Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 14 de 14
Filtrar
Mais filtros










Base de dados
Tipo de estudo
Intervalo de ano de publicação
2.
Nat Commun ; 10(1): 3106, 2019 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-31308374

RESUMO

Immune responses need to be controlled tightly to prevent autoimmune diseases, yet underlying molecular mechanisms remain partially understood. Here, we identify biallelic mutations in three patients from two unrelated families in differentially expressed in FDCP6 homolog (DEF6) as the molecular cause of an inborn error of immunity with systemic autoimmunity. Patient T cells exhibit impaired regulation of CTLA-4 surface trafficking associated with reduced functional CTLA-4 availability, which is replicated in DEF6-knockout Jurkat cells. Mechanistically, we identify the small GTPase RAB11 as an interactor of the guanine nucleotide exchange factor DEF6, and find disrupted binding of mutant DEF6 to RAB11 as well as reduced RAB11+CTLA-4+ vesicles in DEF6-mutated cells. One of the patients has been treated with CTLA-4-Ig and achieved sustained remission. Collectively, we uncover DEF6 as player in immune homeostasis ensuring availability of the checkpoint protein CTLA-4 at T-cell surface, identifying a potential target for autoimmune and/or cancer therapy.

3.
Haematologica ; 2018 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-30309848

RESUMO

Hyper-IgE Syndromes comprise a group of inborn errors of immunity. STAT3-deficient hyper-IgE syndrome is characterized by elevated serum IgE levels, recurrent infections and eczema, and characteristic skeletal anomalies. A loss-of-function biallelic mutation in IL6ST encoding the GP130 receptor subunit (p.N404Y) has very recently been identified in a singleton patient (herein referred to as PN404Y) as a novel etiology of hyper-IgE syndrome. Here, we studied a patient with hyper-IgE syndrome caused by a novel homozygous mutation in IL6ST (p.P498L; patient herein referred to as PP498L) leading to abrogated GP130 signaling after stimulation with IL-6 and IL-27 in PBMCs as well as IL-6 and IL-11 in fibroblasts. Extending the initial identification of selective GP130 deficiency, we aimed to dissect the effects of aberrant cytokine signaling on T helper cell differentiation in both patients. Our results reveal the importance of IL-6 signaling for the development of CCR6-expressing memory CD4+ T cells (including T helper 17-enriched subsets) and non-conventional CD8+ T cells which were reduced in both patients. Downstream functional analysis of the GP130 mutants (p.N404Y and p.P498L) have shown differences in response to IL-27, with the p.P498L mutation having a more severe effect that is reflected by reduced T helper 1 cells in this patient (PP498L) only. Collectively, our data suggest that characteristic features of GP130-deficient hyper-IgE syndrome phenotype are IL-6 and IL-11 dominated, and indicate selective roles of aberrant IL-6 and IL-27 signaling on the differentiation of T cell subsets.

4.
Front Immunol ; 9: 588, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29651288

RESUMO

Specific granule deficiency (SGD) is a rare disorder characterized by abnormal neutrophils evidenced by reduced granules, absence of granule proteins, and atypical bilobed nuclei. Mutations in CCAAT/enhancer-binding protein-ε (CEBPE) are one molecular etiology of the disease. Although C/EBPε has been studied extensively, the impact of CEBPE mutations on neutrophil biology remains elusive. Here, we identified two SGD patients bearing a previously described heterozygous mutation (p.Val218Ala) in CEBPE. We took this rare opportunity to characterize SGD neutrophils in terms of granule distribution and protein content. Granules of patient neutrophils were clustered and polarized, suggesting that not only absence of specific granules but also defects affecting other granules contribute to the phenotype. Our analysis showed that remaining granules displayed mixed protein content and lacked several glycoepitopes. To further elucidate the impact of mutant CEBPE, we performed detailed proteomic analysis of SGD neutrophils. Beside an absence of several granule proteins in patient cells, we observed increased expression of members of the linker of nucleoskeleton and cytoskeleton complex (nesprin-2, vimentin, and lamin-B2), which control nuclear shape. This suggests that absence of these proteins in healthy individuals might be responsible for segmented shapes of neutrophilic nuclei. We further show that the heterozygous mutation p.Val218Ala in CEBPE causes SGD through prevention of nuclear localization of the protein product. In conclusion, we uncover that absence of nuclear C/EBPε impacts on spatiotemporal expression and subsequent distribution of several granule proteins and further on expression of proteins controlling nuclear shape.

