After priming, naïve CD8
T lymphocytes establish specific heritable transcription programs that define progression to long-lasting memory cells or to short-lived effector cells. Although lineage ...specification is critical for protection, it remains unclear how chromatin dynamics contributes to the control of gene expression programs. We explored the role of gene silencing by the histone methyltransferase Suv39h1. In murine CD8
T cells activated after
infection, Suv39h1-dependent trimethylation of histone H3 lysine 9 controls the expression of a set of stem cell-related memory genes. Single-cell RNA sequencing revealed a defect in silencing of stem/memory genes selectively in
-defective T cell effectors. As a result,
-defective CD8
T cells show sustained survival and increased long-term memory reprogramming capacity. Thus, Suv39h1 plays a critical role in marking chromatin to silence stem/memory genes during CD8
T effector terminal differentiation.
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BFBNIB, NMLJ, NUK, ODKLJ, PNG, SAZU, UL, UM, UPUK
Despite its crucial role in initiation of cytotoxic immune responses, the molecular pathways underlying antigen cross-presentation remain incompletely understood. The mechanism of antigen exit from ...endocytic compartments into the cytosol is a long-standing matter of controversy, confronting two main models: transfer through specific channels/transporters or rupture of endocytic membranes and leakage of luminal content. By monitoring the occurrence of intracellular damage in conventional dendritic cells (cDCs), we show that cross-presenting cDC1s display more frequent endomembrane injuries and increased recruitment of endosomal sorting complex required for transport (ESCRT)-III, the main repair system for intracellular membranes, relative to cDC2s. Silencing of CHMP2a or CHMP4b, two effector subunits of ESCRT-III, enhances cytosolic antigen export and cross-presentation. This phenotype is partially reversed by chemical inhibition of RIPK3, suggesting that endocytic damage is related to basal activation of the necroptosis pathway. Membrane repair therefore proves crucial in containing antigen export to the cytosol and cross-presentation in cDCs.
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•Cross-presenting dendritic cells (cDC1s) undergo endomembrane damage at steady state•Occurrence of endocytic injuries triggers ESCRT-III recruitment in cDC1s•ESCRT-III deficiency results in persistence of unrepaired endomembrane damage•Endomembrane repair defects enhance cytosolic antigen export and cross-presentation
Despite their rate-limiting nature, the molecular events leading to cytosolic export of antigens during cross-presentation remain incompletely understood. Gros et al. identify the ESCRT-III membrane repair complex as a negative regulator of antigen export to the cytosol and point to endomembrane rupture as a major route for antigens in cross-presentation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Naive CD4⁺ T lymphocytes differentiate into different effector types, including helper and regulatory cells (Th and Treg, respectively). Heritable gene expression programs that define these effector ...types are established during differentiation, but little is known about the epigenetic mechanisms that install and maintain these programs. Here, we use mice defective for different components of heterochromatin-dependent gene silencing to investigate the epigenetic control of CD4⁺ T cell plasticity. We show that, upon T cell receptor (TCR) engagement, naive and regulatory T cells defective for TRIM28 (an epigenetic adaptor for histone binding modules) or for heterochromatin protein 1 β and γ isoforms (HP1β/γ, 2 histonebinding factors involved in gene silencing) fail to effectively signal through the PI3K–AKT–mTOR axis and switch to glycolysis. While differentiation of naive TRIM28−/− T cells into cytokine-producing effector T cells is impaired, resulting in reduced induction of autoimmune colitis, TRIM28−/− regulatory T cells also fail to expand in vivo and to suppress autoimmunity effectively. Using a combination of transcriptome and chromatin immunoprecipitation-sequencing (ChIP-seq) analyses for H3K9me3, H3K9Ac, and RNA polymerase II, we show that reduced effector differentiation correlates with impaired transcriptional silencing at distal regulatory regions of a defined set of Treg-associated genes, including, for example, NRP1 or Snai3. We conclude that TRIM28 and HP1β/γ control metabolic reprograming through epigenetic silencing of a defined set of Treg-characteristic genes, thus allowing effective T cell expansion and differentiation into helper and regulatory phenotypes.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
...expression of CD25 and the inhibitory T-cell coreceptors programmed cell death 1 (PD-1) and cytotoxic T lymphocyte-associated protein 4 (CTLA-4) was enhanced on T cells from patients with RA and ...SpA, whereas levels of inducible T-cell costimulator (ICOS) were increased only in patients with RA (Fig 1, A, and see Fig E1). Because CD4+ T cells from patients showed phenotypic signs of exhaustion, we studied their response to polyclonal TCR-dependent stimulation. Here we found that patients with RA and those with SpA carry CD4+ T cells with different degrees of phenotypic and functional exhaustion. Because we analyzed polyclonal CD4+ T-cell proliferation, our results indicated that not only single autoreactive T-cell clones but also the entire T-cell repertoire was affected.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Oncogenesis often implicates epigenetic alterations, including derepression of transposable elements (TEs) and defects in alternative splicing. Here, we explore the possibility that noncanonical ...splice junctions between exons and TEs represent a source of tumor-specific antigens. We show that mouse normal tissues and tumor cell lines express wide but distinct ranges of mRNA junctions between exons and TEs, some of which are tumor specific. Immunopeptidome analyses in tumor cell lines identified peptides derived from exon-TE splicing junctions associated to MHC-I molecules. Exon-TE junction-derived peptides were immunogenic in tumor-bearing mice. Both prophylactic and therapeutic vaccinations with junction-derived peptides delayed tumor growth in vivo. Inactivation of the TE-silencing histone 3-lysine 9 methyltransferase
caused overexpression of new immunogenic junctions in tumor cells. Our results identify exon-TE splicing junctions as epigenetically controlled, immunogenic, and protective tumor antigens in mice, opening possibilities for tumor targeting and vaccination in patients with cancer.
