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Identification and characterization of androgen responsive biomarker genes in zebrafish embryos

ABSTRACT: Exposure experiments with the non-aromatizable fish androgen, 11-ketotestosterone in the range of 0.05-5000 nM were conducted in order to identify potential androgen-responsive genes in zebrafish embryos by microarray analysis. Zebrafish embryos were treated from 96 hpf to 120 hpf in a single experiment with three controls (embryonic medium). Microarray studies were performed using a Custom 8x60k Gene Expression Microarrays (Amadid G4102A, based on the ensembl zebrafish genome version 3) from total RNA with low input labelling and hybridization kit (Agilent Technologies) and one-color design according to the manufacturer instructions. Fluorescent intensities of individual microarray spots were extracted using the Agilent Feature Extraction software. Raw microarray data were converted to log2 values and quantile-normalized. For further statistical analysis, fold changes in relation to the mean of the controls were calculated for each treatment.

ORGANISM(S): Danio rerio

PROVIDER: GSE59499 | GEO | 2014/09/30

SECONDARY ACCESSION(S): PRJNA255434

REPOSITORIES: GEO

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Project description:Congenital malformations are a prevalent cause of infant mortality in the United States and their induction has been linked to a variety of factors, including exposure to teratogens. However, the molecular mechanisms of teratogenicity are not fully understood. MicroRNAs are an important group of small, non-coding RNAs that regulate mRNA expression. MicroRNA roles in early embryonic development are well established, and their disruption during development can cause abnormalities. We hypothesized that developmental exposure to teratogens such as valproic acid alters microRNA expression profiles in developing embryos. Valproic acid is an anticonvulsant and mood-stabilizing drug used to treat epilepsy, bipolar disorder and migraines. To examine the effects of valproic acid on microRNA expression during development, we used zebrafish embryos as a model vertebrate developmental system. Zebrafish embryos were continuously exposed to valproic acid (1 mM) or vehicle control (ethanol) starting from 4 hours post-fertilization (hpf) and sampled at 48 and 96 hpf to determine the miRNA expression profiles prior to and after the onset of developmental defects. At 96 hpf, 95% of the larvae showed skeletal deformities, abnormal swimming behavior, and pericardial effusion. Microarray expression profiling was done using Agilent zebrafish miRNA microarrays. Microarray results revealed changes in miRNA expression at both the time points. Thirteen miRNAs were differentially expressed at 48 hpf and 22 miRNAs were altered at 96 hpf. Among them, six miRNAs (miR-16a, 18c, 122, 132, 457b, and 724) were common to both time points. Bioinformatic target prediction and examination of published literature revealed that these miRNAs target several genes involved in the normal functioning of the central nervous system. These results suggest that the teratogenic effects of valproic acid could involve altered miRNA expression. Small RNA profiles were deteremined in valproic acid exposed zebrafish embryos using Agilent miRNA microarrays

Project description:The MTF-1 transcription factor is considered to be a master regulator of zinc homoestasis. We previously characterized a constitutively nuclear, dominant-negative zebrafish MTF-1/eGFP fusion protein (dnMTF-1). In this study, in vitro transcribed dnMTF-1 mRNA was microinjected into zebrafish embryos (2-cell stage), with controls consisting of zebrafish embryos (2-cell stage) microinjected with in vitro transcribed enhanced green fluorescent protein (eGFP) mRNA. Transcriptomic profiling was performed using an Agilent 4 x 44K array on 4 replicate pools of thirty 28- and 36-hpf embryos for each treatment. The role of MTF-1 signaling in zebrafish embryos was examined by injection of in vitro transcribed dnMTF-1 mRNA into zebrafish embryos (2-cell stage), with controls consisting of zebrafish embryos (2-cell stage) microinjected with in vitro transcribed enhanced green fluorescent protein (eGFP) mRNA. Transcriptomic profiling was performed using an Agilent 4 x 44K array on 4 replicate pools of thirty 28- and 36-hpf embryos for each treatment. A Narishige IM-300 microinjector was used to microinject 1-2 cell embryos with ~100 pg of dnMTF-1 IVT mRNA (~2.1 nL microinjection volume with a concentration 50 ng/M-BM-5L IVT mRNA), or ~100 pg of enhanced green fluorescent protein (eGFP) IVT mRNA. Immediately after microinjection, embryos from each treatment were divided into 4 replicates of 30 pooled embryos and held in 25 mL of 0.3X DanieauM-bM-^@M-^Ys at 28.5M-BM-0C under a 14 hour light/10 hour dark cycle. eGFP positive embryos (dnMTF-1 and eGFP) were collected at 28 and 36 hpf and flash frozen in liquid nitrogen for future RNA isolation and microarray hybridization. Total RNA was prepared using the RNA STAT60 protocol (Tel-Test, Inc., TX). RNA was quantified using a Nanodrop 2000C spectrophotometer and assessed for quality using an Agilent 2100 Bioanalyzer Lab-on-chip system. Only samples with RNA integrity number (RIN) between 9.8-10 were used for microarray analysis. For each RNA sample, a single microarray was hybridized with 750 ng Cy3 labeled cDNA using AgilentM-bM-^@M-^Ys standard conditions for single-color microarrays. The samples were hybridized to a the Agilent 4x44K feature zebrafish microarray using the Agilent In situ Hybridization Kit Plus by the Genome Technology Core at the Whitehead Institute for Biomedical Research (Cambridge, MA). Post-hybridization, microarray slides were washed as per the Agilent In situ Hybridization Kit Plus and scanned with an Agilent DNA Microarray Scanner. Extraction of raw microarray results was performed using AgilentM-bM-^@M-^Ys Feature Extraction software with background detrending (spatial and multiplicative). The data were normalized using a non-linear scaling method based on rank invariant probes. Cy3 signal saturated probes and probes not above background in all replicated were then removed prior to statistical analysis. Statistical tests were performed using the MeV microarray analysis suite. All data were log transformed and median centered for each probe. A two-factor ANOVA was performed for time (28 vs. 36 hpf), treatment (dnMTF-1 vs. eGPF), and their interaction with p-value based on 1000 permutations of the data and alpha of 0.01. For post-hoc analyses to find biologically relevant results, the probes significant for treatment and time-treatment interaction were secondarily examined using Rank Product (RP) analysis. Rank product analysis was performed to provide lists of probes up- and down-regulated between GFP control and MTF-1 for each time point. For each test, a two-class unpaired RP analysis was performed using 1000 permutation of the data with a false discovery rate (FDR) not exceeding 5%.

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Identification and characterization of androgen responsive biomarker genes in zebrafish embryos

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