Dataset Information


Micro-RNAs in Adult Rat Liver are Refractory to 19 Hours Dioxin Exposure

ABSTRACT: Dioxin-like chemicals are well-known for their ability to upregulate expression of numerous genes via the AH receptor (AHR). However, recent transcriptomic analyses in several laboratories indicate that dioxin-like chemicals or AHR genotype itself also can downregulate levels of mRNAs encoded by numerous genes. The mechanism responsible for such downregulation is unknown. We hypothesized that microRNAs (miRNAs), which have emerged as powerful negative regulators of mRNA levels in several systems, might be responsible for mRNA downregulation in dioxin/AHR pathways. We used the Ambion miRNA array platform as well as quantitative RT-PCR to measure miRNA levels in dioxin-sensitive Long-Evans (Turku/AB; L-E) rats vs. dioxin-resistant Han/Wistar(Kuopio; H/W) rats. Treatment with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in vivo caused no significant changes in miRNA levels in rat livers. AHR genotype had no effect on hepatic miRNA levels in response to TCDD – no miRNAs differed in expression between between L-E rats (that have wildtype AHR) compared to H/W rats (whose AHR has a large deletion in the transactivation domain). It is unlikely that mRNA downregulation by dioxins is mediated by miRNAs, nor are miRNAs likely to play a significant role in dioxin toxicity in adult rodent liver. Manuscript Submitted: Moffat ID, Boutros PC, Celius T, Pohjanvirta R & Okey AB. Micro-RNAs in rodent liver are refractory to dioxin treatment. Toxicological Sciences May, 2007. Keywords: miRNA expression, response to xenobiotics, genetic modification, comparative genome hybridization Overall design: In the dioxin-sensitive L-E rats we compared miRNA expression levels 19 h post-TCDD treatment vs. corn oil vehicle treatment. In the dioxin-resistant H/W rats we compared miRNA levels 19 h post-TCDD treatment vs.corn oil vehicle treatment.

INSTRUMENT(S): Ambion Human_Mouse_Rat mirVana miRNA Bioarray_1566V1

ORGANISM(S): Rattus norvegicus  

SUBMITTER: Ivy Moffat  

PROVIDER: GSE8467 | GEO | 2007-08-15



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