Project description:To investigate the molecular basis for the B cell developmental arrest in Pax5R31Q/– mice, we performed RNA-sequencing (RNA-seq) with ex vivo sorted Pax5+/+ and Pax5R31Q/– pro-B cells. We identified Pax5-activated and Pax5-repressed genes that were no longer properly regulated by the Pax5-R31Q protein in Pax5R31Q/– pro-B cells. Notably, these genes were only a subset of the activated and repressed genes identified by comparing Pax5+/+ and Pax5–/– pro-B cells, which raised the question whether binding of the Pax5-R31Q protein may be selectively lost at the subset of deregulated genes in Pax5R31Q/– pro-B cells. By using a Pax5 paired domain antibody for chromatin immunoprecipitation coupled with deep sequencing (ChIP-seq) of short-term cultured Pax5+/+ and Pax5R31Q/– pro-B cells, we identified all associated Pax5 binding sites. Common Pax5 peaks had a similar Pax5-binding density in contrast to the strong binding difference observed at the unique peaks present in Pax5+/+ pro-B cells. To investigate a correlation between the loss of Pax5 binding and gene expression, we focused our analysis on Pax5 peaks in the TSS region of activated genes. We systematically investigated the correlation between loss of Pax5 binding at the TSS and down-regulation of gene expression in Pax5R31Q/– pro-B cells. The ratio of Pax5 binding between Pax5R31Q/– and Pax5+/+ pro-B cells at the TSS of these activated genes was significantly reduced compared to that of expressed non-regulated genes. We next explored whether the Pax5-binding difference at the TSS also correlated with the magnitude of gene expression difference. The loss of Pax5 binding at the TSS also correlated with the degree of expression change in Pax5R31Q/– pro-B cells compared to Pax5+/+ pro-B cells. We conclude therefore that the selective DNA-binding of Pax5-R31Q is responsible for the observed gene expression differences in Pax5R31Q/– pro-B cells.
Project description:Pax5 is a critical regulator of B cell commitment. Here we identified direct Pax5 target genes by streptavidin-mediated ChIP-chip analysis of pro-B cells expressing in vivo biotinylated Pax5. By binding to promoters and enhancers, Pax5 directly regulates the expression of multiple transcription factor, cell surface receptor and signal transducer genes. One of the newly identified enhancers was shown by transgenic analysis to confer Pax5-dependent B-cell-specific activity to the Nedd9 gene controlling B cell trafficking. Profiling of histone modifications in Pax5-deficient and committed wild-type pro-B cells demonstrated that Pax5 induces active chromatin at activated target genes, while eliminating active chromatin at repressed genes in committed pro-B cells. Pax5 rapidly induces these chromatin and transcription changes by recruiting chromatin-remodeling, histone-modifying and basal transcription factor complexes to its target genes. These data provide novel insight into the regulatory network and epigenetic regulation, by which Pax5 controls B cell commitment. Analysis of chromatin and TF binding in rag2-/- and pax5-/- rag2-/- pro-B cells. Chip-Chip with 1-3 experiments for each antibody and celltype combination.
Project description:Pax5 is a critical regulator of B cell commitment. Here we identified direct Pax5 target genes by streptavidin-mediated ChIP-chip analysis of pro-B cells expressing in vivo biotinylated Pax5. By binding to promoters and enhancers, Pax5 directly regulates the expression of multiple transcription factor, cell surface receptor and signal transducer genes. One of the newly identified enhancers was shown by transgenic analysis to confer Pax5-dependent B-cell-specific activity to the Nedd9 gene controlling B cell trafficking. Profiling of histone modifications in Pax5-deficient and committed wild-type pro-B cells demonstrated that Pax5 induces active chromatin at activated target genes, while eliminating active chromatin at repressed genes in committed pro-B cells. Pax5 rapidly induces these chromatin and transcription changes by recruiting chromatin-remodeling, histone-modifying and basal transcription factor complexes to its target genes. These data provide novel insight into the regulatory network and epigenetic regulation, by which Pax5 controls B cell commitment.
Project description:Comparison of the RNA-expression pattern of Pax5-deficient progenitor-cell tumors with wild-type pro-B-cells Keywords: Genetic modification