A mammalian bromodomain protein, Brd4, interacts with replication factor C and inhibits progression to S phase

Tetsuo Maruyama, Andrea Farina, Anup Dey, Jae Hun Cheong, Vladimir P. Bermudez, Tomohiko Tamura, Selvaggia Sciortino, Jon Shuman, Jerard Hurwitz, Keiko Ozato

Research output: Contribution to journalArticlepeer-review

123 Citations (Scopus)


Brd4 belongs to the BET family of nuclear proteins that carry two bromodomains implicated in the interaction with chromatin. Expression of Brd4 correlates with cell growth and is induced during early G1 upon mitogenic stimuli. In the present study, we investigated the role of Brd4 in cell growth regulation. We found that ectopic expression of Brd4 in NIH 3T3 and HeLa cells inhibits cell cycle progression from G1 to S. Coimmunoprecipitation experiments showed that endogenous and transfected Brd4 interacts with replication factor C (RFC), the conserved five-subunit complex essential for DNA replication. In vitro analysis showed that Brd4 binds directly to the largest subunit, RFC-140, thereby interacting with the entire RFC. In line with the inhibitory activity seen in vivo, recombinant Brd4 inhibited RFC-dependent DNA elongation reactions in vitro. Analysis of Brd4 deletion mutants indicated that both the interaction with RFC-140 and the inhibition of entry into S phase are dependent on the second bromodomain of Brd4. Lastly, supporting the functional importance of this interaction, it was found that cotransfection with RFC-140 reduced the growth-inhibitory effect of Brd4. Taken as a whole, the present study suggests that Brd4 regulates cell cycle progression in part by interacting with RFC.

Original languageEnglish
Pages (from-to)6509-6520
Number of pages12
JournalMolecular and cellular biology
Issue number18
Publication statusPublished - 2002 Sept
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


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