RESUMEN
Since their discovery almost two decades ago, interleukin-17-producing CD4+ T cells (TH17 cells) have been implicated in the pathogenesis of multiple autoimmune and inflammatory disorders. In addition, TH17 cells have been found to play an important role in tissue homeostasis, especially in the intestinal mucosa. Recently, the use of single-cell technologies, along with fate mapping and various mutant mouse models, has led to substantial progress in the understanding of TH17 cell heterogeneity in tissues and of TH17 cell plasticity leading to alternative T cell states and differing functions. In this Review, we discuss the heterogeneity of TH17 cells and the role of this heterogeneity in diverse functions of TH17 cells from homeostasis to tissue inflammation. In addition, we discuss TH17 cell plasticity and its incorporation into the current understanding of T cell subsets and alternative views on the role of TH17 cells in autoimmune and inflammatory diseases.
Asunto(s)
Inflamación , Células Th17 , Animales , Ratones , Plasticidad de la Célula , Subgrupos de Linfocitos T/metabolismo , Modelos Animales de EnfermedadRESUMEN
The immune response to SARS-CoV-2 antigen after infection or vaccination is defined by the durable production of antibodies and T cells. Population-based monitoring typically focuses on antibody titer, but there is a need for improved characterization and quantification of T cell responses. Here, we used multimodal sequencing technologies to perform a longitudinal analysis of circulating human leukocytes collected before and after immunization with the mRNA vaccine BNT162b2. Our data indicated distinct subpopulations of CD8+ T cells, which reliably appeared 28 days after prime vaccination. Using a suite of cross-modality integration tools, we defined their transcriptome, accessible chromatin landscape and immunophenotype, and we identified unique biomarkers within each modality. We further showed that this vaccine-induced population was SARS-CoV-2 antigen-specific and capable of rapid clonal expansion. Moreover, we identified these CD8+ T cell populations in scRNA-seq datasets from COVID-19 patients and found that their relative frequency and differentiation outcomes were predictive of subsequent clinical outcomes.
Asunto(s)
Linfocitos T CD8-positivos , COVID-19 , Humanos , Vacunas contra la COVID-19 , SARS-CoV-2 , Vacuna BNT162 , COVID-19/prevención & control , Vacunación , Anticuerpos AntiviralesRESUMEN
Lymphoid cells that produce interleukin (IL)-17 cytokines protect barrier tissues from pathogenic microbes but are also prominent effectors of inflammation and autoimmune disease. T helper 17 (Th17) cells, defined by RORγt-dependent production of IL-17A and IL-17F, exert homeostatic functions in the gut upon microbiota-directed differentiation from naive CD4+ T cells. In the non-pathogenic setting, their cytokine production is regulated by serum amyloid A proteins (SAA1 and SAA2) secreted by adjacent intestinal epithelial cells. However, Th17 cell behaviors vary markedly according to their environment. Here, we show that SAAs additionally direct a pathogenic pro-inflammatory Th17 cell differentiation program, acting directly on T cells in collaboration with STAT3-activating cytokines. Using loss- and gain-of-function mouse models, we show that SAA1, SAA2, and SAA3 have distinct systemic and local functions in promoting Th17-mediated inflammatory diseases. These studies suggest that T cell signaling pathways modulated by the SAAs may be attractive targets for anti-inflammatory therapies.
