Concentration-response gene expression analysis in zebrafish reveals phenotypically-anchored transcriptional responses to retene
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ABSTRACT:
ORGANISM(S): Danio rerio
PROVIDER: GSE203258 | GEO | 2022/05/21
REPOSITORIES: GEO
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Project description:Concentration-response gene expression analysis in zebrafish reveals phenotypically-anchored transcriptional responses to retene
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Project description:Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental contaminants and are associated with human disease. Canonically, many PAHs induce toxicity via activation of the aryl hydrocarbon receptor (AHR) pathway. While the interaction between PAHs and the AHR is well-established, understanding which AHR-regulated transcriptional effects directly result in observable phenotypes and which are adaptive or benign is important to better understand PAH toxicity. Retene is a frequently detected PAH in environmental sampling and has been associated with AHR2-dependent developmental toxicity in zebrafish, though its mechanism of toxicity has not been fully elucidated. To interrogate transcriptional changes causally associated with retene toxicity, we conducted whole-animal RNA sequencing at 48 h post-fertilization after exposure to eight retene concentrations. We aimed to identify the most sensitive transcriptomic responses and to determine whether this approach could uncover gene sets uniquely differentially expressed at concentrations which induce a phenotype. We identified a concentration-response relationship for differential gene expression in both number of differentially expressed genes (DEGs) and magnitude of expression change. Elevated expression of cyp1a at retene concentrations below the threshold for teratogenicity suggested that while cyp1a expression is a sensitive biomarker of AHR activation, it may be too sensitive to serve as a biomarker of teratogenicity. Genes differentially expressed at only non-teratogenic concentrations were enriched for transforming growth factor-β (TGF-β) signaling pathway disruption while DEGs identified at only teratogenic concentrations were significantly enriched for response to xenobiotic stimulus and reduction-oxidation reaction activity. DEGs which spanned both non-teratogenic and teratogenic concentrations showed similar disrupted biological processes to those unique to teratogenic concentrations, indicating these processes were disrupted at low exposure concentrations. Gene co-expression network analysis identified several gene modules, including those associated with PAHs and AHR2 activation. One, Module 7, was strongly enriched for AHR2-associated genes and contained the strongest responses to retene. Benchmark concentration (BMC) of Module seven genes identified a median BMC of 7.5 µM, nearly the highest retene concentration with no associated teratogenicity, supporting the hypothesis that Module seven genes are largely responsible for retene toxicity.
| S-EPMC9453431 | biostudies-literature
Project description:Phenotypically anchored mRNA and miRNA expression profiling in zebrafish reveals flame retardant chemical toxicity networks
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Project description:Phenotypically Anchored Transcriptomics of Diverse Agrichemicals Revealed Congruent Pathways and Unique Gene Expression Signatures
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Project description:The ubiquitous use of flame retardant chemicals (FRCs) in the manufacture of many consumer products leads to inevitable environmental releases and human exposures. Studying toxic effects of FRCs as a group is challenging since they widely differ in physicochemical properties. We previously used zebrafish as a model to screen 61 representative FRCs and showed that many induced behavioral and teratogenic effects, with aryl phosphates identified as the most active. In this study, we selected 10 FRCs belonging to diverse physicochemical classes and zebrafish toxicity profiles to identify the gene expression responses following exposures. For each FRC, we executed paired mRNA-micro-RNA (miR) sequencing, which enabled us to study mRNA expression patterns and investigate the role of miRs as posttranscriptional regulators of gene expression. We found widespread disruption of mRNA and miR expression across several FRCs. Neurodevelopment was a key disrupted biological process across multiple FRCs and was corroborated by behavioral deficits. Several mRNAs (e.g., osbpl2a) and miRs (e.g., mir-125b-5p), showed differential expression common to multiple FRCs (10 and 7 respectively). These common miRs were also predicted to regulate a network of differentially expressed genes with diverse functions, including apoptosis, neurodevelopment, lipid regulation and inflammation. Commonly disrupted transcription factors (TFs) such as retinoic acid receptor, retinoid X receptor, and vitamin D regulator were predicted to regulate a wide network of differentially expressed mRNAs across a majority of the FRCs. Many of the differential mRNA-TF and mRNA-miR pairs were predicted to play important roles in development as well as cancer signaling. Specific comparisons between TBBPA and its derivative TBBPA-DBPE showed contrasting gene expression patterns that corroborated with their phenotypic profiles. The newer generation FRCs such as IPP and TCEP produced distinct gene expression changes compared to the legacy FRC BDE-47. Our study is the first to establish a mRNA-miR-TF regulatory network across a large group of structurally diverse FRCs and diverse phenotypic responses. The purpose was to discover common and unique biological targets that will help us understand mechanisms of action for these important chemicals and establish this approach as an important tool for better understanding toxic effects of environmental contaminants.
