# Chromatin regulation of TCR locus V(D)J recombination

> **NIH NIH R35** · DUKE UNIVERSITY · 2021 · $507,573

## Abstract

Summary of Work
The somatic assembly of antigen receptor (AgR) genes by V(D)J recombination creates the diverse antigen
receptor repertoires of T and B lymphocytes and is fundamental to adaptive immunity in jawed vertebrates.
AgR genes are contained within large and complex genetic loci that must be regulated at multiple levels to
achieve essential outcomes of early lymphocyte development. Recombination must be developmentally
ordered to allow the production and selection of lymphocyte subsets with appropriate characteristics and in
appropriate numbers. Recombination may be subject to allelic regulation to ensure that each lymphocyte
expresses a single receptor with unique antigen specificity. Recombination must be subject to safeguards that
ensure genomic integrity. Recombination must also be sufficiently stochastic to generate AgR repertoires
characterized by extensive combinatorial diversity. RAG recombinase activity is targeted to AgR loci by
multiple chromatin-based mechanisms, including local modifications to AgR chromatin structure, large-scale
conformational features and long-distance DNA contacts, and subnuclear compartmentalization of AgR loci.
Our studies aim to reveal fundamental molecular mechanisms underpinning the developmental regulation of
V(D)J recombination at T cell receptor (TCR) loci in developing thymocytes in vivo. Among the various AgR
loci, the Tcra-Tcrd locus is unrivaled in its complexity, because it contains two sets of gene segments that
undergo recombination at different stages of T cell development and contribute to the formation of TCR chains
expressed by distinct subsets of T cells. Notably, a single allele can undergo multiple cycles of rearrangement,
with initial Tcrd rearrangement followed by a succession of primary and secondary Tcra rearrangements, with
each deletional rearrangement replacing the one prior. We have developed substantial insights into how this
recombination program is enforced at the level of chromatin, and now seek to understand two major aspects of
this program. First, what role does Tcrd recombination play in the development of a combinatorially diverse
Tcra repertoire? Second, what is the role of the DNA damage response in pacing the succession of Tcra
rearrangements? Temporal regulation is essential to allow thymocyte selection based on expression of TCR
proteins before the rearranged Tcra gene is deleted by a subsequent Tcra recombination event. Among the
TCR loci, only Tcrb is subject to allelic exclusion. This locus is also highly unusual in that it associates with the
nuclear lamina (NL), a compartment generally considered repressive for transcription and V(D)J
recombination. Yet the locus associates with the NL during the developmental stage when the locus is initially
transcribed and undergoes rearrangement. Our recent work provides both a map and mechanistic insight into
Tcrb-NL interactions. We now plan to leverage this knowledge to determine how association with the NL
regulates...

## Key facts

- **NIH application ID:** 10148787
- **Project number:** 5R35GM136284-02
- **Recipient organization:** DUKE UNIVERSITY
- **Principal Investigator:** Michael S Krangel
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $507,573
- **Award type:** 5
- **Project period:** 2020-05-01 → 2025-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10148787

## Citation

> US National Institutes of Health, RePORTER application 10148787, Chromatin regulation of TCR locus V(D)J recombination (5R35GM136284-02). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10148787. Licensed CC0.

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