5.
Nat Immunol ; 17(12): 1352-1360, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27776107

RESUMO

RASGRP1 is an important guanine nucleotide exchange factor and activator of the RAS-MAPK pathway following T cell antigen receptor (TCR) signaling. The consequences of RASGRP1 mutations in humans are unknown. In a patient with recurrent bacterial and viral infections, born to healthy consanguineous parents, we used homozygosity mapping and exome sequencing to identify a biallelic stop-gain variant in RASGRP1. This variant segregated perfectly with the disease and has not been reported in genetic databases. RASGRP1 deficiency was associated in T cells and B cells with decreased phosphorylation of the extracellular-signal-regulated serine kinase ERK, which was restored following expression of wild-type RASGRP1. RASGRP1 deficiency also resulted in defective proliferation, activation and motility of T cells and B cells. RASGRP1-deficient natural killer (NK) cells exhibited impaired cytotoxicity with defective granule convergence and actin accumulation. Interaction proteomics identified the dynein light chain DYNLL1 as interacting with RASGRP1, which links RASGRP1 to cytoskeletal dynamics. RASGRP1-deficient cells showed decreased activation of the GTPase RhoA. Treatment with lenalidomide increased RhoA activity and reversed the migration and activation defects of RASGRP1-deficient lymphocytes.


Assuntos
Actinas/metabolismo , Linfócitos B/imunologia , Citoesqueleto/metabolismo , Proteínas de Ligação a DNA/genética , Fatores de Troca do Nucleotídeo Guanina/genética , Síndromes de Imunodeficiência/genética , Células Matadoras Naturais/imunologia , Linfócitos T/imunologia , Adolescente , Inibidores da Angiogênese/farmacologia , Linfócitos B/efeitos dos fármacos , Movimento Celular/efeitos dos fármacos , Movimento Celular/genética , Proliferação de Células/genética , Criança , Citotoxicidade Imunológica/genética , Análise Mutacional de DNA , Dineínas/metabolismo , Feminino , Células HEK293 , Humanos , Switching de Imunoglobulina/genética , Síndromes de Imunodeficiência/tratamento farmacológico , Células Jurkat , Células Matadoras Naturais/efeitos dos fármacos , Lenalidomida , Masculino , Mutação/genética , Linhagem , RNA Interferente Pequeno/genética , Linfócitos T/efeitos dos fármacos , Talidomida/análogos & derivados , Talidomida/farmacologia
6.
J Proteome Res ; 15(9): 2900-2909, 2016 09 02.
Artigo em Inglês | MEDLINE | ID: mdl-27416764

RESUMO

NF-κB signaling is a central pathway of immunity and integrates signal transduction upon a wide array of inflammatory stimuli. Noncanonical NF-κB signaling is activated by a small subset of TNF family receptors and characterized by NF-κB2/p52 transcriptional activity. The medical relevance of this pathway has recently re-emerged from the discovery of primary immunodeficiency patients that have loss-of-function mutations in the MAP3K14 gene encoding NIK. Nevertheless, knowledge of protein interactions that regulate noncanonical NF-κB signaling is sparse. Here we report a detailed state-of-the-art mass spectrometry-based protein-protein interaction network including the noncanonical NF-κB signaling nodes TRAF2, TRAF3, IKKα, NIK, and NF-κB2/p100. The value of the data set was confirmed by the identification of interactions already known to regulate this pathway. In addition, a remarkable number of novel interactors were identified. We provide validation of the novel NIK and IKKα interactor FKBP8, which may regulate processes downstream of noncanonical NF-κB signaling. To understand perturbed noncanonical NF-κB signaling in the context of misregulated NIK in disease, we also provide a differential interactome of NIK mutants that cause immunodeficiency. Altogether, this data set not only provides critical insight into how protein-protein interactions can regulate immune signaling but also offers a novel resource on noncanonical NF-κB signaling.


