In T-cell acute lymphoblastic leukemia (T-ALL) NOTCH 1 receptors are frequently mutated. This leads to aberrantly high Notch signaling, but how this translates into deregulated cell cycle control and the transformed cell type is poorly understood. In this report, we analyze downstream responses resulting from the high level of NOTCH 1 signaling in T-ALL. Notch activity, measured immediately downstream of the NOTCH 1 receptor, is high, but expression of the canonical downstream Notch response genes HES 1 and HEY 2 is low both in primary cells from T-ALL patients and in T-ALL cell lines. This suggests that other immediate Notch downstream genes are activated, and we found that Notch signaling controls the levels of expression of the E3 ubiquitin ligase SKP2 and its target protein p27Kip1. We show that in T-ALL cell lines, recruitment of NOTCH 1 ICD to the SKP2 promoter was accompanied by high SKP2 and low p27Kip1 protein levels were low. In contrast, pharmacologically blocking Notch signaling reversed this picture and led to loss of NOTCH 1 ICD occupancy of the SKP2 promoter, decreased SKP2 and increased p27Kip1 expression. T-ALL cells show a rapid G1-S cell cycle transition, while blocked Notch signaling resulted in G0/G1 cell cycle arrest, also observed by transfection of p27Kip1 or, to a smaller extent, a dominant negative SKP2 allele. Collectively, our data suggest that the aberrantly high Notch signaling in T-ALL maintains SKP2 at a high level and reduces p27Kip1, which leads to more rapid cell cycle progression.
Notch signaling induces SKP2 expression and promotes reduction of p27Kip1 in T-cell acute lymphoblastic leukemia cell lines.
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View SamplesVascular smooth muscle cells (VSMC) are important for contraction, blood flow distribution and regulation of blood vessel diameter, but to what extent they contribute to the integrity of blood vessels and blood-brain barrier function is less well understood. In this report, we explored the impact of the progressive loss of VSMC in the Notch3-/- mouse on blood vessel integrity in the central nervous system
Notch3 is necessary for blood vessel integrity in the central nervous system.
Age, Specimen part
View SamplesBackground: Interaction between key signaling mechanisms is important to generate the diversity in signaling output required for proper control of cellular differentiation and function, although the molecular manifestations of such cross-talk are only partially understood. Notch signaling and the cellular response to hypoxia intersect at different points in the signaling cascades, and in this report we analyze the consequences of this cross-talk at the transcriptome level. Results: Mouse ES cells were subjected to various combinations of hypoxia and/or activated Notch signaling, and the transcriptome changes could be grouped into different categories, reflecting various modes of hypoxia and Notch signaling integration. Two principal categories of novel Notch- and hypoxia-induced genes were identified: i) a larger set of genes induced by one pathway and not significantly affected by the activity status of the other pathway; and ii) a smaller set of genes co-regulated by Notch and hypoxia. In the latter category, we identified genes that were induced by hypoxia and the expression of which was enhanced by active Notch signaling. In addition, a number of genes were induced by Notch and hypoxia independently, and a final category of genes required simultaneous activation of Notch and hypoxia to be significantly induced. Several of the hypoxia- and Notch-induced genes were found to be upregulated in various forms of cancer. Conclusions: We identify novel Notch and hypoxia downstream genes and genes co-regulated by the two pathways, providing a molecular platform to better understand the intersection between the two signaling cascades in normal development and cancer.
Interactions between Notch- and hypoxia-induced transcriptomes in embryonic stem cells.
Sex, Specimen part, Treatment
View SamplesHyperactivation of Notch signaling and the cellular hypoxic response are frequently observed in cancers, with increasing reports of connections to tumor initiation and progression. The two signaling mechanisms are known to intersect, but while it is well established that hypoxia regulates Notch signaling, less is known about whether Notch can regulate the cellular hypoxic response. We now report that Notch signaling specifically controls expression of HIF2a, a key mediator of the cellular hypoxic response. Transcriptional upregulation of HIF2a by Notch under normoxic conditions leads to elevated HIF2a protein levels in primary breast cancer cells as well as in human breast cancer, medulloblastoma and renal cell carcinoma cell lines. The elevated level of HIF2a protein was in certain tumor cell types accompanied by down-regulation of HIF1a protein levels, indicating that high Notch signaling may drive a HIF1a-to-HIF2a switch. At the transcriptome level, the presence of HIF2a was required for approximately 21% of all Notch-induced genes: among the 1062 genes that were upregulated by Notch in medulloblastoma cells during normoxia, upregulation was abrogated in 227 genes when HIF2a expression was knocked down by HIF2a siRNA. In conclusion, our data show that Notch signaling affects the hypoxic response via regulation of HIF2a, which may be important for future cancer therapies. Overall design: DAOY-NERT2 cells, +/- Notch induction by Tamoxifen (TMX) for 48 hours, +/- hypoxia (1% O2) treatment for 48 hours, where HIF1a or HIF2a had been knocked down by siRNA, were subjected to RNA sequencing. The quality of the cDNA libraries was tested on an Agilent 2100 bioanalyzer. The libraries were sequenced on an Illumina HiSeq 2000 system, and the reads were aligned to the human genome (assembly hg19) and a transcriptome database (RefSeq and Ensembl) using bowtie. RPKM values were generated using rpkmforgenes.
Notch signaling promotes a HIF2α-driven hypoxic response in multiple tumor cell types.