Asunto(s)
Síndrome del Colon Irritable/metabolismo , Proteína Amiloide A Sérica/metabolismo , Células Th17/metabolismo , Adulto , Animales , Enfermedades Autoinmunes/metabolismo , Diferenciación Celular/inmunología , Citocinas/metabolismo , Encefalomielitis Autoinmune Experimental/metabolismo , Femenino , Humanos , Inflamación/metabolismo , Interleucina-17/metabolismo , Síndrome del Colon Irritable/sangre , Masculino , Ratones , Ratones Endogámicos C57BL , Miembro 3 del Grupo F de la Subfamilia 1 de Receptores Nucleares/metabolismo , Células TH1 , Células Th17/inmunologíaRESUMEN
Targeting glycolysis has been considered therapeutically intractable owing to its essential housekeeping role. However, the context-dependent requirement for individual glycolytic steps has not been fully explored. We show that CRISPR-mediated targeting of glycolysis in T cells in mice results in global loss of Th17 cells, whereas deficiency of the glycolytic enzyme glucose phosphate isomerase (Gpi1) selectively eliminates inflammatory encephalitogenic and colitogenic Th17 cells, without substantially affecting homeostatic microbiota-specific Th17 cells. In homeostatic Th17 cells, partial blockade of glycolysis upon Gpi1 inactivation was compensated by pentose phosphate pathway flux and increased mitochondrial respiration. In contrast, inflammatory Th17 cells experience a hypoxic microenvironment known to limit mitochondrial respiration, which is incompatible with loss of Gpi1. Our study suggests that inhibiting glycolysis by targeting Gpi1 could be an effective therapeutic strategy with minimum toxicity for Th17-mediated autoimmune diseases, and, more generally, that metabolic redundancies can be exploited for selective targeting of disease processes.
Asunto(s)
Diferenciación Celular/inmunología , Encefalomielitis Autoinmune Experimental/inmunología , Glucosa-6-Fosfato Isomerasa/metabolismo , Glucólisis/genética , Fosforilación Oxidativa , Vía de Pentosa Fosfato/fisiología , Células Th17/metabolismo , Animales , Hipoxia de la Célula/genética , Hipoxia de la Célula/inmunología , Quimera/genética , Cromatografía de Gases , Cromatografía Liquida , Infecciones por Clostridium/inmunología , Citocinas/deficiencia , Citocinas/genética , Citocinas/metabolismo , Encefalomielitis Autoinmune Experimental/genética , Encefalomielitis Autoinmune Experimental/metabolismo , Glucosa-6-Fosfato Isomerasa/genética , Gliceraldehído-3-Fosfato Deshidrogenasa (Fosforilante)/genética , Gliceraldehído-3-Fosfato Deshidrogenasa (Fosforilante)/metabolismo , Glucólisis/inmunología , Homeostasis/genética , Homeostasis/inmunología , Inflamación/genética , Inflamación/inmunología , Espectrometría de Masas , Ratones , Ratones Endogámicos C57BL , Mitocondrias/metabolismo , Membrana Mucosa/inmunología , Membrana Mucosa/metabolismo , Membrana Mucosa/microbiología , Vía de Pentosa Fosfato/genética , Vía de Pentosa Fosfato/inmunología , RNA-Seq , Análisis de la Célula Individual , Células Th17/inmunología , Células Th17/patologíaRESUMEN
The mammalian alimentary tract harbors hundreds of species of commensal microorganisms (microbiota) that intimately interact with the host and provide it with genetic, metabolic, and immunological attributes. Recent reports have indicated that the microbiota composition and its collective genomes (microbiome) are major factors in predetermining the type and robustness of mucosal immune responses. In this review, we discuss the recent advances in our understanding of host-microbiota interactions and their effect on the health and disease susceptibility of the host.
Asunto(s)
Enfermedades Transmisibles/inmunología , Enfermedades Transmisibles/microbiología , Inflamación/inmunología , Inflamación/microbiología , Metagenoma/inmunología , Inmunidad Adaptativa , Animales , Interacciones Huésped-Patógeno/inmunología , Humanos , Inmunidad Innata , Inmunidad Mucosa , Mucosa Intestinal/inmunología , Mucosa Intestinal/metabolismo , Linfocitos/inmunología , Linfocitos/metabolismo , Transducción de SeñalRESUMEN
T helper 17 (Th17) cells regulate mucosal barrier defenses but also promote multiple autoinflammatory diseases. Although many molecular determinants of Th17 cell differentiation have been elucidated, the transcriptional programs that sustain Th17 cells in vivo remain obscure. The transcription factor RORγt is critical for Th17 cell differentiation; however, it is not clear whether the closely related RORα, which is co-expressed in Th17 cells, has a distinct role. Here, we demonstrated that although dispensable for Th17 cell differentiation, RORα was necessary for optimal Th17 responses in peripheral tissues. The absence of RORα in T cells led to reductions in both RORγt expression and effector function among Th17 cells. Cooperative binding of RORα and RORγt to a previously unidentified Rorc cis-regulatory element was essential for Th17 lineage maintenance in vivo. These data point to a non-redundant role of RORα in Th17 lineage maintenance via reinforcement of the RORγt transcriptional program.
