomide in GBM via activation of Notch signaling

2020 ◽  
Author(s):  
Wahafu Alafate ◽  
Dongze Xu ◽  
Wei Wu ◽  
Jianyang Xiang ◽  
Xudong Ma ◽  
...  
Keyword(s):  
Notch Signaling ◽  
Acquired Resistance ◽  
Notch Pathway ◽  
Notch Signaling Pathway ◽  
Gene Expression Omnibus ◽  
Primary Brain Tumor ◽  
Biological Behavior ◽  
Clinical Samples

Abstract BackgroundGlioblastoma (GBM) is a lethal type of primary brain tumor with a median survival less than 15 months. Despite the recent improvements of comprehensive strategies, the outcomes for GBM patients remain dismal. Accumulating evidence indicates that rapid acquired chemoresistance is the major cause of GBM recurrence thus leads to worse clinical outcomes. Therefore, developing novel biomarkers and therapeutic targets for chemoresistant GBM is crucial for long-term cures. MethodsTranscriptomic profiles of glioblastoma were downloaded from gene expression omnibus (GEO) and TCGA database. Differentially expressed genes were analyzed and candidate gene PLK2 was selected for subsequent validation. Clinical samples and corresponding data were collected from our center and measured using immunohistochemistry analysis. Lentiviral transduction and in vivo xenograft transplantation were used to validate the bioinformatic findings. GSEA analyses were conducted to identify potential signaling pathways related to PLK2 expression and further confirmed by in vitro mechanistic assays. ResultsIn this study, we identified PLK2 as an extremely suppressed kinase-encoding gene in GBM samples, particularly in therapy resistant GBM. Additionally, reduced PLK2 expression implied poor prognosis and TMZ resistance in GBM patients. Functionally, up-regulated PLK2 attenuated cell proliferation, migration, invasion, and tumorigenesis of GBM cells. Besides, exogenous overexpression of PLK2 reduced acquired TMZ resistance of GBM cells. Furthermore, bioinformatics analysis indicated that PLK2 was negatively correlated with Notch signaling pathway in GBM. Mechanically, loss of PLK2 activated Notch pathway through negative transcriptional regulation of HES1 and degradation of Notch1.ConclusionLoss of PLK2 enhances aggressive biological behavior of GBM through activation of Notch signaling, indicating that PLK2 could be a prognostic biomarker and potential therapeutic target for chemoresistant GBM.

scholarly journals Loss of PLK2 induces acquired resistance to temozolomide in GBM via activation of notch signaling

2020 ◽  
Vol 39 (1) ◽  
Author(s):  
Wahafu Alafate ◽  
Dongze Xu ◽  
Wei Wu ◽  
Jianyang Xiang ◽  
Xudong Ma ◽  
...  
Keyword(s):  
Notch Signaling ◽  
Acquired Resistance ◽  
Notch Pathway ◽  
Notch Signaling Pathway ◽  
Gene Expression Omnibus ◽  
Primary Brain Tumor ◽  
Biological Behavior ◽  
Clinical Samples

Abstract Background Glioblastoma (GBM) is a lethal type of primary brain tumor with a median survival less than 15 months. Despite the recent improvements of comprehensive strategies, the outcomes for GBM patients remain dismal. Accumulating evidence indicates that rapid acquired chemoresistance is the major cause of GBM recurrence thus leads to worse clinical outcomes. Therefore, developing novel biomarkers and therapeutic targets for chemoresistant GBM is crucial for long-term cures. Methods Transcriptomic profiles of glioblastoma were downloaded from gene expression omnibus (GEO) and TCGA database. Differentially expressed genes were analyzed and candidate gene PLK2 was selected for subsequent validation. Clinical samples and corresponding data were collected from our center and measured using immunohistochemistry analysis. Lentiviral transduction and in vivo xenograft transplantation were used to validate the bioinformatic findings. GSEA analyses were conducted to identify potential signaling pathways related to PLK2 expression and further confirmed by in vitro mechanistic assays. Results In this study, we identified PLK2 as an extremely suppressed kinase-encoding gene in GBM samples, particularly in therapy resistant GBM. Additionally, reduced PLK2 expression implied poor prognosis and TMZ resistance in GBM patients. Functionally, up-regulated PLK2 attenuated cell proliferation, migration, invasion, and tumorigenesis of GBM cells. Besides, exogenous overexpression of PLK2 reduced acquired TMZ resistance of GBM cells. Furthermore, bioinformatics analysis indicated that PLK2 was negatively correlated with Notch signaling pathway in GBM. Mechanically, loss of PLK2 activated Notch pathway through negative transcriptional regulation of HES1 and degradation of Notch1. Conclusion Loss of PLK2 enhances aggressive biological behavior of GBM through activation of Notch signaling, indicating that PLK2 could be a prognostic biomarker and potential therapeutic target for chemoresistant GBM.

