Transcriptional interference: an unexpected layer of complexity in gene regulation.

Much of the genome is transcribed into long untranslated RNAs, mostly of unknown function. Growing evidence suggests that transcription of sense and antisense untranslated RNAs in eukaryotes can repress a neighboring gene by a phenomenon termed transcriptional interference. Transcriptional interference by the untranslated RNA may prevent recruitment of the initiation complex or prevent transcriptional elongation. Recent work in yeast, mammals, and Drosophila highlights the diverse roles that untranslated RNAs play in development. Previously, untranslated RNAs of the bithorax complex of Drosophila were proposed to be required for its activation. Recent studies show that these untranslated RNAs in fact silence Ultrabithorax in early embryos, probably by transcriptional interference.