Diversity of B and T cell antigen receptor repertoires underlies the ability of adaptive immunity to respond with high specificity to pathogen challenge. The main source of diversity is generated during lymphocyte development via the process of VDJ recombination. As a consequence, each B or T cell expresses one out of many variable (V) gene segments present in the germline. The goals of this project are to understand how B lymphocytes efficiently utilize the entire repertoire of close to one hundred VH gene segments of the immunoglobulin heavy chain (IgH) gene locus. During FY19 we found that: VH gene segments are excluded from a topological chromatin domain within which the VDJ recombinase machinery scans the genome for complementary recombination signal sequences (RSSs) with high efficiency. We used mutated IgH alleles in which the scanning domain is increased in size to examine rules that govern VH gene recombination. On such alleles VH recombination is restricted to 2 out 100 gene segments, and these gene segments recombine without directional preference to either 5 or 3 RSSs of unrearranged DH gene segments. Our interpretation is that VH gene segments find complementary RSSs by a diffusion rather than a scanning mechanism. The altered chromatin loop generated on such alleles also greatly increases recombination efficiency of the selected VH gene segments resulting in reduced diversity. We propose that the chromatin configuration of wild type IgH alleles sacrifices efficiency for diversity. Reduced efficiency may also impose allelic exclusion by increasing recombinational asynchrony between the two alleles in each cell.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Investigator-Initiated Intramural Research Projects (ZIA)
Project #
1ZIAAG000372-12
Application #
10012622
Study Section
Project Start
Project End
Budget Start
Budget End
Support Year
12
Fiscal Year
2019
Total Cost
Indirect Cost
Name
National Institute on Aging
Department
Type
DUNS #
City
State
Country
Zip Code
Qiu, Xiang; Kumari, Gita; Gerasimova, Tatiana et al. (2018) Sequential Enhancer Sequestration Dysregulates Recombination Center Formation at the IgH Locus. Mol Cell 70:21-33.e6
Montefiori, Lindsey; Wuerffel, Robert; Roqueiro, Damian et al. (2016) Extremely Long-Range Chromatin Loops Link Topological Domains to Facilitate a Diverse Antibody Repertoire. Cell Rep 14:896-906
Gerasimova, Tatiana; Guo, Changying; Ghosh, Amalendu et al. (2015) A structural hierarchy mediated by multiple nuclear factors establishes IgH locus conformation. Genes Dev 29:1683-95
Phillips-Cremins, Jennifer E; Sauria, Michael E G; Sanyal, Amartya et al. (2013) Architectural protein subclasses shape 3D organization of genomes during lineage commitment. Cell 153:1281-95
Selimyan, Roza; Gerstein, Rachel M; Ivanova, Irina et al. (2013) Localized DNA demethylation at recombination intermediates during immunoglobulin heavy chain gene assembly. PLoS Biol 11:e1001475
Kumar, Satyendra; Wuerffel, Robert; Achour, Ikbel et al. (2013) Flexible ordering of antibody class switch and V(D)J joining during B-cell ontogeny. Genes Dev 27:2439-44
Subrahmanyam, Ramesh; Sen, Ranjan (2012) Epigenetic features that regulate IgH locus recombination and expression. Curr Top Microbiol Immunol 356:39-63
Subrahmanyam, Ramesh; Du, Hansen; Ivanova, Irina et al. (2012) Localized epigenetic changes induced by DH recombination restricts recombinase to DJH junctions. Nat Immunol 13:1205-12
Roy, Ananda L; Sen, Ranjan; Roeder, Robert G (2011) Enhancer-promoter communication and transcriptional regulation of Igh. Trends Immunol 32:532-9
Osipovich, Oleg A; Subrahmanyam, Ramesh; Pierce, Steven et al. (2009) Cutting edge: SWI/SNF mediates antisense Igh transcription and locus-wide accessibility in B cell precursors. J Immunol 183:1509-13

Showing the most recent 10 out of 11 publications