Transcriptional Responses to IFN-γ Require Mediator Kinase-Dependent Pause Release and Mechanistically Distinct CDK8 and CDK19 Functions

Mol Cell. 2019 Nov 7;76(3):485-499.e8. doi: 10.1016/j.molcel.2019.07.034. Epub 2019 Sep 5.


Transcriptional responses to external stimuli remain poorly understood. Using global nuclear run-on followed by sequencing (GRO-seq) and precision nuclear run-on sequencing (PRO-seq), we show that CDK8 kinase activity promotes RNA polymerase II pause release in response to interferon-γ (IFN-γ), a universal cytokine involved in immunity and tumor surveillance. The Mediator kinase module contains CDK8 or CDK19, which are presumed to be functionally redundant. We implemented cortistatin A, chemical genetics, transcriptomics, and other methods to decouple their function while assessing enzymatic versus structural roles. Unexpectedly, CDK8 and CDK19 regulated different gene sets via distinct mechanisms. CDK8-dependent regulation required its kinase activity, whereas CDK19 governed IFN-γ responses through its scaffolding function (i.e., it was kinase independent). Accordingly, CDK8, not CDK19, phosphorylates the STAT1 transcription factor (TF) during IFN-γ stimulation, and CDK8 kinase inhibition blocked activation of JAK-STAT pathway TFs. Cytokines such as IFN-γ rapidly mobilize TFs to "reprogram" cellular transcription; our results implicate CDK8 and CDK19 as essential for this transcriptional reprogramming.

Keywords: CDK19; CDK8; Mediator kinase; RNA polymerase II; STAT1; cortistatin A; eRNA; interferon; promoter-proximal pausing; transcription.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cyclin-Dependent Kinase 8 / genetics
  • Cyclin-Dependent Kinase 8 / metabolism*
  • Cyclin-Dependent Kinases / genetics
  • Cyclin-Dependent Kinases / metabolism*
  • Fibroblasts / drug effects*
  • Fibroblasts / enzymology
  • Fibroblasts / virology
  • HCT116 Cells
  • Host-Pathogen Interactions
  • Humans
  • Interferon-gamma / pharmacology*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Phosphorylation
  • RNA Polymerase II / metabolism
  • STAT1 Transcription Factor / metabolism
  • Signal Transduction
  • Transcription, Genetic / drug effects*
  • Vesiculovirus / pathogenicity


  • IFNG protein, human
  • IFNG protein, mouse
  • STAT1 Transcription Factor
  • STAT1 protein, human
  • Stat1 protein, mouse
  • Interferon-gamma
  • CDK19 protein, human
  • CDK19 protein, mouse
  • CDK8 protein, human
  • Cdk8 protein, mouse
  • Cyclin-Dependent Kinase 8
  • Cyclin-Dependent Kinases
  • RNA Polymerase II