| Budget Amount *help |
¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000)
Fiscal Year 2010: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
Fiscal Year 2009: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000)
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| Research Abstract |
MicroRNA (miRNA) is a class of small RNA that functions as a negative regulator of gene expression. Human and mouse genomes encode over 1,400 and 700 miRNAs, respectively, and most of the cellular pathways are considered to be modulated by miRNAs. However, it is still largely unknown about the pathophysiological role of miRNAs. Thus, we investigated the possible involvement of miRNAs in the toxic responses to xenobiotic chemicals.
Here, we searched for miRNAs responsible for inducing liver damage in mice exposed to 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD) and found that miR-101a and miR-122 are differentially downregulated by TCDD in a time-dependent manner. Since miRNA exerts multiple actions by repressing its target genes, we quantified the target genes of miR-101a, such as cyclooxygenase-2 (COX-2), enhancer of zeste homolog 2 (EZH2), and cFos, and found the upregulation of these genes, which suggests that miR-101a downregulates the expressions of these genes in the mouse liver. A COX-2 selective inhibitor, NS-398, suppressed the onset of TCDD-induced liver damage. In conclusion, this study demonstrated that TCDD dysregulates the expression of miR101a and miR122, and that COX-2, a target gene of miR101a, plays a significant role in liver damage in mice exposed to TCDD.
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