RESUMEN
Dynamic tuning of cellular responsiveness as a result of repeated stimuli improves the ability of cells to distinguish physiologically meaningful signals from each other and from noise. In particular, lymphocyte activation thresholds are subject to tuning, which contributes to maintaining tolerance to self-antigens and persisting foreign antigens, averting autoimmunity and immune pathogenesis, but allowing responses to strong, structured perturbations that are typically associated with acute infection. Such tuning is also implicated in conferring flexibility to positive selection in the thymus, in controlling the magnitude of the immune response, and in generating memory cells. Additional functional properties are dynamically and differentially tuned in parallel via subthreshold contact interactions between developing or mature lymphocytes and self-antigen-presenting cells. These interactions facilitate and regulate lymphocyte viability, maintain their functional integrity, and influence their responses to foreign antigens and accessory signals, qualitatively and quantitatively. Bidirectional tuning of T cells and antigen-presenting cells leads to the definition of homeostatic set points, thus maximizing clonal diversity.
Asunto(s)
Linfocitos/inmunología , Linfocitos/metabolismo , Animales , Supervivencia Celular/inmunología , Homeostasis , Humanos , Memoria Inmunológica , Infecciones/inmunología , Infecciones/metabolismo , Activación de Linfocitos/genética , Activación de Linfocitos/inmunología , Linfocitos/citología , Fenotipo , Subgrupos de Linfocitos T/citología , Subgrupos de Linfocitos T/inmunología , Subgrupos de Linfocitos T/metabolismo , Timocitos/citología , Timocitos/inmunología , Timocitos/metabolismoRESUMEN
Upregulation of diverse self-antigens that constitute components of the inflammatory response overlaps spatially and temporally with the emergence of pathogen-derived foreign antigens. Therefore, discrimination between these inflammation-associated self-antigens and pathogen-derived molecules represents a unique challenge for the adaptive immune system. Here, we demonstrate that CD8+ T cell tolerance to T cell-derived inflammation-associated self-antigens is efficiently induced in the thymus and supported by redundancy in cell types expressing these molecules. In addition to thymic epithelial cells, this included thymic eosinophils and innate-like T cells, a population that expressed molecules characteristic for all major activated T cell subsets. We show that direct T cell-to-T cell antigen presentation by minute numbers of innate-like T cells was sufficient to eliminate autoreactive CD8+ thymocytes. Tolerance to such effector molecules was of critical importance, as its breach caused by decreased thymic abundance of a single model inflammation-associated self-antigen resulted in autoimmune elimination of an entire class of effector T cells.
Asunto(s)
Presentación de Antígeno , Autoantígenos , Linfocitos T CD8-positivos , Inflamación , Timocitos , Timo , Animales , Autoantígenos/inmunología , Linfocitos T CD8-positivos/inmunología , Ratones , Timo/inmunología , Inflamación/inmunología , Presentación de Antígeno/inmunología , Timocitos/inmunología , Timocitos/metabolismo , Ratones Endogámicos C57BL , Inmunidad Innata , Autoinmunidad/inmunología , Tolerancia Inmunológica/inmunología , Ratones Transgénicos , Ratones Noqueados , Activación de Linfocitos/inmunología , Eosinófilos/inmunologíaRESUMEN
The nature of activation signals is essential in determining T cell subset differentiation; however, the features that determine T cell subset preference acquired during intrathymic development remain elusive. Here we show that naive CD4+ T cells generated in the mouse thymic microenvironment lacking Scd1, encoding the enzyme catalyzing oleic acid (OA) production, exhibit enhanced regulatory T (Treg) cell differentiation and attenuated development of experimental autoimmune encephalomyelitis. Scd1 deletion in K14+ thymic epithelia recapitulated the enhanced Treg cell differentiation phenotype of Scd1-deficient mice. The dearth of OA permitted DOT1L to increase H3K79me2 levels at the Atp2a2 locus of thymocytes at the DN2-DN3 transition stage. Such epigenetic modification persisted in naive CD4+ T cells and facilitated Atp2a2 expression. Upon T cell receptor activation, ATP2A2 enhanced the activity of the calcium-NFAT1-Foxp3 axis to promote naive CD4+ T cells to differentiate into Treg cells. Therefore, OA availability is critical for preprogramming thymocytes with Treg cell differentiation propensities in the periphery.
