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Updated: Aug 12, 2025
Induction and Assessment of Class Switch Recombination in Purified Murine B Cells
Published on: August 13, 2010
Huwe1 supports B-cell development, B-cell-dependent immunity, somatic hypermutation and class switch recombination by
Aldo Spanjaard1, Maria Stratigopoulou2, Daniël de Groot1
1Division of Tumor Biology and Immunology, Netherlands Cancer Institute, Amsterdam, Netherlands.
Insights
The E3 ligase HUWE1 is crucial for B-cell development and immunoglobulin gene diversification. HUWE1 deficiency impairs B-cell proliferation, somatic hypermutation, and class switch recombination by affecting AID expression and Myc target genes.
Area of Science:
- Immunology
- Molecular Biology
- Cell Biology
Background:
- B-cell development and immunoglobulin gene diversification are vital for adaptive immunity.
- The ubiquitin E3 ligase HUWE1 regulates cell proliferation and DNA repair pathways.
- HUWE1's role in B-cell specific processes like somatic hypermutation (SHM) and class switch recombination (CSR) requires further investigation.
Purpose of the Study:
- To investigate the role of HUWE1 in B-cell proliferation and immunoglobulin gene diversification.
- To determine HUWE1's involvement in SHM and CSR.
- To elucidate the mechanisms by which HUWE1 influences B-cell activation and maturation.
Main Methods:
- B-cell-specific deletion of the Huwe1 gene in mice.
- In vitro and in vivo analyses of B-cell development, proliferation, SHM, and CSR.
- Assessment of activation-induced cytidine deaminase (AID) expression and Myc target gene output.
Main Results:
- B-cell-specific deletion of Huwe1 impaired B-cell development, differentiation, and maturation.
- HUWE1 deficiency diminished SHM and CSR by reducing B-cell proliferation and AID expression.
- HUWE1's role in these processes was independent of its regulation of base excision repair (BER).
- HUWE1-deficient B cells exhibited increased Myc target gene expression despite reduced proliferation.
Conclusions:
- HUWE1 is essential for coordinating the transition of naive B cells to antigen-activated cells.
- HUWE1 regulates mutagenic processes in B cells by controlling AID expression and post-transcriptional output of Myc target genes.
- These findings highlight HUWE1 as a key regulator in B-cell adaptive immune responses.
Abstract:
The development and differentiation of B cells is intimately linked to cell proliferation and the generation of diverse immunoglobulin gene (Ig) repertoires. The ubiquitin E3 ligase HUWE1 controls proliferation, DNA damage responses, and DNA repair, including the base excision repair (BER) pathway. These processes are of crucial importance for B-cell development in the bone marrow, and the germinal center (GC) response, which results in the clonal expansion and differentiation of B cells expressing high affinity immunoglobulins. Here, we re-examined the role of HUWE1 in B-cell proliferation and Ig gene diversification, focusing on its involvement in somatic hypermutation (SHM) and class switch recombination (CSR). B-cell-specific deletion of Huwe1 resulted in impaired development, differentiation and maturation of B cells in the bone marrow and peripheral lymphoid organs. HUWE1 deficiency diminished SHM and CSR by impairing B-cell proliferation and AID expression upon activation in vitro and in vivo, and was unrelated to the HUWE1-dependent regulation of the BER pathway. Interestingly, we found that HUWE1-deficient B cells showed increased mRNA expression of Myc target genes upon in vitro activation despite diminished proliferation. Our results confirm that the E3 ligase HUWE1 is an important contributor in coordinating the rapid transition of antigen naïve, resting B cells into antigen-activated B cells and regulates mutagenic processes in B cells by controlling AID expression and the post-transcriptional output of Myc target genes.
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