RESUMEN
The expanding number of rare immunodeficiency syndromes offers an opportunity to understand key genes that support immune defence against infectious diseases. However, analysis of these in patients is complicated by their treatments and co-morbid infections requiring the use of mouse models for detailed investigations. Here we develop a mouse model of DOCK2 immunodeficiency and demonstrate that these mice have delayed clearance of herpes simplex virus type 1 (HSV-1) infections. We also uncovered a critical, cell intrinsic role of DOCK2 in the priming of anti-viral CD8+ T cells and in particular their initial expansion, despite apparently normal early activation of these cells. When this defect was overcome by priming in vitro, DOCK2-deficient CD8+ T cells were surprisingly protective against HSV-1-disease, albeit not as effectively as wild type cells. These results shed light on a cellular deficiency that is likely to impact anti-viral immunity in DOCK2-deficient patients.
RESUMEN
The expanding number of rare immunodeficiency syndromes offers an opportunity to understand key genes that support immune defence against infectious diseases. However, patients with these diseases are by definition rare. In addition, any analysis is complicated by treatments and co-morbid infections requiring the use of mouse models for detailed investigations. Here we develop a mouse model of DOCK2 immunodeficiency and demonstrate that these mice have delayed clearance of herpes simplex virus type 1 (HSV-1) infections. Further, we found that they have a critical, cell intrinsic role of DOCK2 in the clonal expansion of anti-viral CD8+ T cells despite normal early activation of these cells. Finally, while the major deficiency is in clonal expansion, the ability of primed and expanded DOCK2-deficient CD8+ T cells to protect against HSV-1-infection is also compromised. These results provide a contributing cause for the frequent and devastating viral infections seen in DOCK2-deficient patients and improve our understanding of anti-viral CD8+ T cell immunity.
RESUMEN
Self-tolerance and immunity are actively acquired in parallel through a poorly understood ability of antigen receptors to switch between signaling death or proliferation of antigen-binding lymphocytes in different contexts. It is not known whether this tolerance-immunity switch requires global rewiring of the signaling apparatus or if it can arise from a single molecular change. By introducing individual CARD11 mutations found in human lymphomas into antigen-activated mature B lymphocytes in mice, we find here that lymphoma-derived CARD11 mutations switch the effect of self-antigen from inducing B cell death into T cell-independent proliferation, Blimp1-mediated plasmablast differentiation, and autoantibody secretion. Our findings demonstrate that regulation of CARD11 signaling is a critical switch governing the decision between death and proliferation in antigen-stimulated mature B cells and that mutations in this switch represent a powerful initiator for aberrant B cell responses in vivo.
Asunto(s)
Autoanticuerpos/inmunología , Autoantígenos/inmunología , Linfocitos B/inmunología , Proteínas Adaptadoras de Señalización CARD/inmunología , Proliferación Celular , Guanilato Ciclasa/inmunología , Traslado Adoptivo , Animales , Autoanticuerpos/metabolismo , Autoantígenos/metabolismo , Linfocitos B/metabolismo , Linfocitos B/trasplante , Western Blotting , Proteínas Adaptadoras de Señalización CARD/genética , Proteínas Adaptadoras de Señalización CARD/metabolismo , Muerte Celular/inmunología , Diferenciación Celular/inmunología , Femenino , Citometría de Flujo , Guanilato Ciclasa/genética , Guanilato Ciclasa/metabolismo , Proteínas de Homeodominio/genética , Proteínas de Homeodominio/inmunología , Proteínas de Homeodominio/metabolismo , Humanos , Inmunoglobulina G/inmunología , Inmunoglobulina G/metabolismo , Linfoma/genética , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Ratones Transgénicos , Mutación , Células Plasmáticas/inmunología , Células Plasmáticas/metabolismo , Factor 1 de Unión al Dominio 1 de Regulación Positiva , Factores de Transcripción/genética , Factores de Transcripción/inmunología , Factores de Transcripción/metabolismoRESUMEN
Effective vaccine adjuvants must induce expression of major histocompatibility (MHC) class II proteins and the costimulatory molecule CD86 on dendritic cells (DCs). However, some adjuvants elicit production of cytokines resulting in adverse inflammatory consequences. Development of agents that selectively increase MHC class II and CD86 expression without triggering unwanted cytokine production requires a better understanding of the molecular mechanisms influencing the production and degradation of MHC class II and CD86 in DCs. Here, we investigate how CD83, an immunoglobulin protein expressed on the surface of mature DCs, promotes MHC class II and CD86 expression. Using mice with an N-ethyl-N-nitrosourea-induced mutation eliminating the transmembrane (TM) region of CD83, we found that the TM domain of CD83 enhances MHC class II and CD86 expression by blocking MHC class II association with the ubiquitin ligase MARCH1. The TM region of CD83 blocks interleukin 10-driven, MARCH1-dependent ubiquitination and degradation of MHC class II and CD86 in DCs. Exploiting this posttranslational pathway for boosting MHC class II and CD86 expression on DCs may provide an opportunity to enhance the immunogenicity of vaccines.