scholarly journals Transcription Factor RBPJL Is Able to Repress Notch Target Gene Expression but Is Non-Responsive to Notch Activation

Cancers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 5027
Author(s):  
Leiling Pan ◽  
Philipp Hoffmeister ◽  
Aleksandra Turkiewicz ◽  
N. N. Duyen Huynh ◽  
Andreas Große-Berkenbusch ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Notch Signaling ◽  
Single Molecule ◽  
Transcriptional Repression ◽  
Target Genes ◽  
Notch Pathway ◽  
Structural Similarity ◽  
Time Lapse ◽  
Notch Signaling Pathway ◽  
Migration Dynamics

The Notch signaling pathway is an evolutionary conserved signal transduction cascade present in almost all tissues and is required for embryonic and postnatal development, as well as for stem cell maintenance, but it is also implicated in tumorigenesis including pancreatic cancer and leukemia. The transcription factor RBPJ forms a coactivator complex in the presence of a Notch signal, whereas it represses Notch target genes in the absence of a Notch stimulus. In the pancreas, a specific paralog of RBPJ, called RBPJL, is expressed and found as part of the heterotrimeric PTF1-complex. However, the function of RBPJL in Notch signaling remains elusive. Using molecular modeling, biochemical and functional assays, as well as single-molecule time-lapse imaging, we show that RBPJL and RBPJ, despite limited sequence homology, possess a high degree of structural similarity. RBPJL is specifically expressed in the exocrine pancreas, whereas it is mostly undetectable in pancreatic tumour cell lines. Importantly, RBPJL is not able to interact with Notch−1 to −4 and it does not support Notch-mediated transactivation. However, RBPJL can bind to canonical RBPJ DNA elements and shows migration dynamics comparable to that of RBPJ in the nuclei of living cells. Importantly, RBPJL is able to interact with SHARP/SPEN, the central corepressor of the Notch pathway. In line with this, RBPJL is able to fully reconstitute transcriptional repression at Notch target genes in cells lacking RBPJ. Together, RBPJL can act as an antagonist of RBPJ, which renders cells unresponsive to the activation of Notch.

scholarly journals Loss of PLK2 Induces Acquired Resistance to Temozolomide in GBM via Activation of Notch Signaling

2020 ◽  
Author(s):  
Wahafu Alafate ◽  
Dongze Xu ◽  
Wei Wu ◽  
Jianyang Xiang ◽  
Xudong Ma ◽  
...  
Keyword(s):  
Notch Signaling ◽  
Acquired Resistance ◽  
Notch Pathway ◽  
Notch Signaling Pathway ◽  
Gene Expression Omnibus ◽  
Primary Brain Tumor ◽  
Biological Behavior ◽  
Clinical Samples

Abstract BackgroundGlioblastoma (GBM) isa lethal type of primary brain tumor with a median survival less than 15 months.Despiting the recent improvements of comprehensive strategies,the outcomes for GBM patients remain dismal.Accumulating evidence indicates that rapid acquired chemoresistance is the major cause ofGBM recurrence thus leads to worse clinical outcomes. Therefore, developing novel biomarkers and therapeutic targets for chemoresistant GBM is crucial for long-term cures. MethodsTranscriptomic profiles of glioblastoma were downloaded from gene expression omnibus (GEO) and TCGA database. Differentially expressed genes were analyzed and candidate gene PLK2 was selected for subsequent validation. Clinical samples and corresponding data were collected from our center and measured using immunohistochemistry analysis. Lentiviral transduction and in vivo xenograft transplantation were used to validate the bioinformatic findings. GSEA analyses were conducted to identify potential signaling pathways related to PLK2 expression and further confirmed by in vitro mechanistic assays. ResultsIn this study, we identified PLK2 as an extremely suppressed kinase-encoding gene in GBM samples, particularly in therapy resistant GBM. Additionally, reduced PLK2 expression implied poor prognosis and TMZ resistance in GBM patients. Functionally, up-regulated PLK2 attenuated cell proliferation, immigration, invasion, and tumorigenesis of GBM cells. Besides, exogenous overexpression of PLK2 reduced acquired TMZ resistance of GBM cells. Furthermore, bioinformatics analysis indicated that PLK2 was negatively correlated with Notch signaling pathway in GBM. Mechanically, loss of PLK2 activated Notch pathway through negative transcriptional regulation of HES1 and degradation of Notch1.ConclusionLoss of PLK2 enhances aggressive biological behavior of GBM through activation of Notch signaling, indicating that PLK2 could be a prognostic biomarker and potential therapeutic target for chemoresistant GBM.

