Regulation of RNA polymerase III transcription by DNA methylation and chromatin

Mammalian genomes contain huge numbers of short interspersed elements (SINEs). An extreme case is provided by the human genome, which carries ~106 copies of Alu SINEs that together account for ~10% of total chromosomal DNA. SINEs spread by retrotransposition, which depends on their transcription by pol III. This transcription is heavily suppressed. Silencing is thought to involve DNA methylation and packaging the SINEs into chromatin structures that deny access of transcription factors. It has been argued that this may be of great importance to prevent SINEs from competing with essential genes for a limited pool of transcription machinery. Our investigation of this has revealed some unexpected findings. This study has also investigated the effects of SWI/SNF chromatin remodellers on tRNA transcription