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The generation of protective antibodies by somatic hypermutation (SHM) is essential for antibody maturation and adaptive immunity. SHM involves co-transcriptional mutagenesis of immunoglobulin variable (V) regions regulated by enhancers located hundreds of kilobases away. How 3D chromatin topology affects SHM is poorly understood. Here, we measure higher-order interactions on single alleles of the human immunoglobulin heavy-chain locus (IGH) using Tri-C. We find that SHM is underpinned by a multiway hub wherein the V region is proximal to all enhancers. Cohesin-mediated loop extrusion is dispensable for IGH transcription and hub architecture. Transcription and mutagenesis of IGH switch regions, which are necessary for antibody class-switch recombination, create new chromatin loops that can form without cohesin. However, these additional loops do not compromise hub integrity, V region transcription, or SHM. Thus, antibody maturation occurs within a multiway hub accommodating several gene-enhancer loops in which transcription and mutagenesis of different segments occur non-competitively.
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http://dx.doi.org/10.1016/j.molcel.2025.06.003 | DOI Listing |
Mol Carcinog
September 2025
Department of Urology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
B cells located in tertiary lymphoid structures (TLSs) may undergo clonal expansion, somatic hypermutation, isotype switching, and tumor-specific antibody production, suggesting that antibody-producing plasma cells may be involved in antitumor immunity. This study used a combination of single-cell sequencing (five samples from our center, and four samples from PRJNA662018) and spatial transcriptome (one sample from our center, and four samples from GSE169379) research methods to investigate the relationship between TLSs and the immunoglobulin repertoire in muscle invasive bladder cancer (MIBC). 405 patients with MIBC from TCGA and 348 patients with metastatic urothelial carcinoma on PD-L1 inhibitor treatment from the IMvigor210 trial were included in this study.
View Article and Find Full Text PDFKorean J Clin Oncol
August 2025
Department of Surgery, Soonchunhyang University Bucheon Hospital, Soonchunhyang University College of Medicine, Bucheon, Korea.
Purpose: Multiple primary tumors arising in the same individual pose challenges for precision oncology, particularly in the context of hereditary cancer syndromes such as Lynch syndrome. While these tumors may originate from a shared germline predisposition, it remains unclear whether they also share somatic alterations that could be therapeutically exploited. This study aimed to characterize the extent of somatic genomic overlap between synchronous or metachronous gastric and colorectal cancers within young Korean patients.
View Article and Find Full Text PDFJ Autoimmun
September 2025
Garvan Institute of Medical Research, Darlinghurst, NSW, Australia; Cellular Genomics Futures Institute & School of Biomedical Sciences, UNSW Sydney, Australia. Electronic address:
Background: In autoimmune disease it is not understood how self-reactive B cells escape immune tolerance checkpoints to produce pathogenic autoantibodies.
Objective: In patients with demyelinating polyneuropathy caused by IgM autoantibodies against myelin associated glycoprotein (MAG) and the sulphated trisaccharide CD57, we aimed to test the hypothesis that B cells making the autoantibody escaped tolerance by acquiring lymphoma driver somatic mutations.
Methods: Deep single-cell RNA, DNA, flow cytometric and antibody specificity analysis of blood from three patients with MAG neuropathy.
DNA Repair (Amst)
August 2025
Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Laboratory of Genome Diversification & Integrity, Berlin, Germany; Charité-Universitätsmedizin Berlin, Berlin 10117, Germany. Electronic address:
The ability of B lymphocytes to diversify immunoglobulin (Ig) genes is central to the generation of high-affinity, class-switched antibodies and the establishment of effective humoral immunity. This diversification is achieved through three DNA remodeling processes that occur at defined stages of B cell development and maturation: V(D)J recombination, somatic hypermutation (SHM), and class switch recombination (CSR). These reactions all rely on the induction of programmed DNA lesions at Ig genes and their productive resolution by ubiquitous DNA repair pathways.
View Article and Find Full Text PDFA key goal of vaccinology is to train the immune system to combat current pathogens while simultaneously preparing it for future evolved variants. Understanding factors contributing to anticipatory breadth, wherein affinity maturation against an ancestral strain yields neutralization capacity against evolved variants, is therefore of great importance. Here, we investigated the mechanism of anticipatory breadth development in a public antibody family targeting the functionally restricted ACE2 binding site on SARS-CoV-2.
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