Asunto(s)
Ácido Oléico , Timocitos , Animales , Ratones , Ácido Oléico/metabolismo , Timo , Linfocitos T Reguladores , Diferenciación Celular , Factores de Transcripción Forkhead/genéticaRESUMEN
Thymocytes bearing autoreactive T cell receptors (TCRs) are agonist-signaled by TCR/co-stimulatory molecules to either undergo clonal deletion or to differentiate into specialized regulatory T (Treg) or effector T (Teff) CD4+ cells. How these different fates are achieved during development remains poorly understood. We now document that deletion and differentiation are agonist-signaled at different times during thymic selection and that Treg and Teff cells both arise after clonal deletion as alternative lineage fates of agonist-signaled CD4+CD25+ precursors. Disruption of agonist signaling induces CD4+CD25+ precursors to initiate Foxp3 expression and become Treg cells, whereas persistent agonist signaling induces CD4+CD25+ precursors to become IL-2+ Teff cells. Notably, we discovered that transforming growth factor-ß induces Foxp3 expression and promotes Treg cell development by disrupting weaker agonist signals and that Foxp3 expression is not induced by IL-2 except under non-physiological in vivo conditions. Thus, TCR signaling disruption versus persistence is a general mechanism of lineage fate determination in the thymus that directs development of agonist-signaled autoreactive thymocytes.
Asunto(s)
Supresión Clonal , Timocitos , Timocitos/metabolismo , Interleucina-2/genética , Interleucina-2/metabolismo , Linfocitos T CD4-Positivos/metabolismo , Timo/metabolismo , Receptores de Antígenos de Linfocitos T/metabolismo , Factores de Transcripción Forkhead/genética , Factores de Transcripción Forkhead/metabolismo , Linfocitos T Reguladores/metabolismoRESUMEN
The development of CD4+ T cells and CD8+ T cells in the thymus is critical to adaptive immunity and is widely studied as a model of lineage commitment. Recognition of self-peptide major histocompatibility complex (MHC) class I or II by the T cell antigen receptor (TCR) determines the CD8+ or CD4+ T cell lineage choice, respectively, but how distinct TCR signals drive transcriptional programs of lineage commitment remains largely unknown. Here we applied CITE-seq to measure RNA and surface proteins in thymocytes from wild-type and T cell lineage-restricted mice to generate a comprehensive timeline of cell states for each T cell lineage. These analyses identified a sequential process whereby all thymocytes initiate CD4+ T cell lineage differentiation during a first wave of TCR signaling, followed by a second TCR signaling wave that coincides with CD8+ T cell lineage specification. CITE-seq and pharmaceutical inhibition experiments implicated a TCR-calcineurin-NFAT-GATA3 axis in driving the CD4+ T cell fate. Our data provide a resource for understanding cell fate decisions and implicate a sequential selection process in guiding lineage choice.
Asunto(s)
Linfocitos T CD4-Positivos , Linfocitos T CD8-positivos , Ratones , Animales , Linaje de la Célula , Timocitos , Multiómica , Ratones Transgénicos , Diferenciación Celular , Receptores de Antígenos de Linfocitos T/metabolismo , Timo , Antígenos de Histocompatibilidad Clase I , Antígenos CD4RESUMEN
T cell differentiation requires Notch1 signaling. In the present study, we show that an enhancer upstream of Notch1 active in double-negative (DN) mouse thymocytes is responsible for raising Notch1 signaling intrathymically. This enhancer is required to expand multipotent progenitors intrathymically while delaying early differentiation until lineage restrictions have been established. Early thymic progenitors lacking the enhancer show accelerated differentiation through the DN stages and increased frequency of B, innate lymphoid (IL) and natural killer (NK) cell differentiation. Transcription regulators for T cell lineage restriction and commitment are expressed normally, but IL and NK cell gene expression persists after T cell lineage commitment and T cell receptor ß VDJ recombination, Cd3 expression and ß-selection have been impaired. This Notch1 enhancer is inactive in double-positive (DP) thymocytes. Its aberrant reactivation at this stage in Ikaros mutants is required for leukemogenesis. Thus, the DN-specific Notch1 enhancer harnesses the regulatory architecture of DN and DP thymocytes to achieve carefully orchestrated changes in Notch1 signaling required for early lineage restrictions and normal T cell differentiation.
