Human oncogenes involved in the development of hematological malignancies have been widely used to model experimental leukemia. Here, we used the fli1 promoter in zebrafish to target the expression of oncogenic HRAS to endothelial cells, including the hemogenic endothelium and observed the development of a myelo-erythroid proliferative disease. In larvae, the pathological phenotype is characterized by some disruption of the vascular system with prominent expansion of the caudal hematopoietic tissue, increase of expression of stem cell markers and myelo-erythroid specific genes and production of a large number of l-plastin leukocytes. In mosaic juveniles, increased number of hematopoietic blasts and arrest of myeloid maturation was found in kidney marrow. Peripheral blood showed delays of erythrocyte maturation and increased number of circulating myeloid progenitors. We found that the abnormal phenotype is associated with a down regulation of the Notch pathway as shown by the decrease of expression of Notch target genes, whereas overexpressing an activated form of Notch together with the oncogene prevents the expansion of the myelo-erythroid compartment. This study identifies the downregulation of the Notch pathway following an oncogenic event in the hemogenic endothelium as an important step in the pathogenesis of myelo-erythroid diseases and describes a number of potential effectors of this transformation. Overall design: Methods: mRNA profiles of transgenic zebrafish overexpressing the oncogene HRAS in endothelial cells (Tg(fli1ep:GAL4FF)ubs3; Tg(UAS:eGFP-HRASV12)io006); or expressing activate Notch in endothelial cells (Tg(fli1ep:GAL4FF)ubs3; tg(UAS:NICD)kca3) were generated by deep sequencing using Illumina HiSeq 2000. The sequence reads that passed quality filters were analyzed using the CLC bio Assembly Cell software (version 3.2) and the Ensembl (release 63) predicted cDNAs for the Zv9 genome assembly. qRT–PCR validation was performed using TaqMan and SYBR Green assays.
Targeting oncogene expression to endothelial cells induces proliferation of the myelo-erythroid lineage by repressing the Notch pathway.
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RNA-Seq provides new insights in the transcriptome responses induced by the carcinogen benzo[a]pyrene.
Cell line, Compound, Time
View SamplesWhole-genome transcriptome measurements are pivotal for characterizing carcinogenic mechanisms of chemicals and predicting toxic classes, such as genotoxicity, from in vitro and in vivo assays. DNA microarrays have evolved as the gold standard for this purpose. In recent years deep sequencing technologies have been developed that hold the promise of measuring the transcriptome with RNA-seq in a more accurate and unbiased manner than microarrays. So far, however, few applications have been published that assess the performance of RNA-seq within a toxicogenomics context. Here, we applied RNA-seq for the characterization of the in vitro transcriptomic responses in HepG2 cells upon exposure to benzo[a]pyrene (BaP), a well-known DNA damaging carcinogen. We demonstrate the performance of RNA-seq with respect to the identification of differentially expressed genes and associated pathways, in comparison with microarray technology. RNA-seq data generates more complete and thus accurate data on differentially expressed genes and affected pathways than microarrays. Additionally, we highlight the potential of RNA-seq for characterizing mechanisms related to alternative splicing and thereby gathering new information. Exposure to BaP alters the isoform distribution for many genes, including regulators of cell death and DNA repair such as TP53, BCL2 and XPA, which are relevant for genotoxic responses. Finally, we demonstrate that RNA-seq enables to investigate allele-specific gene expression, although no changes for that could be observed. Our results provide evidence that RNA-seq is a powerful tool for toxicology which, compared to microarrays, is capable of adding valuable information at the transcriptome level for characterizing toxic effects caused by chemicals.
RNA-Seq provides new insights in the transcriptome responses induced by the carcinogen benzo[a]pyrene.
