We used microarrays to analyze gene expression changes in liver after treatment of rats with two compounds from drug development (R1, R2) to identify potential effects related to hepatotoxicity.
Gene expression-based in vivo and in vitro prediction of liver toxicity allows compound selection at an early stage of drug development.
Sex, Specimen part, TreatmentView Samples
Hyperactivation 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, SubjectView Samples
Acute lung rejection is a risk factor for chronic rejection, jeopardizing the long-term survival of lung transplant recipients. At present, acute rejection is diagnosed by transbronchial lung biopsies, which are invasive, expensive, and subject to significant sampling error. In this study, we sought to identify groups of genes whose collective expression in BAL cells best classifies acute rejection versus no-rejection. BAL samples were analyzed from 32 unique subjects whose concurrent histology showed acute rejection (n=14) or no rejection (n=18). Global BAL cell gene expression was measured using Affymetrix U133A microarrays. The nearest shrunken centroid method with 10-fold cross validation was used to define the classification model. 250 runs of the algorithm were performed to determine the range of misclassification error and the most influential genes in determining classifiers. The estimated overall misclassification rate was below 20%. Seven transcripts were present in every classifier and 52 transcripts were present in at least 70% of classifiers; these transcripts were notable for involvement with T-cell function, cytotoxic CD8 activity, and granulocyte degranulation. The proportions of both lymphocytes and neutrophils in BAL samples increased with increasing probability of acute rejection; this trend was more pronounced with neutrophils. We conclude that there is a prominent acute rejection-associated signature in BAL cells characterized by increased T-cell, CD8+ cytotoxic cell, and neutrophil gene expression; this is consistent with established mechanistic concepts of the acute rejection response.
Bronchoalveolar lavage cell gene expression in acute lung rejection: development of a diagnostic classifier.
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The ability to sequence genomes has far outstripped approaches for deciphering the information they encode. Here we present a suite of techniques, based on ribosome profiling (the deep-sequencing of ribosome-protected mRNA fragments), to provide genome-wide maps of protein synthesis as well as a pulse-chase strategy for determining rates of translation elongation. We exploit the propensity of harringtonine to cause ribosomes to accumulate at sites of translation initiation together with a machine learning algorithm to define protein products systematically. Analysis of translation in mouse embryonic stem cells reveals thousands of strong pause sites and novel translation products. These include amino-terminal extensions and truncations and upstream open reading frames with regulatory potential, initiated at both AUG and non-AUG codons, whose translation changes after differentiation. We also define a new class of short, polycistronic ribosome-associated coding RNAs (sprcRNAs) that encode small proteins. Our studies reveal an unanticipated complexity to mammalian proteomes. Overall design: Examination of translation in mouse embryonic stem cells and during differentiation into embryoid bodies
Ribosome profiling provides evidence that large noncoding RNAs do not encode proteins.
Cell line, Treatment, SubjectView Samples
Bronchoalveolar lavage samples collected from lung transplant recipients. Numeric portion of sample name is an arbitrary patient ID and AxBx number indicates the perivascular (A) and bronchiolar (B) scores from biopsies collected on the same day as the BAL fluid was collected. Several patients have more than one sample in this series and can be determined by patient number followed by a lower case letter. Acute rejection state is determined by the combined A and B score - specifically, a combined AB score of 2 or greater is considered an acute rejection.
Gene expression profiling of bronchoalveolar lavage cells in acute lung rejection.
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Influenza A viruses generate annual epidemics and occasional pandemics of respiratory disease with important consequences for human health and economy. Therefore, a large effort has been devoted to the development of new anti-influenza drugs directed to viral targets, as well as to the identification of cellular targets amenable for anti-influenza therapy. Here we describe a new approach to identify such potential cellular targets by screening collections of drugs approved for human use. We reasoned that this would most probably ensure addressing a cellular target and, if successful, the compound would have a well known pharmacological profile. In addition, we reasoned that a screening using a GFP-based recombinant replicon system would address virus trancription/replication and/or gene expression, and hence address a stage in virus infection more useful for inhibition. By using such strategy we identified Montelukast as an inhibitor of virus gene expression, which reduced virus multiplication in virus-infected cells but did not alter virus RNA synthesis in vitro or viral RNA accumulation in vivo. By deep sequencing of RNA isolated from mock- and virus-infected human cells, treated or not with Montelukast, we identified the PERK-mediated unfolded protein response as the pathway responsible for Montelukast action. Accordingly, PERK phosphorylation was inhibited in infected cells but stimulated in Montelukast-treated cells. These results suggest the PERK-mediated unfolded protein response as a potential cellular target to modulate influenza virus infection. Overall design: Comparison of gene expression measured by deep sequencing (single-ends, 50nt, RNA-seq) of "Infected", "Not infected", "Infected+Montelukast" and "Not infect+Montelukast" in human A549 cells. Infected means "Infected with influenza virus".
Chemical Genomics Identifies the PERK-Mediated Unfolded Protein Stress Response as a Cellular Target for Influenza Virus Inhibition.
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Notch 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 HIF1Â± 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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Human abdominal adipose tissue was obtained with informed consent from a 33-year old Caucasian female (BMI = 32.96 Kg/m2) undergoing lipoaspiration. Adipose stromal cells (hASCs) were isolated and differentiated into adipocytes in vitro.
Comparative epigenomic analysis of murine and human adipogenesis.
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Loss of the epithelial adhesion molecule E-cadherin is thought to enable metastasis by disrupting intercellular contacts - an early step in metastatic dissemination. To further investigate the molecular basis of this notion, we use two methods to inhibit E-cadherin function that distinguish between E-cadherin's cell-cell adhesion and intracellular signaling functions. While the disruption of cell-cell contacts alone does not enable metastasis, the loss of E-cadherin protein does, through induction of an epithelial-to-mesenchymal transition, invasiveness and anoikis-resistance. We find the E-cadherin binding partner beta-catenin to be necessary but not sufficient for induction of these phenotypes. In addition, gene expression analysis shows that E-cadherin loss results in the induction of multiple transcription factors, at least one of which, Twist, is necessary for E-cadherin loss-induced metastasis. These findings indicate that E-cadherin loss in tumors contributes to metastatic dissemination by inducing wide-ranging transcriptional and functional changes.
Loss of E-cadherin promotes metastasis via multiple downstream transcriptional pathways.