Asunto(s)
Inmunidad Innata , Timocitos , Ratones , Animales , Timocitos/metabolismo , Receptor Notch1/genética , Receptor Notch1/metabolismo , Linfocitos/metabolismo , Timo , Diferenciación Celular/genética , Linaje de la Célula/genéticaRESUMEN
Type 2 innate lymphoid cells (ILC2) contribute to immune homeostasis, protective immunity and tissue repair. Here we demonstrate that functional ILC2 cells can arise in the embryonic thymus from shared T cell precursors, preceding the emergence of CD4+CD8+ (double-positive) T cells. Thymic ILC2 cells migrated to mucosal tissues, with colonization of the intestinal lamina propria. Expression of the transcription factor RORα repressed T cell development while promoting ILC2 development in the thymus. From RNA-seq, assay for transposase-accessible chromatin sequencing (ATAC-seq) and chromatin immunoprecipitation followed by sequencing (ChIP-seq) data, we propose a revised transcriptional circuit to explain the co-development of T cells and ILC2 cells from common progenitors in the thymus. When Notch signaling is present, BCL11B dampens Nfil3 and Id2 expression, permitting E protein-directed T cell commitment. However, concomitant expression of RORα overrides the repression of Nfil3 and Id2 repression, allowing ID2 to repress E proteins and promote ILC2 differentiation. Thus, we demonstrate that RORα expression represents a critical checkpoint at the bifurcation of the T cell and ILC2 lineages in the embryonic thymus.
Asunto(s)
Linfocitos T CD4-Positivos/metabolismo , Linfocitos T CD8-positivos/metabolismo , Diferenciación Celular , Linaje de la Célula , Inmunidad Innata , Miembro 1 del Grupo F de la Subfamilia 1 de Receptores Nucleares/metabolismo , Timocitos/metabolismo , Timo/metabolismo , Animales , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/genética , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/metabolismo , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD8-positivos/inmunología , Movimiento Celular , Células Cultivadas , Técnicas de Cocultivo , Femenino , Regulación del Desarrollo de la Expresión Génica , Proteína 2 Inhibidora de la Diferenciación/genética , Proteína 2 Inhibidora de la Diferenciación/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Miembro 1 del Grupo F de la Subfamilia 1 de Receptores Nucleares/genética , Técnicas de Cultivo de Órganos , Fenotipo , Proteínas Represoras/genética , Proteínas Represoras/metabolismo , Transducción de Señal , Timocitos/inmunología , Timo/embriología , Timo/inmunología , Proteínas Supresoras de Tumor/genética , Proteínas Supresoras de Tumor/metabolismoRESUMEN
The development of TCRαß and TCRγδ T cells comprises a step-wise process in which regulatory events control differentiation and lineage outcome. To clarify these mechanisms, we employed RNA-sequencing, ATAC-sequencing and ChIPmentation on well-defined thymocyte subsets that represent the continuum of human T cell development. The chromatin accessibility dynamics show clear stage specificity and reveal that human T cell-lineage commitment is marked by GATA3- and BCL11B-dependent closing of PU.1 sites. A temporary increase in H3K27me3 without open chromatin modifications is unique for ß-selection, whereas emerging γδ T cells, which originate from common precursors of ß-selected cells, show large chromatin accessibility changes due to strong T cell receptor (TCR) signaling. Furthermore, we unravel distinct chromatin landscapes between CD4+ and CD8+ αß-lineage cells that support their effector functions and reveal gene-specific mechanisms that define mature T cells. This resource provides a framework for studying gene regulatory mechanisms that drive normal and malignant human T cell development.
