title: Genome-wide screening of dioxin-responsive genes in fetal brain: bioinformatic and experimental approaches.
abstract: Many of the effects of dioxins, which are potent environmental pollutants and teratogens, are mediated through the aryl hydrocarbon receptor, also known as the dioxin receptor. The purpose of the present study was to characterize dioxin-responsive genes in a comprehensive manner using two complementary approaches: bioinformatic analysis and microarray analysis. First, we characterized the overall distribution of the cis-regulatory element for the dioxin-responsive element sequence (DRE) 'gcgtg' within putative promoter regions. We assembled the upstream sequences 10 kb from the transcription start site and evaluated their location and frequency in the human and mouse genomes. Second, we characterized the expression profile of mouse embryonic day 12 fetal brain exposed to 2,3,7,8-tetrarchlorodibenzo-p-dioxin. The distributions of 26,680 DREs among 2,843 human genes and 98,711 DREs among 18,541 mouse genes were examined. In both species, the DREs tended to be located close to the transcription start site. Forty genes exhibited significant induction or repression following dioxin exposure in fetal mice. The set of genes exhibited a strong functional coherence, with statistically significant enrichment in organogenesis and the DNA-dependent regulation of transcription, according to Gene Ontology annotations. In both humans and mice, DREs were preferentially distributed close to transcription start sites. Evolutionary conservation of this unique DRE distribution pattern suggests that DREs may be involved in transcriptional regulation. In mice, prenatal dioxin exposure altered the expression of 10 transcription factors, many of which have been documented to play a role in organogenesis. These genes may represent potential mediators of dioxin's effects in fetal tissues.
authors.affiliation: Department of Pediatrics, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Fujita
authors.forename: Hazuki
authors.initials: H
authors.lastname: Samejima
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Kitagawa
authors.forename: Takayuki
authors.initials: T
authors.lastname: Mitsuhashi
authors.forename: Takanori
authors.initials: T
authors.lastname: Washio
authors.forename: Junzo
authors.initials: J
authors.lastname: Yonemoto
authors.forename: Masaru
authors.initials: M
authors.lastname: Tomita
authors.forename: Takao
authors.initials: T
authors.lastname: Takahashi
authors.forename: Kenjiro
authors.initials: K
authors.lastname: Kosaki
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects / Q000196:embryology* / Q000378:metabolism; D019295:Computational Biology; D017124:Conserved Sequence; D004785:Environmental Pollutants / Q000633:toxicity*; D005260:Female; D005333:Fetus / Q000033:anatomy & histology; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects*; D016678:Genome; D015894:Genome, Human; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D020411:Oligonucleotide Array Sequence Analysis; D000072317:Polychlorinated Dibenzodioxins / Q000633:toxicity*; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D011401:Promoter Regions, Genetic; D018336:Receptors, Aryl Hydrocarbon; D013723:Teratogens / Q000633:toxicity*; D024363:Transcription Initiation Site
chemical_list: D004785:Environmental Pollutants; D000072317:Polychlorinated Dibenzodioxins; D018336:Receptors, Aryl Hydrocarbon; D013723:Teratogens