Assuntos
NF-kappa B/metabolismo , Mapas de Interação de Proteínas , Transdução de Sinais/imunologia , Humanos , Quinase I-kappa B/metabolismo , Espectrometria de Massas , Mutação , Ligação Proteica , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas de Ligação a Tacrolimo/metabolismo
8.
J Clin Immunol ; 35(6): 523-6, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26233237

RESUMO

Protein kinase C delta (PRKCD) has essential functions in controlling B-cell proliferation and apoptosis, development of B-cell tolerance and NK-cell cytolitic activity. Human PRKCD deficiency was recently identified to be causative for an autoimmune lymphoproliferative syndrome like disorder with significant B-cell proliferation particularly of immature B cells. Here we report a child with a novel mutation in PRKCD gene who presented with CMV infection and an early onset SLE-like disorder which was successfully treated with hydroxychloroquine.


Assuntos
Antirreumáticos/administração & dosagem , Síndrome Linfoproliferativa Autoimune/imunologia , Linfócitos B/imunologia , Infecções por Citomegalovirus/imunologia , Citomegalovirus/imunologia , Hidroxicloroquina/administração & dosagem , Células Matadoras Naturais/imunologia , Lúpus Eritematoso Sistêmico/imunologia , Proteína Quinase C-delta/genética , Síndrome Linfoproliferativa Autoimune/tratamento farmacológico , Síndrome Linfoproliferativa Autoimune/genética , Pré-Escolar , Infecções por Citomegalovirus/tratamento farmacológico , Humanos , Lactente , Lúpus Eritematoso Sistêmico/tratamento farmacológico , Lúpus Eritematoso Sistêmico/genética , Masculino , Mutação/genética
9.
Nat Commun ; 5: 5360, 2014 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-25406581

RESUMO

Primary immunodeficiency disorders enable identification of genes with crucial roles in the human immune system. Here we study patients suffering from recurrent bacterial, viral and Cryptosporidium infections, and identify a biallelic mutation in the MAP3K14 gene encoding NIK (NF-κB-inducing kinase). Loss of kinase activity of mutant NIK, predicted by in silico analysis and confirmed by functional assays, leads to defective activation of both canonical and non-canonical NF-κB signalling. Patients with mutated NIK exhibit B-cell lymphopenia, decreased frequencies of class-switched memory B cells and hypogammaglobulinemia due to impaired B-cell survival, and impaired ICOSL expression. Although overall T-cell numbers are normal, both follicular helper and memory T cells are perturbed. Natural killer (NK) cells are decreased and exhibit defective activation, leading to impaired formation of NK-cell immunological synapses. Collectively, our data illustrate the non-redundant role for NIK in human immune responses, demonstrating that loss-of-function mutations in NIK can cause multiple aberrations of lymphoid immunity.


Assuntos
Agamaglobulinemia/genética , Linfopenia/genética , Proteínas Serina-Treonina Quinases/genética , Agamaglobulinemia/imunologia , Linfócitos B/imunologia , Infecções Bacterianas/imunologia , Pré-Escolar , Simulação por Computador , Criptosporidiose/imunologia , Feminino , Humanos , Switching de Imunoglobulina , Síndromes de Imunodeficiência/genética , Memória Imunológica , Ligante Coestimulador de Linfócitos T Induzíveis/metabolismo , Lactente , Células Matadoras Naturais/imunologia , Contagem de Leucócitos , Contagem de Linfócitos , Linfopenia/imunologia , Mutação , Linhagem , Recidiva , Linfócitos T Auxiliares-Indutores/imunologia , Viroses/imunologia
10.
J Clin Immunol ; 34(8): 941-53, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25205547

RESUMO

PURPOSE: Idiopathic CD4 lymphopenia constitutes a heterogeneous group of immunodeficiencies with characteristically low CD4+ T-cell counts with largely unknown genetic etiology. We here sought to determine the underlying molecular cause in an index family with two patients suffering from combined immunodeficiency that evolved into predominant CD4+ lymphopenia. The more severely affected index patient also presented with selective antibody deficiency against bacterial polysaccharide antigens. METHODS: For the genetic analysis, we used combined homozygosity mapping and exome sequencing. Functional assays included immunoblot analysis, flow cytometry and TCR Vß spectratyping. RESULTS: A novel homozygous missense mutation was revealed in the kinase domain of JAK3 (c.T3196C, p.Cys1066Arg). Further analysis showed revertant chimerism in CD8+ T-cells in both patients. The additional presence of revertant CD4+ T-cells was associated with a milder clinical and immunological phenotype in the second patient, although the role somatic chimerism plays in amelioration of disease phenotype is uncertain, as presence of revertant cells had no effect on residual CD4 cell JAK3 signaling function. Residual activity of JAK3-dependent STAT3 and STAT5 signaling was also found in immortalized B-cell lines indicating a hypomorphic nature of the described mutation which likely contributes to the milder clinical phenotype. CONCLUSIONS: We here present the first case of revertant mosaicism in JAK3 deficiency, manifesting as combined immunodeficiency evolving into predominant CD4+ lymphopenia. Revertant chimerism or hypomorphic mutations in genes typically associated with more severe T-cell deficiency should be considered when assessing patients with milder forms of combined immunodeficiencies.


