Project description:Interferon regulatory factor 4 (IRF4) is a master transcription factor required for the maturation of germinal center B cells that eventually develop into antibody secreting plasma cells and memory B cells. IRF4-deficient mice exhibit a profound reduction in serum immunoglobulin levels. In spite of wealth of the information relating to IRF4 and B cell biology, little is known about the intricate molecular details of the role of this transcription factor during B cell development. We therefore examined the genome-wide targets of IRF4 by ChIP-chip analysis in GC derived BL2 Burkittâs lymphoma cells. ChIP studies were further supplemented by whole genome expression analysis after shRNA-mediated knockdown of IRF4. Our study revealed that IRF4 regulates expression of genes important for a) BCR signaling b) antigen processing and presentation by MHC. In addition we found that IRF4 possibly in some way involved to regulate LTA, LTB and CXCR5 those involved in immune system development, particularly light zone development related genes such as FDC clustering regulating and IL21R and IL10 who are involved in B cell development.. On the other hand, IRF4 suppressesd genes in the oxidative phosphorylation pathway. Our findings illuminate hitherto unexplored roles of IRF4 in GC B cell development. BL2 Burkitt's lymphoma-derived B cells were infected with lentivirus expressing shRNA for IRF4 or control, and total RNA was subjected to Illumina BeadsExpression Arrays analysis.
Project description:IRF4, a master transcription factor, regulates genes involved in BCR signaling, antigen processing and presentation, and GC development [expression array]
Project description:IRF4, a master transcription factor, regulates genes involved in BCR signaling, antigen processing and presentation, and GC development [ChIP-chip]
Project description:Interferon regulatory factor 4 (IRF4) is a master transcription factor required for the maturation of germinal center B cells that eventually develop into antibody secreting plasma cells and memory B cells. IRF4-deficient mice exhibit a profound reduction in serum immunoglobulin levels. In spite of wealth of the information relating to IRF4 and B cell biology, little is known about the intricate molecular details of the role of this transcription factor during B cell development. We therefore examined the genome-wide targets of IRF4 by ChIP-chip analysis in GC derived BL2 Burkitt’s lymphoma cells. ChIP studies were further supplemented by whole genome expression analysis after shRNA-mediated knockdown of IRF4. Our study revealed that IRF4 regulates expression of genes important for a) BCR signaling b) antigen processing and presentation by MHC. In addition we found that IRF4 possibly in some way involved to regulate LTA, LTB and CXCR5 those involved in immune system development, particularly light zone development related genes such as FDC clustering regulating and IL21R and IL10 who are involved in B cell development.. On the other hand, IRF4 suppressesd genes in the oxidative phosphorylation pathway. Our findings illuminate hitherto unexplored roles of IRF4 in GC B cell development.
Project description:Interferon regulatory factor 4 (IRF4) is a master transcription factor required for the maturation of germinal center B cells that eventually develop into antibody secreting plasma cells and memory B cells. IRF4-deficient mice exhibit a profound reduction in serum immunoglobulin levels. In spite of wealth of the information relating to IRF4 and B cell biology, little is known about the intricate molecular details of the role of this transcription factor during B cell development. We therefore examined the genome-wide targets of IRF4 by ChIP-chip analysis in GC derived BL2 Burkitt’s lymphoma cells. ChIP studies were further supplemented by whole genome expression analysis after shRNA-mediated knockdown of IRF4. Our study revealed that IRF4 regulates expression of genes important for a) BCR signaling b) antigen processing and presentation by MHC. In addition we found that IRF4 possibly in some way involved to regulate LTA, LTB and CXCR5 those involved in immune system development, particularly light zone development related genes such as FDC clustering regulating and IL21R and IL10 who are involved in B cell development.. On the other hand, IRF4 suppressesd genes in the oxidative phosphorylation pathway. Our findings illuminate hitherto unexplored roles of IRF4 in GC B cell development.
Project description:Upon antigen recognition B cells undertake a bifurcated response in which some cells rapidly differentiate into plasmablasts while others undergo affinity maturation in germinal centers (GC). We uncover a double negative feedback loop between interferon regulatory factors IRF4 and IRF8, which regulates the initial bifurcation of activated B cells as well as the GC response. IRF8 dampens BCR signaling, facilitates antigen specific interaction with helper T cells, and promotes selection of high affinity clones while antagonizing IRF4 driven plasmablast differentiation. Genomic analysis reveals concentration dependent action of IRF4 and IRF8 in regulating distinctive gene expression programs. Stochastic modeling suggests that the double negative feedback is sufficient to initiate bifurcating B cell developmental trajectories.