Asunto(s)
Receptores de Antígenos de Linfocitos T alfa-beta/metabolismo , Receptores de Antígenos de Linfocitos T gamma-delta/metabolismo , Linfocitos T/fisiología , Timocitos/fisiología , Diferenciación Celular , Linaje de la Célula , Células Cultivadas , Cromatina/metabolismo , Selección Clonal Mediada por Antígenos , Epigénesis Genética , Factor de Transcripción GATA3/genética , Factor de Transcripción GATA3/metabolismo , Regulación Neoplásica de la Expresión Génica , Histonas/metabolismo , Humanos , Activación de Linfocitos , Proteínas Represoras/genética , Proteínas Represoras/metabolismo , Análisis de Secuencia de ARN , Transducción de Señal , Proteínas Supresoras de Tumor/genética , Proteínas Supresoras de Tumor/metabolismoRESUMEN
Mucosal-associated invariant T cells (MAIT cells) recognize the microbial metabolite 5-(2-oxopropylideneamino)-6-D-ribitylaminouracil (5-OP-RU) presented by the MHC class Ib molecule, MR1. MAIT cells acquire effector functions during thymic development, but the mechanisms involved are unclear. Here we used single-cell RNA-sequencing to characterize the developmental path of 5-OP-RU-specific thymocytes. In addition to the known MAIT1 and MAIT17 effector subsets selected on bone-marrow-derived hematopoietic cells, we identified 5-OP-RU-specific thymocytes that were selected on thymic epithelial cells and differentiated into CD44- naive T cells. MAIT cell positive selection required signaling through the adapter, SAP, that controlled the expression of the transcription factor, ZBTB16. Pseudotemporal ordering of single cells revealed transcriptional trajectories of 5-OP-RU-specific thymocytes selected on either thymic epithelial cells or hematopoietic cells. The resulting model illustrates T cell lineage decisions.
Asunto(s)
Linaje de la Célula/inmunología , Células T Invariantes Asociadas a Mucosa/citología , Células T Invariantes Asociadas a Mucosa/inmunología , Ribitol/análogos & derivados , Timocitos/citología , Timocitos/inmunología , Uracilo/análogos & derivados , Animales , Secuencia de Bases , Diferenciación Celular/genética , Diferenciación Celular/inmunología , Antígenos de Histocompatibilidad Clase I/metabolismo , Receptores de Hialuranos/metabolismo , Activación de Linfocitos/inmunología , Ratones , Ratones Noqueados , Antígenos de Histocompatibilidad Menor/metabolismo , Proteína de la Leucemia Promielocítica con Dedos de Zinc/biosíntesis , Receptores de Antígenos de Linfocitos T alfa-beta/inmunología , Ribitol/inmunología , Análisis de Secuencia de ARN , Familia de Moléculas Señalizadoras de la Activación Linfocitaria/metabolismo , Timo/citología , Timo/inmunología , Uracilo/inmunologíaRESUMEN
Proliferation is tightly regulated during T cell development, and is limited to immature CD4-CD8- thymocytes. The major proliferative event is initiated at the 'ß-selection' stage following successful rearrangement of Tcrß, and is triggered by and dependent on concurrent signaling by Notch and the pre-T cell receptor (TCR); however, it is unclear how these signals cooperate to promote cell proliferation. Here, we found that ß-selection-associated proliferation required the combined activity of two Skp-cullin-F-box (SCF) ubiquitin ligase complexes that included as substrate recognition subunits the F-box proteins Fbxl1 or Fbxl12. Both SCF complexes targeted the cyclin-dependent kinase inhibitor Cdkn1b for polyubiquitination and proteasomal degradation. We found that Notch signals induced the transcription of Fbxl1, whereas pre-TCR signals induced the transcription of Fbxl12. Thus, concurrent Notch and pre-TCR signaling induced the expression of two genes, Fbxl1 and Fbxl12, whose products functioned identically but additively to promote degradation of Cdkn1b, cell cycle progression, and proliferation of ß-selected thymocytes.
