RESUMEN
Patients with autoimmune polyendocrinopathy syndrome type 1 (APS-1) caused by autosomal recessive AIRE deficiency produce autoantibodies that neutralize type I interferons (IFNs)1,2, conferring a predisposition to life-threatening COVID-19 pneumonia3. Here we report that patients with autosomal recessive NIK or RELB deficiency, or a specific type of autosomal-dominant NF-κB2 deficiency, also have neutralizing autoantibodies against type I IFNs and are at higher risk of getting life-threatening COVID-19 pneumonia. In patients with autosomal-dominant NF-κB2 deficiency, these autoantibodies are found only in individuals who are heterozygous for variants associated with both transcription (p52 activity) loss of function (LOF) due to impaired p100 processing to generate p52, and regulatory (IκBδ activity) gain of function (GOF) due to the accumulation of unprocessed p100, therefore increasing the inhibitory activity of IκBδ (hereafter, p52LOF/IκBδGOF). By contrast, neutralizing autoantibodies against type I IFNs are not found in individuals who are heterozygous for NFKB2 variants causing haploinsufficiency of p100 and p52 (hereafter, p52LOF/IκBδLOF) or gain-of-function of p52 (hereafter, p52GOF/IκBδLOF). In contrast to patients with APS-1, patients with disorders of NIK, RELB or NF-κB2 have very few tissue-specific autoantibodies. However, their thymuses have an abnormal structure, with few AIRE-expressing medullary thymic epithelial cells. Human inborn errors of the alternative NF-κB pathway impair the development of AIRE-expressing medullary thymic epithelial cells, thereby underlying the production of autoantibodies against type I IFNs and predisposition to viral diseases.
Asunto(s)
Autoanticuerpos , Predisposición Genética a la Enfermedad , Interferón Tipo I , FN-kappa B , Humanos , Autoanticuerpos/inmunología , COVID-19/genética , COVID-19/inmunología , Mutación con Ganancia de Función , Heterocigoto , Proteínas I-kappa B/deficiencia , Proteínas I-kappa B/genética , Interferón Tipo I/antagonistas & inhibidores , Interferón Tipo I/inmunología , Mutación con Pérdida de Función , FN-kappa B/deficiencia , FN-kappa B/genética , Subunidad p52 de NF-kappa B/deficiencia , Subunidad p52 de NF-kappa B/genética , Neumonía Viral/genética , Neumonía Viral/inmunología , Timo/anomalías , Timo/inmunología , Timo/patología , Células Epiteliales Tiroideas/metabolismo , Células Epiteliales Tiroideas/patología , Proteína AIRE , Quinasa de Factor Nuclear kappa BRESUMEN
Aberrant inflammation, such as that associated with inflammatory bowel disease (IBD), is fueled by the inordinate activity of RelA/NF-κB factors. As such, the canonical NF-κB module mediates controlled nuclear activation of RelA dimers from the latent cytoplasmic complexes. What provokes pathological RelA activity in the colitogenic gut remains unclear. The noncanonical NF-κB pathway typically promotes immune organogenesis involving Nfkb2 gene products. Because NF-κB pathways are intertwined, we asked whether noncanonical signaling aggravated inflammatory RelA activity. Our investigation revealed frequent engagement of the noncanonical pathway in human IBD. In a mouse model of experimental colitis, we established that Nfkb2-mediated regulations escalated the RelA-driven proinflammatory gene response in intestinal epithelial cells, exacerbating the infiltration of inflammatory cells and colon pathologies. Our mechanistic studies clarified that cell-autonomous Nfkb2 signaling supplemented latent NF-κB dimers, leading to a hyperactive canonical RelA response in the inflamed colon. In sum, the regulation of latent NF-κB dimers appears to link noncanonical Nfkb2 signaling to RelA-driven inflammatory pathologies and may provide for therapeutic targets.