Asunto(s)
Encefalomielitis Autoinmune Experimental , Miembro 3 del Grupo F de la Subfamilia 1 de Receptores Nucleares , Diferenciación Celular , Encefalomielitis Autoinmune Experimental/metabolismo , Regulación de la Expresión Génica , Miembro 3 del Grupo F de la Subfamilia 1 de Receptores Nucleares/genética , Miembro 3 del Grupo F de la Subfamilia 1 de Receptores Nucleares/metabolismo , Células Th17/metabolismo , Factores de Transcripción/metabolismoRESUMEN
Whereas human dendritic cells (DCs) are largely resistant to productive infection with HIV-1, they have a unique ability to take up the virus and transmit it efficiently to T lymphocytes through a process of trans-infection or trans-enhancement. To elucidate the molecular and cell biological mechanism for trans-enhancement, we performed an shRNA screen of several hundred genes involved in organelle and membrane trafficking in immature human monocyte-derived dendritic cells (MDDCs). We identified TSPAN7 and DNM2, which control actin nucleation and stabilization, as having important and distinct roles in limiting HIV-1 endocytosis and in maintaining virus particles on dendrites, which is required for efficient transfer to T lymphocytes. Further characterization of this process may provide insights not only into the role of DCs in transmission and dissemination of HIV-1 but also more broadly into mechanisms controlling capture and internalization of pathogens.
Asunto(s)
Actinas/metabolismo , Células Dendríticas/inmunología , Infecciones por VIH/inmunología , VIH-1/fisiología , Linfocitos T/inmunología , Complejo 2-3 Proteico Relacionado con la Actina/metabolismo , Actomiosina/metabolismo , Citoesqueleto/efectos de los fármacos , Células Dendríticas/virología , Dinamina II , Dinaminas/metabolismo , Endocitosis , Técnicas de Silenciamiento del Gen , Infecciones por VIH/virología , Humanos , Sinapsis Inmunológicas , Monocitos/inmunología , Proteínas del Tejido Nervioso/metabolismo , Linfocitos T/virología , Tetraspaninas/metabolismoRESUMEN
This year's Laskerâ¼DeBakey Clinical Research Award goes to James Allison for discovering that antibody blockade of the T cell molecule CTLA-4 unleashes the body's immune response against malignant tumors. This has led to development of multiple "immune checkpoint therapies" that are prolonging and saving the lives of thousands of cancer patients.
Asunto(s)
Inmunoterapia/historia , Neoplasias/inmunología , Neoplasias/terapia , Animales , Distinciones y Premios , Antígeno CTLA-4 , Historia del Siglo XX , Historia del Siglo XXI , Humanos , Terapia Molecular Dirigida , Linfocitos T/inmunología , Estados UnidosRESUMEN
RORγt(+) Th17 cells are important for mucosal defenses but also contribute to autoimmune disease. They accumulate in the intestine in response to microbiota and produce IL-17 cytokines. Segmented filamentous bacteria (SFB) are Th17-inducing commensals that potentiate autoimmunity in mice. RORγt(+) T cells were induced in mesenteric lymph nodes early after SFB colonization and distributed across different segments of the gastrointestinal tract. However, robust IL-17A production was restricted to the ileum, where SFB makes direct contact with the epithelium and induces serum amyloid A proteins 1 and 2 (SAA1/2), which promote local IL-17A expression in RORγt(+) T cells. We identified an SFB-dependent role of type 3 innate lymphoid cells (ILC3), which secreted IL-22 that induced epithelial SAA production in a Stat3-dependent manner. This highlights the critical role of tissue microenvironment in activating effector functions of committed Th17 cells, which may have important implications for how these cells contribute to inflammatory disease.
