Mouse thymocytes can be classified into four major subsets based on expression of CD4 and CD8 co-receptors. CD4-CD8- (double negative, DN) cells become CD4+CD8+ (double positive, DP) cells following productive T cell receptor (TCR) beta chain rearrangement. A small proportion of DP cells are selected through interaction of clonal TCRalpha/beta and MHC self peptide complex expressed on thymic stromal cells. DP cell expressing MHC class I-restricted TCR become CD4-CD8+ cells, which will finally differentiate into cytotoxic T cells, while MHC class II restricted selection generates CD4+CD8- helper lineage T cells.
Transcription factor AP4 modulates reversible and epigenetic silencing of the Cd4 gene.
Specimen part
View SamplesDuring a binary cell fate decision, a progeny silences the gene expression program associated with the alternative fate. Helper versus cytotoxic lineage decision in the thymus has been studied as a model for gene silencing of alternative lineage genes, including Cd4. While RUNX3 is required for the initiation of Cd4 silencing, it remains unknown how silenced states of Cd4 and other helper lineage genes are maintained. We show that the histone methyltransferase G9a is necessary for heritable silencing of Cd4 and other helper lineage genes in CD8 T cells. Despite normal Cd4 downregulation during the development, G9a-deficient CD8 T cells fail to maintain silencing of helper lineage genes when they repeatedly divide under non-inflammatory conditions. However, Cd4 depression is prevented during division driven by elevated TCR signaling and an inflammatory cytokine signaling. These results reveal the requirement for G9a in silencing of helper lineage genes in CD8 T cells and also suggest that CD8 T cells employ an alternative mechanism to maintain their cellular identity during immune responses. Overall design: RNA-sequencing on CD4+CD8+ G9a KO, CD4–CD8+ G9a KO, and CD4–CD8+ G9a WT T cells after 4 weeks of proliferation in a lymphopenic environment. ChIP-sequencing on H3K9me3 IP''ed from Ehmt2+/+ and Ehmt2-/- CD8+ T cells cultured in vitro with antibodies to CD3 and CD28
Cutting Edge: The Histone Methyltransferase G9a Is Required for Silencing of Helper T Lineage-Associated Genes in Proliferating CD8 T Cells.
Specimen part, Cell line, Subject
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The histone methyltransferase SETDB1 represses endogenous and exogenous retroviruses in B lymphocytes.
Specimen part
View SamplesGenome stability relies on epigenetic mechanisms that enforce repression of endogenous retroviruses (ERVs). Current evidence suggests that distinct chromatin-based mechanisms repress ERVs in cells of embryonic origin (histone methylation-dominant) versus more differentiated cells (DNA methylation-dominant). However, the latter aspect of this model has not been tested. Remarkably, and in contrast to the prevailing model, we find that repressive histone methylation catalyzed by the enzyme SETDB1 is critical for suppression of specific ERV families and exogenous retroviruses in committed B-lineage cells from adult mice. The profile of ERV activation in SETDB1-deficient B cells is distinct from that observed in corresponding embryonic tissues, despite the loss of repressive chromatin modifications at all ERVs. We provide evidence that, upon loss of SETDB1, ERVs are activated in a lineage-specific manner depending on the set of transcription factors available to target proviral regulatory elements. These findings have important implications for genome stability in somatic cells, as well as the interface between epigenetic repression and viral latency.
The histone methyltransferase SETDB1 represses endogenous and exogenous retroviruses in B lymphocytes.
Specimen part
View SamplesGenome stability relies on epigenetic mechanisms that enforce repression of endogenous retroviruses (ERVs). Current evidence suggests that distinct chromatin-based mechanisms repress ERVs in cells of embryonic origin (histone methylation-dominant) versus more differentiated cells (DNA methylation-dominant). However, the latter aspect of this model has not been tested. Remarkably, and in contrast to the prevailing model, we find that repressive histone methylation catalyzed by the enzyme SETDB1 is critical for suppression of specific ERV families and exogenous retroviruses in committed B-lineage cells from adult mice. The profile of ERV activation in SETDB1-deficient B cells is distinct from that observed in corresponding embryonic tissues, despite the loss of repressive chromatin modifications at all ERVs. We provide evidence that, upon loss of SETDB1, ERVs are activated in a lineage-specific manner depending on the set of transcription factors available to target proviral regulatory elements. These findings have important implications for genome stability in somatic cells, as well as the interface between epigenetic repression and viral latency. Overall design: Expression profiling and bisulfite PCR sequencing in Setdb1 C/C and Setdb1 D/D pro-B cells
The histone methyltransferase SETDB1 represses endogenous and exogenous retroviruses in B lymphocytes.