Asunto(s)
Inflamación/patología , Intestinos/patología , Subunidad p52 de NF-kappa B/metabolismo , FN-kappa B/metabolismo , Multimerización de Proteína , Transducción de Señal , Factor de Transcripción ReIA/metabolismo , Animales , Colitis/metabolismo , Colitis/patología , Progresión de la Enfermedad , Células Epiteliales/metabolismo , Homeostasis , Humanos , Inflamación/metabolismo , Enfermedades Inflamatorias del Intestino/metabolismo , Enfermedades Inflamatorias del Intestino/patología , Receptor beta de Linfotoxina/metabolismo , Ratones Endogámicos C57BL , Modelos Biológicos , Subunidad p52 de NF-kappa B/deficiencia , Células del Estroma/metabolismoRESUMEN
Lymphotoxin-beta receptor (LTßR) present on stromal cells engages the noncanonical NF-κB pathway to mediate RelB-dependent expressions of homeostatic chemokines, which direct steady-state ingress of naïve lymphocytes to secondary lymphoid organs (SLOs). In this pathway, NIK promotes partial proteolysis of p100 into p52 that induces nuclear translocation of the RelB NF-κB heterodimers. Microbial infections often deplete homeostatic chemokines; it is thought that infection-inflicted destruction of stromal cells results in the downregulation of these chemokines. Whether inflammation per se also regulates these processes remains unclear. We show that TNF accumulated upon non-infectious immunization of mice similarly downregulates the expressions of these chemokines and consequently diminishes the ingress of naïve lymphocytes in inflamed SLOs. Mechanistically, TNF inactivated NIK in LTßR-stimulated cells and induced the synthesis of Nfkb2 mRNA encoding p100; these together potently accumulated unprocessed p100, which attenuated the RelB activity as inhibitory IκBδ. Finally, a lack of p100 alleviated these TNF-mediated inhibitions in inflamed SLOs of immunized Nfkb2-/- mice. In sum, we reveal that an inhibitory TNF-p100 pathway modulates the adaptive compartment during immune responses.
Asunto(s)
Mediadores de Inflamación/metabolismo , Tejido Linfoide/metabolismo , FN-kappa B/metabolismo , Factor de Necrosis Tumoral alfa/metabolismo , Inmunidad Adaptativa , Animales , Quimiocinas/genética , Quimiocinas/metabolismo , Regulación hacia Abajo , Quinasa I-kappa B/metabolismo , Linfangitis/inmunología , Linfangitis/metabolismo , Linfangitis/patología , Tejido Linfoide/inmunología , Tejido Linfoide/patología , Receptor beta de Linfotoxina/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Subunidad p52 de NF-kappa B/deficiencia , Subunidad p52 de NF-kappa B/genética , Subunidad p52 de NF-kappa B/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Transducción de Señal , Factor 2 Asociado a Receptor de TNF/metabolismo , Factor 3 Asociado a Receptor de TNF/metabolismo , Factor de Transcripción ReIB/metabolismo , Quinasa de Factor Nuclear kappa BRESUMEN
DNA double-strand breaks (DSBs) activate a canonical DNA damage response, including highly conserved cell cycle checkpoint pathways that prevent cells with DSBs from progressing through the cell cycle. In developing B cells, pre-B cell receptor (pre-BCR) signals initiate immunoglobulin light (Igl) chain gene assembly, leading to RAG-mediated DNA DSBs. The pre-BCR also promotes cell cycle entry, which could cause aberrant DSB repair and genome instability in pre-B cells. Here, we show that RAG DSBs inhibit pre-BCR signals through the ATM- and NF-κB2-dependent induction of SPIC, a hematopoietic-specific transcriptional repressor. SPIC inhibits expression of the SYK tyrosine kinase and BLNK adaptor, resulting in suppression of pre-BCR signaling. This regulatory circuit prevents the pre-BCR from inducing additional Igl chain gene rearrangements and driving pre-B cells with RAG DSBs into cycle. We propose that pre-B cells toggle between pre-BCR signals and a RAG DSB-dependent checkpoint to maintain genome stability while iteratively assembling Igl chain genes.
Asunto(s)
Roturas del ADN de Doble Cadena , Proteínas de Homeodominio/metabolismo , Receptores de Células Precursoras de Linfocitos B/metabolismo , Células Precursoras de Linfocitos B/inmunología , Células Precursoras de Linfocitos B/metabolismo , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Animales , Proteínas de la Ataxia Telangiectasia Mutada/deficiencia , Proteínas de la Ataxia Telangiectasia Mutada/genética , Proteínas de la Ataxia Telangiectasia Mutada/metabolismo , Puntos de Control del Ciclo Celular/inmunología , Proliferación Celular , Proteínas de Unión al ADN/deficiencia , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Reordenamiento Génico de Cadena Ligera de Linfocito B , Proteínas de Homeodominio/genética , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Ratones , Ratones Noqueados , Ratones Transgénicos , Subunidad p52 de NF-kappa B/deficiencia , Subunidad p52 de NF-kappa B/genética , Subunidad p52 de NF-kappa B/metabolismo , Células Precursoras de Linfocitos B/citología , Proteínas Serina-Treonina Quinasas/metabolismo , Proteínas Tirosina Quinasas/metabolismo , Proteínas Proto-Oncogénicas/metabolismo , Transducción de Señal/inmunología , Quinasa Syk , Transactivadores/metabolismo , Quinasa de Factor Nuclear kappa BRESUMEN