Asunto(s)
Antígenos CD/inmunología , Antígeno B7-2/inmunología , Antígenos de Histocompatibilidad Clase II/inmunología , Inmunoglobulinas/inmunología , Interleucina-10/inmunología , Glicoproteínas de Membrana/inmunología , Ubiquitina-Proteína Ligasas/metabolismo , Ubiquitinación , Secuencia de Aminoácidos , Animales , Antígenos CD/química , Antígenos CD/genética , Secuencia de Bases , Membrana Celular/inmunología , Células Dendríticas/inmunología , Células HEK293 , Humanos , Inmunoglobulinas/química , Inmunoglobulinas/genética , Masculino , Glicoproteínas de Membrana/química , Glicoproteínas de Membrana/genética , Ratones , Datos de Secuencia Molecular , Alineación de Secuencia , Ubiquitina-Proteína Ligasas/inmunología , Antígeno CD83RESUMEN
To identify genes and mechanisms involved in humoral immunity, we did a mouse genetic screen for mutations that do not affect the first wave of antibody to immunization but disrupt response maturation and persistence. The first two mutants identified had loss-of-function mutations in the gene encoding a previously obscure member of a family of Rho-Rac GTP-exchange factors, DOCK8. DOCK8-mutant B cells were unable to form marginal zone B cells or to persist in germinal centers and undergo affinity maturation. Dock8 mutations disrupted accumulation of the integrin ligand ICAM-1 in the B cell immunological synapse but did not alter other aspects of B cell antigen receptor signaling. Humoral immunodeficiency due to Dock8 mutation provides evidence that organization of the immunological synapse is critical for signaling the survival of B cell subsets required for long-lasting immunity.
Asunto(s)
Formación de Anticuerpos , Linfocitos B/inmunología , Centro Germinal/inmunología , Factores de Intercambio de Guanina Nucleótido/genética , Factores de Intercambio de Guanina Nucleótido/inmunología , Mutación , Sinapsis/inmunología , Secuencia de Aminoácidos , Animales , Linfocitos B/metabolismo , Secuencia de Bases , Centro Germinal/metabolismo , Factores de Intercambio de Guanina Nucleótido/química , Factores de Intercambio de Guanina Nucleótido/metabolismo , Humanos , Activación de Linfocitos , Ratones , Ratones Endogámicos C57BL , Modelos Moleculares , Datos de Secuencia Molecular , Estructura Cuaternaria de Proteína , Alineación de SecuenciaRESUMEN
T cell antigen receptor (TCR) signaling in CD4(+)CD8(+) double-positive thymocytes determines cell survival and lineage commitment, but the genetic and molecular basis of this process is poorly defined. To address this issue, we used ethylnitrosourea mutagenesis to identify a previously unknown T lineage-specific gene, Themis, which is critical for the completion of positive selection. Themis contains a tandem repeat of a unique globular domain (called 'CABIT' here) that includes a cysteine motif that defines a family of five uncharacterized vertebrate proteins with orthologs in most animal species. Themis-deficient thymocytes showed no substantial impairment in early TCR signaling but did show altered expression of genes involved in the cell cycle and survival before and during positive selection. Our data suggest a unique function for Themis in sustaining positive selection.
Asunto(s)
Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD8-positivos/inmunología , Linaje de la Célula/fisiología , Proteínas/fisiología , Receptores de Antígenos de Linfocitos T/fisiología , Secuencia de Aminoácidos , Animales , Linfocitos T CD4-Positivos/citología , Linfocitos T CD8-positivos/citología , Diferenciación Celular , Línea Celular , Supervivencia Celular/fisiología , Etilnitrosourea/farmacología , Femenino , Humanos , Péptidos y Proteínas de Señalización Intercelular , Ratones , Datos de Secuencia Molecular , Mutación , Análisis de Secuencia por Matrices de Oligonucleótidos , Proteínas/genética , Proteínas/inmunología , Receptores de Antígenos de Linfocitos T/genética , Receptores de Antígenos de Linfocitos T/inmunología , Transducción de SeñalRESUMEN
Despite the sequencing of the human and mouse genomes, few genetic mechanisms for protecting against autoimmune disease are currently known. Here we systematically screen the mouse genome for autoimmune regulators to isolate a mouse strain, sanroque, with severe autoimmune disease resulting from a single recessive defect in a previously unknown mechanism for repressing antibody responses to self. The sanroque mutation acts within mature T cells to cause formation of excessive numbers of follicular helper T cells and germinal centres. The mutation disrupts a repressor of ICOS, an essential co-stimulatory receptor for follicular T cells, and results in excessive production of the cytokine interleukin-21. sanroque mice fail to repress diabetes-causing T cells, and develop high titres of autoantibodies and a pattern of pathology consistent with lupus. The causative mutation is in a gene of previously unknown function, roquin (Rc3h1), which encodes a highly conserved member of the RING-type ubiquitin ligase protein family. The Roquin protein is distinguished by the presence of a CCCH zinc-finger found in RNA-binding proteins, and localization to cytosolic RNA granules implicated in regulating messenger RNA translation and stability.