Recent insights into regulation of transcription by RNA polymerase III and the cellular functions of its transcripts

The products of transcription by the multisubunit enzyme RNA polymerase III (Pol III), such as 5S rRNA, tRNAs, U6 snRNA, are important for cell growth, proliferation and differentiation. The known range of the Pol III transcriptome has expanded over recent years, and novel functions of the newly discovered and already well known transcripts have been identified, including regulation of stress responses and apoptosis. Furthermore, transcription by Pol III has turned out to be strongly regulated, differing between diverse class III genes, among cell types and under stress conditions. The mechanisms involved in regulation of Pol III transcription are being elucidated and disturbances in that regulation have been implicated in various diseases, including cancer. This review summarizes the novel data on the regulation of RNA polymerase III transcription, including epigenetic and gene specific mechanisms and outlines recent insights into the cellular functions of the Pol III transcriptome, in particular of SINE RNAs.