title: Analysis of 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced gene expression profile in vivo using pathway-specific cDNA arrays.
abstract: In the current study, we used pathway-specific cDNA arrays to detect the transcriptional signature induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in vivo by studying simultaneously the expression profiles of 83 genes involved in apoptosis, cytokine production and angiogenesis. To this end, C57BL/6 mice were injected i.p. with 50 microg/kg body weight of TCDD and 1 or 3 days later, the thymus was analyzed for gene expression profiles. In the thymus, 23 out of 37 apoptotic genes screened were up-regulated by TCDD by a factor of two or more when compared to the vehicle-treated controls. In contrast, in the spleen, 20 out of 22 and in the liver, 16 out of 37 apoptotic genes were up-regulated. In the thymus, several genes encoding caspases, and members of the TNF family, including Fas ligand, were induced. Also, in the thymus, eight out of 23, and in the spleen, six out of 23 cytokine genes were up-regulated. In the liver and to a lesser extent in the thymus, certain angiogenesis genes were induced while others were repressed. When mice were injected with 0.1, 1, 10 or 50 microg/kg body weight of TCDD and the thymus was analyzed for apoptotic genes 1 day later, a dose-dependent response was not seen with most apoptotic genes. However, certain apoptotic genes were induced in the thymus even at low doses of 0.1 microg/kg body weight of TCDD. These data demonstrate that TCDD alters the expression of a large array of genes involved in apoptosis, cytokine production and angiogenesis. Thus, pathway-specific cDNA arrays may help in the identification of specific gene expression profiles induced by xenobiotics and to delineate the molecular mechanisms of toxicity.
authors.affiliation: Department of Microbiology and Immunology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA 23113, USA.
authors.forename: Ahmet
authors.initials: A
authors.lastname: Zeytun
authors.forename: Robert J
authors.initials: RJ
authors.lastname: McKallip
authors.forename: Michael
authors.initials: M
authors.lastname: Fisher
authors.forename: Iris
authors.initials: I
authors.lastname: Camacho
authors.forename: Mitzi
authors.initials: M
authors.lastname: Nagarkatti
authors.forename: Prakash S
authors.initials: PS
authors.lastname: Nagarkatti
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics*; D016207:Cytokines / Q000096:biosynthesis; D004785:Environmental Pollutants / Q000633:toxicity*; D005260:Female; D020869:Gene Expression Profiling; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D020411:Oligonucleotide Array Sequence Analysis; D000072317:Polychlorinated Dibenzodioxins / Q000633:toxicity*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013154:Spleen / Q000187:drug effects / Q000378:metabolism; D013950:Thymus Gland / Q000187:drug effects / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D016207:Cytokines; D004785:Environmental Pollutants; D000072317:Polychlorinated Dibenzodioxins