Asunto(s)
Microbioma Gastrointestinal , Interleucinas/metabolismo , Intestinos/inmunología , Receptores de Interleucina/metabolismo , Proteína Amiloide A Sérica/metabolismo , Células Th17/inmunología , Animales , Inmunidad Innata , Interleucinas/inmunología , Intestinos/anatomía & histología , Intestinos/microbiología , Linfocitos/inmunología , Ratones , Ratones Endogámicos C57BL , Receptores de Interleucina/inmunología , Transducción de Señal , Interleucina-22RESUMEN
Innate lymphoid cells (ILCs) promote tissue homeostasis and immune defense but also contribute to inflammatory diseases. ILCs exhibit phenotypic and functional plasticity in response to environmental stimuli, yet the transcriptional regulatory networks (TRNs) that control ILC function are largely unknown. Here, we integrate gene expression and chromatin accessibility data to infer regulatory interactions between transcription factors (TFs) and genes within intestinal type 1, 2, and 3 ILC subsets. We predicted the "core" TFs driving ILC identities, organized TFs into cooperative modules controlling distinct gene programs, and validated roles for c-MAF and BCL6 as regulators affecting type 1 and type 3 ILC lineages. The ILC network revealed alternative-lineage-gene repression, a mechanism that may contribute to reported plasticity between ILC subsets. By connecting TFs to genes, the TRNs suggest means to selectively regulate ILC effector functions, while our network approach is broadly applicable to identifying regulators in other in vivo cell populations.
Asunto(s)
Intestinos/fisiología , Subgrupos Linfocitarios/fisiología , Linfocitos/fisiología , Animales , Diferenciación Celular , Linaje de la Célula , Plasticidad de la Célula , Ensamble y Desensamble de Cromatina , Represión Epigenética , Redes Reguladoras de Genes , Inmunidad Innata , Inmunomodulación , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Proteínas Proto-Oncogénicas c-bcl-6/genética , Proteínas Proto-Oncogénicas c-maf/genética , TranscriptomaRESUMEN
Microglia are the resident macrophages of the CNS, and their functions have been extensively studied in various brain pathologies. The physiological roles of microglia in brain plasticity and function, however, remain unclear. To address this question, we generated CX3CR1(CreER) mice expressing tamoxifen-inducible Cre recombinase that allow for specific manipulation of gene function in microglia. Using CX3CR1(CreER) to drive diphtheria toxin receptor expression in microglia, we found that microglia could be specifically depleted from the brain upon diphtheria toxin administration. Mice depleted of microglia showed deficits in multiple learning tasks and a significant reduction in motor-learning-dependent synapse formation. Furthermore, Cre-dependent removal of brain-derived neurotrophic factor (BDNF) from microglia largely recapitulated the effects of microglia depletion. Microglial BDNF increases neuronal tropomyosin-related kinase receptor B phosphorylation, a key mediator of synaptic plasticity. Together, our findings reveal that microglia serve important physiological functions in learning and memory by promoting learning-related synapse formation through BDNF signaling.