To develop a patient decision aid facilitating shared decision making for patients with potential pancreatic cancer deciding about no treatment, surgical or medical treatment.
Based on a user-centred ...design by Wittemann et al., we developed a shared decision making intervention in three phases: 1) Understanding decision needs 2) Development of a patient decision aid (PtDA) based on a generic template 3) Assessment of the intervention from interviews with patients (n = 11), relatives (n = 11), nurses (n = 4) and surgeons (n = 2) analysed with thematic analysis, and measuring patients' perceptions of choice of options with the Decisional Conflict Scale.
Results showed varying experiences with the use of the PtDA, with surgeons not finding PtDA useful as it was impractical and constraining with patients' conversations. There was no difference in patients' perceptions in choosing options for those being presented vs those patients not being presented for the PtDA.
The format and structure of the PtDA was not feasible for the surgeons as fundamental users in the present clinic.
This study highlights the urgent need to consider clinical context before introducing a predefined tool and shows the importance of a multistakeholder approach. Research should focus on finding means to successful implement shared decision making.
•Novel investigation facilitating shared decision making for patients with potential pancreatic cancer deciding about their treatment.•Entail shared decision making to patients undergoing surgery for a time-critical cancer disease with limited survival and with alternative treatment options in a dichotomous irreversible choice.•The insight gained showed how the use of a generic patient decision aid template worked, not as a facilitator, but as a barrier for enhancing shared decision making.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Triazolo4,5-dpyrimidin-5-amines were identified as novel ERK3 inhibitors with sub-100 nanomolar biochemical potencies.•Highly potent inhibitors such as 18 revealed an attractive ...kinase selectivity profile.•ERK3 crystal structures clarified inhibitor binding in ATP site with potential conformational impact on MK5 recognition.•Inhibitors were also highly potent in a cellular ERK3 NanoBRET assay with excellent correlation to the biochemical assay.
Triazolo4,5-dpyrimidin-5-amines were identified from kinase selectivity screening as novel ERK3 inhibitors with sub-100 nanomolar potencies in a biochemical assay using MK5 as substrate and with an attractive kinase selectivity profile. ERK3 crystal structures clarified the inhibitor binding mode in the ATP pocket with impact on A-loop, GC-loop and αC-helix conformations suggesting a potential structural link towards MK5 interaction via the FHIEDE motif. The inhibitors also showed sub-100 nM potencies in a cellular ERK3 NanoBRET assay and with excellent correlation to the biochemical IC50s. This novel series provides valuable tool compounds to further investigate the biological function and activation mechanism of ERK3.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
T helper cells secreting interleukin (IL)-17 (Th17 cells) play a crucial role in autoimmune diseases like multiple sclerosis (MS). Th17 differentiation, which is induced by a combination of ...transforming growth factor (TGF)-beta/IL-6 or IL-21, requires expression of the transcription factor retinoic acid receptor-related orphan receptor gamma t (ROR gamma t). We identify the nuclear receptor peroxisome proliferator-activated receptor gamma (PPAR gamma) as a key negative regulator of human and mouse Th17 differentiation. PPAR gamma activation in CD4(+) T cells selectively suppressed Th17 differentiation, but not differentiation into Th1, Th2, or regulatory T cells. Control of Th17 differentiation by PPAR gamma involved inhibition of TGF-beta/IL-6-induced expression of ROR gamma t in T cells. Pharmacologic activation of PPAR gamma prevented removal of the silencing mediator for retinoid and thyroid hormone receptors corepressor from the ROR gamma t promoter in T cells, thus interfering with ROR gamma t transcription. Both T cell-specific PPAR gamma knockout and endogenous ligand activation revealed the physiological role of PPAR gamma for continuous T cell-intrinsic control of Th17 differentiation and development of autoimmunity. Importantly, human CD4(+) T cells from healthy controls and MS patients were strongly susceptible to PPAR gamma-mediated suppression of Th17 differentiation. In summary, we report a PPAR gamma-mediated T cell-intrinsic molecular mechanism that selectively controls Th17 differentiation in mice and in humans and that is amenable to pharmacologic modulation. We therefore propose that PPAR gamma represents a promising molecular target for specific immunointervention in Th17-mediated autoimmune diseases such as MS.
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