Isoflavones Regulate Target Genes Transcription Through Estrogen Receptors

The two isoflavones Genistein and daidzein can bind to estrogen receptors and induce estrogenic effects. A better understanding of the mechanisms of these two phytoestrogens will offer criterions for its pharmacological use. So in this study we used Hela cells as the model system to exam their transcriptional regulation of taget genes and the related molecular mechanisms. Our results showed that both genistein and daidzein could transactivate ERE reportor gene through ER α and ER β . After further investigation about the effects of ER α domains on the transactivation, we found ER α A/B may play a negative role in the activativation of ERE reportor gene, DNA binding dormain was independent to the transactivation and ligand bingding dormain especially AF-2 was the key dormain for the transactive induction. In our study, no stronger transactivation was seen by genistein and daidzein in the presence of SRC-1 and TIF-2. Genistein and daidzein all could inhibit the transcription of CRE reporter gene through ER α , but neither genistein nor daidzein could regulate transcription of CRE reporter gene through ER β .