Mediator and RNA polymerase II clusters associate in transcription-dependent condensates

Science. 2018 Jul 27;361(6400):412-415. doi: 10.1126/science.aar4199. Epub 2018 Jun 21.


Models of gene control have emerged from genetic and biochemical studies, with limited consideration of the spatial organization and dynamics of key components in living cells. We used live-cell superresolution and light-sheet imaging to study the organization and dynamics of the Mediator coactivator and RNA polymerase II (Pol II) directly. Mediator and Pol II each form small transient and large stable clusters in living embryonic stem cells. Mediator and Pol II are colocalized in the stable clusters, which associate with chromatin, have properties of phase-separated condensates, and are sensitive to transcriptional inhibitors. We suggest that large clusters of Mediator, recruited by transcription factors at large or clustered enhancer elements, interact with large Pol II clusters in transcriptional condensates in vivo.

Publication types

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

MeSH terms

  • Animals
  • Cells, Cultured
  • Chromatin / metabolism
  • Embryonic Stem Cells / metabolism
  • Enhancer Elements, Genetic
  • Gene Expression Regulation*
  • Luminescent Proteins / analysis
  • Luminescent Proteins / chemistry
  • Mediator Complex / analysis
  • Mediator Complex / chemistry
  • Mediator Complex / metabolism*
  • Mice
  • Molecular Imaging / methods
  • RNA Polymerase II / analysis
  • RNA Polymerase II / chemistry
  • RNA Polymerase II / metabolism*
  • Transcription Factors / metabolism*
  • Transcription, Genetic*


  • Chromatin
  • Dendra2 protein, Dendronephthya
  • Luminescent Proteins
  • Mediator Complex
  • Transcription Factors
  • RNA Polymerase II