NF-kB subunits direct kinetically distinct transcriptional cascades in antigen receptor-activated B cells [RNA-seq II]

The NF-kB family of transcription factors orchestrates signal-induced gene expression in a diversity of cell types. Cellular responses to NF-kB activation are regulated at the level of cell- and signal-specificity, as well as differential use of family members (subunit specificity). Here we used time-dependent multi-omics to investigate selective functions of Rel and RelA, two closely related NF-kB proteins, in primary B lymphocytes activated via the B cell receptor. Despite large numbers of shared binding sites genome wide, Rel and RelA directed kinetically distinct cascades of gene expression in activated B cells. Single cell RNA-Seq revealed marked heterogeneity of Rel- and RelA-specific responses and sequential binding of these factors was not a major mechanism of protracted transcription. Moreover, nuclear co-expression of Rel and RelA led to functional antagonism between the two factors. By rigorously identifying target genes of each NF-kB subunit, these studies provide insights into exclusive functions of Rel and RelA in immunity and cancer. Mouse splenocytes were staining with antibodies for B220, AA4.1, CD23 and CD21/35. FO and MZ B cells were FACS sorted, and activated with anti-IgM and collected at various time points (unstimulated, 1, 4, 18h). Total RNA was prepared and bulk RNA-seq was performed.