Poised enhancers marked by H3K27me3 in pluripotent stem cells have been implicated in the establishment of somatic expression programs during embryonic stem cell (ESC) differentiation. However, the ...functional relevance and mechanism of action of poised enhancers remain unknown. Using CRISPR/Cas9 technology to engineer precise genetic deletions, we demonstrate that poised enhancers are necessary for the induction of major anterior neural regulators. Interestingly, circularized chromosome conformation capture sequencing (4C-seq) shows that poised enhancers already establish physical interactions with their target genes in ESCs in a polycomb repressive complex 2 (PRC2)-dependent manner. Loss of PRC2 does not activate poised enhancers or induce their putative target genes in undifferentiated ESCs; however, loss of PRC2 in differentiating ESCs severely and specifically compromises the induction of major anterior neural genes representing poised enhancer targets. Overall, our work illuminates an unexpected function for polycomb proteins in facilitating neural induction by endowing major anterior neural loci with a permissive regulatory topology.
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•Poised enhancers are necessary for the induction of major anterior neural genes•Poised enhancers physically contact their target genes in embryonic stem cells•The interaction between poised enhancers and their target genes is PRC2 dependent•PRC2 provides major anterior neural loci with a permissive regulatory topology
Cruz-Molina et al. demonstrate that pluripotent-associated poised enhancers are necessary for the induction of anterior neural genes. Poised enhancers physically interact with their target genes in embryonic stem cells in a PRC2-dependent manner. Thus, polycomb proteins might facilitate neural induction by providing anterior neural loci with a permissive regulatory topology.
Humans encode two inflammatory caspases that detect cytoplasmic LPS, caspase‐4 and caspase‐5. When activated, these trigger pyroptotic cell death and caspase‐1‐dependent IL‐1β production; however the ...mechanism underlying this process is not yet confirmed. We now show that a specific NLRP3 inhibitor, MCC950, prevents caspase‐4/5‐dependent IL‐1β production elicited by transfected LPS. Given that both caspase‐4 and caspase‐5 can detect cytoplasmic LPS, it is possible that these proteins exhibit some degree of redundancy. Therefore, we generated human monocytic cell lines in which caspase‐4 and caspase‐5 were genetically deleted either individually or together. We found that the deletion of caspase‐4 suppressed cell death and IL‐1β production following transfection of LPS into the cytoplasm, or in response to infection with Salmonella typhimurium. Although deletion of caspase‐5 did not confer protection against transfected LPS, cell death and IL‐1β production were reduced after infection with Salmonella. Furthermore, double deletion of caspase‐4 and caspase‐5 had a synergistic effect in the context of Salmonella infection. Our results identify the NLRP3 inflammasome as the specific platform for IL‐1β maturation, downstream of cytoplasmic LPS detection by caspase‐4/5. We also show that both caspase‐4 and caspase‐5 are functionally important for appropriate responses to intracellular Gram‐negative bacteria.
DCs often require stimulation from CD4+ T cells to propagate CD8+ T cell responses, but precisely how T cell help optimizes the priming capacity of DCs and why this appears to differ between varying ...types of CD8+ T cell immunity remains unclear. We show that CD8+ T cell priming upon HSV-1 skin infection depended on DCs receiving stimulation from both IFN-α/β and CD4+ T cells to provide IL-15. This was not an additive effect but resulted from CD4+ T cells amplifying DC production of IL-15 in response to IFN-α/β. We also observed that increased innate stimulation reversed the helper dependence of CD8+ T cell priming and that the innate stimulus, rather than the CD4+ T cells themselves, determined how “help’” was integrated into the priming response by DCs. These findings identify T cell help as a flexible means to amplify varying suboptimal innate signals in DCs.
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•IFN-α/β and CD4+ T cells cooperate in enabling CD8+ DCs to provide IL-15•Innate circuit stimulation determines cytokine requirements of CTL priming•T cell help for CD8+ T cell priming is a means to amplify innate circuits in DCs
Greyer et al. show that “T cell help” optimizes CD8+ T cell priming by amplifying innate signals in DCs, illustrating that the innate circuits stimulated during priming and not the CD4+ T cells, dictate how T cell help is integrated into CD8+ T cell priming.