| S-EPMC8063052 | biostudies-literature
Project description:Triclosan (TCS) is an antimicrobial agent commonly found in a variety of personal care products and cosmetics. TCS readily enters the environment through wastewater and is detected in human plasma, urine, and breast milk due to its widespread use. Studies have implicated TCS as a disruptor of thyroid and estrogen signaling; therefore, research examining the developmental effects of TCS is warranted. In this study, we used embryonic zebrafish to investigate the developmental toxicity and potential mechanism of action of TCS. Embryos were exposed to graded concentrations of TCS from 6 to 120hours post-fertilization (hpf) and the concentration where 80% of the animals had mortality or morbidity at 120hpf (EC80) was calculated. Transcriptomic profiling was conducted on embryos exposed to the EC80 (7.37μM). We identified a total of 922 significant differentially expressed transcripts (FDR adjusted P-value≤0.05; fold change ≥2). Pathway and gene ontology enrichment analyses identified biological networks and transcriptional hubs involving normal liver functioning, suggesting TCS may be hepatotoxic in zebrafish. Tissue-specific gene enrichment analysis further supported the role of the liver as a target organ for TCS toxicity. We also examined the in vitro bioactivity profile of TCS reported by the ToxCast screening program. TCS had a diverse bioactivity profile and was a hit in 217 of the 385 assay endpoints we identified. We observed similarities in gene expression and hepatic steatosis assays; however, hit data for TCS were more concordant with the hypothesized CAR/PXR activity of TCS from rodent and human in vitro studies.
| S-EPMC5023494 | biostudies-literature
Project description:In this study, we performed RNA-seq on 5 dpf whole larvae of uhrf1-hi272 mutants and phenotypically wild-type siblings to determine changes in the transcriptomic profile.
2020-12-01 | GSE160708 | GEO
Project description:Characterizing phenotypically distinct T cell populations
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Project description:Purpose: The goals of this study are to examine mRNA and miR networks on exposures to flame retardant chemicals (FRCs), an ubiquitous group of chemicals in the environment Methods: Four biological replicates were created by pooling eight embryos per replicate from individual wells which were placed into an Eppendorf Safelock Tube and excess solution removed. 0.5 mM zirconium oxide beads were added along with 500 µL of RNAzol (Molecular Research Center, Inc.) and the tubes were immediately placed into a bullet blender (Next Advance), using settings recommended by the manufacturer. The RNA was purified using the Direct-zol MiniPrep kit (Zymo Research), including an optional DNase-1 digestion treatment for 15 minutes. RNA integrity (RIN) was assessed using an Agilent Bioanalyzer (Santa Clara, CA), and RNA samples with RIN values >8 were processed for library preparation and sequencing at the Oregon State University Center for Genome Research and Biocomputing. Total RNA was used as input for both mRNA and miRNA sequencing. For mRNA sequencing, mRNA was poly A selected, libraries were prepared with the PrepX™ mRNA and Illumina sequencing workflow (Wafergen Biosystems). For miRNA seq, the Illumina TruSeq Small RNA library kit was used to generate small RNA libraries from total RNA. For sequencing, an Illumina HiSeq 3000 sequencer (Illumina, San Diego) was used for mRNA and small RNA single-end sequencing at 100 and 50 base pairs, respectively. Bioinformatics analysis of sequencing data was performed on an R platform. Briefly, reads were evaluated by FastQC v0.11.3 to detect major sequencing problems, and then trimmed for quality control with Skewer v0.2.2 . RNA-seq alignment and