Homo sapiens
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PROVIDER: PRJNA113435 | ENA |
REPOSITORIES: ENA
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Project description:Hexavalent Chromium, Cr(VI), exposure is known to cause cancer and is a significant human health concern. While the effect of Cr(VI) exposure on exposed individuals is well studied, long-term effects of the same on the progeny of exposed individual are not known. In this study, using Drosophila model system, we show that Cr(VI) exposure of mothers leads to phenotypic variations in the progeny who have never been exposed to Cr(VI). These phenotypic variations arise due to epigenetic instability in the somatic tissues of the progeny rather than novel genetic mutations. Using a Drosophila cancer model system, we also show that maternal Cr(VI) exposure can lead to cancer phenotypes in the progeny and the propensity to cause cancer phenotypes in the progeny is fixed in the population for at least three generations. Thus, we show for the first time that effects of Cr(VI) exposure can last for several generations. This study also lays the foundation to use Drosophila model system to provide novel insights into Cr(VI) and other heavy metal toxicity.
2019-01-01 | GSE111834 | GEO
Project description:Living organisms are exposed on a daily basis to widespread mixtures of toxic compounds. Mixtures pose a major problem in the assessment of health effects because they often generate substance-specific effects that cannot be attributed to a single mechanism. Two compounds often found together in the environment are the heavy metal chromium and the polycyclic aromatic hydrocarbon benzo[a]pyrene (B[a]P). We have examined how long-term exposure to a low concentration of Cr(VI) affects the transcriptional response to B[a]P, a second toxicant with an unrelated mechanism of action. Growth of mouse hepatoma cells for 20 passages in medium with 0.1 or 0.5 uM Cr(VI) increases DNA damage and apoptosis and decreases clonogenic ability. These cells also show transcriptome changes indicative of increased expression of DNA damage response and repair genes. In them, B[a]P activates cancer progression pathways, unlike cells never exposed to Cr(VI), where B[a]P activates mostly xenobiotic metabolism pathways. Cells grown in Cr(VI) for 20 passages and then cultured for an additional 5 passages in the absence of Cr(VI) recover from some but not all the chromium effects. They show B[a]P-dependent transcriptome changes strongly weighted towards xenobiotic metabolism, similar to those in B[a]P-treated cells that had no previous Cr(VI) exposure, but retain a high level of Cr(VI)-induced DNA damage and silence the expression of DNA damage and cancer progression genes. We conclude that the combined effect of these two toxicants appears to be neither synergistic nor cumulative, generating a toxic/adaptive condition that cannot be predicted from the effect of each toxicant alone. Mouse Hepa-1 cells treated with Cr, Bap, Cr+Bap and untreated were profiled using RNAseq in duplicates.
2013-08-07 | E-GEOD-49571 | biostudies-arrayexpress
Project description:Although the consequences of genotoxic injury include cell cycle arrest and apoptosis, cell survival responses after genotoxic injury can produce intrinsic death-resistance and contribute to the development of a transformed phenotype. Protein tyrosine phosphatases (PTPs) are integral components of key survival pathways, and are responsible for their inactivation, while PTP inhibition is are often associated with enhanced cell proliferation. Our aim was to elucidate signaling events that modulate cell survival after genotoxin exposure. Diploid human lung fibroblasts (HLF) were treated with Cr(VI) (as Na2CrO4), a well known human respiratory carcinogen that induces a wide spectrum of DNA damage, in the presence and absence of a broad-range PTP inhibitor, sodium orthovanadate. Notably, PTP inhibition abrogated Cr(VI)-induced clonogenic lethality. The enhanced survival of Cr(VI)-exposed cells after PTP inhibition was predominantly due to a bypass of cell cycle arrest and was not due to decreased Cr uptake as evidenced by unchanged Cr-DNA adduct burden. Additionally, the bypass of Cr-induced growth arrest by PTP inhibition, was accompanied by a decrease in Cr(VI)-induced expression of cell cycle inhibiting genes, and an increase in the Cr(VI)-induced expression of cell cycle promoting genes. Importantly, PTP inhibition resulted in an increase in forward mutations at the HPRT locus, supporting the hypothesis that PTP inhibition in the presence of DNA damage may lead to genomic instability, via bypass of cell cycle checkpoints. Experiment Overall Design: Experimental factor was chemical treatment type (3 of them) Experiment Overall Design: (1) No: HLF 1-1, HLF 1-2, HLF 1-3, HLF 1-4 Experiment Overall Design: (2) 1uM Cr(VI): HLF 3-1, HLF 3-2, HLF 3-3, HLF 3-4 Experiment Overall Design: (3) 10uM SOV + 1uM Cr(VI): HLF 4-1, HLF 4-2, HLF 4-3, HLF 4-4 Experiment Overall Design: Biological replicates: 4 different RNA extractions from 4 different cell cultures=quadruplicate per chemical treatment type
2009-01-13 | E-GEOD-12205 | biostudies-arrayexpress
Project description:Living organisms are exposed on a daily basis to widespread mixtures of toxic compounds. Mixtures pose a major problem in the assessment of health effects because they often generate substance-specific effects that cannot be attributed to a single mechanism. Two compounds often found together in the environment are the heavy metal chromium and the polycyclic aromatic hydrocarbon benzo[a]pyrene (B[a]P). We have examined how long-term exposure to a low concentration of Cr(VI) affects the transcriptional response to B[a]P, a second toxicant with an unrelated mechanism of action. Growth of mouse hepatoma cells for 20 passages in medium with 0.1 or 0.5 uM Cr(VI) increases DNA damage and apoptosis and decreases clonogenic ability. These cells also show transcriptome changes indicative of increased expression of DNA damage response and repair genes. In them, B[a]P activates cancer progression pathways, unlike cells never exposed to Cr(VI), where B[a]P activates mostly xenobiotic metabolism pathways. Cells grown in Cr(VI) for 20 passages and then cultured for an additional 5 passages in the absence of Cr(VI) recover from some but not all the chromium effects. They show B[a]P-dependent transcriptome changes strongly weighted towards xenobiotic metabolism, similar to those in B[a]P-treated cells that had no previous Cr(VI) exposure, but retain a high level of Cr(VI)-induced DNA damage and silence the expression of DNA damage and cancer progression genes. We conclude that the combined effect of these two toxicants appears to be neither synergistic nor cumulative, generating a toxic/adaptive condition that cannot be predicted from the effect of each toxicant alone.