Assuntos
Linfócitos T CD4-Positivos , Janus Quinase 3/genética , Linfopenia , Imunodeficiência Combinada Severa , Adolescente , Adulto , Sequência de Aminoácidos , Linfócitos T CD4-Positivos/imunologia , Células Cultivadas , Criança , Pré-Escolar , Quimerismo , Feminino , Humanos , Imunoglobulinas/sangue , Lactente , Janus Quinase 3/metabolismo , Linfopenia/genética , Masculino , Dados de Sequência Molecular , Mutação , Fator de Transcrição STAT5/metabolismo , Alinhamento de Sequência , Transdução de Sinais/genética
11.
Nat Genet ; 46(9): 1021-7, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25129144

RESUMO

The analysis of individuals with severe congenital neutropenia (SCN) may shed light on the delicate balance of factors controlling the differentiation, maintenance and decay of neutrophils. We identify 9 distinct homozygous mutations in the JAGN1 gene encoding Jagunal homolog 1 in 14 individuals with SCN. JAGN1-mutant granulocytes are characterized by ultrastructural defects, a paucity of granules, aberrant N-glycosylation of multiple proteins and increased incidence of apoptosis. JAGN1 participates in the secretory pathway and is required for granulocyte colony-stimulating factor receptor-mediated signaling. JAGN1 emerges as a factor that is necessary in the differentiation and survival of neutrophils.


Assuntos
Proteínas de Membrana/deficiência , Proteínas de Membrana/genética , Células Mieloides/metabolismo , Neutropenia/congênito , Adolescente , Adulto , Apoptose/genética , Diferenciação Celular/genética , Sobrevivência Celular/genética , Criança , Pré-Escolar , Feminino , Glicosilação , Homeostase/genética , Humanos , Lactente , Recém-Nascido , Masculino , Proteínas de Membrana/metabolismo , Mutação , Neutropenia/genética , Neutropenia/metabolismo , Neutropenia/patologia , Neutrófilos/metabolismo , Receptores de Fator Estimulador de Colônias de Granulócitos/genética , Receptores de Fator Estimulador de Colônias de Granulócitos/metabolismo , Transdução de Sinais , Adulto Jovem
12.
RNA Biol ; 10(2): 192-204, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23353575

RESUMO

Adenosine to inosine deamination of RNA is widespread in metazoa. Inosines are recognized as guanosines and, therefore, this RNA-editing can influence the coding potential, localization and stability of RNAs. Therefore, RNA editing contributes to the diversification of the transcriptome in a flexible manner. The editing reaction is performed by adenosine deaminases that act on RNA (ADARs), which are essential for normal life and development in many organisms. Changes in editing levels are observed during development but also in neurological pathologies like schizophrenia, depression or tumors. Frequently, changes in editing levels are not reflected by changes in ADAR levels suggesting a regulation of enzyme activity. Until now, only a few factors are known that influence the activity of ADARs. Here we present a two-stage in vivo editing screen aimed to isolate enhancers of editing. A primary, high-throughput yeast-screen is combined with a more accurate secondary screen in mammalian cells that uses a fluorescent read-out to detect minor differences in RNA-editing. The screen was successfully employed to identify DSS1/SHFM1, the RNA binding protein hnRNP A2/B1 and a 3' UTR as enhancers of editing. By varying intracellular DSS1/SHFM1 levels, we can modulate A to I editing by up to 30%. Proteomic analysis indicates an interaction of DSS1/SHFM1 and hnRNP A2/B1 suggesting that both factors may act by altering the cellular RNP landscape. An extension of this screen to cDNAs from different tissues or developmental stages may prove useful for the identification of additional enhancers of RNA-editing.


