B-cell Differentiation is Regulated by Targeted DNA Hypomethylation [RRBS_1]

B cells provide humoral immunity by differentiating into antibody secreting plasma cells. Differentiation is dependent upon division and transcriptional changes, with commitment to B cell lineages associated with epigenetic changes. Analysis of early transcriptional and epigenetic events in B cell differentiation revealed that plasmablasts and plasma cells undergo dynamic changes in gene expression and a progressive DNA hypomethylation targeted to at least 10% of genes/loci. Of the differentially methylated loci, more than 99.7% were demethylated during differentiation and these clustered in cis-regulatory features such as enhancers and transcription factor binding sites. Changes in gene expression and DNA methylation coincided with each other at specific divisions during differentiation and inhibition of DNA methylation resulted in augmented plasma cell commitment in a division-dependent manner. These data identify a major epigenetic reprogramming event during early B cell differentiation coupled division and provide an approach to modulating humoral immune responses. Overall design: Splenic B cells (B220+ CD43-) from naïve C57/BL6J mice, and Day 3 LPS-induced Plasmablasts (B220mid CD138+) and Plasma Cells (B220low CD138+) were analyzed by Illumina Gene Expression Microarray and Reduced Representation Bisulfite Sequencing