Actin is closely associated with RNA polymerase II and involved in activation of gene transcription

Biochem Biophys Res Commun. 2004 Aug 27;321(3):623-30. doi: 10.1016/j.bbrc.2004.05.229.


Biochemical and morphological studies have demonstrated the presence of actin in the nucleus of different eukaryotic cells, whereas its role remains unclear. In this work, we studied the interaction and the functional relationship between nuclear actin and RNA polymerase II (RNAP II). The immunofluorescence study demonstrated a clear co-localization of nuclear actin with RNAP II in HeLa cells. Meanwhile, actin can be immunoprecipitated by anti-RNAP II antibody, indicating that they could interact with each other. Treatment of cells with alpha-amanitin induced the formation of actin bundle network in the nucleoplasm. Blocking of the formation of filamentous actin (F-actin) by cytochalasin B modified the distribution of actin. Although the actin content remained unchanged in resting and concanavalinA stimulated mouse lymphocytes, the actin content in the nuclei showed a progressive increase after stimulation. Furthermore, the antibody against actin blocked RNA synthesis in a eukaryotic in vitro transcription system. These observations implicate that nuclear actin interacts with RNAP II and may have function on the RNAP II-mediated transcription.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / metabolism*
  • Amanitins / metabolism
  • Animals
  • Cell Nucleus / metabolism
  • Cells, Cultured
  • Concanavalin A / pharmacology
  • Cytochalasin B / metabolism
  • Gene Expression Regulation*
  • HeLa Cells
  • Humans
  • Lymphocyte Activation
  • Mice
  • Nuclear Proteins / metabolism
  • Nucleic Acid Synthesis Inhibitors / metabolism
  • RNA Polymerase II / metabolism*
  • T-Lymphocytes / cytology
  • T-Lymphocytes / drug effects
  • T-Lymphocytes / metabolism
  • Transcription, Genetic*


  • Actins
  • Amanitins
  • Nuclear Proteins
  • Nucleic Acid Synthesis Inhibitors
  • Concanavalin A
  • Cytochalasin B
  • RNA Polymerase II