BCL6 orchestrates Tfh differentiation via multiple distinct mechanisms
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE59933 | GEO | 2015/03/20
SECONDARY ACCESSION(S): PRJNA257089
REPOSITORIES: GEO
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Project description:Tfh cells are required for T cell help to B cells, and BCL6 is the defining transcription factor of Tfh cells. However, the functions of Bcl6 in Tfh have largely remained unclear. Here we defined the BCL6 cistrome in primary human germinal center Tfh cells to assess mechanisms of BCL6 regulation of CD4 T cells, comparing and contrasting BCL6 function in T and B cells. BCL6 primarily acts as a repressor in Tfh cells, and BCL6 binding was associated with control of Tfh cell migration and repression of alternative cell fates. Interestingly, although some BCL6 bound genes possessed BCL6 DNA binding motifs, many BCL6-bound loci were instead characterized by the presence of DNA motifs for AP1 or STAT. AP1 complexes are key positive downstream mediators of TCR signaling and external stimuli. We show that BCL6 can directly bind AP1, and BCL6 depends on AP1 for recruitment to BCL6 binding sites with AP1 motifs, suggesting that BCL6 subverts AP1 activity. These findings reveal that BCL6 has broad and multifaceted effects on Tfh biology, and provide insight into how this master regulator mediates distinct cell-context dependent phenotypes.
2015-03-01 | GSE66373 | GEO
Project description:Tfh cells are required for T cell help to B cells, and BCL6 is the defining transcription factor of Tfh cells. However, the functions of Bcl6 in Tfh have largely remained unclear. Here we defined the BCL6 cistrome in primary human germinal center Tfh cells to assess mechanisms of BCL6 regulation of CD4 T cells, comparing and contrasting BCL6 function in T and B cells. BCL6 primarily acts as a repressor in Tfh cells, and BCL6 binding was associated with control of Tfh cell migration and repression of alternative cell fates. Interestingly, although some BCL6 bound genes possessed BCL6 DNA binding motifs, many BCL6-bound loci were instead characterized by the presence of DNA motifs for AP1 or STAT. AP1 complexes are key positive downstream mediators of TCR signaling and external stimuli. We show that BCL6 can directly bind AP1, and BCL6 depends on AP1 for recruitment to BCL6 binding sites with AP1 motifs, suggesting that BCL6 subverts AP1 activity. These findings reveal that BCL6 has broad and multifaceted effects on Tfh biology, and provide insight into how this master regulator mediates distinct cell-context dependent phenotypes. Sorted naM-CM-/ve tonsil cells were activated with anti-CD3+CD28 Ab coated beads and transduced with BCL6 or control lentiviral vectors as described. RNA was isolated at day 5 following LV infection and microarrays performed as discussed herein. RNA was isolated with the RNeasy Micro Kit (QIAGEN). The quantity and quality of the RNA were confirmed with a NanoDrop 2000c (Thermo Fisher Scientific) and an Experion Electrophoresis System (Bio-Rad). Samples (20 ng) were amplified with Illumina MessageAmp II aRNA Amplification Kits (Ambion), hybridized to HumanHT-12_V4 BeadChips (Illumina), and quantified with Genome Studio (Illumina). Normalized data (heatmap of blood cells) or raw data (heatmap of tonsil cells and Volcano plot) were analyzed with the GenePattern software suite.
2015-03-01 | E-GEOD-66373 | biostudies-arrayexpress
Project description:CD4+ T follicular helper (Tfh) cells are essential for germinal center (GC) and high-affinity antibody responses. Yet the regulation that determines the initial development of Tfh cells is still largely unknown. Here we find that transcription factor Foxp1, previously shown to be essential in maintaining T cell quiescence, is a rate-limiting and essential negative regulator of Tfh cell differentiation. NaM-CM-/ve CD4+ T cells constitutively express Foxp1A, and stimulation through the T cell receptor (TCR) transiently induces the expression of a shorter Foxp1D isoform. In T cell-dependent (TD) humoral responses, CD4+ T cells deficient in all Foxp1 isoforms preferentially differentiate into Tfh cells, resulting in substantially increased GC and antibody responses. This negative regulation of Foxp1 on Tfh cell differentiation shows profound dominance: even in the absence of B cells, Foxp1-deficient CD4+ T cells differentiate into Tfh cells with high frequencies and sustained Bcl6 expression. Further, in the absence of Foxp1, Tfh cells are generated in higher frequencies than seen with Bcl6 overexpression and Tfh cell differentiation becomes significantly resistant to Blimp1-mediated repression. Finally, our experiments reveal specific roles of Foxp1A and Foxp1D in inhibiting Tfh cell differentiation: TCR-induced Foxp1D functions as a M-bM-^@M-^XgatekeeperM-bM-^@M-^Y to block the initial Tfh cell development, and together Foxp1A and Foxp1D proteins inversely determine Tfh cell generation in a dosage-dependent manner. Our study suggests that two Foxp1 isoforms provide a M-bM-^@M-^\double checkM-bM-^@M-^] mechanism as fundamental regulators in Tfh cell differentiation and humoral responses. Gene expression analysis of ex vivo OT-II Foxp1-WT Tfh cells and OT-II Foxp-conditional knockout (CKO) Tfh cells 5 days after immunization.