Defects in apoptosis can cause autoimmune disease. Loss-of-function mutations in the 'death receptor' FAS impair the deletion of autoreactive lymphocytes in the periphery, leading to progressive lymphadenopathy and systemic lupus erythematosus-like autoimmune disease in mice (Fas(lpr/lpr) (mice homozygous for the lymphoproliferation inducing spontaneous mutation)) and humans. The REL/nuclear factor-κB (NF-κB) transcription factors regulate a broad range of immune effector functions and are also implicated in various autoimmune diseases. We generated compound mutant mice to investigate the individual functions of the NF-κB family members NF-κB1, NF-κB2 and c-REL in the various autoimmune pathologies of Fas(lpr/lpr) mutant mice. We show that loss of each of these transcription factors resulted in amelioration of many classical features of autoimmune disease, including hypergammaglobulinaemia, anti-nuclear autoantibodies and autoantibodies against tissue-specific antigens. Remarkably, only c-REL deficiency substantially reduced immune complex-mediated glomerulonephritis and extended the lifespan of Fas(lpr/lpr) mice. Interestingly, compared with the Fas(lpr/lpr) animals, Fas(lpr/lpr)nfkb2(-/-) mice presented with a dramatic acceleration and augmentation of lymphadenopathy that was accompanied by severe lung pathology due to extensive lymphocytic infiltration. The Fas(lpr/lpr)nfkb1(-/-) mice exhibited the combined pathologies caused by defects in FAS-mediated apoptosis and premature ageing due to loss of NF-κB1. These findings demonstrate that different NF-κB family members exert distinct roles in the development of the diverse autoimmune and lymphoproliferative pathologies that arise in Fas(lpr/lpr) mice, and suggest that pharmacological targeting of c-REL should be considered as a strategy for therapeutic intervention in autoimmune diseases.
Asunto(s)
Lupus Eritematoso Sistémico/complicaciones , Enfermedades Linfáticas/complicaciones , Subunidad p50 de NF-kappa B/deficiencia , Subunidad p52 de NF-kappa B/deficiencia , Proteínas Proto-Oncogénicas c-rel/metabolismo , Receptor fas/metabolismo , Animales , Autoanticuerpos/sangre , Quimiocinas/sangre , Quimiocinas/metabolismo , Dermatitis/sangre , Dermatitis/complicaciones , Dermatitis/inmunología , Factores de Transcripción Forkhead/metabolismo , Genotipo , Hipergammaglobulinemia/sangre , Hipergammaglobulinemia/complicaciones , Tolerancia Inmunológica/inmunología , Leucocitos/patología , Longevidad , Lupus Eritematoso Sistémico/sangre , Enfermedades Linfáticas/sangre , Ratones Endogámicos C57BL , Ratones Noqueados , Ratones Mutantes , Subunidad p50 de NF-kappa B/metabolismo , Subunidad p52 de NF-kappa B/metabolismo , Especificidad de Órganos , Esplenomegalia/sangre , Factores de Transcripción/metabolismo , Proteína AIRERESUMEN
Tissue microenvironment functions as an important determinant of the inflammatory response elicited by the resident cells. Yet, the underlying molecular mechanisms remain obscure. Our systems-level analyses identified a duration code that instructs stimulus specific crosstalk between TLR4-activated canonical NF-κB pathway and lymphotoxin-ß receptor (LTßR) induced non-canonical NF-κB signaling. Indeed, LTßR costimulation synergistically enhanced the late RelA/NF-κB response to TLR4 prolonging NF-κB target gene-expressions. Concomitant LTßR signal targeted TLR4-induced newly synthesized p100, encoded by Nfkb2, for processing into p52 that not only neutralized p100 mediated inhibitions, but potently generated RelA:p52/NF-κB activity in a positive feedback loop. Finally, Nfkb2 connected lymphotoxin signal within the intestinal niche in reinforcing epithelial innate inflammatory RelA/NF-κB response to Citrobacter rodentium infection, while Nfkb2(-/-) mice succumbed to gut infections owing to stromal defects. In sum, our results suggest that signal integration via the pleiotropic NF-κB system enables tissue microenvironment derived cues in calibrating physiological responses.
