Project description:This study examined transcripts that are enriched in neonatal mouse cochlear supporting cells at postnatal day 1 and postnatal day 6 after inhibition of the Notch signaling pathway. Cochleas from postnatal day 0 and postnatal day 5 were cultured for 24 hours in the gamma secretase inhibitor DAPT or DMSO as a vehicle control. Supporting cells were purified by FACS sorting for GFP fluorescence from the cochleas of transgenic mice in which a BAC including the LFng locus drives the expression of GFP. Two replicates of GFP+ supporting cells were compared with all other cochlear cell types that were GFP-. We performed this experiment at two different ages, postnatal day 0+24 hours culture and postnatal day 5 + 24 hours culture. (corresponding to P1 and P6). mRNA profiles of P0 and P5 supporting cells (GFP+) and all other cochlear cell types (GFP-) treated with DAPT or DMSO, two replicates each, were generated by deep sequencing using Illumna TruSeq.
Project description:This study examined transcripts that are enriched in neonatal mouse cochlear supporting cells at postnatal day 1 and postnatal day 6. Supporting cells were purified by FACS sorting for GFP fluorescence from the cochleas of transgenic mice in which a BAC including the LFng locus drives the expression of GFP. Two replicates of GFP+ supporting cells were compared with all other cochlear cell types that were GFP-. We performed this experiment at two different ages, postnatal day 1 and postnatal day 6. mRNA profiles of supporting cells (GFP+) and all other cochlear cell types (GFP-), two replicates each, at P1 and P6 mice were generated by deep sequencing using Illumna TruSeq.
Project description:γ-secretase is an intra-membrane-cleaving aspartyl protease implicated in the processing of a wide range of type I membrane proteins including the Notch receptor and the amyloid-β precursor protein (APP). It thus regulates a diverse array of cellular and biological processes including the differentiation of neuronal embryonic stem cells, or intestinal stem cells, with the latter controlling the self-renewing of the intestinal epithelium. Indeed, proteolysis of these proteins by γ-secretase triggers signaling cascades by releasing intracellular domains (ICDs) which, following association with adaptor proteins and nuclear translocation, modulate the transcription of different genes by binding directly to their promoters. The pronounced proliferative and regenerative effects of Notch signaling and its implication in the generation of the Aβ-peptides, makes γ-secretase a therapeutic target for several types of cancer and for Alzheimerâs disease. To investigate the broad effects of γ-secretase activity onto the cellular transcriptome, Chinese hamster ovary (CHO) cells with enhanced γ-secretase were compared to cells with abolished γ-secretase activity via a microarray designed for a genetically close species, mouse. Our findings will potentially help to decipher the biology of γ-secretase, including a better understanding of the roles of this enzyme in gene transcription. We compared the transcriptomes of two CHO cell lines displaying extreme differences in γ-secretase activity. The S-1 cell line overexpressed the four components of γ-secretase (NCT, APH1aL, PS1, and PEN2) and was characterized by a marked increase in the level of PS1 heterodimers associated with 8-fold increased γ-secretase activity compared to untransfected controls. The other cell line consisted of wild type CHO cells incubated with DAPT, a well-known γ-secretase inhibitor. The two cell lines were used in combination with a mouse microarray to analyze gene transcription under enhanced γ-secretase. Two samples, S1 and DAPT treated CHO- were used in biological triplicates each.
Project description:We have investigated the role of the Notch pathway in the generation and maintenance of KrasG12V-driven non-small cell lung carcinomas (NSCLCs). We demonstrate by genetic means that γ-secretase and Rbpj activities are both essential in the formation of NSCLCs. Interestingly, pharmacologic treatment of mice carrying endogenous NSCLCs with a γ-secretase inhibitor (GSI) blocks cancer growth and induces partial regression. Treated cancers show a reduction in Hes1 levels, reduced phosphorylated Erk, decreased proliferation and higher apoptosis. We demonstrate that HES1 directly binds and represses the promoter of DUSP1, a dual phosphatase with activity against phospho-ERK, and this repression is relieved by GSI treatment both in mouse and human NSCLCs. Our data provide proof for the in vivo therapeutic potential of γ-secretase inhibitors in primary NSCLCs and provide a mechanistic explanation for its therapeutical effect. We have included 6 samples. 3 with vehicle and 3 with the gamma-secretase inhibitor DAPT and we compare both groups.
