Actin is part of pre-initiation complexes and is necessary for transcription by RNA polymerase II

Nat Cell Biol. 2004 Nov;6(11):1094-101. doi: 10.1038/ncb1182. Epub 2004 Oct 24.


Actin is abundant in the nucleus and has been implicated in transcription; however, the nature of this involvement has not been established. Here we demonstrate that beta-actin is critically involved in transcription because antibodies directed against beta-actin, but not muscle actin, inhibited transcription in vivo and in vitro. Chromatin immunoprecipitation assays demonstrated the recruitment of actin to the promoter region of the interferon-gamma-inducible MHC2TA gene as well as the interferon-alpha-inducible G1P3 gene. Further investigation revealed that actin and RNA polymerase II co-localize in vivo and also co-purify. We employed an in vitro system with purified nuclear components to demonstrate that antibodies to beta-actin block the initiation of transcription. This assay also demonstrates that beta-actin stimulates transcription by RNA polymerase II. Finally, DNA-binding experiments established the presence of beta-actin in pre-initiation complexes and also showed that the depletion of actin prevented the formation of pre-initiation complexes. Together, these data suggest a fundamental role for actin in the initiation of transcription by RNA polymerase II.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Actins / physiology*
  • Base Sequence
  • DNA Primers
  • HeLa Cells
  • Humans
  • Mitochondrial Proteins
  • Nuclear Proteins / genetics
  • Promoter Regions, Genetic
  • Proteins / genetics
  • RNA Polymerase II / physiology*
  • Trans-Activators / genetics
  • Transcription, Genetic / physiology*


  • Actins
  • DNA Primers
  • IFI6 protein, human
  • MHC class II transactivator protein
  • Mitochondrial Proteins
  • Nuclear Proteins
  • Proteins
  • Trans-Activators
  • RNA Polymerase II