2013-08-07 | GSE49571 | GEO
Project description:Hexavalent chromium compounds are well-established respiratory carcinogens utilized in industrial processes. While inhalation exposure constitutes an occupational risk affecting mostly chromium workers, environmental exposure from drinking water is a widespread gastrointestinal carcinogen, affecting millions of people throughout the world. Cr(VI) is genotoxic, by forming protein-Cr-DNA adducts and silencing tumor suppressor genes, but its mechanism of action at the molecular level is poorly understood. We have used FAIRE to show that Cr(VI) elicits broad changes in chromatin accessibility resulting from disruption of the binding of transcription factors CTCF and AP-1 to their cognate sites in chromatin. Here, we have used two complementary approaches to test the hypothesis that chromium perturbs chromatin organization and dynamics. DANPOS2 analyses of MNase.seq data identified several chromatin alterations induced by Cr(VI) affecting nucleosome architecture, including occupancy changes at specific genome locations; position shifts of 10 nucleotides or more; and fuzziness, or changes in signal amplitude. Using ATAC to analyze changes in chromatin accessibility, we found that Cr(VI) opened differentially accessible chromatin domains in a dose-dependent manner. These domains were enriched for the previously identified binding motifs for CTCF and AP-1, many located in promoters of differentially expressed genes. Cr(VI)-enriched CTCF sites were confirmed by ChIP.seq and, when compared with ENCODE-validated CTCF site datasets from mouse liver, correlated with evolutionarily conserved similar sites occupied in vivo. Our results show that Cr(VI) exposure promotes broad changes in chromatin accessibility and suggest that the subsequent dysregulation of transcription may result from the disruption of CTCF binding and nucleosome spacing, suggesting that transcription regulatory mechanisms are primary Cr(VI) targets.
2018-01-01 | GSE104564 | GEO
Project description:Hexavalent chromium compounds are well-established respiratory carcinogens utilized in industrial processes. While inhalation exposure constitutes an occupational risk affecting mostly chromium workers, environmental exposure from drinking water is a widespread gastrointestinal carcinogen, affecting millions of people throughout the world. Cr(VI) is genotoxic, by forming protein-Cr-DNA adducts and silencing tumor suppressor genes, but its mechanism of action at the molecular level is poorly understood. We have used FAIRE to show that Cr(VI) elicits broad changes in chromatin accessibility resulting from disruption of the binding of transcription factors CTCF and AP-1 to their cognate sites in chromatin. Here, we have used two complementary approaches to test the hypothesis that chromium perturbs chromatin organization and dynamics. DANPOS2 analyses of MNase.seq data identified several chromatin alterations induced by Cr(VI) affecting nucleosome architecture, including occupancy changes at specific genome locations; position shifts of 10 nucleotides or more; and fuzziness, or changes in signal amplitude. Using ATAC to analyze changes in chromatin accessibility, we found that Cr(VI) opened differentially accessible chromatin domains in a dose-dependent manner. These domains were enriched for the previously identified binding motifs for CTCF and AP-1, many located in promoters of differentially expressed genes. Cr(VI)-enriched CTCF sites were confirmed by ChIP.seq and, when compared with ENCODE-validated CTCF site datasets from mouse liver, correlated with evolutionarily conserved similar sites occupied in vivo. Our results show that Cr(VI) exposure promotes broad changes in chromatin accessibility and suggest that the subsequent dysregulation of transcription may result from the disruption of CTCF binding and nucleosome spacing, suggesting that transcription regulatory mechanisms are primary Cr(VI) targets.
