The regulation of elongation by eukaryotic RNA polymerase II: a recent view

The elongation of mRNA by RNA polymerase II (RNAPII) is controlled by the diverse actions of cis- and trans-acting elements that respond to a variety of biological signals. Elongation regulation, which determines the processivity of RNAPII, occurs during the steps of transcription initiation and elongation through both negative and positive influences. It has been generally accepted that negative elongation factors repress the elongation reaction. It is also generally accepted that positive elongation factors act by allowing the stalled RNAPII to escape from an inactive state, thus facilitating the production of full-length transcripts. However, recent data suggests that these opposing regulatory mechanisms can be achieved through a coupling pattern, rather than through independent activity. In addition, biochemical experiments using 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) have identified several factors involved in DRB-sensitive transcription, and elucidated the mechanism of interplay between the positive and negative elongation factors. Here, we will review the major findings from studies on RNAPII elongation control. We will further discuss the properties of newly identified factors that have resulted from studies on the action of DRB on elongation.