Biology subjects

Seyres, D.

Publications and source records attributed to Seyres, D..

8 recordsLinked to original sources

bioRxiv2025

Tmem127-mediated immune receptor degradation regulates T cell homeostasis through the common gamma chain

Maintenance of T cell population size, which is important for immune homeostasis, is controlled by interleukin-7 (IL-7) and low-affinity TCR/MHC interactions that provide limited survival cues. Using arrayed CRISPR screening of miR-17[~]92 targets, Bio-ID proximity labeling and proteomics we identified Tmem127 as an essential regulator of the T cell surface proteome. We validated interaction with the common gamma chain (IL-2R{gamma}) in a multi-protein complex. Tmem127 reduces IL-7 receptor surface expression to restrict homeostatic proliferation, thereby controlling naive and central memory T cell population sizes. Tmem127 germline knockout (KO) mice display splenomegaly, accelerated experimental autoimmune encephalomyelitis and Tmem127-deficient bone marrow displays a competitive advantage over wildtype cells. Thus, we identified Tmem127 as an important regulator of the common gamma chain and immune homeostasis.

immunology↗

bioRxiv2023

Epitope Engineered Human Haematopoietic Stem Cells are Shielded from CD123-targeted Immunotherapy

Targeted eradication of transformed or otherwise dysregulated cells using monoclonal antibodies (mAb), antibody-drug conjugates (ADC), T cell engagers (TCE) or chimeric antigen receptor (CAR) cells is very effective for haematologic diseases. Unlike the breakthrough progress achieved for B cell malignancies, there is a pressing need to find suitable antigens for immunotherapy of myeloid malignancies. CD123, the interleukin-3 (IL-3) receptor alpha-chain, is highly expressed in various haematological malignancies, including acute myeloid leukaemia (AML) and blastic plasmacytoid dendritic cell neoplasm (BPDCN). However, shared expression of CD123 on healthy haematopoietic stem and progenitor cells (HSPCs) bears the risk for extensive myelotoxicity upon targeted depletion. Here, we demonstrate that rationally designed, epitope-engineered HSPCs were completely shielded from CD123-targeted immunotherapy but remained fully functional while CD123-deficient HSPCs displayed a competitive disadvantage. Thus, molecularly shielded HSPCs could allow tumor-selective targeted immunotherapy and in parallel enable rebuilding a fully functional haematopoietic system. We envision that this approach is broadly applicable to many targets and cells, could render hitherto undruggable targets accessible to immunotherapy and will allow continued posttransplant immunotherapy, for instance to treat minimal residual disease (MRD) or be used as a salvage therapy. Since the function of the engineered targets is preserved, multiplexed molecular shielding could also enable targeted combination immunotherapies to address tumor heterogeneity. More generally, epitope shielding will be applicable for replacement of other cell types including the many immune cells which are currently being considered for engineered cellular therapies.

bioengineering↗

bioRxiv2023

T helper cells exhibit a dynamic and reversible 3'UTR landscape.

3 untranslated regions (3UTRs) are critical elements of messenger RNAs, as they contain binding sites for RNA-binding proteins (RBP) and microRNAs that affect various aspects of the RNA life cycle including transcript stability and cellular localisation. In response to T cell receptor activation, T cells undergo massive expansion during the effector phase of the immune response and dynamically modify their 3UTRs. Whether this serves to directly regulate the abundance of specific mRNAs or is a secondary effect of proliferation remains unclear. To study 3UTR dynamics in T helper cells we investigated division-dependent alternative polyadenylation (APA). We generated 3 end UTR sequencing data from naive, activated, memory and regulatory CD4+ T cells. 3UTR length changes were estimated using a non-negative matrix factorization approach and were compared with those inferred from long-read PacBio sequencing. We found that APA events were transient and reverted after effector phase expansion. Using an orthogonal bulk RNAseq dataset, we did not find evidence of APA association with differential gene expression or transcript usage, indicating that APA has only a marginal effect on transcript abundance. 3UTR sequence analysis revealed conserved binding sites for T cell-relevant microRNAs and RBPs in the alternative 3UTRs. These results indicate that polyA site usage could play an important role in the control of cell fate decisions and homeostasis.

immunology↗

bioRxiv2020

The non-coding RNA miR-17~92 is a central mediator of T cell activation

T cell activation is paramount for productive adaptive immune responses. CD28 is a key clinically targeted immunoregulatory receptor because it provides the prototypical costimulatory signal required for T cell activation. Therefore, a precise understanding of the molecular consequences of CD28 costimulation has direct therapeutic relevance. Here, we uncover that the microRNA cluster miR-17~92 is part of the molecular program triggered by CD28 costimulation and hence T cell activation. Combining genetics, transcriptomics, bioinformatics and biochemical miRNA:mRNA interaction maps we demonstrate that transgenic miR-17~92 can cell-intrinsically largely overcome defects caused by CD28-deficiency. miR-17~92 promotes transcription of a proinflammatory gene signature by enhancing the calcineurin/NFAT pathway. miR-17~92 binds to and represses a network of genes including several negative regulators of T cell activation. Finally, CD28-deficient T cells exhibit derepressed miR-17~92 target genes during activation, demonstrating that this non-coding RNA is required to shape the transcriptome. Thus, we propose that miR-17~92 constitutes a central mediator for T cell activation, integrating signals by the TCR and CD28 costimulation. In this model miR-17~92 facilitates T cell activation by dampening the breaks that prevent T cell activation.

immunology↗

bioRxiv2020

Extreme phenotypes define epigenetic and metabolic signatures in cardiometabolic syndrome.

