Functional intersection of ATM and DNA-dependent protein kinase catalytic subunit in coding end joining during V(D)J recombination

Baeck Seung Lee, Eric J. Gapud, Shichuan Zhang, Yair Dorsett, Andrea Bredemeyer, Rosmy George, Elsa Callen, Jeremy A. Daniel, Oleg Osipovich, Eugene M. Oltz, Craig H. Bassing, Andre Nussenzweig, Susan Lees-Miller, Michal Hammel, Benjamin P.C. Chen, Barry P. Sleckman

Research output: Contribution to journalArticlepeer-review

32 Scopus citations


V(D)J recombination is initiated by the RAG endonuclease, which introduces DNA double-strand breaks (DSBs) at the border between two recombining gene segments, generating two hairpin-sealed coding ends and two blunt signal ends. ATM and DNA-dependent protein kinase catalytic subunit (DNA-PKcs) are serine-threonine kinases that orchestrate the cellular responses to DNA DSBs. During V(D)J recombination, ATM and DNA-PKcs have unique functions in the repair of coding DNA ends. ATM deficiency leads to instability of postcleavage complexes and the loss of coding ends from these complexes. DNA-PKcs deficiency leads to a nearly complete block in coding join formation, as DNA-PKcs is required to activate Artemis, the endonuclease that opens hairpin-sealed coding ends. In contrast to loss of DNA-PKcs protein, here we show that inhibition of DNA-PKcs kinase activity has no effect on coding join formation when ATM is present and its kinase activity is intact. The ability of ATM to compensate for DNA-PKcs kinase activity depends on the integrity of three threonines in DNA-PKcs that are phosphorylation targets of ATM, suggesting that ATM can modulate DNA-PKcs activity through direct phosphorylation of DNA-PKcs. Mutation of these threonine residues to alanine (DNA-PKcs3A) renders DNA-PKcs dependent on its intrinsic kinase activity during coding end joining, at a step downstream of opening hairpinsealed coding ends. Thus, DNA-PKcs has critical functions in coding end joining beyond promoting Artemis endonuclease activity, and these functions can be regulated redundantly by the kinase activity of either ATM or DNA-PKcs.

Original languageEnglish
Pages (from-to)3568-3579
Number of pages12
JournalMolecular and cellular biology
Issue number18
StatePublished - 2013


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