Isolation of region-specific factors driving antibody class-switch recombination from the immunoglobulin heavy chain locus.

Authors

Santosh Kumar Gothwal

Published in

Journal of immunological methods. Pages 114105. Aug 11, 2026. Epub Aug 11, 2026.

Abstract

Activation-Induced Cytidine Deaminase (AID) induces DNA double-strand breaks (DSBs) at the switch (S) regions of the Immunoglobulin heavy chain (IgH) locus, which are essential for class switch recombination (CSR) and somatic hypermutation (SHM), key processes for effective antibody production. While AID activity is critical, its off-target effects, such as DSBs at the Myc locus, can cause chromosomal translocations like IgH-Myc fusions, contributing to B-cell lymphomas. The factors assembled on the IgH locus that help restrict AID-induced DSBs and subsequently CSR, remain unknown. To address this, we developed a method to isolate CSR-specific factors by inserting a 5×-GAL4-UAS sequence at the switch-mu (Sμ) region in CH12 cells. This engineered site enables recruitment of a 3-FLAG-GAL4 DNA-binding protein (3F-GAL4-DBD), allowing specific pulldown of proteins enriched at the Sμ region. Successful recovery of the known CSR regulator BRD2 from the Sμ region, along with enrichment of the DNA repair factors 53BP1 and gH2AX, validated this approach. Identification and characterization of IgH-enriched factors establish a validated methodological framework to facilitate future proteomic discovery of CSR regulators and highlight mechanisms that balance antibody diversification with genomic integrity in B cells.

PMID:
42580583
Bibliographic data and abstract were imported from PubMed on 12 Aug 2026.

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