Widespread cryptic RAG-mediated recombination in developing T lymphocytes
V(D)J recombination generates antigen receptor diversity through the targeted activity of the RAG1/2 recombinase, but the extent to which RAG also engages cryptic genomic targets during normal lymphocyte development remains poorly defined. Here, we developed a targeted PCR-sequencing approach to detect and quantify rare RAG-mediated rearrangements in mouse thymocytes. We first examined the TCRb…
A groundbreaking study has unveiled a complex realm of cryptic RAG-mediated recombination occurring during the development of T lymphocytes in mice. The research team devised a cutting-edge PCR-sequencing method to detect and quantify rare rearrangements, focusing on the TCRb locus. Surprisingly, they discovered that four of the twelve pseudogenes within this locus undergo detectable rearrangement, challenging the notion of these components being non-functional.
Extending their analysis across the locus, they identified 33 previously unknown cryptic recombination sites, scattered across both the Vb region and the largely inaccessible intergenic region between Vb30 and Db1. These events occurred at varying recombination frequencies, revealing a wide spectrum of low-frequency recombination events.
The researchers found that these cryptic sites were highly diverse in sequence and chromatin context, with no single factor like RSS resemblance, predicted Z-DNA formation, local epigenetic features, or chromosomal interactions being able to reliably predict recombination occurrence. Moreover, they uncovered additional cryptic RAG-mediated rearrangements at the Bcl11b locus, indicating that such processes extend beyond antigen receptor loci.
These findings paint a vivid picture of an unexpectedly extensive landscape of low-frequency RAG-mediated DNA rearrangements in developing T lymphocytes, suggesting that the selection of cryptic targets may be more intricate than previously thought, based solely on the local genetic and epigenetic landscape.
Written by urgent.news from bioRxiv's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
