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

Swagat Ray, Tatiana Panova, Gail Miller, Arsen Volkov, Andrew C G Porter, Jackie Russell, Konstantin I Panov, Joost C B M Zomerdijk

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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 IIa 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 IIa is a component of the initiation-competent RNA polymerase Iß 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 IIa functions in RNA polymerase I transcription to produce topological changes at the rDNA promoter that facilitate efficient de novo pre-initiation complex formation.
Original languageEnglish
Article number1598
Number of pages12
JournalNature Communications
Volume4
DOIs
Publication statusPublished - 19 Mar 2013

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