The phosphatase PP1 sustains global transcription by promoting RNA polymerase II pause release

RNA polymerase II progression from initiation to elongation is driven in part by a cascade of protein kinases acting on the core transcription machinery. Conversely, the corresponding phosphatases, notably PP2A and PP1—the most abundant serine-threonine phosphatases in cells—are thought to mainly impede polymerase progression, respectively restraining pause release at promoters and elongation at terminators. Here, we reveal an unexpected role of PP1, within the phosphatase 1 nuclear targeting subunit (PNUTS)-PP1 complex, in sustaining global transcriptional activation in human cells. Acute disruption of PNUTS-PP1 leads to severe defects in the release of paused polymerase and subsequent downregulation for the majority of transcribed genes. PNUTS-PP1 promotes pause release by dephosphorylating multiple substrates, including the 7SK small nuclear ribonucleoprotein particle (snRNP) subunit MEPCE, a known pausing regulator. PNUTS-PP1 exhibits antagonistic functions compared with Integrator-PP2A (INTAC) phosphatase, which generally inhibits pause release. Our research thus highlights opposing roles of PP1 and PP2A in modulating genome-wide transcriptional pausing and gene expression. [Display omitted] •PNUTS-PP1 promotes the release of paused RNA Pol II to sustain global transcription•PNUTS-PP1 independently facilitates RNA Pol II release and 3′ termination•PNUTS-PP1 phosphatase targets multiple regulators of RNA Pol II•PNUTS-PP1 and INTAC phosphatases play antagonistic roles in RNA Pol II pause release The major cellular protein phosphatases are widely recognized as transcriptional repressors. However, Wang et al. identify the PP1 phosphatase as a global transcriptional activator that activates pause release by dephosphorylating multiple substrates. They also reveal that PP1 plays an antagonistic role to the other major phosphatase, PP2A, in transcriptional regulation.