The effect of PCBs in TR-mediated transcription on native-TRE

Abstract

Polychlolinated biphenyls(PCBs) are known as environmental contaminants that cause various effects in many organs including the central nerves system.We have previously reported that PCB5005 (hydroxylated PCB) suppressed Thyroid hormone(TH) receptor (TR)-mediated transcription on several artificial TH-response elements (TREs).In this study, we examined TR-mediated transcription on native TRE. We used malic enzyme (ME) response element contains three TRE half sites. Transcriptional activity of ME was measured by using transient transfection based repotor gene assay in fibroblast-derived clonal cells (CV-1) and neuroblastoma-derived clonal cells (TE671).TR-mediated transcription was suppressed by PCB5005.However PCB6002 did not affect on the transcription.On the other hand, PCB187 induced the TR-mediated transcription congeners.Next, to study the effects of these congeners on endogenous ME gene expression, we applied the reverse-transcriptional polymerase chain reaction (RT-PCR). PCB5005 exposure suppressed the expression of ME mRNA. These results indicate that exposure of PCBs affects TR-mediated transcription on native promoter. [J Physiol Sci. 2006;56 Suppl:S216]