quantification proceeded with Bowtie2 v2.2.3 being used to build HISAT2 (Kim et al., 2013) genome index files from the Genome Reference Consortium Zebrafish Build 10 (GRCz10) genome. For miR identification and quantification, a combination of miRDeep2 v2.0.0.8, miRBase release 22 and Bowtie v1.2.1.1 were used. Differential expression between experimental and control samples was determined with functions from the Bioconductor package, edgeR; mRNAs with a log2 fold change ≥1.5 and Benjamini-Hochberg (BH) adjusted p ≤ 0.05 were considered differentially expressed while an adjusted p ≤ 0.05 was applied to miRs without any fold change cutoffs. Heatmap clustering of differentially expressed genes were generated in R based on their log2 fold changes using the ggplot2 package. Results: We found widespread disruption of mRNA and miR expression. Neurodevelopment was a key disrupted biological process across multiple FRCs and was corroborated by behavioral deficits. Several mRNAs (eg: osbpl2a) and miRs (eg- mir-125b-5p), showed differential expression common to multiple FRCs (10 and 7 respectively). These common miRs were also predicted to regulate a network of differentially expressed genes with diverse functions, including apoptosis, neurodevelopment, lipid regulation and inflammation. Commonly disrupted transcription factors (TFs) such as RXR, RAR and VDR were predicted to regulate a wide network of differentially expressed mRNAs across a majority of the FRCs. Many of the differential mRNA-TF and mRNA-miR pairs were predicted to play important roles in development as well as cancer signaling. Specific comparisons between TBBPA and its derivative TBBPA-DBPE showed contrasting gene expression patterns that corroborated with their phenotypic profiles. The newer generation FRCs such as IPP and TCEP produced distinct gene expression changes compared to the legacy FRC BDE-47. Conclusions: Our study is the first to establish a mRNA-miR-TF regulatory network across a large group of structurally diverse FRCs and diverse phenotypic responses. The purpose was to discover common and unique biological targets that will help us understand mechanisms of action for these important chemicals.
2021-03-17 | GSE169013 | GEO
Project description:Environmental metals are known to cause harmful effects to fish of which many molecular mechanisms still require elucidation. Particularly concentration dependence of gene expression effects is unclear. Focusing on this matter, zebrafish embryo toxicity tests were used in combination with transcriptomics. Embryos were exposed to three concentrations of copper (CuSO4), cadmium (CdCl2) and cobalt (CoSO4) from just after fertilization until the end of the 48 hpf pre- and 96 hpf post-hatch stage. The RNA was then analyzed on Agilent’s Zebrafish (V3, 4x44K) arrays. Enrichment for GO terms of biological processes illustrated for cadmium that most affected GO terms were represented in all three concentrations, while for cobalt and copper most GO terms were represented in the lowest test concentration only. This suggested a different response to the non-essential cadmium than cobalt and copper. In cobalt and copper treated embryos, many developmental and cellular processes as well as the Wnt and Notch signaling pathways were found significantly enriched. Also, different exposure concentrations affected varied functional networks. In contrast, the largest clusters of enriched GO terms for all three concentrations of cadmium included responses to cadmium ion, metal ion, xenobiotic stimulus, stress and chemicals. However, concentration dependence of mRNA levels was evident for several genes in all metal exposures. Some of these genes may be indicative of the mechanisms of action of the individual metals in zebrafish embryos.
2017-08-31 | GSE101058 | GEO