Asunto(s)
Citrobacter rodentium/inmunología , Infecciones por Enterobacteriaceae/inmunología , Inmunidad Innata/genética , Inflamación/genética , FN-kappa B/genética , Transducción de Señal/genética , Animales , Citrobacter rodentium/patogenicidad , Regulación de la Expresión Génica/inmunología , Mucosa Intestinal/inmunología , Mucosa Intestinal/microbiología , Receptor beta de Linfotoxina/genética , Receptor beta de Linfotoxina/inmunología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , FN-kappa B/inmunología , Subunidad p52 de NF-kappa B/deficiencia , Subunidad p52 de NF-kappa B/genética , Factor de Transcripción ReIA/genética , Factor de Transcripción ReIA/inmunologíaRESUMEN
Formation of the splenic marginal zone (MZ) depends on the alternative NF-κB signaling pathway. Recently, we reported that unrestricted activation of this pathway in NF-κB2/p100-deficient (p100(-/-) ) knock-in mice alters the phenotype of MZ stroma and B cells. Here, we show that lack of the p100 inhibitor resulted in an expansion of both MZ B and peritoneal B-1 cells. However, these cells failed to generate proliferating blasts in response to T-cell-independent type 2 (TI-2) Ags, correlating with dampened IgM and absent IgG3 responses. This phenotype was in part due to increased activity of the NF-κB subunit RelB. Moreover, p100(-/-) âB6 BM chimeras were more susceptible to infection by encapsulated Streptococcus pneumoniae bacteria, pathogens that induce TI-2 responses. In contrast to the TI-2 defect, p100 deficiency did not impair immune responses to the TI-1 Ag LPS and p100(-/-) MZ B cells showed normal Ag transportation into B-cell follicles. Furthermore, p100(-/-) MZ B and B-1 cells failed to respond to TI-2 Ags in the presence of WT accessory cells. Thus, NF-κB2/p100 deficiency caused a predominant B-cell-intrinsic TI-2 defect that could largely be attributed to impaired proliferation of plasmablasts. Importantly, p100 was also necessary for efficient defense against clinically relevant TI-2 pathogens.
Asunto(s)
Antígenos T-Independientes/inmunología , Subgrupos de Linfocitos B/inmunología , Subgrupos de Linfocitos B/metabolismo , Subunidad p52 de NF-kappa B/deficiencia , Animales , Formación de Anticuerpos/genética , Formación de Anticuerpos/inmunología , Antígenos T-Independientes/metabolismo , Subgrupos de Linfocitos B/efectos de los fármacos , Bacterias/inmunología , Infecciones Bacterianas/genética , Infecciones Bacterianas/inmunología , Movimiento Celular/genética , Citocinas/farmacología , Predisposición Genética a la Enfermedad , Inmunidad Humoral/genética , Ratones , Ratones Noqueados , Subunidad p52 de NF-kappa B/genética , Subunidad p52 de NF-kappa B/metabolismo , Unión Proteica , Transporte de Proteínas , Receptores de Antígenos de Linfocitos B/metabolismo , Receptores Toll-Like/metabolismo , Factor de Transcripción ReIB/genética , Factor de Transcripción ReIB/metabolismoRESUMEN
BACKGROUND: Constitutive activation of the alternative NF-κB pathway leads to marginal zone B cell expansion and disorganized spleen microarchitecture. Furthermore, uncontrolled alternative NF-κB signaling may result in the development and progression of cancer. Here, we focused on the question how does the constitutive alternative NF-κB signaling exert its effects in these malignant processes. METHODOLOGY/PRINCIPAL FINDINGS: To explore the consequences of unrestricted alternative NF-κB activation on genome-wide transcription, we compared gene expression profiles of wild-type and NF-κB2/p100-deficient (p100(-/-)) primary mouse embryonic fibroblasts (MEFs) and spleens. Microarray experiments revealed only 73 differentially regulated genes in p100(-/-) vs. wild-type MEFs. Chromatin immunoprecipitation (ChIP) assays showed in p100(-/-) MEFs direct binding of p52 and RelB to the promoter of the Enpp2 gene encoding ENPP2/Autotaxin, a protein with an important role in lymphocyte homing and cell migration. Gene ontology analysis revealed upregulation of genes with anti-apoptotic/proliferative activity (Enpp2/Atx, Serpina3g, Traf1, Rrad), chemotactic/locomotory activity (Enpp2/Atx, Ccl8), and lymphocyte homing activity (Enpp2/Atx, Cd34). Most importantly, biochemical and gene expression analyses of MEFs and spleen, respectively, indicated a marked crosstalk between classical and alternative NF-κB pathways. CONCLUSIONS/SIGNIFICANCE: Our results show that p100 deficiency alone was insufficient for full induction of genes regulated by the alternative NF-κB pathway. Moreover, alternative NF-κB signaling strongly synergized both in vitro and in vivo with classical NF-κB activation, thereby extending the number of genes under the control of the p100 inhibitor of the alternative NF-κB signaling pathway.
