Chip-chip from pro-B cells with H3K4me3, H3K4me2 and H3K9ac

The transcription factor Pax5 represses B-lineage-inappropriate genes and activates B-cell-specific genes in B-lymphocytes. Here we have identified 170 novel Pax5-activated genes. Conditional mutagenesis demonstrated that the Pax5-regulated genes require continuous Pax5 activity for normal expression in pro-B and mature B cells. Expression of half of the Pax5-activated genes is either absent or significantly reduced upon Pax5 loss in plasma cells. Direct Pax5 target genes were identified based on their protein synthesis-independent activation by a Pax5-estrogen receptor fusion protein. Chromatin immunoprecipitation (ChIP) of Pax5 together with chromatin profiling by ChIP-on-chip analysis demonstrated that Pax5 directly activates the chromatin at promoters or putative enhancers of Pax5 target genes. The novel Pax5-activated genes code for key regulatory and structural proteins involved in B cell signaling, adhesion, migration, antigen presentation and germinal center B cell formation, thus revealing a complex regulatory network, which is activated by Pax5 to control B cell development and function. Keywords: Chip-chip, cell type comparison comparison of Pax5-/-Rag2-/- vs Rag2-/- pro-B cells