Asunto(s)
Proteínas F-Box/metabolismo , Receptores de Antígenos de Linfocitos T alfa-beta/metabolismo , Receptores Notch/metabolismo , Proteínas Ligasas SKP Cullina F-box/metabolismo , Linfocitos T/fisiología , Timocitos/fisiología , Animales , Diferenciación Celular , Proliferación Celular , Selección Clonal Mediada por Antígenos , Inhibidor p27 de las Quinasas Dependientes de la Ciclina/metabolismo , Proteínas F-Box/genética , Regulación de la Expresión Génica , Genes Codificadores de la Cadena beta de los Receptores de Linfocito T , Ratones , Ratones Endogámicos C57BL , Receptor Cross-Talk , Transducción de SeñalRESUMEN
γδ T cells that produce the cytokine IL-17 (Tγδ17 cells) are innate-like mediators of immunity that undergo effector programming in the thymus. While regulators of Tγδ17 specialization restricted to various Vγ subsets are known, a commitment factor essential to all Tγδ17 cells has remained undefined. In this study, we identified the transcription factor c-Maf as a universal regulator of Tγδ17 cell differentiation and maintenance. Maf deficiency caused an absolute lineage block at the immature CD24+CD45RBlo γδ thymocyte stage, which revealed a critical checkpoint in the acquisition of effector functions. Here, c-Maf enforced Tγδ17 cell identity by promoting chromatin accessibility and expression of key type 17 program genes, notably Rorc and Blk, while antagonizing the transcription factor TCF1, which promotes interferon-γ-producing γδ T cells (Tγδ1 cells). Furthermore, γδ T cell antigen receptor (γδTCR) signal strength tuned c-Maf expression, which indicates that c-Maf is a core node that connects γδTCR signals to Tγδ17 cell transcriptional programming.
Asunto(s)
Interleucina-17/metabolismo , Proteínas Proto-Oncogénicas c-maf/metabolismo , Receptores de Antígenos de Linfocitos T gamma-delta/metabolismo , Células Th17/fisiología , Timocitos/fisiología , Animales , Antígeno CD24/metabolismo , Diferenciación Celular/genética , Linaje de la Célula/genética , Células Cultivadas , Inmunidad Innata , Antígenos Comunes de Leucocito/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Miembro 3 del Grupo F de la Subfamilia 1 de Receptores Nucleares/genética , Proteínas Proto-Oncogénicas c-maf/genética , Transducción de Señal , Familia-src Quinasas/genéticaRESUMEN
Regulatory T (Treg) cells expressing the transcription factor Foxp3 are an essential suppressive T cell lineage of dual origin: Foxp3 induction in thymocytes and mature CD4+ T cells gives rise to thymic (tTreg) and peripheral (pTreg) Treg cells, respectively. While tTreg cells suppress autoimmunity, pTreg cells enforce tolerance to food and commensal microbiota. However, the role of Foxp3 in pTreg cells and the mechanisms supporting their differentiation remain poorly understood. Here, we used genetic tracing to identify microbiota-induced pTreg cells and found that many of their distinguishing features were Foxp3 independent. Lineage-committed, microbiota-dependent pTreg-like cells persisted in the colon in the absence of Foxp3. While Foxp3 was critical for the suppression of a Th17 cell program, colitis, and mastocytosis, pTreg cells suppressed colonic effector T cell expansion in a Foxp3-independent manner. Thus, Foxp3 and the tolerogenic signals that precede and promote its expression independently confer distinct facets of pTreg functionality.
Asunto(s)
Factores de Transcripción Forkhead , Linfocitos T Reguladores , Factores de Transcripción Forkhead/metabolismo , Tolerancia Inmunológica , Células Th17/metabolismo , Timocitos/metabolismoRESUMEN
The T cell antigen receptor (TCR) expressed on thymocytes interacts with self-peptide major histocompatibility complex (pMHC) ligands to signal apoptosis or survival. Here, we found that negative-selection ligands induced thymocytes to exert forces on the TCR and the co-receptor CD8 and formed cooperative TCR-pMHC-CD8 trimolecular 'catch bonds', whereas positive-selection ligands induced less sustained thymocyte forces on TCR and CD8 and formed shorter-lived, independent TCR-pMHC and pMHC-CD8 bimolecular 'slip bonds'. Catch bonds were not intrinsic to either the TCR-pMHC or the pMHC-CD8 arm of the trans (cross-junctional) heterodimer but resulted from coupling of the extracellular pMHC-CD8 interaction to the intracellular interaction of CD8 with TCR-CD3 via associated kinases to form a cis (lateral) heterodimer capable of inside-out signaling. We suggest that the coupled trans-cis heterodimeric interactions form a mechanotransduction loop that reinforces negative-selection signaling that is distinct from positive-selection signaling in the thymus.