Asunto(s)
Subunidad p52 de NF-kappa B/deficiencia , Transducción de Señal , Factor de Transcripción ReIB/metabolismo , Transcripción Genética , Factores de Necrosis Tumoral/metabolismo , Animales , Embrión de Mamíferos/citología , Fibroblastos/metabolismo , Perfilación de la Expresión Génica , Regulación de la Expresión Génica , Ratones , Subunidad p52 de NF-kappa B/metabolismo , Hidrolasas Diéster Fosfóricas/genética , Regiones Promotoras Genéticas/genética , Unión Proteica , Bazo/metabolismoRESUMEN
HMGB1 is a chromatin architectural protein that is released by dead or damaged cells at sites of tissue injury. Extracellular HMGB1 functions as a proinflammatory cytokine and chemoattractant for immune effector and progenitor cells. Previously, we have shown that the inhibitor of NF-κB kinase (IKK)ß- and IKKα-dependent NF-κB signaling pathways are simultaneously required for cell migration to HMGB1. The IKKß-dependent canonical pathway is needed to maintain expression of receptor for advanced glycation end products, the ubiquitously expressed receptor for HMGB1, but the target of the IKKα non-canonical pathway was not known. In this study, we show that the IKKα-dependent p52/RelB noncanonical pathway is critical to sustain CXCL12/SDF1 production in order for cells to migrate toward HMGB1. Using both mouse bone marrow-derived macrophages and mouse embryo fibroblasts (MEFs), it was observed that neutralization of CXCL12 by a CXCL12 mAb completely eliminated chemotaxis to HMGB1. In addition, the HMGB1 migration defect of IKKα KO and p52 KO cells could be rescued by adding recombinant CXCL12 to cells. Moreover, p52 KO MEFs stably transduced with a GFP retroviral vector that enforces physiologic expression of CXCL12 also showed near normal migration toward HMGB1. Finally, both AMD3100, a specific antagonist of CXCL12's G protein-coupled receptor CXCR4, and an anti-CXCR4 Ab blocked HMGB1 chemotactic responses. These results indicate that HMGB1-CXCL12 interplay drives cell migration toward HMGB1 by engaging receptors of both chemoattractants. This novel requirement for a second receptor-ligand pair enhances our understanding of the molecular mechanisms regulating HMGB1-dependent cell recruitment to sites of tissue injury.
Asunto(s)
Comunicación Autocrina/inmunología , Movimiento Celular/inmunología , Quimiocina CXCL12/biosíntesis , Proteína HMGB1/fisiología , Quinasa I-kappa B/fisiología , Subunidad p52 de NF-kappa B/fisiología , Transducción de Señal/inmunología , Factor de Transcripción ReIB/fisiología , Animales , Transformación Celular Neoplásica , Quimiocina CXCL12/antagonistas & inhibidores , Quimiocina CXCL12/fisiología , Quinasa I-kappa B/biosíntesis , Quinasa I-kappa B/deficiencia , Ratones , Ratones Noqueados , Ratones Transgénicos , Subunidad p52 de NF-kappa B/biosíntesis , Subunidad p52 de NF-kappa B/deficiencia , Factor de Transcripción ReIB/biosíntesis , Células Tumorales CultivadasRESUMEN
Cancer cells with p53 mutations, in general, grow more aggressively than those with wild-type p53 and show "gain of function" (GOF) phenotypes such as increased growth rate, enhanced resistance to chemotherapeutic drugs, increased cell motility and tumorigenicity; although the mechanism for this function remains unknown. In this communication we report that p53-mediated NF-κB2 up-regulation significantly contributes to the aggressive oncogenic behavior of cancer cells. Lowering the level of mutant p53 in a number of cancer cell lines resulted in a loss of GOF phenotypes directly implicating p53 mutants in the process. RNAi against NF-κB2 in naturally occurring cancer cell lines also lowers GOF activities. In H1299 cells expressing mutant p53, chromatin immunoprecipitation (ChIP) assays indicate that mutant p53 induces histone acetylation at specific sites on the regulatory regions of its target genes. ChIP assays using antibodies against transcription factors putatively capable of interacting with the NF-κB2 promoter show increased interaction of CBP and STAT2 in the presence of mutant p53. Thus, we propose that in H1299 cells, mutant p53 elevates expression of genes capable of enhancing cell proliferation, motility, and tumorigenicity by inducing acetylation of histones via recruitment of CBP and STAT2 on the promoters causing CBP-mediated histone acetylation.
