BioProject

Although many drugs and environmental chemicals are teratogenic, the mechanisms by which most toxicants disrupt embryonic development are not well understood. More...

Although many drugs and environmental chemicals are teratogenic, the mechanisms by which most toxicants disrupt embryonic development are not well understood. microRNAs (miRNAs), single-stranded RNA molecules of ~22 nt that regulate protein expression by inhibiting mRNA translation and promoting mRNA sequestration or degradation, are important regulators of a variety of cellular processes including embryonic development and cellular differentiation. We hypothesized that exposure to xenobiotics can alter miRNA expression and contribute to the mechanisms by which environmental chemicals disrupt embryonic development. To test this hypothesis for one well-known teratogen, we exposed zebrafish embryos to DMSO (0.1%) or TCDD (5 nM) for 1 hr at 30 hours post fertilization (hpf) and measured microRNA expression using several methods at 36 and 60 hpf. TCDD caused strong induction of CYP1A at 36 hpf (62-fold) and 60 hpf (135-fold) as determined by qPCR, verifying the effectiveness of the exposure. microRNA expression profiles were determined using microarrays (Agilent and Exiqon), next-generation sequencing (SOLiD) and real time RT-PCR. The two microarray platforms yielded results that were similar but not identical; both showed significant changes in expression of miR-451, 23a, 23b, 24 and 27e at 60 hpf. Multiple analyses were performed on the SOLiD sequences yielding a total of 16 miRNAs as potentially differentially expressed by TCDD in zebrafish embryos. However, miR-27e was the only miRNA to be identified as differentially expressed by all three methods (both microarrays, SOLiD sequencing, and qPCR). These results suggest that TCDD exposure causes modest changes in expression of microRNAs, including some (miR-451, 23a, 23b, 24 and 27e) that are critical for hematopoiesis and cardiovascular development. Overall design: MicroRNA profiling was performed (N=3 biological replicates per group) using custom designed Agilent miRNA microarrays (8x15K) and exiqon miRCURY LNA microarrays. Custom-made Agilent oligonucleotide miRNA microarrays were designed based on zebrafish mature miRNA sequences from miRbase v.16. Each individual array contained a total of 548 unique probes representing 259 mature miRNAs from zebrafish (245), Fugu rubripes (11) and Tetraodon nigriviridis (3). Exiqon miRNA probes were based on zebrafish miRNA sequences from miRbase v. 12. Less...