scholarly journals The Murine Ortholog of Notchless, a Direct Regulator of the Notch Pathway in Drosophila melanogaster, Is Essential for Survival of Inner Cell Mass Cells

2006 ◽  
Vol 26 (9) ◽  
pp. 3541-3549 ◽  
Author(s):  
Sarah Cormier ◽  
Stéphanie Le Bras ◽  
Céline Souilhol ◽  
Sandrine Vandormael-Pournin ◽  
Béatrice Durand ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Notch Signaling ◽  
Cell Fate ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Notch Pathway ◽  
Notch Signaling Pathway ◽  
Direct Regulator

ABSTRACT Notch signaling is an evolutionarily conserved pathway involved in intercellular communication and is essential for proper cell fate choices. Numerous genes participate in the modulation of the Notch signaling pathway activity. Among them, Notchless (Nle) is a direct regulator of the Notch activity identified in Drosophila melanogaster. Here, we characterized the murine ortholog of Nle and demonstrated that it has conserved the ability to modulate Notch signaling. We also generated mice deficient for mouse Nle (mNle) and showed that its disruption resulted in embryonic lethality shortly after implantation. In late mNle −/− blastocysts, inner cell mass (ICM) cells died through a caspase 3-dependent apoptotic process. Most deficient embryos exhibited a delay in the temporal down-regulation of Oct4 expression in the trophectoderm (TE). However, mNle-deficient TE was able to induce decidual swelling in vivo and properly differentiated in vitro. Hence, our results indicate that mNle is mainly required in ICM cells, being instrumental for their survival, and raise the possibility that the death of mNle-deficient embryos might result from abnormal Notch signaling during the first steps of development.

scholarly journals Transcript and protein profiling identifies signaling, growth arrest, apoptosis, and NF-κB survival signatures following GNRH receptor activation

2012 ◽  
Vol 20 (1) ◽  
pp. 123-136 ◽  
Author(s):  
Colette Meyer ◽  
Andrew H Sims ◽  
Kevin Morgan ◽  
Beth Harrison ◽  
Morwenna Muir ◽  
...  
Keyword(s):  
Target Genes ◽  
Cultured Cells ◽  
Receptor Activation ◽  
Gnrh Receptor ◽  
Phase Changes ◽  
Protein Profiling ◽  
Proteomic Profiling ◽  
Pathway Gene

GNRH significantly inhibits proliferation of a proportion of cancer cell lines by activating GNRH receptor (GNRHR)-G protein signaling. Therefore, manipulation of GNRHR signaling may have an under-utilized role in treating certain breast and ovarian cancers. However, the precise signaling pathways necessary for the effect and the features of cellular responses remain poorly defined. We used transcriptomic and proteomic profiling approaches to characterize the effects of GNRHR activation in sensitive cells (HEK293-GNRHR, SCL60)in vitroandin vivo, compared to unresponsive HEK293. Analyses of gene expression demonstrated a dynamic response to the GNRH superagonist Triptorelin. Early and mid-phase changes (0.5–1.0 h) comprised mainly transcription factors. Later changes (8–24 h) included a GNRH target gene,CGA, and up- or downregulation of transcripts encoding signaling and cell division machinery. Pathway analysis identified altered MAPK and cell cycle pathways, consistent with occurrence of G2/M arrest and apoptosis. Nuclear factor kappa B (NF-κB) pathway gene transcripts were differentially expressed between control and Triptorelin-treated SCL60 cultures. Reverse-phase protein and phospho-proteomic array analyses profiled responses in cultured cells and SCL60 xenograftsin vivoduring Triptorelin anti-proliferation. Increased phosphorylated NF-κB (p65) occurred in SCL60in vitro, and p-NF-κB and IκBε were higher in treated xenografts than controls after 4 days Triptorelin. NF-κB inhibition enhanced the anti-proliferative effect of Triptorelin in SCL60 cultures. This study reveals details of pathways interacting with intense GNRHR signaling, identifies potential anti-proliferative target genes, and implicates the NF-κB survival pathway as a node for enhancing GNRH agonist-induced anti-proliferation.