Cellular heterogeneity within embryonic and adult tissues is involved in multiple biological and pathological processes. Here, we present a simple epigenomic strategy that allows the functional ...dissection of cellular heterogeneity. By integrating H3K27me3 chromatin immunoprecipitation sequencing (ChIP-seq) and RNA sequencing (RNA-seq) data, we demonstrate that the presence of broad H3K27me3 domains at transcriptionally active genes reflects the heterogeneous expression of major cell identity regulators. Using dorsoventral patterning of the spinal neural tube as a model, the proposed approach successfully identifies the majority of previously known dorsoventral patterning transcription factors with high sensitivity and precision. Moreover, poorly characterized patterning regulators can be similarly predicted, as shown for ZNF488, which confers p1/p2 neural progenitor identity. Finally, we show that, as our strategy is based on universal chromatin features, it can be used to functionally dissect cellular heterogeneity within various organisms and tissues, thus illustrating its potential applicability to a broad range of biological and pathological contexts.
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•A simple epigenomic strategy to functionally dissect cellular heterogeneity is developed•Patterning regulators are identified with high sensitivity and precision•ZNF488 acts as a dorsoventral patterning regulator in the chicken spinal tube•This strategy is applicable to a broad range of tissues and organisms
Rehimi et al. describe a simple epigenomic approach whereby the presence of broad H3K27me3 domains at transcriptionally active genes signifies the heterogeneous expression of major cell identity regulators. This approach is broadly applicable, enabling the functional dissection of cellular heterogeneity within various tissues and organisms.
Tissue-resident memory T cells provide local immune protection in barrier tissues, such as skin and mucosa. However, the molecular mechanisms controlling effector T cell retention and subsequent ...memory formation in those locations are not fully understood. In this study, we analyzed the role of CD69, an early leukocyte activation marker, in regulating effector T cell egress from peripheral tissues. We provide evidence that CD69 surface expression by skin-infiltrating CD8 T cells can be regulated at multiple levels, including local Ag stimulation and signaling through type I IFNRs, and it coincides with the transcriptional downregulation of the sphingosine-1-phosphate receptor S1P1. Importantly, we demonstrate that expression of CD69, by interfering with sphingosine-1-phosphate receptor function, is a critical determinant of prolonged T cell retention and local memory formation. Our results define an important step in the generation of long-lived adaptive immune memory at body surfaces.
Staphylococcus aureus can cause difficult-to-treat chronic infections. We recently reported that S. aureus chronic infection was associated with a profound inhibition of T cell responses. In this ...study, we investigated the mechanisms responsible for the suppression of T cell responses during chronic S. aureus infection. Using in vitro coculture systems, as well as in vivo adoptive transfer of CFSE-labeled OT-II cells, we demonstrated the presence of immunosuppressive mechanisms in splenocytes of S. aureus-infected mice that inhibited the response of OT-II cells to cognate antigenic stimulation. Immunosuppression was IL-10/TGF-β independent but required cell-cell proximity. Using DEREG and Foxp3(gfp) mice, we demonstrated that CD4(+)CD25(+)Foxp3(+) regulatory T cells contributed, but only to a minor degree, to bystander immunosuppression. Neither regulatory B cells nor tolerogenic dendritic cells contributed to immunosuppression. Instead, we found a significant expansion of granulocytic (CD11b(+)Ly6G(+)Ly6C(low)) and monocytic (CD11b(+)Ly6G(-)Ly6C(high)) myeloid-derived suppressor cells (MDSC) in chronically infected mice, which exerted a strong immunosuppressive effect on T cell responses. Splenocytes of S. aureus-infected mice lost most of their suppressive activity after the in vivo depletion of MDSC by treatment with gemcitabine. Furthermore, a robust negative correlation was observed between the degree of T cell inhibition and the number of MDSC. An increase in the numbers of MDSC in S. aureus-infected mice by adoptive transfer caused a significant exacerbation of infection. In summary, our results indicate that expansion of MDSC and, to a minor degree, of regulatory T cells in S. aureus-infected mice may create an immunosuppressive environment that sustains chronic infection.
Objective: In the multicenter study Comparison of Methylphenidate and Psychotherapy in Adult ADHD (COMPAS), the efficacy of treatments has been primarily evaluated by observer-rated symptom change. ...Here, we additionally analyzed the patients’ subjective evaluation of therapy effects. Method: COMPAS compared ADHD-specific group therapy with unspecific clinical management with/without concomitant pharmacotherapy in a four-armed design. Evaluation through the patients’ retrospective perspective was performed after 1 year (post-treatment) and after another 1.5 years (follow-up). Results: In respect to patients’ subjective ratings, ADHD-specific group psychotherapy outperformed unspecific management post-treatment (z = 4.88, p < .0001) and at follow-up (z = 2.90, p = .004). Rank correlations with rater-based symptom change were small to moderate (post-treatment: rs = 0.28, follow-up: rs = 0.16). Conclusion: Therapy evaluation based on the patients’ perspective supports the concept of ADHD-specific group psychotherapy as a potentially useful therapy option in ADHD.
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