Asunto(s)
Factor Neurotrófico Derivado del Encéfalo/metabolismo , Aprendizaje/fisiología , Microglía/fisiología , Sinapsis , Animales , Receptor 1 de Quimiocinas CX3C , Expresión Génica , Ratones , Microglía/citología , Plasticidad Neuronal , Proteínas Quinasas/metabolismo , Receptores de Quimiocina/genética , Receptores de Quimiocina/metabolismo , Transducción de SeñalRESUMEN
The mutualistic relationship of gut-resident microbiota and the host immune system promotes homeostasis that ensures maintenance of the microbial community and of a largely non-aggressive immune cell compartment1,2. The consequences of disturbing this balance include proximal inflammatory conditions, such as Crohn's disease, and systemic illnesses. This equilibrium is achieved in part through the induction of both effector and suppressor arms of the adaptive immune system. Helicobacter species induce T regulatory (Treg) and T follicular helper (TFH) cells under homeostatic conditions, but induce inflammatory T helper 17 (TH17) cells when induced Treg (iTreg) cells are compromised3,4. How Helicobacter and other gut bacteria direct T cells to adopt distinct functions remains poorly understood. Here we investigated the cells and molecular components required for iTreg cell differentiation. We found that antigen presentation by cells expressing RORγt, rather than by classical dendritic cells, was required and sufficient for induction of Treg cells. These RORγt+ cells-probably type 3 innate lymphoid cells and/or Janus cells5-require the antigen-presentation machinery, the chemokine receptor CCR7 and the TGFß activator αv integrin. In the absence of any of these factors, there was expansion of pathogenic TH17 cells instead of iTreg cells, induced by CCR7-independent antigen-presenting cells. Thus, intestinal commensal microbes and their products target multiple antigen-presenting cells with pre-determined features suited to directing appropriate T cell differentiation programmes, rather than a common antigen-presenting cell that they endow with appropriate functions.
Asunto(s)
Diferenciación Celular , Microbioma Gastrointestinal , Miembro 3 del Grupo F de la Subfamilia 1 de Receptores Nucleares , Linfocitos T Reguladores , Células Dendríticas/inmunología , Microbioma Gastrointestinal/inmunología , Homeostasis , Inmunidad Innata , Integrina alfaV/metabolismo , Miembro 3 del Grupo F de la Subfamilia 1 de Receptores Nucleares/metabolismo , Receptores CCR7/metabolismo , Linfocitos T Reguladores/citología , Linfocitos T Reguladores/inmunología , Células Th17/inmunología , Factor de Crecimiento Transformador beta/metabolismo , Presentación de Antígeno/inmunología , Células Presentadoras de Antígenos/citología , Células Presentadoras de Antígenos/inmunologíaRESUMEN
During development, progenitor cells with binary potential give rise to daughter cells that have distinct functions. Heritable epigenetic mechanisms then lock in gene-expression programs that define lineage identity. Regulation of the gene encoding the T cell-specific coreceptor CD4 in helper and cytotoxic T cells exemplifies this process, with enhancer- and silencer-regulated establishment of epigenetic memory for stable gene expression and repression, respectively. Using a genetic screen, we identified the DNA-methylation machinery as essential for maintaining silencing of Cd4 in the cytotoxic lineage. Furthermore, we found a requirement for the proximal enhancer in mediating the removal of DNA-methylation marks from Cd4, which allowed stable expression of Cd4 in helper T cells. Our findings suggest that stage-specific methylation and demethylation events in Cd4 regulate its heritable expression in response to the distinct signals that dictate lineage 'choice' during T cell development.