Treatment of Intrauterine Adhesions with Human Amnion Mesenchymal Stromal Cells (hAMSCs) on Promoting Endometrial Regeneration and Repair Via Notch Signaling Pathway Regulation

2020 ◽  
Author(s):  
Jie Yu ◽  
Wenwen Zhang ◽  
Jiayue Huang ◽  
Yating Gou ◽  
Congcong Sun ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Notch Signaling ◽  
Signaling Pathway ◽  
Notch Signaling Pathway ◽  
Intrauterine Adhesions ◽  
Epithelial Markers ◽  
Qrt Pcr ◽  
Endometrial Epithelial Cells

Abstract Background: Human amniotic mesenchymal stem cells(hAMSCs) can repair and improve the damaged endometrium which its aplastic disorder is the main reason for intrauterine adhesions(IUAs).Methods: We conducted in vivo and in vitro experiments. In vivo experiments: 45 female Sprague-Dawley(SD) rats were involved and randomized equally into Sham group, IUA group, Estradiol(E2) group, hAMSCs group, and E2 + hAMSCs group. The effect of hAMSCs and E2 only or combined was evaluated by Hematoxylin-eosin(HE) and Masson staining. The expression of epithelial markers and key proteins of Notch signaling pathway by Immunohistochemistry. In vitro experiments: Firstly, the hAMSCs cells were taken and divided into control group and induced group in which hAMSCs were differentiated into endometrial epithelial cells in induced microenvironment, and extracted their RNA respectively. The expression of epithelial markers and Notch1 messenger RNA (mRNA) was detected by Real-time quantitative polymerase chain reaction(qRT-PCR). and the changes in expression position of Notch intracellular domain(NICD) and expression amount of target gene, hairy enhancer of split 1(Hes1) were detected by Immunofluorescence. Then, Activated and inhibited the Notch signaling pathway while induction, and detected mRNA expression of hAMSCs epithelial markers by quantitative real-time polymerase chainreaction (qRT-PCR) respectively and detected hAMSCs cell cycle by flow cytometric. Results:This study showed that hAMSCs alone or combined with E2 could promote endometrial repair, and Notch signaling pathway a great role in it. And otherwise, the activation or habitation of Notch signaling pathway determines whether hAMSCs could differentiate into endometrial epithelial cells or not.Conclusion: we concluded that activate the Notch signaling pathway promote the differentiation of hAMSCs into endometrial epithelial cells, and further treat IUAs.

scholarly journals NBS1 interacts with Notch signaling in neuronal homeostasis

2020 ◽  
Vol 48 (19) ◽  
pp. 10924-10939
Author(s):  
Zhong-Wei Zhou ◽  
Murat Kirtay ◽  
Nadine Schneble ◽  
George Yakoub ◽  
Mingmei Ding ◽  
...  
Keyword(s):  
Notch Signaling ◽  
Notch Pathway ◽  
Direct Consequence ◽  
Nijmegen Breakage Syndrome ◽  
Neuron Development ◽  
Genetic Ablation ◽  
Notch Activity ◽  
And Migration

Abstract NBS1 is a critical component of the MRN (MRE11/RAD50/NBS1) complex, which regulates ATM- and ATR-mediated DNA damage response (DDR) pathways. Mutations in NBS1 cause the human genomic instability syndrome Nijmegen Breakage Syndrome (NBS), of which neuronal deficits, including microcephaly and intellectual disability, are classical hallmarks. Given its function in the DDR to ensure proper proliferation and prevent death of replicating cells, NBS1 is essential for life. Here we show that, unexpectedly, Nbs1 deletion is dispensable for postmitotic neurons, but compromises their arborization and migration due to dysregulated Notch signaling. We find that Nbs1 interacts with NICD-RBPJ, the effector of Notch signaling, and inhibits Notch activity. Genetic ablation or pharmaceutical inhibition of Notch signaling rescues the maturation and migration defects of Nbs1-deficient neurons in vitro and in vivo. Upregulation of Notch by Nbs1 deletion is independent of the key DDR downstream effector p53 and inactivation of each MRN component produces a different pattern of Notch activity and distinct neuronal defects. These data indicate that neuronal defects and aberrant Notch activity in Nbs1-deficient cells are unlikely to be a direct consequence of loss of MRN-mediated DDR function. This study discloses a novel function of NBS1 in crosstalk with the Notch pathway in neuron development.

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