Transcription Factor Pax5 Activates the Chromatin of Key Genes Involved in B Cell Signaling, Adhesion, Migration, and Immune Function

Abstract

The transcription factor Pax5 represses B lineage-inappropriate genes and activates B cell-specific genes in B lymphocytes. Here we have identified 170 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 substantially 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 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 that is activated by Pax5 to control B cell development and function.

Molecular functions of the transcription factors E2A and E2-2 in controlling germinal center B cell and plasma cell development

“…For ChIP-seq analysis, activated B cells after 2 d of anti-CD40 plus IL-4 stimulation were used for ChIP with an anti-H3K27ac antibody (see Antibodies), as previously described (Schebesta et al, 2007). The ChIP-precipitated DNA (5 ng) was used for library preparation.…”

Cloning of genes involved in chromosomal translocations by high-resolution single nucleotide polymorphism genomic microarray

“…3D and data not shown). We examined 10 downstream target genes (seven positively regulated direct target genes and three negatively regulated genes) of PAX5 (10)(11)(12) and found that four, including ATP1B1, BLK, NEDD5 and TCF7L2, were down-regulated by induction of either PAX5-C20orf112S or PAX5-C20orf112L protein. However, expression of other reported PAX5 downstream target genes, including three positively regulated direct target genes (IRF8, BST1, CD19) and three negatively regulated genes (CCR2, CCR5, NOTCH1) were not affected by the induction of expression of the fusion proteins in these cells.…”

The reduced and altered activities of PAX5 are linked to the protein–protein interaction motif (coiled-coil domain) of the PAX5–PML fusion protein in t(9;15)-associated acute lymphocytic leukemia

“…PAX5 is considered as the most important transcription factor for the expression of CD19 gene. PAX5-binding sites have also been identified in the regulatory sequences of a number of other genes, including BLK, BLNK and RAG2 (Lauring and Schlissel, 1999;Schebesta et al, 2002Schebesta et al, , 2007Delogu et al, 2006). PAX5 can act as an activator or a repressor of transcription in a promoter-dependent way.…”