Asunto(s)
Proteína de Unión a CREB/metabolismo , Mutación , Subunidad p52 de NF-kappa B/genética , Regiones Promotoras Genéticas/genética , Factores de Transcripción STAT/metabolismo , Transcripción Genética/genética , Proteína p53 Supresora de Tumor/metabolismo , Acetilación , Animales , Línea Celular Tumoral , Movimiento Celular/genética , Proliferación Celular , Cromatina/genética , Cromatina/metabolismo , Histonas/metabolismo , Humanos , Ratones , Subunidad p52 de NF-kappa B/deficiencia , Subunidad p52 de NF-kappa B/metabolismo , Unión Proteica/genética , Interferencia de ARN , Proteína p53 Supresora de Tumor/deficiencia , Proteína p53 Supresora de Tumor/genética , Regulación hacia Arriba/genéticaRESUMEN
BACKGROUND: Deregulated c-Myc expression is a hallmark of several human cancers where it promotes proliferation and an aggressive tumour phenotype. Myc overexpression is associated with reduced activity of Rel/NF-kappaB, transcription factors that control the immune response, cell survival, and transformation, and that are frequently altered in cancer. The Rel/NF-kappaB family member NFKB2 is altered by chromosomal translocations or deletions in lymphoid malignancies and deletion of the C-terminal ankyrin domain of NF-kappaB2 augments lymphocyte proliferation. METHODS: Precancerous Emicro-Myc-transgenic B cells, Emicro-Myc lymphomas and human Burkitt lymphoma samples were assessed for Nfkb2 expression. The contribution of Nfkb2 to Myc-driven apoptosis, proliferation, and lymphomagenesis was tested genetically in vivo. RESULTS: Here we report that the Myc oncoprotein suppresses Nfkb2 expression in vitro in primary mouse fibroblasts and B cells, and in vivo in the Emicro-Myc transgenic mouse model of human Burkitt lymphoma (BL). NFKB2 suppression by Myc was also confirmed in primary human BL. Promoter-reporter assays indicate that Myc-mediated suppression of Nfkb2 occurs at the level of transcription. The contribution of Nfkb2 to Myc-driven lymphomagenesis was tested in vivo, where Nfkb2 loss was shown to accelerate lymphoma development in Emicro-Myc transgenic mice, by impairing Myc's apoptotic response. CONCLUSIONS: Nfkb2 is suppressed by c-Myc and harnesses Myc-driven lymphomagenesis. These data thus link Myc-driven lymphomagenesis to the non-canonical NF-kappaB pathway.
Asunto(s)
Apoptosis , Linfoma de Burkitt/metabolismo , Proliferación Celular , Subunidad p52 de NF-kappa B/metabolismo , Proteínas Proto-Oncogénicas c-myc/metabolismo , Animales , Linfocitos B/metabolismo , Linfocitos B/patología , Linfoma de Burkitt/genética , Linfoma de Burkitt/patología , Células Cultivadas , Regulación hacia Abajo , Fibroblastos/metabolismo , Fibroblastos/patología , Regulación Neoplásica de la Expresión Génica , Humanos , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Ratones Transgénicos , Subunidad p52 de NF-kappa B/deficiencia , Subunidad p52 de NF-kappa B/genética , Regiones Promotoras Genéticas , Proteínas Proto-Oncogénicas c-myc/genética , ARN Mensajero/metabolismo , Factores de Tiempo , Transcripción Genética , TransfecciónRESUMEN
The NF-kappaB transcription factors have many essential functions in B cells, such as during differentiation and proliferation of Ag-challenged mature B cells, but also during final maturation of developing B cells in the spleen. Among the various specific functions NF-kappaB factors carry out in these biologic contexts, their ability to assure the survival of mature and maturing B cells in the periphery stands out. Less clear is what if any roles NF-kappaB factors play during earlier stages of B cell development in the bone marrow. Using mice deficient in both NF-kappaB1 and NF-kappaB2, which are thus partially compromised in both the classical and alternative activation pathways, we demonstrate a B cell-autonomous contribution of NF-kappaB to the survival of immature B cells in the bone marrow. NF-kappaB1 and NF-kappaB2 also play a role during the earlier transition from proB to late preB cells; however, in this context these factors do not act in a B cell-autonomous fashion. Although NF-kappaB1 and NF-kappaB2 are not absolutely required for survival and progression of immature B cells in the bone marrow, they nevertheless make a significant contribution that marks the beginning of the profound cell-autonomous control these factors exert during all subsequent stages of B cell development. Therefore, the lifelong dependency of B cells on NF-kappaB-mediated survival functions is set in motion at the time of first expression of a full BCR.