Project description:Human pluripotent stem cells were differentiated into PDX1+/NKX6-1+ Pancreatic Progenitors (PPd15 cells), which were subsequently captured and expanded in culture. These culture Pancreatic Progenitors (cPP cells) were capable of self-renewal and could be passaged up to 20 times. Furthermore, cPP cells were capable of differentiation into multiple pancreatic lineages, including c-peptide+ beta-like cells, both in vitro and in vivo.
Project description:Glioblastomas (GBM) are poorly differentiated astrocytic tumors arising in the Central Nervous System (CNS), which despite aggressive treatments are still characterized by a fatal outcome. Several studies have shown the existence of a subpopulation of cells within glioma tumors displaying cancer stem cells properties. As the term âtumor initiating cellsâ (TICs) is frequentely used to describe cells as these with cancer stem cells capacity. Because TICs promotes the tumor chemo- and radio-resistance and angiogenesis it is conceivable that finding a mean to kill these cells would lead to a better therapy for GBM. The NOTCH gene has an important role during the CNS development, in the maintenance of dividing cells in promoting neural lineage entry of Embryonic Stem Cells and the differentiation of astroglia from the rat adult hippocampus-derived multipotent progenitors. The activation of the NOTCH signaling requires the proteolytic processing of this type I integral membrane protein by a two step process catalyzed first by a metalloprotease and then by the gamma-secretase. An increased activation of the NOTCH signaling has been implicated in several tumors types. Recently some studies showed that this pathway induces the survival/proliferation in GBM and glioma cells, and the expression of stem cell properties in glioma cells. Accordingly to these findings, the inhibition of this pathway leads to depletion of stem-like cells and blocks the engraftment in embryonal brain tumors. Furthermore, enhanced NOTCH signaling may lead to one of the tumor resistance mechanisms deployed by GBM. Targeting the NOTCH pathway specifically in GBM TICs appears therefore as a rational approach for exploring novel and hopefully more effective therapeutic strategies for the management of this malignancy. Several molecular tools are available for targeting the Notch pathway such as specific siRNAs, shRNAs or drugs such as gamma-secretase inhibitors. Among these tools, the latter are small peptides/molecules able to inhibit the gamma-secretase by distinct mechanisms. In this study we used two drugs known as gamma-secretase inhibitors, to investigate by gene expression profiling, their ability to interfere specifically with the proliferative properties of GBM TICs previously obtained in our laboratory. Our data show that one of these two drugs, LLNle, is effective in killing these cells in vitro by activating protein catabolic process mediated by the proteasome, suggesting that preclinical studies should definitely be carried on to evaluate whether LLNle is able to significantly improve the survival in hybrid human GBM-animal models. Gamma-secretase inhibitors have been proposed as drugs able to kill cancer cells by targeting the NOTCH pathway. In this study we employed two of such inhibitors, namely the z-Leu-leu-Nle-CHO (LLNle) and N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT), to verify whether they were effective in vitro in the killing of human GBM tumor initiating cells (TICs). We first established that of the two drugs only LLNle reduces the viability of GBM TICs obtained from three different patients in the low micromolar range. Cells were treated with 7.5 μM LLNle or DAPT or vehicle alone (DMSO 0.1%) and kept in a humidified 5% CO2 atmosphere at 37°C for the indicated time period (24 or 48 hours). To establish which cellular processes are activated in GBM TICs by LLNle we generated and analyzed the gene expression profile after treatment with this compound and with DAPT and DMSO (vehicle). Our data show that LLNle induces upregulation of genes coding for proteasome subunits and subsequently mitotic arrest in these cells by repressing genes required for DNA synthesis and mitotic progression and by activation of genes acting as mitotic inhibitors. Our data are consistent with proteasome inhibition by LLNle, subsequent upregulation of proteasome activity and subsequent unleash of the apoptotic process in GBM TICs.
