Coordinated regulation of RNA polymerase II pausing and elongation progression by PAF1

Pleiotropic transcription regulator RNA polymerase II (Pol II)-associated factor 1 (PAF1) governs multiple transcriptional steps and the deposition of several epigenetic marks. However, it remains unclear how ultimate transcriptional outcome is determined by PAF1 and whether it relates to PAF1-controlled epigenetic marks. We utilize rapid degradation systems and reveal direct PAF1 functions in governing pausing partially by recruiting Integrator-PP2A (INTAC), in addition to ensuring elongation. Following acute PAF1 degradation, destabilized polymerase undergoes early termination or effective release, which presumably relies on skewed balance between INTAC and P-TEFb resulting in hyperphosphorylated substrates including SPT5. Impaired Pol II progression during elongation, along with altered pause release frequency, determines the final transcriptional outputs. Moreover, PAF1 degradation causes a cumulative decline in histone modifications. These epigenetic alterations in chromatin likely further influence the production of transcripts from PAF1 target genes. We performed PRO-seq, ChIP-seq, or TT-seq to investigate the role of PAF1 in regulating transcription. In this study, samples for each condition were collected in biological duplicates. Cells were treated with dTAG13 for 3,or 24 hours, the corresponding control cells were treated for the same duration with vehicle only (DMSO) at the same vol/vol dilution.