The conserved MRE11-RAD50-NBS1 (MRN) complex is an important sensor of DNA double-strand breaks (DSBs) and facilitates DNA repair by homologous recombination (HR) and end joining. Here, we identify NBS1 as a target of cyclin-dependent kinase (CDK) phosphorylation. We show that NBS1 serine 432 phosphorylation occurs in the S, G2 and M phases of the cell cycle and requires CDK activity. This modification stimulates MRN-dependent conversion of DSBs into structures that are substrates for repair by HR. Impairment of NBS1 phosphorylation not only negatively affects DSB repair by HR, but also prevents resumption of DNA replication after replication-fork stalling. Thus, CDK-mediated NBS1 phosphorylation defines a molecular switch that controls the choice of repair mode for DSBs.

• MeSH
• DNA vazebné proteiny chemie   MeSH
• dvouřetězcové zlomy DNA MeSH
• enzymy opravy DNA chemie   MeSH
• homologní rekombinace * MeSH
• jaderné proteiny * genetika   metabolismus   MeSH
• lidé MeSH
• mutageneze cílená MeSH
• nádorové buněčné linie MeSH
• oprava DNA MeSH
• proteinkinasa CDC2 * chemie   metabolismus   MeSH
• proteiny buněčného cyklu * chemie   genetika   metabolismus   MeSH
• replikace DNA * MeSH
• štěpení DNA * MeSH
• substituce aminokyselin MeSH
• Check Tag
• lidé MeSH

In the S and G2 phases of the cell cycle, DNA double-strand breaks (DSBs) are processed into single-stranded DNA, triggering ATR-dependent checkpoint signalling and DSB repair by homologous recombination. Previous work has implicated the MRE11 complex in such DSB-processing events. Here, we show that the human CtIP (RBBP8) protein confers resistance to DSB-inducing agents and is recruited to DSBs exclusively in the S and G2 cell-cycle phases. Moreover, we reveal that CtIP is required for DSB resection, and thereby for recruitment of replication protein A (RPA) and the protein kinase ATR to DSBs, and for the ensuing ATR activation. Furthermore, we establish that CtIP physically and functionally interacts with the MRE11 complex, and that both CtIP and MRE11 are required for efficient homologous recombination. Finally, we reveal that CtIP has sequence homology with Sae2, which is involved in MRE11-dependent DSB processing in yeast. These findings establish evolutionarily conserved roles for CtIP-like proteins in controlling DSB resection, checkpoint signalling and homologous recombination.

• MeSH
• ATM protein MeSH
• DNA vazebné proteiny metabolismus   MeSH
• DNA * metabolismus   MeSH
• dvouřetězcové zlomy DNA účinky léků   MeSH
• endonukleasy MeSH
• G2 fáze MeSH
• jaderné proteiny genetika   metabolismus   nedostatek   MeSH
• jednovláknová DNA metabolismus   MeSH
• konzervovaná sekvence MeSH
• lidé MeSH
• molekulární evoluce MeSH
• nádorové buněčné linie MeSH
• oprava DNA * účinky léků   MeSH
• protein-serin-threoninkinasy metabolismus   MeSH
• proteiny buněčného cyklu metabolismus   MeSH
• rekombinace genetická * účinky léků   MeSH
• S fáze MeSH
• Saccharomyces cerevisiae - proteiny chemie   MeSH
• transportní proteiny genetika   metabolismus   MeSH
• Check Tag
• lidé MeSH