Asunto(s)
Mecanotransducción Celular/inmunología , Receptores de Antígenos de Linfocitos T/inmunología , Timocitos/inmunología , Timo/inmunología , Animales , Supresión Clonal/inmunología , Ratones , Ratones Transgénicos , Receptores de Antígenos de Linfocitos T/metabolismo , Timocitos/metabolismoRESUMEN
Thymocyte development requires a complex orchestration of multiple transcription factors. Ablating either TCF-1 or HEB in CD4+CD8+ thymocytes elicits similar developmental outcomes including increased proliferation, decreased survival, and fewer late Tcra rearrangements. Here, we provide a mechanistic explanation for these similarities by showing that TCF-1 and HEB share ~7,000 DNA-binding sites genome wide and promote chromatin accessibility. The binding of both TCF-1 and HEB was required at these shared sites for epigenetic and transcriptional gene regulation. Binding of TCF-1 and HEB to their conserved motifs in the enhancer regions of genes associated with T cell differentiation promoted their expression. Binding to sites lacking conserved motifs in the promoter regions of cell-cycle-associated genes limited proliferation. TCF-1 displaced nucleosomes, allowing for chromatin accessibility. Importantly, TCF-1 inhibited Notch signaling and consequently protected HEB from Notch-mediated proteasomal degradation. Thus, TCF-1 shifts nucleosomes and safeguards HEB, thereby enabling their cooperation in establishing the epigenetic and transcription profiles of CD4+CD8+ thymocytes.
Asunto(s)
Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/inmunología , Regulación de la Expresión Génica/inmunología , Factor Nuclear 1-alfa del Hepatocito/inmunología , Linfopoyesis/inmunología , Timocitos/inmunología , Animales , Antígenos CD4/inmunología , Antígenos CD8/inmunología , Ratones , Ratones Endogámicos C57BL , Ratones TransgénicosRESUMEN
Self-tolerance to immune reactions is established via promiscuous expression of tissue-restricted antigens (TRAs) in medullary thymic epithelial cells (mTECs), leading to the elimination of T cells that respond to self-antigens. The transcriptional regulator Aire has been thought to be sufficient for the induction of TRAs, despite some indications that other factors may promote TRA expression in the thymus. Here, we show that the transcription factor Fezf2 directly regulates various TRA genes in mTECs independently of Aire. Mice lacking Fezf2 in mTECs displayed severe autoimmune symptoms, including the production of autoantibodies and inflammatory cell infiltration targeted to peripheral organs. These responses differed from those detected in Aire-deficient mice. Furthermore, Fezf2 expression and Aire expression are regulated by distinct signaling pathways and promote the expression of different classes of proteins. Thus, two independent factors, Fezf2 and Aire, permit the expression of TRAs in the thymus to ensure immune tolerance.
Asunto(s)
Proteínas de Unión al ADN/metabolismo , Tolerancia Inmunológica , Proteínas del Tejido Nervioso/metabolismo , Timo/inmunología , Animales , Autoantígenos/inmunología , Autoinmunidad , Proteínas de Unión al ADN/genética , Humanos , Ratones , Proteínas del Tejido Nervioso/genética , Transducción de Señal , Timocitos/inmunología , Factores de Transcripción/metabolismo , Proteína AIRERESUMEN
THEMIS, a T cell-specific protein with high expression in CD4+CD8+ thymocytes, has a crucial role in positive selection and T cell development. THEMIS lacks defined catalytic domains but contains two tandem repeats of a distinctive module of unknown function (CABIT). Here we found that THEMIS directly regulated the catalytic activity of the tyrosine phosphatase SHP-1. This action was mediated by the CABIT modules, which bound to the phosphatase domain of SHP-1 and promoted or stabilized oxidation of SHP-1's catalytic cysteine residue, which inhibited the tyrosine-phosphatase activity of SHP-1. Deletion of SHP-1 alleviated the developmental block in Themis-/- thymocytes. Thus, THEMIS facilitates thymocyte positive selection by enhancing the T cell antigen receptor signaling response to low-affinity ligands.
