Involvement of CREM in the silencing mechanism of target gene of Aryl hydrocarbon receptor

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CREMtau acts on the basic transcriptional element (BTE), which is located upstream of the CYP1A1 promoter. The results of the chromatin immunoprecipitation (ChIP) assay showed that CREMtau and Sp1 bind to BTE, but there were no changes in the amount of binding at the transcriptional state before and after the induction of transcription. In addition, histone deacetylase 1 (HDAC1) binds to this region at a transcription-suppressive state. In the transcriptionally active state, CREB-binding protein (CBP), which has histone acetyltransferase activity, binds to the site of HDAC1. Using the Re-ChIP assay, an interaction between Sp1 and HDAC1 was observed when the transcriptionally suppressed state of CYP1A1 was analyzed. In contrast, interaction between CREMtau and CBP was detected with the transcriptionally active state of CYP1A1. We performed immunoprecipitation, western blotting, and the Re-ChIP assay using an anti-phospho-Ser antibody. The results showed that the level of phosphorylation of Sp1 was changed by treatment with TCDD or OP.