Chromosomal reinsertion of broken RSS ends during T cell development
John D Curry1, Danae Schulz, Cynthia J Guidos
1Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
The Journal of Experimental Medicine
|September 6, 2007
Summary
The V(D)J recombinase can mistakenly insert DNA ends into "cryptic" sites, potentially causing lymphoid malignancies. The noncore RAG2 protein limits these V(D)J recombination errors, protecting genome integrity.
Area of Science:
- Genetics
- Molecular Biology
- Immunology
Background:
- V(D)J recombination is crucial for adaptive immunity but can cause harmful chromosomal translocations in lymphoid malignancies.
- Understanding the "mistakes" made by the V(D)J recombinase is critical for preventing oncogenesis.
Purpose of the Study:
- To characterize the types of DNA insertions resulting from V(D)J recombination errors.
- To investigate the role of RAG2 in preventing aberrant V(D)J recombination events.
Main Methods:
- A novel assay was developed to detect V(D)J recombination signal sequence (RSS) end insertions in murine genomic DNA.
- Analysis of RSS end insertions in thymocytes from wild-type and various mutant mouse models (p53, p53 x scid, H2Ax, ATM, core-RAG2).
Main Results:
- 48 unique TCRbeta RSS end insertions were identified, with nearly half targeting "cryptic" RSS-like elements.
- No target-site duplications were observed, differentiating these events from in vitro transposition.
- Core-RAG2 mutant thymocytes exhibited a sevenfold increase in RSS end insertions compared to wild-type.
Conclusions:
- V(D)J recombination errors, particularly targeting cryptic RSS sites, can occur in vivo.
- The noncore domain of RAG2 plays a significant role in suppressing mistargeted V(D)J recombination and maintaining genome stability.
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