Asunto(s)
Selección Clonal Mediada por Antígenos/inmunología , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Proteína Tirosina Fosfatasa no Receptora Tipo 6/metabolismo , Receptores de Antígenos de Linfocitos T/metabolismo , Transducción de Señal , Linfocitos T/inmunología , Linfocitos T/metabolismo , Animales , Diferenciación Celular/genética , Diferenciación Celular/inmunología , Línea Celular , Eliminación de Gen , Humanos , Péptidos y Proteínas de Señalización Intracelular/genética , Ratones , Ratones Noqueados , Oxidación-Reducción , Unión Proteica , Dominios y Motivos de Interacción de Proteínas , Proteína Tirosina Fosfatasa no Receptora Tipo 6/antagonistas & inhibidores , Proteína Tirosina Fosfatasa no Receptora Tipo 6/química , Proteína Tirosina Fosfatasa no Receptora Tipo 6/genética , Especies Reactivas de Oxígeno/metabolismo , Linfocitos T/citología , Timocitos/citología , Timocitos/inmunología , Timocitos/metabolismoRESUMEN
The acquisition of a protective vertebrate immune system hinges on the efficient generation of a diverse but self-tolerant repertoire of T cells by the thymus through mechanisms that remain incompletely resolved. Here we identified the endosomal-sorting-complex-required-for-transport (ESCRT) protein CHMP5, known to be required for the formation of multivesicular bodies, as a key sensor of thresholds for signaling via the T cell antigen receptor (TCR) that was essential for T cell development. CHMP5 enabled positive selection by promoting post-selection thymocyte survival in part through stabilization of the pro-survival protein Bcl-2. Accordingly, loss of CHMP5 in thymocyte precursor cells abolished T cell development, a phenotype that was 'rescued' by genetic deletion of the pro-apoptotic protein Bim or transgenic expression of Bcl-2. Mechanistically, positive selection resulted in the stabilization of CHMP5 by inducing its interaction with the deubiquitinase USP8. Our results thus identify CHMP5 as an essential component of the post-translational machinery required for T cell development.
Asunto(s)
Diferenciación Celular/inmunología , Complejos de Clasificación Endosomal Requeridos para el Transporte/inmunología , Receptores de Antígenos de Linfocitos T/inmunología , Linfocitos T/inmunología , Timocitos/inmunología , Animales , Proteína 11 Similar a Bcl2/inmunología , Endopeptidasas/inmunología , Immunoblotting , Inmunoprecipitación , Ratones , Microscopía Electrónica de Transmisión , Microscopía Fluorescente , Procesamiento Proteico-Postraduccional , Proteínas Proto-Oncogénicas c-bcl-2/inmunología , Reacción en Cadena en Tiempo Real de la Polimerasa , Transducción de Señal/inmunología , Linfocitos T/citología , Timocitos/citología , Ubiquitina Tiolesterasa/inmunologíaRESUMEN
The transcription factor RORγt regulates differentiation of the TH17 subset of helper T cells, thymic T cell development and lymph-node genesis. Although elimination of RORγt prevents TH17 cell-mediated experimental autoimmune encephalomyelitis (EAE), it also disrupts thymocyte development, which could lead to lethal thymic lymphoma. Here we identified a two-amino-acid substitution in RORγt (RORγtM) that 'preferentially' disrupted TH17 differentiation but not thymocyte development. Mice expressing RORγtM were resistant to EAE associated with defective TH17 differentiation but maintained normal thymocyte development and normal lymph-node genesis, except for Peyer's patches. RORγtM showed less ubiquitination at Lys69 that was selectively required for TH17 differentiation but not T cell development. This study will inform the development of treatments that selectively target TH17 cell-mediated autoimmunity but do not affect thymocyte development or induce lymphoma.