Asunto(s)
Metilación de ADN/inmunología , Expresión Génica/inmunología , Linfocitos T Citotóxicos/inmunología , Linfocitos T Colaboradores-Inductores/inmunología , Animales , Antígenos CD4/genética , Antígenos CD4/inmunología , Antígenos CD4/metabolismo , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD4-Positivos/metabolismo , Linfocitos T CD8-positivos/inmunología , Linfocitos T CD8-positivos/metabolismo , Diferenciación Celular/genética , Diferenciación Celular/inmunología , Linaje de la Célula/genética , Linaje de la Célula/inmunología , Células Cultivadas , Cromatina/genética , Cromatina/inmunología , Cromatina/metabolismo , ADN (Citosina-5-)-Metiltransferasa 1 , ADN (Citosina-5-)-Metiltransferasas/genética , ADN (Citosina-5-)-Metiltransferasas/inmunología , ADN (Citosina-5-)-Metiltransferasas/metabolismo , Citometría de Flujo , Células HEK293 , Humanos , Ratones Noqueados , Ratones Transgénicos , Interferencia de ARN/inmunología , Linfocitos T Citotóxicos/metabolismo , Linfocitos T Colaboradores-Inductores/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/inmunología , Factores de Transcripción/metabolismoRESUMEN
The intestinal barrier is vulnerable to damage by microbiota-induced inflammation that is normally restrained through mechanisms promoting homeostasis. Such disruptions contribute to autoimmune and inflammatory diseases including inflammatory bowel disease. We identified a regulatory loop whereby, in the presence of the normal microbiota, intestinal antigen-presenting cells (APCs) expressing the chemokine receptor CX3CR1 reduced expansion of intestinal microbe-specific T helper 1 (Th1) cells and promoted generation of regulatory T cells responsive to food antigens and the microbiota itself. We identified that disruption of the microbiota resulted in CX3CR1+ APC-dependent inflammatory Th1 cell responses with increased pathology after pathogen infection. Colonization with microbes that can adhere to the epithelium was able to compensate for intestinal microbiota loss, indicating that although microbial interactions with the epithelium can be pathogenic, they can also activate homeostatic regulatory mechanisms. Our results identify a cellular mechanism by which the microbiota limits intestinal inflammation and promotes tissue homeostasis.
Asunto(s)
Receptor 1 de Quimiocinas CX3C/metabolismo , Microbioma Gastrointestinal/inmunología , Mucosa Intestinal/inmunología , Sistema Mononuclear Fagocítico/inmunología , Linfocitos T Reguladores/inmunología , Células TH1/inmunología , Animales , Presentación de Antígeno , Adhesión Bacteriana/inmunología , Modelos Animales de Enfermedad , Femenino , Homeostasis , Tolerancia Inmunológica , Inmunidad Mucosa , Inflamación/inmunología , Enfermedades Inflamatorias del Intestino/inmunología , Interleucina-10/inmunología , Interleucina-10/metabolismo , Mucosa Intestinal/microbiología , Masculino , Ratones , Células RAW 264.7RESUMEN
Th17 cells have critical roles in mucosal defense and are major contributors to inflammatory disease. Their differentiation requires the nuclear hormone receptor RORγt working with multiple other essential transcription factors (TFs). We have used an iterative systems approach, combining genome-wide TF occupancy, expression profiling of TF mutants, and expression time series to delineate the Th17 global transcriptional regulatory network. We find that cooperatively bound BATF and IRF4 contribute to initial chromatin accessibility and, with STAT3, initiate a transcriptional program that is then globally tuned by the lineage-specifying TF RORγt, which plays a focal deterministic role at key loci. Integration of multiple data sets allowed inference of an accurate predictive model that we computationally and experimentally validated, identifying multiple new Th17 regulators, including Fosl2, a key determinant of cellular plasticity. This interconnected network can be used to investigate new therapeutic approaches to manipulate Th17 functions in the setting of inflammatory disease.
Asunto(s)
Redes Reguladoras de Genes , Células Th17/citología , Células Th17/metabolismo , Animales , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/metabolismo , Diferenciación Celular , Encefalomielitis Autoinmune Experimental/inmunología , Antígeno 2 Relacionado con Fos/inmunología , Antígeno 2 Relacionado con Fos/metabolismo , Estudio de Asociación del Genoma Completo , Humanos , Factores Reguladores del Interferón/metabolismo , Ratones , Ratones Noqueados , Datos de Secuencia Molecular , Miembro 3 del Grupo F de la Subfamilia 1 de Receptores Nucleares/metabolismo , Células Th17/inmunologíaRESUMEN
Centenarians have a decreased susceptibility to ageing-associated illnesses, chronic inflammation and infectious diseases1-3. Here we show that centenarians have a distinct gut microbiome that is enriched in microorganisms that are capable of generating unique secondary bile acids, including various isoforms of lithocholic acid (LCA): iso-, 3-oxo-, allo-, 3-oxoallo- and isoallolithocholic acid. Among these bile acids, the biosynthetic pathway for isoalloLCA had not been described previously. By screening 68 bacterial isolates from the faecal microbiota of a centenarian, we identified Odoribacteraceae strains as effective producers of isoalloLCA both in vitro and in vivo. Furthermore, we found that the enzymes 5α-reductase (5AR) and 3ß-hydroxysteroid dehydrogenase (3ß-HSDH) were responsible for the production of isoalloLCA. IsoalloLCA exerted potent antimicrobial effects against Gram-positive (but not Gram-negative) multidrug-resistant pathogens, including Clostridioides difficile and Enterococcus faecium. These findings suggest that the metabolism of specific bile acids may be involved in reducing the risk of infection with pathobionts, thereby potentially contributing to the maintenance of intestinal homeostasis.