Project description:Upon antigen recognition B cells undertake a bifurcated response in which some cells rapidly differentiate into plasmablasts while others undergo affinity maturation in germinal centers (GC). We uncover a double negative feedback loop between interferon regulatory factors IRF4 and IRF8, which regulates the initial bifurcation of activated B cells as well as the GC response. IRF8 dampens BCR signaling, facilitates antigen specific interaction with helper T cells, and promotes selection of high affinity clones while antagonizing IRF4 driven plasmablast differentiation. Genomic analysis reveals concentration dependent action of IRF4 and IRF8 in regulating distinctive gene expression programs. Stochastic modeling suggests that the double negative feedback is sufficient to initiate bifurcating B cell developmental trajectories.
Project description:During a germinal center (GC) response, B cells diversify their immunoglobulin (Ig) genes by somatic hyper-mutation (SHM) and undergo clonal expansion and positive selection thereby enabling the generation of higher affinity antibodies. We have analyzed the genomic states underlying GC B cell dynamics by single cell RNA-Seq. Profiling of antigen specific GC B cells during the peak of the response, revealed four distinctive genomic states characterized by antigen presentation, apoptotic, mitochondrial and mitotic gene expression modules. Intersection of genomic states and Ig heavy-chain (Igh) class-switch trajectory suggested that mitochondrial machinery is utilized to support class-switch recombination (CSR). Furthermore, by analyzing the transcriptomes of B cells with varying affinity BCR sequences that assembled from single-cell RNA-seq data through a novel algorithm, we show that high affinity GC B cells manifest enhanced mitotic and BCR signaling transduction, but compromised antigen processing and presentation gene expression modules. Thus, we are developing a comprehensive framework of the genomic states and molecular pathways underlying GC B cell dynamics.
Project description:Upon antigen recognition B cells undertake a bifurcated response in which some cells rapidly differentiate into plasmablasts while others undergo affinity maturation in germinal centers (GC). We uncover a double negative feedback loop between interferon regulatory factors IRF4 and IRF8, which regulates the initial bifurcation of activated B cells as well as the GC response. IRF8 dampens BCR signaling, facilitates antigen specific interaction with helper T cells, and promotes selection of high affinity clones while antagonizing IRF4 driven plasmablast differentiation. Genomic analysis reveals concentration dependent action of IRF4 and IRF8 in regulating distinctive gene expression programs. Stochastic modeling suggests that the double negative feedback is sufficient to initiate bifurcating B cell developmental trajectories. Naïve B cells were isolated from wild type (WT) mice spleen and activated in vitro with 10μg/ml LPS (Sigma). ChIP was performed by using anti-IRF4, -IRF8 antibodies (Santa Cruz Biotech). For massively parallel sequencing, 10-20 μg of chromatin fragments from indicated samples were immunoprecipitated by using anti-IRF-4 and anti-IRF8 antibodies, and DNA libraries were prepared with Illumina Kit. DNA was sequenced by using the Illumina HiSeq2500. Reads were aligned to the mouse genome (mm9) by using Taphat2 and peak calling were performed by homer 2. GC B cells were sorted from WT mice on dpi 13 post NP-KLH immunization. Cells were flash frozen immediately and process by Active Motif for IRF8 ChIP-Seq. Reads were aligned to mm9 by using BAM and peak calling were performed by using MACS. More details are provided in the manuscript.
Project description:Upon antigen recognition B cells undertake a bifurcated response in which some cells rapidly differentiate into plasmablasts while others undergo affinity maturation in germinal centers (GC). We uncover a double negative feedback loop between interferon regulatory factors IRF4 and IRF8, which regulates the initial bifurcation of activated B cells as well as the GC response. IRF8 dampens BCR signaling, facilitates antigen specific interaction with helper T cells, and promotes selection of high affinity clones while antagonizing IRF4 driven plasmablast differentiation. Genomic analysis reveals concentration dependent action of IRF4 and IRF8 in regulating distinctive gene expression programs. Stochastic modeling suggests that the double negative feedback is sufficient to initiate bifurcating B cell developmental trajectories. Naïve B cells were isolated from Irf8+/+ (wild type, WT) mice spleen and activated in vitro with 10μg/ml LPS (Sigma). CD138hi IgMhi (IRF4hi*) cells and CD138lo IgMlo (IRF8hi*) cells were sorted by flow cytometry at 72 hours. Total RNA was prepared by using Rneasy Mini kit (Qiagen) and sequenced with Illumina HiSeq2500. Alignment was performed with Taphat2, and transcript abundance quantification using Cuffdiff function from Cufflinks. GC B cells were sorted from CD19cre/+ Irf8+/+ (Ctrl) or CD19cre/+ Irf8flox/flox (Irf8 cKO) mice on dpi 13 post NP-KLH immunization. Total RNA was prepared by using Rneasy Mini kit (Qiagen) and amplified with with Ovation RNA-Seq System v2 (NuGEN). The data were analyzed by Wardrobe. More details are provided in the manuscript.