# Defining the mechanistic basis of ATM’s impact on VDJ recombination

> **NIH NIH R01** · MICHIGAN STATE UNIVERSITY · 2024 · $387,500

## Abstract

Project Summary
The ATM kinase is central to the DNA damage response; it follows that this large kinase is central to regulating
how developing lymphocytes respond to their self-imposed DNA damage during VDJ recombination. Although
the evidence is overwhelming and unequivocal that ATM contributes to accurate non-homologous end joining of
VDJ coding segments, and restrains their participation in genomic translocations, a clear mechanistic
understanding of how ATM actually does this job is lacking.
Recently, we found that ATM ablation in many cultured cell strains results in increased VDJ joining in episomal
assays, a completely counter-intuitive result if ATM were to have a direct functional role in end joining. We
considered that if ATM's role was instead, to regulate the RAG post cleavage complex(s), loss of ATM might
result in increased release of VDJ recombination intermediates and more rapid joining, explaining the increased
recombination observed. We fine-tuned the assay so that a structure/function, reductionist approach could be
employed to delineate if and how ATM directly affects the RAG complex. We find that ATM inhibition of signal
joining requires the non-core C-termini of both RAG1 and RAG2. This prompted an examination of these regions
for potential ATM/DNA-PK target sites. Blocking these sites not only blocks ATM's effect on signal joining in
cellular assays, it also ablates robust phosphorylation of RAG1/RAG2 on highly purified and fully functional RAG
complexes by ATM and DNA-PK in vitro. These data support our model that ATM directly regulates VDJ
recombination by phosphorylation of the RAG complex. The experiments proposed in this application will use
biochemical approaches to define how ATM affects cleavage and signal end release, and will use a cellular
model of chromosomal VDJ recombination to further define how ATM regulates VDJ recombination.

## Key facts

- **NIH application ID:** 10827366
- **Project number:** 5R01AI147634-05
- **Recipient organization:** MICHIGAN STATE UNIVERSITY
- **Principal Investigator:** Katheryn D Meek
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $387,500
- **Award type:** 5
- **Project period:** 2019-05-20 → 2026-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10827366

## Citation

> US National Institutes of Health, RePORTER application 10827366, Defining the mechanistic basis of ATM’s impact on VDJ recombination (5R01AI147634-05). Retrieved via AI Analytics 2026-06-11 from https://api.ai-analytics.org/grant/nih/10827366. Licensed CC0.

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