Cell Reports
Volume 21, Issue 4, 24 October 2017, Pages 979-993
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Article
The Conserved ATM Kinase RAG2-S365 Phosphorylation Site Limits Cleavage Events in Individual Cells Independent of Any Repair Defect

https://doi.org/10.1016/j.celrep.2017.09.084Get rights and content
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Highlights

  • A phosphorylation site on RAG2-S365 is involved in feedback control of RAG cleavage

  • A RAG2-S365A mutation leads to bi-allelic and bi-locus RAG-mediated breaks

  • Deregulated cleavage is a driver of chromosomal instability without a repair defect

  • Cleavage control and maintenance of genome stability involves ATM’s kinase activity

Summary

Many DNA lesions associated with lymphoid malignancies are linked to off-target cleavage by the RAG1/2 recombinase. However, off-target cleavage has mostly been analyzed in the context of DNA repair defects, confounding any mechanistic understanding of cleavage deregulation. We identified a conserved SQ phosphorylation site on RAG2 365 to 366 that is involved in feedback control of RAG cleavage. Mutation of serine 365 to a non-phosphorylatable alanine permits bi-allelic and bi-locus RAG-mediated breaks in the same cell, leading to reciprocal translocations. This phenomenon is analogous to the phenotype we described for ATM kinase inactivation. Here, we establish deregulated cleavage itself as a driver of chromosomal instability without the associated repair defect. Intriguingly, a RAG2-S365E phosphomimetic rescues the deregulated cleavage of ATM inactivation, reducing the incidence of reciprocal translocations. These data support a model in which feedback control of cleavage and maintenance of genome stability involves ATM-mediated phosphorylation of RAG2.

Keywords

RAG cleavage regulation
genome stability
V(D)J recombination
ATM
RAG2S365
reciprocal translocations
developing lymphocytes

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4

Present address: Biological Sciences Department, Columbia University, New York, NY 10027, USA

5

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