Control of non-productive RNA polymerase II transcription via its early termination in metazoans

Transcription establishes the universal first step of gene expression where RNA is produced by a DNA-dependent RNA polymerase. The most versatile of eukaryotic RNA polymerases, RNA polymerase II (Pol II), transcribes a broad range of DNA including protein-coding and a variety of non-coding transcription units. Although Pol II can be configured as a durable enzyme capable of transcribing hundreds of kilobases, there is reliable evidence of widespread abortive Pol II transcription termination shortly after initiation, which is often followed by rapid degradation of the associated RNA. The molecular details underlying this phenomenon are still vague but likely reflect the action of quality control mechanisms on the early Pol II complex. Here, we summarize current knowledge of how and when such promoter-proximal quality control is asserted on metazoan Pol II.