Topoisomerase IIα promotes activation of RNA polymerase I transcription by facilitating pre-initiation complex formation

Nat Commun. 2013;4:1598. doi: 10.1038/ncomms2599.

Abstract

Type II DNA topoisomerases catalyse DNA double-strand cleavage, passage and re-ligation to effect topological changes. There is considerable interest in elucidating topoisomerase II roles, particularly as these proteins are targets for anti-cancer drugs. Here we uncover a role for topoisomerase IIα in RNA polymerase I-directed ribosomal RNA gene transcription, which drives cell growth and proliferation and is upregulated in cancer cells. Our data suggest that topoisomerase IIα is a component of the initiation-competent RNA polymerase Iβ complex and interacts directly with RNA polymerase I-associated transcription factor RRN3, which targets the polymerase to promoter-bound SL1 in pre-initiation complex formation. In cells, activation of rDNA transcription is reduced by inhibition or depletion of topoisomerase II, and this is accompanied by reduced transient double-strand DNA cleavage in the rDNA-promoter region and reduced pre-initiation complex formation. We propose that topoisomerase IIα functions in RNA polymerase I transcription to produce topological changes at the rDNA promoter that facilitate efficient de novo pre-initiation complex formation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antigens, Neoplasm / metabolism*
  • DNA / metabolism
  • DNA Topoisomerases, Type II / metabolism*
  • DNA-Binding Proteins / metabolism*
  • Enzyme Activation
  • Hydrolysis
  • Promoter Regions, Genetic
  • RNA Polymerase I / genetics*
  • Transcription, Genetic*

Substances

  • Antigens, Neoplasm
  • DNA-Binding Proteins
  • DNA
  • RNA Polymerase I
  • DNA Topoisomerases, Type II