Orientation regulation of class-switch recombination in human B cells

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Item Type:	Article
Title:	Orientation regulation of class-switch recombination in human B cells
Creators Name:	Du, L., Oksenych, V., Wan, H., Ye, X., Dong, J., Ye, A.Y., Abolhassani, H., Vlachiotis, S., Zhang, X., de la Rosa, K., Hammarström, L., van der Burg, M., Alt, F.W. and Pan-Hammarström, Q.
Abstract:	We developed a linear amplification-mediated high-throughput genome-wide translocation sequencing method to profile Ig class-switch recombination (CSR) in human B cells in an unbiased and quantitative manner. This enables us to characterize CSR junctions resulting from either deletional recombination or inversion for each Ig class/subclass. Our data showed that more than 90% of CSR junctions detected in peripheral blood in healthy control subjects were due to deletional recombination. We further identified two major CSR junction signatures/patterns in human B cells. Signature 1 consists of recombination junctions resulting from both IgG and IgA switching, with a dominance of Sµ-Sγ junctions (72%) and deletional recombination (87%). Signature 2 is contributed mainly by Sµ-Sα junctions (96%), and these junctions were almost all due to deletional recombination (99%) and were characterized by longer microhomologies. CSR junctions identified in healthy individuals can be assigned to both signatures but with a dominance of signature 1, whereas almost all CSR junctions found in patients with defects in DNA-PKcs or Artemis, two classical nonhomologous end joining (c-NHEJ) factors, align with signature 2. Thus, signature 1 may represent c-NHEJ activity during CSR, whereas signature 2 is associated with microhomology-mediated alternative end joining in the absence of the studied c-NHEJ factors. Our findings suggest that in human B cells, the efficiency of the c-NHEJ machinery and the features of switch regions are crucial for the regulation of CSR orientation. Finally, our high-throughput method can also be applied to study the mechanism of rare types of recombination, such as switching to IgD and locus suicide switching.
Keywords:	B-Lymphocytes, DNA End-Joining Repair, High-Throughput Nucleotide Sequencing, Immunoglobulin Class Switching, Genetic Recombination
Source:	Journal of Immunology
ISSN:	0022-1767
Publisher:	American Association of Immunologists
Volume:	213
Number:	8
Page Range:	1093-1104
Date:	15 October 2024
Additional Information:	Copyright © 2024 by The American Association of Immunologists, Inc. This article is distributed under The American Association of Immunologists, Inc., Reuse Terms and Conditions for Author Choice articles (https://journals.aai.org/jimmunol/pages/author_choice).
Official Publication:	https://doi.org/10.4049/jimmunol.2300842
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