2014-05-18 | E-GEOD-50725 | biostudies-arrayexpress
Project description:T follicular helper (Tfh) cell is a unique T cell subset specialized in promoting germinal center reactions. Bcl6 has been identified as an obligatory transcription factor in Tfh cells; however, the molecular mechanism underlying Bcl6 function still remains unknown. Here, we combined genome-wide Bcl6 occupancy and transcriptome profiling to systemically analyze Bcl6 targets in Tfh cells. We found that Bcl6 exhibits unique binding preferences in Tfh cells from those in Th9, B cells and macrophage and its binding is closely associated with decrease in 5-hydroxymethylcytosine (5hmC). Importantly, Bcl6 directly binds to the IL-7R/CD127 gene and suppresses its expression. Bcl6 also binds the same sequences recognized by signal transducer and activator of transcription (STAT) 5, downstream of IL-7R. Bcl6 promotes CD127loPDhi Tfh cell differentiation; deletion of the Bcl6 gene in T cells results in enhanced IL-7R-STAT5 signaling and substantial expansion of CD127hiPDlo non-Tfh cells. Our study thus systemically examines Bcl6-controlled regulatory networks and provides novel insights into its biological functions in Tfh cells.
2016-01-31 | GSE72188 | GEO
Project description:Transcriptional regulation of cell fate decisions in the immune system endows cells with specialized function; an iterative process that adapts to the changing landscape of infections. As coordinators of the immune system, T helper cells of the CD4+ lineage possess the ability to differentiate into an array of functional cell states in order to guide the response towards antibody production via the formation of T follicular helper (Tfh) cells or inflammation by the generation of T effector (Teff) cells. Tfh–Teff cell fate choice is mediated by the BCL6–Blimp-1 counter-antagonistic gene regulatory module, polarizing Tfh and Teff cells, respectively. A key question is how T helper cells establish and negotiate BCL6–Blimp-1 counter antagonism to control the output of Tfh and Teff cells. We show that the T cell receptor (TCR)-signal induced transcription factor, IRF4, is necessary for the generation of both BCL6-expressing Tfh cells and Blimp-1-expressing Teff cells. Importantly, we show that increasing TCR signal strength augments the amounts of IRF4 expressed as well as Teff cell fate trajectories that occur at the expense of Tfh cells. Using an orthogonal genetic system, based on a tet-inducible allele of Irf4, we demonstrate that increasing IRF4 expression during priming redirected Tfh cell fate choices towards those of Teff. Importantly, promotion of Teff cell fate trajectories by increased IRF4 expression occurred independently of IL-2 signals. At the molecular level, we link greater IRF4 abundance with its recruitment to low affinity DNA binding sites embedded within regulatory elements affiliated with the Teff gene program, including Blimp-1. Together, these results demonstrate that the Irf4 locus functions as the “reader” of TCR signal strength, in turn, the concentration dependent activity of the IRF4 transcription factor “writes” T helper cell fate choice.
2017-10-25 | GSE92272 | GEO
Project description:CD4+ T follicular helper cells (TFH) are critical for the formation and function of B cell responses to infection or immunization, but also play an important role in autoimmunity. The factors that contribute to the differentiation of this helper cell subset are incompletely understood, although several cytokines including IL-6, IL-21 and IL-12 can promote TFH cell formation. Yet, none of these factors, nor their downstream cognate STATs, have emerged as non-redundant, essential drivers of TFH cells. This suggests a model in which multiple factors can contribute to the phenotypic characteristics of TFH cells. As type I interferons (IFNs) are often generated in immune responses, we set out to investigate if these factors are relevant to TFH cell differentiation. Type I IFNs promote Th1 responses, thus one possibility was these factors antagonized TFH-expressed genes. However, we show that type I IFNs (IFN-α/β) induced Bcl6 expression, the master regulator transcription factor for TFH cells, and CXCR5 and PD-1 (encoded by Pdcd1), key surface molecules expressed by TFH cells. In contrast, type I IFNs failed to induce IL-21, the signature cytokine for TFH cells. The induction of Bcl6 was regulated directly by STAT1, which bound to the Bcl6, Cxcr5 and Pdcd1 loci. These data suggest that type I IFNs (IFN-α/β) and STAT1 can contribute to some features of TFH cells but are inadequate in inducing complete programming of this subset. The role of STAT1 in type I interferon treated CD4+ T cells was investigated by Chip-seq of STAT1.