Asunto(s)
Sustitución de Aminoácidos , Diferenciación Celular/genética , Mutación , Miembro 3 del Grupo F de la Subfamilia 1 de Receptores Nucleares/genética , Células Th17/citología , Células Th17/metabolismo , Timocitos/citología , Timocitos/metabolismo , Animales , Biomarcadores , Diferenciación Celular/inmunología , Análisis por Conglomerados , Encefalomielitis Autoinmune Experimental/genética , Encefalomielitis Autoinmune Experimental/inmunología , Encefalomielitis Autoinmune Experimental/metabolismo , Perfilación de la Expresión Génica , Regulación de la Expresión Génica , Inmunofenotipificación , Ganglios Linfáticos/inmunología , Ganglios Linfáticos/metabolismo , Ratones , Ratones Noqueados , Ganglios Linfáticos Agregados/inmunología , Ganglios Linfáticos Agregados/metabolismo , Subgrupos de Linfocitos T/citología , Subgrupos de Linfocitos T/inmunología , Subgrupos de Linfocitos T/metabolismo , Células Th17/inmunología , Timocitos/inmunología , UbiquitinaciónRESUMEN
TCRαß+CD4-CD8α+CD8ß- intestinal intraepithelial lymphocytes (CD8αα IELs) are an abundant population of thymus-derived T cells that protect the gut barrier surface. We sought to better define the thymic IEL precursor (IELp) through analysis of its maturation, localization and emigration. We defined two precursor populations among TCRß+CD4-CD8- thymocytes by dependence on the kinase TAK1 and rigorous lineage-exclusion criteria. Those IELp populations included a nascent PD-1+ population and a T-bet+ population that accumulated with age. Both gave rise to intestinal CD8αα IELs after adoptive transfer. The PD-1+ IELp population included more strongly self-reactive clones and was largely restricted by classical major histocompatibility complex (MHC) molecules. Those cells localized to the cortex and efficiently emigrated in a manner dependent on the receptor S1PR1. The T-bet+ IELp population localized to the medulla, included cells restricted by non-classical MHC molecules and expressed the receptor NK1.1, the integrin CD103 and the chemokine receptor CXCR3. The two IELp populations further differed in their use of the T cell antigen receptor (TCR) α-chain variable region (Vα) and ß-chain variable region (Vß). These data provide a foundation for understanding the biology of CD8αα IELs.
Asunto(s)
Linfocitos T CD8-positivos/inmunología , Mucosa Intestinal/inmunología , Células Precursoras de Linfocitos T/inmunología , Timocitos/inmunología , Inmunidad Adaptativa/inmunología , Traslado Adoptivo , Animales , Antígenos CD , Antígenos Ly/inmunología , Antígenos CD8/inmunología , Linaje de la Célula , Movimiento Celular/inmunología , Citometría de Flujo , Técnica del Anticuerpo Fluorescente , Antígenos de Histocompatibilidad/inmunología , Inmunidad Mucosa/inmunología , Cadenas alfa de Integrinas , Mucosa Intestinal/citología , Linfocitos , Ratones , Subfamilia B de Receptores Similares a Lectina de Células NK/inmunología , Fenotipo , Receptor de Muerte Celular Programada 1/inmunología , Receptores de Antígenos de Linfocitos T alfa-beta/inmunología , Receptores CXCR3 , Receptores de Lisoesfingolípidos/inmunología , Receptores de Esfingosina-1-Fosfato , Proteínas de Dominio T Box/inmunología , Timocitos/citología , Timo/citologíaRESUMEN
T cell antigen receptor (TCR) signaling in the thymus initiates positive selection, but the CD8+-lineage fate is thought to be induced by cytokines after TCR signaling has ceased, although this remains controversial and unproven. We have identified four cytokines (IL-6, IFN-γ, TSLP and TGF-ß) that did not signal via the common γ-chain (γc) receptor but that, like IL-7 and IL-15, induced expression of the lineage-specifying transcription factor Runx3d and signaled the generation of CD8+ T cells. Elimination of in vivo signaling by all six of these 'lineage-specifying cytokines' during positive selection eliminated Runx3d expression and completely abolished the generation of CD8+ single-positive thymocytes. Thus, this study proves that signaling during positive selection by lineage-specifying cytokines is responsible for all CD8+-lineage-fate 'decisions' in the thymus.