RESUMO
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD; dioxin), a member of a class of environmental pollutants represented by polychlorinated dibenzo-p-dioxins and dibenzofurans, is one of the most toxic artificial compounds ever developed. In this study, we identified a novel TCDD target gene, DIF-3 (dioxin inducible factor-3), by cDNA representational difference analysis. DIF-3 protein is a nuclear factor and possesses a zinc-finger motif at its N-terminus. High DIF-3 mRNA expression in the testes was demonstrated by Northern blot analysis and abundant DIF-3 protein was detected during spermatogenesis. Thus, these results suggest that DIF-3 may be a target gene mediating the reproductive toxicity induced by TCDD.
Assuntos
Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Proteínas Nucleares/genética , Dibenzodioxinas Policloradas/farmacologia , Espermatogênese , Animais , Animais Recém-Nascidos , Northern Blotting , Western Blotting , Linhagem Celular , DNA Complementar , Etiquetas de Sequências Expressas , Técnica Indireta de Fluorescência para Anticorpo , Perfilação da Expressão Gênica , Masculino , Camundongos , Dados de Sequência Molecular , Peso Molecular , Proteínas Nucleares/análise , Proteínas Nucleares/química , Proteínas Nucleares/fisiologia , Análise de Sequência com Séries de Oligonucleotídeos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Células-Tronco , Testículo/metabolismo , Dedos de ZincoRESUMO
The compound 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has been shown recently to be carcinogenic, but little is currently known about the molecular mechanism of TCDD affecting cell proliferation and carcinogenesis. In this report, we demonstrate that TCDD suppresses the expression of the checkpoint protein, Mad2. Suppression of Mad2 was also observed in aryl hydrocarbon receptor-deficient mouse embryonic fibroblasts, suggesting that TCDD suppresses Mad2 by a novel TCDD receptor signaling mechanism. In addition, HeLa cells treated with TCDD failed to arrest in mitosis after nocodazole treatment. The Mad2 protein plays a significant role in accurate chromosome segregation in mitotic cells. Our data suggest that TCDD may increase chromosomal instability through the suppression of Mad2 expression.