Specimen part, Subject
View SamplesNotch signaling is an important regulator of stem cell differentiation. All canonical Notch signaling is transmitted through the DNA-binding protein CSL and hyperactivated Notch signaling is associated with tumor development; thus it may be anticipated that CSL deficiency should reduce tumor growth. In contrast, we report that genetic removal of CSL in breast tumor cells caused accelerated growth of xenografted tumors. Loss of CSL unleashed a hypoxic response during normoxic conditions, manifested by stabilization of the HIF1± protein and acquisition of a polyploid giant-cell, cancer stem cell-like, phenotype. At the transcriptome level, loss of CSL upregulated more than 1750 genes and less than 3% of those genes were part of the Notch transcriptional signature. Collectively, this suggests that CSL exerts functions beyond serving as the central node in the Notch signaling cascade and reveals a novel role for CSL in tumorigenesis and regulation of the cellular hypoxic response. Overall design: CSL +/+ and CSL -/- MDA-MB-231 were subjected to Notch activation/inhibition and xenograft experiment. Total RNA were extracted from the samples and sent to NGS. Single Cell RNA-sequencing was also performed from cells isolated from xenograft tumors.
Loss of CSL Unlocks a Hypoxic Response and Enhanced Tumor Growth Potential in Breast Cancer Cells.
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View SamplesBy analyzing 250 astrocyte single cell transcriptomes from adult brain, we provide gene expresssion profile of brain astrocyte Overall design: We chose adult mice about 3 months old and analysed single cells in the brain. We chose a methodology based on fluorescence-activated cell sorting (FACS) into 384-well plates followed by the SmartSeq2 methodology.
Single-cell RNA sequencing of mouse brain and lung vascular and vessel-associated cell types.
Specimen part, Cell line, Subject
View SamplesNeedle biopsies were performed to obtain liver samples from patients for clinical purposes from patients with Alagille syndrome. A small portion was snap frozen and later used for RNA sequencing analysis. Needle biospies from 5 patients with other liver disorders were included as controls. Overall design: Examination of RNA expression in Alagille patients'' liver samples, compared to other control liver samples (with other chronic liver diseases).
Mouse Model of Alagille Syndrome and Mechanisms of Jagged1 Missense Mutations.
Specimen part, Disease stage, Subject
View SamplesRNA sequencing of control or Notch1-expressing mouse cells co-cultured with control, Jag1WT, or Jag1Ndr-expressing human cells. Deep sequencing and bioinformatical separation of mouse and human reads reveals transcripts specifically regulated in mouse receptor-expressing cells. Overall design: Mouse C2C12 control and C2C12-FLNotch1, and human HEK-293-Flp-In cells (Hansson et al., 2010): HEK293-Flp control (Flp Ctrl), HEK293-Flp-Jag1WT (Flp Jag1+), HEK293-Flp-Jag1Ndr (Flp Jag1Ndr) were used in this experiment. In one 12-well plate, we seeded 3 wells of mouse C2C12 control cells and 3 wells of C2C12-FLN1 cells, with 3.6x105 cells in 1 mL antibiotic-free medium per well. Cells were allowed to settle for 8 hours. C2C12 control and C2C12-FLN1 cells were transfected with pcDNA5 (1.6 ug/well). All transfections were done using Lipofectamine® 2000 (InvitrogenTM, cat. no. 11668-019) with Opti-MEM® I Reduced Serum Medium (Gibco®, cat. no. 31985-062), according to manufacturer's instructions. The following day (18 hours post transfection), 3.6x105 cells in 0.5 mL antibiotic-free medium of Flp Ctrl, Flp Jag1+, or Flp Jag1Ndr cells were added. Cells were co-cultured for 6 hours, then lysed in 350 uL per well Buffer RLT (QIAGEN, cat. no. 79216) with 1% 2-Mercaptoethanol (Sigma-Aldrich®, cat. no. M3148) and stored at -80°C until RNA extraction.
Mouse Model of Alagille Syndrome and Mechanisms of Jagged1 Missense Mutations.
Subject
View SamplesWe analyzed the genome-wide expression by RNA-seq of a yeast strain that expresses Cas9d and a guideRNA targeted to the GAL10 locus (called +116), which inhibits GAL10 ncRNA expression from the antisense strand. We compared this strain to a strain expressing a scrambled guideRNA. The goal was to examine the effects of ncRNA inhibition and to examine if CRISPR inhibition of gene expression has off-target effects. We find that CRISPR-mediated inhibtion of GAL10 ncRNA only significantly changes expression of transcripts at the GAL1-10 locus, showing that CRISPR is highly specific, and that GAL10 ncRNA only control genes at the GAL locus. Overall design: RNA-seq of 2 strains with CRISPR scrambled and 2 strains with CRISPR +116, the latter of which inhibits GAL10 ncRNA
Single-Molecule Imaging Reveals a Switch between Spurious and Functional ncRNA Transcription.
Cell line, Subject
View SamplesTreatment induced senescence (TIS) is a terminal cell cycle arrest program, increasingly recognized as a tumor suppressor mechanism complementing apoptosis in response to standard chemotherapy regimens. In particular cells with blocked apoptotic pathways rely on senescence as the only remaining failsafe mechanism to keep the neoplastic growth in check. However, little is known about biological properties, long-term fate of senescent tumor cells and their impact on the microenvironment.
Opposing roles of NF-κB in anti-cancer treatment outcome unveiled by cross-species investigations.
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