2014-01-22 | E-GEOD-51531 | biostudies-arrayexpress
Project description:CD4+ T follicular helper (Tfh) cells are essential for germinal center (GC) and high-affinity antibody responses. Yet the regulation that determines the initial development of Tfh cells is still largely unknown. Here we find that transcription factor Foxp1, previously shown to be essential in maintaining T cell quiescence, is a rate-limiting and essential negative regulator of Tfh cell differentiation. Naïve CD4+ T cells constitutively express Foxp1A, and stimulation through the T cell receptor (TCR) transiently induces the expression of a shorter Foxp1D isoform. In T cell-dependent (TD) humoral responses, CD4+ T cells deficient in all Foxp1 isoforms preferentially differentiate into Tfh cells, resulting in substantially increased GC and antibody responses. This negative regulation of Foxp1 on Tfh cell differentiation shows profound dominance: even in the absence of B cells, Foxp1-deficient CD4+ T cells differentiate into Tfh cells with high frequencies and sustained Bcl6 expression. Further, in the absence of Foxp1, Tfh cells are generated in higher frequencies than seen with Bcl6 overexpression and Tfh cell differentiation becomes significantly resistant to Blimp1-mediated repression. Finally, our experiments reveal specific roles of Foxp1A and Foxp1D in inhibiting Tfh cell differentiation: TCR-induced Foxp1D functions as a ‘gatekeeper’ to block the initial Tfh cell development, and together Foxp1A and Foxp1D proteins inversely determine Tfh cell generation in a dosage-dependent manner. Our study suggests that two Foxp1 isoforms provide a “double check” mechanism as fundamental regulators in Tfh cell differentiation and humoral responses.
2014-05-18 | GSE50725 | GEO
Project description:T Follicular helper (Tfh) cell is an effector CD4+ T cell subset specialized in helping B cells in germinal centers (GC) reactions. Although Bcl6 was identified as a Tfh-specific transcription factor essential for their development, the molecular mechanisms underlying Bcl6 regulation and Tfh cell commitment remain unclear. Here, we report that Tox2 transcription factor is highly expressed in Tfh cells, regulated by Bcl6 and STAT3. Forced expression of Tox2 drives Bcl6 expression and Tfh development. Mechanistically, Tox2 directly binds to Tfh-associated genes, including Bcl6, and functions to promote their chromatin accessibility and modulate the activities of other Tfh-regulating factors. Conversely, genetic deletion of Tox2 results in defective Tfh differentiation, and inhibiting both Tox and Tox2 in T cells abolishes Tfh differentiation and GC response. Thus, our results demonstrate that Tox2 is a key transcription factor that regulates Bcl6 expression and Tfh development and suggest a Tox2-Bcl6 axis in feed-forward regulation of Tfh program.
2019-10-30 | GSE136539 | GEO
Project description:T Follicular helper (Tfh) cell is an effector CD4+ T cell subset specialized in helping B cells in germinal centers (GC) reactions. Although Bcl6 was identified as a Tfh-specific transcription factor essential for their development, the molecular mechanisms underlying Bcl6 regulation and Tfh cell commitment remain unclear. Here, we report that Tox2 transcription factor is highly expressed in Tfh cells, regulated by Bcl6 and STAT3. Forced expression of Tox2 drives Bcl6 expression and Tfh development. Mechanistically, Tox2 directly binds to Tfh-associated genes, including Bcl6, and functions to promote their chromatin accessibility and modulate the activities of other Tfh-regulating factors. Conversely, genetic deletion of Tox2 results in defective Tfh differentiation, and inhibiting both Tox and Tox2 in T cells abolishes Tfh differentiation and GC response. Thus, our results demonstrate that Tox2 is a key transcription factor that regulates Bcl6 expression and Tfh development and suggest a Tox2-Bcl6 axis in feed-forward regulation of Tfh program.
2019-10-30 | GSE136538 | GEO
Project description:T Follicular helper (Tfh) cell is an effector CD4+ T cell subset specialized in helping B cells in germinal centers (GC) reactions. Although Bcl6 was identified as a Tfh-specific transcription factor essential for their development, the molecular mechanisms underlying Bcl6 regulation and Tfh cell commitment remain unclear. Here, we report that Tox2 transcription factor is highly expressed in Tfh cells, regulated by Bcl6 and STAT3. Forced expression of Tox2 drives Bcl6 expression and Tfh development. Mechanistically, Tox2 directly binds to Tfh-associated genes, including Bcl6, and functions to promote their chromatin accessibility and modulate the activities of other Tfh-regulating factors. Conversely, genetic deletion of Tox2 results in defective Tfh differentiation, and inhibiting both Tox and Tox2 in T cells abolishes Tfh differentiation and GC response. Thus, our results demonstrate that Tox2 is a key transcription factor that regulates Bcl6 expression and Tfh development and suggest a Tox2-Bcl6 axis in feed-forward regulation of Tfh program.
2019-10-30 | GSE136537 | GEO