GSE128321
Distinct requirements of CHD4 during B cell development and antibody response
Immunoglobulin heavy chain (Igh) class switch recombination (CSR) requires B cell proliferation, germline transcription, AID-instigated generation of DNA double strand breaks and DNA end-joining. How these various DNA-protein interactions and DNA transactions at Igh occur within the context of the chromatin landscape are largely unknown. Histone post-translational modifications can modulate chromatin accessibility and one such epigenetic mark, H3K9me3 is present at activated Igh switch sequences that serve as recombination targets during CSR. The chromatin remodeling protein CHD4 binds H3K9me3 and shapes chromatin accessibility and gene expression in various cell types, but its role in B cell biology is yet to be elucidated. Here, we conditionally ablated CHD4 expression in different stages of B cell development. We find that while CHD4 is essential for early B cell development, it is dispensable for homeostatic maintenance of mature naïve B cells and differentiation into antigen-specific early memory B cells and plasmablasts. However, loss of CHD4 in activated B cells leads to a severe defect in CSR, accompanied by markedly impaired cellular proliferation. Conditional deletion of p53 rescued the proliferation defect but failed to restore CSR due to a failure of AID to be efficiently recruited to Igh. This work unmasks a context-dependent role of CHD4 in B cell development and identifies CHD4 as a novel effector of CSR that influences B cell proliferation and recruitment of AID to Igh. Overall design: RNA-seq was performed on purified splenic B cells unstimulated (0hr) or stimulated ex vivo with LPS (10µg/ml) plus mouse IL4 (25ng/ml) for 48 hrs.