Asunto(s)
Subgrupos de Linfocitos B/inmunología , Subgrupos de Linfocitos B/metabolismo , Células de la Médula Ósea/inmunología , Células de la Médula Ósea/metabolismo , Diferenciación Celular/inmunología , Subunidad p50 de NF-kappa B/fisiología , Subunidad p52 de NF-kappa B/fisiología , Animales , Receptor del Factor Activador de Células B/fisiología , Subgrupos de Linfocitos B/citología , Subgrupos de Linfocitos B/patología , Células de la Médula Ósea/citología , Células de la Médula Ósea/patología , Diferenciación Celular/genética , Supervivencia Celular/genética , Supervivencia Celular/inmunología , Células Madre Hematopoyéticas/citología , Células Madre Hematopoyéticas/inmunología , Células Madre Hematopoyéticas/patología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Subunidad p50 de NF-kappa B/deficiencia , Subunidad p50 de NF-kappa B/genética , Subunidad p50 de NF-kappa B/metabolismo , Subunidad p52 de NF-kappa B/deficiencia , Subunidad p52 de NF-kappa B/genética , Subunidad p52 de NF-kappa B/metabolismo , Células Precursoras de Linfocitos B/inmunología , Células Precursoras de Linfocitos B/metabolismo , Células Precursoras de Linfocitos B/patología , Transducción de Señal/genética , Transducción de Señal/inmunologíaRESUMEN
Nuclear factor-kappaB (NF-kappaB) transcription factors regulate B-cell development and survival. However, whether they also have a role during early steps of B-cell differentiation is largely unclear. Here, we show that constitutive activation of the alternative NF-kappaB pathway in p100(-/-) knockin mice resulted in a block of early B-cell development at the transition from the pre-pro-B to the pro-B-cell stage due to enhanced RelB activity. Expression of the essential B-cell transcription factors EBF and in particular Pax5 was reduced in p100(-/-) B-cell precursors in a RelB-dependent manner, resulting in reduced mRNA levels of B lineage-specific genes. Moreover, enhanced RelB function in p100(-/-) B-cell precursors was accompanied by increased expression of B lineage-inappropriate genes, such as C/EBP alpha, correlating with a markedly increased myeloid differentiation potential of p100(-/-) progenitor B cells. Ectopic expression of Pax5 in hematopoietic progenitors restored early B-cell development in p100(-/-) bone marrow, suggesting that impaired early B lymphopoiesis in mice lacking the p100 inhibitor may be due to down-regulation of Pax5 expression. Thus, tightly controlled p100 processing and RelB activation is essential for normal B lymphopoiesis and lymphoid/myeloid lineage decision in bone marrow.
Asunto(s)
Linfocitos B/citología , Linfopoyesis , Subunidad p52 de NF-kappa B/fisiología , Factor de Transcripción ReIB/fisiología , Animales , Médula Ósea , Linaje de la Célula , Ratones , Ratones Noqueados , Subunidad p52 de NF-kappa B/deficiencia , Factor de Transcripción PAX5/genética , Transactivadores/genéticaRESUMEN
The NF-kappaB signaling pathway regulates the activity of multiple dimeric transcription factors that are generated from five distinct monomers. The availabilities of specific dimers are regulated during cell differentiation and organ development and determine the cell's responsiveness to inflammatory or developmental signals. An altered dimer distribution is a hallmark of many chronic diseases. Here, we reveal that the cellular processes that generate different NF-kappaB dimers are highly connected through multiple cross-regulatory mechanisms. First, we find that steady-state expression of RelB is regulated by the canonical pathway and constitutive RelA activity. Indeed, synthesis control of RelB is the major determinant of noncanonical NF-kappaB dimer activation. Second, processing, not synthesis, of p100 and p105 is mechanistically linked via competitive dimerization with a limited pool of RelA and RelB. This homeostatic cross-regulatory mechanism determines the availability of the p50- and p52-containing dimers and also of the noncanonical IkappaB p100. Our results inform a wiring diagram to delineate NF-kappaB dimer formation that emphasizes that inflammatory and developmental signaling cannot be considered separately but are highly interconnected.
Asunto(s)
FN-kappa B/metabolismo , Factores de Transcripción/metabolismo , Animales , Células Cultivadas , Dimerización , Quinasa I-kappa B/deficiencia , Quinasa I-kappa B/genética , Quinasa I-kappa B/metabolismo , Ganglios Linfáticos/crecimiento & desarrollo , Ganglios Linfáticos/metabolismo , Ratones , Ratones Noqueados , FN-kappa B/genética , Subunidad p50 de NF-kappa B/deficiencia , Subunidad p50 de NF-kappa B/genética , Subunidad p50 de NF-kappa B/metabolismo , Subunidad p52 de NF-kappa B/deficiencia , Subunidad p52 de NF-kappa B/genética , Subunidad p52 de NF-kappa B/metabolismo , Estructura Cuaternaria de Proteína , ARN Mensajero/genética , ARN Mensajero/metabolismo , Transducción de Señal , Factor de Transcripción ReIA/química , Factor de Transcripción ReIA/deficiencia , Factor de Transcripción ReIA/genética , Factor de Transcripción ReIA/metabolismo , Factor de Transcripción ReIB/química , Factor de Transcripción ReIB/deficiencia , Factor de Transcripción ReIB/genética , Factor de Transcripción ReIB/metabolismo , Factores de Transcripción/química , Factores de Transcripción/genéticaRESUMEN
Proper activation of nuclear factor (NF)-kappaB transcription factors is critical in regulating fundamental biological processes such as cell survival and proliferation, as well as in inflammatory and immune responses. Recently, the NF-kappaB signaling pathways have been categorized into the canonical pathway, which results in the nuclear translocation of NF-kappaB complexes containing p50, and the noncanonical pathway, which involves the induced processing of p100 to p52 and the formation of NF-kappaB complexes containing p52 (Bonizzi, G., and M. Karin. 2004. Trends Immunol. 25:280-288). We demonstrate that loss of tumor necrosis factor (TNF) receptor-associated factor 3 (TRAF3) results in constitutive noncanonical NF-kappaB activity. Importantly, TRAF3-/- B cells show ligand-independent up-regulation of intracellular adhesion molecule 1 and protection from spontaneous apoptosis during in vitro culture. In addition, we demonstrate that loss of TRAF3 results in profound accumulation of NF-kappaB-inducing kinase in TRAF3-/- cells. Finally, we show that the early postnatal lethality observed in TRAF3-deficient mice is rescued by compound loss of the noncanonical NF-kappaB p100 gene. Thus, these genetic data clearly demonstrate that TRAF3 is a critical negative modulator of the noncanonical NF-kappaB pathway and that constitutive activation of the noncanonical NF-kappaB pathway causes the lethal phenotype of TRAF3-deficient mice.