Project description:Decoding genome-wide effects of experimental tissue-tissue or cell-cell interactions is important, for example, to better understand tumor-stroma interactions after transplantation (xenografting). Transcriptome analysis of intermixed human and mouse cells has frequently relied on the need to separate the two cell populations prior to transcriptome analysis, which introduces confounding effects on gene expression. To circumvent this problem, we perform a bioinformatics-based genome-wide transcriptome analysis technique separating the mouse and human transcriptome part of a dataset, which allows a mixed mouse and human cell population to be sequenced without prior cell sorting. We use the new technology – which we call S3 (“S-cube” for Species-specific sequencing) technology – to provide new insights into the Notch downstream response following Notch ligand-stimulation and to explore transcriptional changes following transplantation of luminal (MCF7) and basal-type (MDA-MB-231) human breast cancer cells into mammary fat pad tissue in mice. Analysis of Notch response to ligand in three settings: co-culture, immobilized ligand and xenografted tumors
Project description: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. Experiment Overall Design: Three independent cultures of the MOLT4 cell line before and 48 hours after addition of the gamma-secretase inhibitor DAPT (5 uM).
Project description:The role of Notch signaling in the maintenance and differentiation of adult prostate stem cells remains unclear. We found that Notch ligands are mainly expressed within the basal cell lineage, while active Notch signaling is detected in both the prostate basal and luminal cell lineages. Disrupting the canonical Notch effector RBP-J impairs the differentiation of prostate basal stem cells and increases their proliferation in vitro and in vivo, but does not affect luminal cell biology. Conversely, ectopic Notch activation in adult prostates results in basal cell depletion and luminal cell hyper-proliferation. TGFβ dominates over Notch and overrides Notch ablation-induced proliferation of prostate basal cells. In turn, Notch confers positive feedback by up-regulating a plethora of TGFβ signaling components including TGFβRI. These findings reveal crucial roles of the self-enforced positive reciprocal regulatory loop between TGFβ and Notch in maintaining prostate basal stem cell dormancy. We employed an in vitro prostate sphere assay to further investigate how Notch signaling regulates basal cell proliferation and differentiation. FACS isolated adult murine prostate basal cells (using FVB mice) were cultured in the prostate sphere assay with or without N-[(3,5-Difluorophenyl)acetyl]-L-alanyl-2-phenyl]glycine-1,1-dimethylethyl ester (DAPT), an inhibitor for the γ-Secretase complex. Gene expression profiles were taken of vehicle- and DAPT-treated prostate spheres.
Project description:The adult mammalian heart has been traditionally regarded as a post-mitotic organ with no regenerative capacity. However, this dogma has been refuted by some recent landmark studies. Both cardiac progenitor cells (CPCs) and epicardial progenitor cells (EPDCs) are activated after myocardium infarction and they may influence each other through paracrine mechanisms or direct interactions. Currently, efforts are being made to discover and develop therapeutic molecules to increase the number of CPCs and EPDCs in an infarcted heart. To better understand the characteristics and therapeutic potential of CPCs and EPDCs, as well as the regulatory mechanisms, we performed transcriptomic analysis of human iPSC-derived CPCs and human primary EPDCs and discovered unique gene expression profiles for each cell type. To make sure that the biological and pharmacological findings in cell assays under ambient oxygen conditions are relevant to the in vivo situation, it is important to understand the effect of hypoxia on the behavior, gene expression, and paracrine profiles of the cells. <br>Comparative transcriptomic analysis of human epicardial progenitor cells and hiPSC-derived cardiac progenitor cells was conducted. We performed global transcriptional analysis of two sources of cardiac progenitors, i.e., patient epicardium-derived cells (EPDCs) and cardiac progenitor cells (CPCs) derived from human induced pluripotent stem cells. In addition, we also compared the gene expression profiles of these cells when they were cultured under normoxic- and hypoxic conditions.