No sample metadata fields
View SamplesGerminal center (GC) B cells cycle between two states, the light zone (LZ) and the dark zone (DZ), and in the latter they proliferate and hypermutate their immunoglobulin genes. How this functional transition takes place is still controversial. In this study, we demonstrate that ablation of Foxo1 after GC development led to the loss of the DZ GC B cells and disruption of the GC architecture. Mechanistically, even upon provision of adequate T cell help, Foxo1-deficient GC B cells showed less proliferative expansion than controls. Moreover, we found that the transcription factor BATF was transiently induced in LZ GC B cells in a Foxo1-dependent manner and that deletion of BATF similarly led to GC disruption. Thus, our results are consistent with a model where the switch from the LZ to the DZ is triggered after receipt of T cell help, and suggest that Foxo1-mediated BATF up-regulation is at least partly involved in this switch. Overall design: mRNA profiles of wild-type DZ, LZ, and Foxo1-deficient GC B cells were generated by deep sequencing in triplicate, using Illumina HiSeq 1500.
The transcription factor Foxo1 controls germinal center B cell proliferation in response to T cell help.
Specimen part, Subject
View SamplesVariable strengths of T cell receptor (TCR) signaling can produce divergent outcomes for T cell development and function. The mechanisms leading to different outcomes are incompletely understood, but may include distinct activation thresholds for different transcription factors as well as distinct sensitivities among target genes to transcription factors. IRF4 is one transcription factor implicated in responses to variable TCR signal strength. IRF4 expression increases uniformly with increasing TCR signal strength (i.e., analog), but it is unclear how IRF4 induced distinct genes at different levels, rather than different amounts of the same genes. Here, we analyzed global gene expression in TH2 cells and used ChIP-seq to define the relationship between TCR signal strength, enhancer occupancy and transcriptional activity for BATF/IRF4-dependent genes. We show that enhancers exhibit a spectrum of affinity for the BATF/IRF4 ternary complex mediate graded responsiveness of individual genes to increasing TCR signal strength. Differential gene induction by BATF and IRF4 occurs through interaction with enhancer elements of different affinity for BATF/IRF4 complexes. The increased resolution of factor binding site identified using ChIP-exo allowed the identification of a novel AICE2 motif binding BATF/IRF4 with higher affinity and that this may explain the protective role of a single nucleotide polymorphism in the CTLA-4 locus known to decrease the incidence of autoimmune diseases.
Quality of TCR signaling determined by differential affinities of enhancers for the composite BATF-IRF4 transcription factor complex.
Specimen part
View SamplesRunx/Cbfb heterodimers play important roles in the development of hematopoietic cells in mouse embryos and adults. In order to identify genes that are regulated by Runx/Cbfb, we purified Lin c-kit+ Sca1+ (LSK) cells and Lin c-kit+ Sca1 CD16/32+ (GMP) cells from Vav1-iCre x Cbfb(F/F) and Vav1-iCre x Cbfb(F/+) mice and profiled gene expression using microarray.
Runx1 and Cbfβ regulate the development of Flt3+ dendritic cell progenitors and restrict myeloproliferative disorder.
Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
c-Myc-induced transcription factor AP4 is required for host protection mediated by CD8+ T cells.
Specimen part
View SamplesGene expression of Tfap4/ and WT CD8+ T cells were compared after activation with anti-CD3 and anti-CD28 antibodies in vitro or with Listeria monocytogenes infection in vivo
c-Myc-induced transcription factor AP4 is required for host protection mediated by CD8+ T cells.
No sample metadata fields
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