2018-01-01 | GSE104563 | GEO
Project description:Hexavalent chromium compounds are well-established respiratory carcinogens utilized in industrial processes. While inhalation exposure constitutes an occupational risk affecting mostly chromium workers, environmental exposure from drinking water is a widespread gastrointestinal carcinogen, affecting millions of people throughout the world. Cr(VI) is genotoxic, by forming protein-Cr-DNA adducts and silencing tumor suppressor genes, but its mechanism of action at the molecular level is poorly understood. We have used FAIRE to show that Cr(VI) elicits broad changes in chromatin accessibility resulting from disruption of the binding of transcription factors CTCF and AP-1 to their cognate sites in chromatin. Here, we have used two complementary approaches to test the hypothesis that chromium perturbs chromatin organization and dynamics. DANPOS2 analyses of MNase.seq data identified several chromatin alterations induced by Cr(VI) affecting nucleosome architecture, including occupancy changes at specific genome locations; position shifts of 10 nucleotides or more; and fuzziness, or changes in signal amplitude. Using ATAC to analyze changes in chromatin accessibility, we found that Cr(VI) opened differentially accessible chromatin domains in a dose-dependent manner. These domains were enriched for the previously identified binding motifs for CTCF and AP-1, many located in promoters of differentially expressed genes. Cr(VI)-enriched CTCF sites were confirmed by ChIP.seq and, when compared with ENCODE-validated CTCF site datasets from mouse liver, correlated with evolutionarily conserved similar sites occupied in vivo. Our results show that Cr(VI) exposure promotes broad changes in chromatin accessibility and suggest that the subsequent dysregulation of transcription may result from the disruption of CTCF binding and nucleosome spacing, suggesting that transcription regulatory mechanisms are primary Cr(VI) targets.
2018-01-01 | GSE104565 | GEO
Project description:We profiled plasma miRNA expression in workers exposed to Cr(VI), and assessed genetic damage on chromosome and DNA to compare the sensitivity between epigenetic changes and genetic damage for biomarkers We screened differently expressed plasma miRNAs between high and low Cr(VI) exposed workers using Agilent miRNA microarray. low exposure : <5.49 ng/ml; high exposure >5.49 ng/ml
2014-08-01 | E-GEOD-53135 | biostudies-arrayexpress
Project description:Although the consequences of genotoxic injury include cell cycle arrest and apoptosis, cell survival responses after genotoxic injury can produce intrinsic death-resistance and contribute to the development of a transformed phenotype. Protein tyrosine phosphatases (PTPs) are integral components of key survival pathways, and are responsible for their inactivation, while PTP inhibition is are often associated with enhanced cell proliferation. Our aim was to elucidate signaling events that modulate cell survival after genotoxin exposure. Diploid human lung fibroblasts (HLF) were treated with Cr(VI) (as Na2CrO4), a well known human respiratory carcinogen that induces a wide spectrum of DNA damage, in the presence and absence of a broad-range PTP inhibitor, sodium orthovanadate. Notably, PTP inhibition abrogated Cr(VI)-induced clonogenic lethality. The enhanced survival of Cr(VI)-exposed cells after PTP inhibition was predominantly due to a bypass of cell cycle arrest and was not due to decreased Cr uptake as evidenced by unchanged Cr-DNA adduct burden. Additionally, the bypass of Cr-induced growth arrest by PTP inhibition, was accompanied by a decrease in Cr(VI)-induced expression of cell cycle inhibiting genes, and an increase in the Cr(VI)-induced expression of cell cycle promoting genes. Importantly, PTP inhibition resulted in an increase in forward mutations at the HPRT locus, supporting the hypothesis that PTP inhibition in the presence of DNA damage may lead to genomic instability, via bypass of cell cycle checkpoints.
2008-12-02 | GSE12205 | GEO
Project description:The ability of chromatin to switch back and forth from open euchromatin to closed heterochromatin is vital for transcriptional regulation and genomic stability, and subject to disruption by exposure to environmental agents such as hexavalent chromium. Cr(VI) exposure can cause chromosomal disruption through formation of Cr-DNA adducts, free radical-induced DNA damage, and DNA-Cr-protein and DNA-Cr-DNA cross-links, all of which may disrupt chromatin remodeling mechanisms responsible for maintenance or controlled modification of epigenetic homeostasis. In addition, dose-response analyses have shown that acute exposures to high-concentrations of Cr(VI) and chronic exposures to low-concentrations of the same agent lead to significantly different transcriptomic and genomic stability outcomes. To investigate how transcriptional responses to chromium exposure might correlate to structural changes in chromatin, we have used whole genome Formaldehyde-Assisted Isolation of Regulatory Elements (FAIRE) analysis coupled with deep sequencing to identify regions of the genome that switch from open to closed chromatin or vice versa in response to exposure to varying Cr(VI) concentrations. We find that the switch affects gene expression levels in the target areas that vary depending on Cr(VI) concentration. At either Cr(VI) concentration, chromatin domains surrounding binding sites for AP-1 transcription factors become significantly open, treatment whereas BACH2 and CTCF binding sites are open solely at the low and high concentrations, respectively. Our results suggest that FAIRE may be a useful technique to map chromatin elements targeted by DNA damaging agents for which there is no prior knowledge of their specificity, and to identify subsequent transcriptomic changes induced by those agents.
2014-04-10 | GSE56636 | GEO