Asunto(s)
Subunidad p52 de NF-kappa B/deficiencia , Subunidad p52 de NF-kappa B/genética , Factor 3 Asociado a Receptor de TNF/deficiencia , Factor 3 Asociado a Receptor de TNF/genética , Animales , Linfocitos B/inmunología , Linfocitos B/metabolismo , Células Cultivadas , Regulación hacia Abajo , Genes Letales , Activación de Linfocitos/genética , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Subunidad p52 de NF-kappa B/antagonistas & inhibidores , Subunidad p52 de NF-kappa B/fisiología , Procesamiento Proteico-PostraduccionalRESUMEN
NF-kappaB2-deficient mice have impaired T and B cell responses. We found, however, that in these mice there was severe infiltration of lymphocytes into multiple organs and increased activity of autoantibodies to peripheral tissue antigens in a manner similar to that of autoimmune regulator-deficient (Aire-deficient) mice. We further demonstrated that NF-kappaB2 was required for thymic Aire gene transcriptional regulation. The Nfkb2(-/-) thymus had distinct cortical and medullar structures, but reduced Aire and target gene expression of peripheral tissue antigens. Engraftment of Nfkb2(-/-) thymic stroma to nude mice recapitulated the autoimmune phenotype of the native Nfkb2(-/-) mice, confirming a key defect in central tolerance. Lymphotoxin beta receptor (LTbetaR) ligation-induced Aire gene expression was also largely abolished in the absence of NF-kappaB2. Thus NF-kappaB2 downstream of LTbetaR plays an important role in the regulation of central tolerance in an Aire-dependent manner.
Asunto(s)
Tolerancia Inmunológica/inmunología , Subunidad p52 de NF-kappa B/inmunología , Subunidad p52 de NF-kappa B/metabolismo , Transducción de Señal , Factores de Transcripción/inmunología , Factores de Transcripción/metabolismo , Animales , Autoinmunidad/inmunología , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD4-Positivos/metabolismo , Regulación de la Expresión Génica , Subunidad alfa del Receptor de Interleucina-2/metabolismo , Receptor beta de Linfotoxina/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Subunidad p52 de NF-kappa B/deficiencia , Subunidad p52 de NF-kappa B/genética , Fenotipo , Receptores del Factor de Necrosis Tumoral/metabolismo , Células Madre/inmunología , Células Madre/efectos de la radiación , Células del Estroma/inmunología , Células del Estroma/metabolismo , Factores de Transcripción/deficiencia , Factores de Transcripción/genética , Proteína AIRERESUMEN
Recent studies revealed that the lymphotoxin/lymphotoxin beta receptor (LT)/LTbetaR system activates the noncanonical nuclear factor-kappaB (NF-kappaB) signaling pathway involving I kappa B kinase 1/I kappa B kinase alpha (IKK1/IKKalpha) and NF-kappaB-inducing kinase (NIK) to direct processing of the nfkappab2 protein p100 to yield RelB:p52 complexes. Despite the biochemical evidence, LT-, RelB-, p52-deficient mice show discrepant phenotypes. We now demonstrate that p105/p50 also constitutes an important pathway for LTbetaR signaling. Our studies revealed that mice deficient in either p50 or p52 have defects in the formation of inguinal lymph nodes (LNs), but that the complete defect in lymph node formation and splenic microarchitecture seen in LT-deficient mice is recapitulated only in mice deficient in both p50 and p52. Biochemically, we find not only that both p50- and p52-containing NF-kappaB activities are induced by LTbetaR signaling, but that the induction of NF-kappaB-containing complexes by LTbetaR engagement is perturbed in single knockouts. Importantly, the LTbetaR can additionally activate the less well-characterized p52:RelA and p50:RelB pathways, which play pivotal roles in vivo for the development and organization of lymphoid structures. Our genetic, cellular, and molecular evidence points toward a model of LT-mediated NF-kappaB regulation in which p105/p50 and p100/p52 have distinct and coordinating molecular specificities but differ in the upstream signaling pathways that regulate them.