Improving the understanding of cardiometabolic syndrome pathophysiology and its relationship with thrombosis are ongoing healthcare challenges. Using plasma biomarkers analysis coupled with the transcriptional and epigenetic characterisation of cell types involved in thrombosis, obtained from two extreme phenotype groups (obese and lipodystrophy) and comparing these to lean individuals and blood donors, the present study identifies the molecular mechanisms at play, highlighting patterns of abnormal activation in innate immune phagocytic cells and shows that extreme phenotype groups could be distinguished from lean individuals, and from each other, across all data layers. The characterisation of the same obese group, six months after bariatric surgery shows the loss of the patterns of abnormal activation of innate immune cells previously observed. However, rather than reverting to the gene expression landscape of lean individuals, this occurs via the establishment of novel gene expression landscapes. Netosis and its control mechanisms emerge amongst the pathways that show an improvement after surgical intervention. Taken together, by integrating across data layers, the observed molecular and metabolic differences form a disease signature that is able to discriminate, amongst the blood donors, those individuals with a higher likelihood of having cardiometabolic syndrome, even when not presenting with the classic features.

genomics↗

bioRxiv2020

Genetic Analyses of Blood Cell Structure for Biological and Pharmacological Inference

Thousands of genetic associations with phenotypes of blood cells are known, but few are with phenotypes relevant to cell function. We performed GWAS of 63 flow-cytometry phenotypes, including measures of cell granularity, nucleic acid content, and reactivity, in 39,656 participants in the INTERVAL study, identifying 2,172 variant-trait associations. These include associations mediated by functional cellular structures such as secretory granules, implicated in vascular, thrombotic, inflammatory and neoplastic diseases. By integrating our results with epigenetic data and with signals from molecular abundance/disease GWAS, we infer the hematopoietic origins of population phenotypic variation and identify the transcription factor FOG2 as a regulator of platelet -granularity. We show how flow cytometry genetics can suggest cell types mediating complex disease risk and suggest efficacious drug targets, presenting Daclizumab/Vedolizumab in autoimmune disease as positive controls. Finally, we add to existing evidence supporting IL7/IL7-R as drug targets for multiple sclerosis.

genetics↗

bioRxiv2019

Cell type specific novel lincRNAs and circRNAs in the BLUEPRINT haematopoietic transcriptomes atlas.

Transcriptional profiling of hematopoietic cell subpopulations has helped characterize the developmental stages of the hematopoietic system and the molecular basis of malignant and non-malignant blood diseases for the past three decades. The introduction of high-throughput RNA sequencing has increased knowledge of the full repertoire of RNA molecules in hematopoietic cells of different types, without relying on prior gene annotation. Here, we introduce the analysis of the BLUEPRINT consortium gene expression data for mature hematopoietic cells, comprising 90 total RNA and 32 small RNA sequencing experiments, from 27 different cell types. We used these data to describe the transcriptional profile of each we used guided transcriptome assembly to extend the annotation of the transcribed genome, which led to the identification of hundreds of novel non-coding RNA genes, which display a high degree of cell type specificity. We also characterized the expression of circular RNAs and found that these are also highly cell type specific. This resource refines the active transcriptional landscape of mature hematopoietic cells, highlights abundant genes and transcriptional isoforms for each cell type, and provides valuable data and visualisation tools for the scientific community working on hematological development and diseases.

genomics↗

bioRxiv2018

Histone Acetyltransferase Kat2a Stabilises Pluripotency with Control of Transcriptional Heterogeneity

Cell fate transitions in mammalian stem cell systems have often been associated with transcriptional heterogeneity, however existing data have failed to establish a functional or mechanistic link between the two phenomena. Experiments in unicellular organisms support the notion that transcriptional heterogeneity can be used to facilitate adaptability to environmental changes and have identified conserved chromatin-associated factors that modulate levels of transcriptional noise. Herein, we show destabilisation of pluripotency-associated gene regulatory networks through increased transcriptional heterogeneity of mouse embryonic stem cells in which paradigmatic histone acetyl-transferase, and candidate noise modulator, Kat2a (yeast orthologue Gcn5) has been inhibited. Functionally, network destabilisation associates with reduced pluripotency and accelerated mesendodermal differentiation, with increased probability of transitions into lineage commitment. Thus, we functionally link transcriptional heterogeneity to cell fate transitions through manipulation of the histone acetylation landscape of mouse embryonic stem cells and establish a general paradigm that could be exploited in other normal and malignant stem cell fate transitions.

developmental biology↗