Cell line, Compound, Time
View SamplesFor assessing the cancer-causing potential for humans of a chemical compound, the conventional approach is the use of the 2-year rodent carcinogenicity bioassay, thus alternatives such as in vitro toxicogenomics are highly desired. In the present study, the transcriptomics responses following exposure to genotoxic (GTX) and non-genotoxic (NGTX) hepatocarcinogens and non-carcinogens (NC) in five liver-based in vitro models, namely conventional and epigenetically-stabilized cultures of primary rat hepatocytes, the human hepatoma-derived HepaRG and HepG2 cell lines and the human embryonic stem cell-derived hepatocyte-like cells hES-Heps are examined and compared.
Transcriptomic responses generated by hepatocarcinogens in a battery of liver-based in vitro models.
Specimen part, Cell line, Treatment
View SamplesPreeclampsia complicates more than 3% of all pregnancies in the United States and Europe. High-risk populations include women with diabetes, dyslipidemia, thrombotic disorders, hyperhomocysteinemia, hypertension, renal diseases, previous preeclampsia, twin pregnancies, and low socioeconomic status. In the latter case, the incidence may increase to 20% to 25%. Preeclampsia is a major cause of maternal and fetal morbidity and mortality. Preeclampsia is defined by systolic blood pressure of more than 140 mm Hg and diastolic blood pressure of more than 90 mm Hg after 20 weeks gestation in a previously normotensive patient, and new-onset proteinuria. Abnormal placentation associated with shallow trophoblast invasion (fetal cells from outer cell layer of the blastocyst) into endometrium (decidua) and improper spiral artery remodeling in the decidua are initial pathological steps.
Dysregulation of the circulating and tissue-based renin-angiotensin system in preeclampsia.
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Extensive temporal transcriptome and microRNA analyses identify molecular mechanisms underlying mitochondrial dysfunction induced by multi-walled carbon nanotubes in human lung cells.
Specimen part, Treatment
View SamplesUnderstanding toxicity pathways of engineered nanomaterials (ENM) has recently been brought forward as a key step in 21st century ENM risk assessment. Molecular mechanisms linked to phenotypic end points is a step towards the development of toxicity tests based on key events, which may allow for grouping of ENM according to their mechanisms of action. This study identified molecular mechanisms underlying mitochondrial dysfunction in human bronchial epithelial BEAS 2B cells following exposure to one of the most studied multi-walled carbon nanotubes (MWCNTs; Mitsui-7). Asbestos was used as a positive control and a non-carcinogenic glass wool material was included as a negative fibre control. Decreased mitochondrial membrane potential (MMP) was observed for MWCNTs at a biologically relevant dose (0.25 g/cm2) and for asbestos at 2 g/cm2, but not for glass wool. Extensive temporal transcriptomic and microRNA expression analyses identified a 330-gene signature related to MWCNT- and asbestos-induced MMP. Fourty-nine of the MMP-associated genes showed highly similar expression patterns over time (six time points) and the majority was found to be regulated by two transcription factors strongly involved in mitochondrial homeostasis, APP and NRF1. In addition, four miRNAs were associated with MMP and one of them, miR-1275, was found to negatively correlate with a large part of the MMP-associated genes. Cellular processes such as gluconeogenesis, glucose metabolism, mitochondrial LC-fatty acid -oxidation and spindle microtubule function were enriched among the MMP-associated genes and miRNAs. These results are expected to be useful in the identification of key events in ENM-related toxicity pathways for the development of molecular screening techniques.
Extensive temporal transcriptome and microRNA analyses identify molecular mechanisms underlying mitochondrial dysfunction induced by multi-walled carbon nanotubes in human lung cells.
Specimen part, Treatment
View SamplesThe transcriptomics changes induced in the human liver cell line HepG2 by 17 hepatotoxic compounds, 5 non-hepatotoxic compounds and solvent controls after treatment for 24h
Classification of hepatotoxicants using HepG2 cells: A proof of principle study.
Specimen part, Cell line
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Aflatoxin B1 induces persistent epigenomic effects in primary human hepatocytes associated with hepatocellular carcinoma.
Specimen part, Disease, Compound
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Aflatoxin B1 induces persistent epigenomic effects in primary human hepatocytes associated with hepatocellular carcinoma.
Specimen part
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