Transcriptional activation of a gene involves the ordered recruitment of basal transcriptional machinery as well as the formation of a transcriptionally permissive chromatin structure generated by posttranslational histone modifications and nucleosome remodelling. Activation of the estrogen-responsive gene pS2 has additionally demonstrated a requirement for cyclical changes in the DNA methylation of promoter CpGs. The proteins mediating DNA methylation have been discovered, however the identification of DNA demethylases in humans has remained problematic. The recent discovery that DNA methyl groups can be oxidised to hydroxymethyl groups by the TET family of proteins raises a possible mechanism whereby the transcriptionally repressive methyl mark can effectively be removed from promoters.
This project will focus on identifying the factors involved in the regulation of expression of estrogen-responsive genes in breast cancer cell lines, with emphasis on those mediating DNA methylation and hydroxymethylation. Inhibitors of these factors will be used in order to establish their ability to interfere with the dynamics of ER-regulated transcription.