Asunto(s)
Bacterias/metabolismo , Vías Biosintéticas , Centenarios , Microbioma Gastrointestinal , Ácido Litocólico/análogos & derivados , Ácido Litocólico/biosíntesis , 3-Hidroxiesteroide Deshidrogenasas/metabolismo , Anciano de 80 o más Años , Animales , Antibacterianos/biosíntesis , Antibacterianos/metabolismo , Bacterias/clasificación , Bacterias/enzimología , Bacterias/aislamiento & purificación , Colestenona 5 alfa-Reductasa/metabolismo , Heces/química , Heces/microbiología , Femenino , Bacterias Grampositivas/metabolismo , Humanos , Ácido Litocólico/metabolismo , Masculino , Ratones , SimbiosisRESUMEN
The transcriptional repression of alternative lineage genes is critical for cell fate commitment. Mechanisms by which locus-specific gene silencing is initiated and heritably maintained during cell division are not clearly understood. To study the maintenance of silent gene states, we investigated how the Cd4 gene is stably repressed in CD8+ T cells. Through CRISPR and shRNA screening, we identified the histone chaperone CAF-1 as a critical component for Cd4 repression. We found that the large subunit of CAF-1, Chaf1a, requires the N-terminal KER domain to associate with the histone deacetylases HDAC1/2 and the histone demethylase LSD1, enzymes that also participate in Cd4 silencing. When CAF-1 was lacking, Cd4 derepression was markedly enhanced in the absence of the de novo DNA methyltransferase Dnmt3a but not the maintenance DNA methyltransferase Dnmt1. In contrast to Dnmt1, Dnmt3a deficiency did not significantly alter levels of DNA methylation at the Cd4 locus. Instead, Dnmt3a deficiency sensitized CD8+ T cells to Cd4 derepression mediated by compromised functions of histone-modifying factors, including the enzymes associated with CAF-1. Thus, we propose that the heritable silencing of the Cd4 gene in CD8+ T cells exploits cooperative functions among the DNA methyltransferases, CAF-1, and histone-modifying enzymes.
Asunto(s)
Antígenos CD4/genética , Factor 1 de Ensamblaje de la Cromatina/metabolismo , ADN (Citosina-5-)-Metiltransferasas/metabolismo , Proteína 4 de Unión a Retinoblastoma/metabolismo , Linfocitos T Citotóxicos/inmunología , Linfocitos T Citotóxicos/metabolismo , Animales , Antígenos CD4/metabolismo , ADN (Citosina-5-)-Metiltransferasa 1/genética , ADN (Citosina-5-)-Metiltransferasa 1/metabolismo , ADN (Citosina-5-)-Metiltransferasas/genética , ADN Metiltransferasa 3A , Femenino , Regulación de la Expresión Génica , Silenciador del Gen , Chaperonas de Histonas/metabolismo , Histona Desacetilasas/metabolismo , Histonas/metabolismo , Masculino , Ratones , Dominios ProteicosRESUMEN
Two groups have identified SAMHD1, a protein encoded by an Aicardi-Goutières Syndrome susceptibility gene, as the factor that restricts infection of macrophages and dendritic cells with HIV-1. Here we discuss implications of this discovery for induction of antiviral protective immunity.