Transcription elongation mechanisms that control gene expression in erythropoiesis.

The regulation of RNA transcript abundance relies on the control of two key early steps in gene expression: transcription initiation and productive elongation. Although DNA-directed RNA polymerase provides the intrinsic catalytic activity required for RNA synthesis, its ability to effectively produce a transcript relies on accurate recruitment to specific DNA sites to initiate RNA polymerization, followed by release from promoter-proximal pausing into a productive elongation machine. These steps are governed by accessory factors that not only facilitate the assembly of a functional pre-initiation complex but also exert both negative and positive control over polymerase pause/elongation status. We describe experiments that have elucidated these mechanisms in the context of erythropoiesis.