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The immunoglobulin heavy chain (Igh) locus features a dynamic chromatin landscape to promote class switch recombination (CSR), yet the mechanisms that regulate this landscape remain poorly understood. CHD4, a component of the chromatin remodeling NuRD complex, directly binds H3K9me3, an epigenetic mark present at the Igh locus during CSR. We find that CHD4 is essential for early B cell development but is dispensable for the homeostatic maintenance of mature, naive B cells. However, loss of CHD4 in mature B cells impairs CSR because of suboptimal targeting of AID to the Igh locus. Additionally, we find that CHD4 represses p53 expression to promote B cell proliferation. This work reveals distinct roles for CHD4 in B cell development and CSR and links the H3K9me3 epigenetic mark with AID recruitment to the Igh locus.
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http://dx.doi.org/10.1016/j.celrep.2019.04.011 | DOI Listing |
Am J Clin Pathol
September 2025
Laboratory for Clinical Genomics and Advanced Technology (CGAT)-Department of Pathology and Laboratory Medicine, Dartmouth Hitchcock Medical Center, Lebanon, NH, United States.
Objective: Differentiating between the repertoire of immunoglobulin rearrangements is important in guiding diagnoses and management of B-cell lymphoma processes. A subset of these disease entities, such as chronic lymphocytic leukemia (CLL) and mantle cell lymphoma (MCL), can show distinct genomic profiles with a shared cell of origin. In this report, we describe a rare case in which differentiating between the immunoglobulin family of rearrangements (IGH, IGK, IGL) with optical genome mapping (OGM) helped revise the clinical suspicion of CLL.
View Article and Find Full Text PDFEMBO J
September 2025
The Babraham Institute, Cambridge, CB22 3AT, UK.
The diversity of antibodies underpins robust immune responses. During the formation of the antibody repertoire in early bone marrow B-cells, random antibody heavy-chain proteins are generated from recombined VH, DH, and JH gene segments. Many are non-functional and are negatively selected.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
September 2025
Emory Vaccine Center, Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA 30322.
Chronic lymphocytic leukemia (CLL) remains incurable despite treatment advances, and a major challenge is that biomarkers that predict response and resistance to current therapies are lacking. We report that activated and proliferating malignant CLL B cells in circulation express PD-1, a protein normally expressed in T cells. PD-1 expression is absent in circulating B cells from healthy controls and nonmalignant B cells from patients with CLL.
View Article and Find Full Text PDFGenome Res
August 2025
University of Oslo, Akershus University Hospital;
Genetic diversity within the human immunoglobulin heavy chain (IGH) locus influences the expressed antibody repertoire and susceptibility to infectious and autoimmune diseases. However, repetitive sequences and complex structural variation pose significant challenges for large-scale characterization. Here, we introduce a method that combines Oxford Nanopore Technologies ultra-long sequencing and adaptive sampling with a bioinformatic pipeline to produce haplotype-resolved, annotated IGH assemblies.
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