Primed to Burst: Corepressors Coordinate Transcriptional Activation and Efficient Switching Between Cell States.

Recapitulation of the nuclear auxin response pathway in yeast led to the hypothesis that corepressors prime loci for rapid bursts of transcription. Specifically, the TPL corepressor, which inhibits transcription in the absence of auxin, interfaces with Mediator and core components of the transcription pre-initiation complex (PIC). Once auxin is perceived, RNA Pol-II is likely to essentially displace TPL, allowing for rapid transcription initiation (and likely re-firing). Here, we present the current evidence supporting the role of TPL-type corepressors in multiple levels of transcriptional control, including modulation of regulatory transcription factor activity, interactions between cis-elements and the core promoter, and in organizing multiple loci within the nucleoplasm. We also highlight critical areas for future investigations.