Assuntos
Adenosina Desaminase/metabolismo , Elementos Facilitadores Genéticos , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Edição de RNA , Regiões 3' não Traduzidas , Adenosina Desaminase/genética , Animais , DNA Complementar/genética , DNA Complementar/metabolismo , Vetores Genéticos/genética , Vetores Genéticos/metabolismo , Células HEK293 , Células HeLa , Ribonucleoproteínas Nucleares Heterogêneas Grupo A-B/genética , Ribonucleoproteínas Nucleares Heterogêneas Grupo A-B/metabolismo , Humanos , Complexo de Endopeptidases do Proteassoma/genética , Complexo de Endopeptidases do Proteassoma/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteínas de Ligação a RNA , Ratos , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo
13.
Nucleic Acids Res ; 41(4): 2581-93, 2013 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-23275536

RESUMO

RNA editing by adenosine deaminases that act on RNA (ADARs) diversifies the transcriptome by changing adenosines to inosines. In mammals, editing levels vary in different tissues, during development, and also in pathogenic conditions. From a screen for repressors of editing we have isolated three proteins that repress ADAR2-mediated RNA editing. The three proteins RPS14, SFRS9 and DDX15 interact with RNA. Overexpression or depletion of these proteins can decrease or increase editing levels by 15%, thus allowing a modulation of RNA editing up to 30%. Interestingly, the three proteins alter RNA editing in a substrate-specific manner that correlates with their RNA binding preferences. In mammalian cells, SFRS9 significantly affects editing of the two substrates CFLAR and cyFIP2, while the ribosomal protein RPS14 mostly inhibits editing of cyFIP2 messenger RNA. The helicase DDX15, in turn, has a strong effect on editing in Caenorhabditis elegans. Expression of the three factors decreases during mouse brain development. Moreover, expression levels of SFRS9 and DDX15 respond strongly to neuronal stimulation or repression, showing an inverse correlation with editing levels. Colocalization and immunoprecipitation studies demonstrate a direct interaction of SFRS9 and RPS14 with ADAR2, while DDX15 associates with other helicases and splicing factors. Our data show that different editing sites can be specifically altered in their editing pattern by changing the local RNP landscape.


Assuntos
Adenosina Desaminase/metabolismo , Proteínas de Caenorhabditis elegans/metabolismo , Edição de RNA , Proteínas de Ligação a RNA/metabolismo , Animais , Encéfalo/embriologia , Encéfalo/crescimento & desenvolvimento , Encéfalo/metabolismo , Caenorhabditis elegans , Proteínas de Caenorhabditis elegans/antagonistas & inibidores , Proteínas de Caenorhabditis elegans/genética , Células Cultivadas , Células HeLa , Humanos , Camundongos , Neurônios/metabolismo , Neurônios/fisiologia , Proteínas Nucleares/metabolismo , RNA/metabolismo , RNA Helicases/metabolismo , Interferência de RNA , Proteínas de Ligação a RNA/antagonistas & inibidores , Proteínas de Ligação a RNA/genética , Ratos , Ratos Sprague-Dawley , Proteínas Ribossômicas/metabolismo , Saccharomyces cerevisiae/genética , Fatores de Processamento de Serina-Arginina
14.
Blood ; 121(16): 3112-6, 2013 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-23319571

RESUMO

Primary B-cell disorders comprise a heterogeneous group of inherited immunodeficiencies, often associated with autoimmunity causing significant morbidity. The underlying genetic etiology remains elusive in the majority of patients. In this study, we investigated a patient from a consanguineous family suffering from recurrent infections and severe lupuslike autoimmunity. Immunophenotyping revealed progressive decrease of CD19(+) B cells, a defective class switch indicated by low numbers of IgM- and IgG-memory B cells, as well as increased numbers of CD21(low) B cells. Combined homozygosity mapping and exome sequencing identified a biallelic splice-site mutation in protein C kinase δ (PRKCD), causing the absence of the corresponding protein product. Consequently, phosphorylation of myristoylated alanine-rich C kinase substrate was decreased, and mRNA levels of nuclear factor interleukin (IL)-6 and IL-6 were increased. Our study uncovers human PRKCD deficiency as a novel cause of common variable immunodeficiency-like B-cell deficiency with severe autoimmunity.


Assuntos
Autoimunidade , Linfócitos B/patologia , Síndromes de Imunodeficiência/genética , Síndromes de Imunodeficiência/patologia , Mutação , Proteína Quinase C-delta/genética , Adulto , Antígenos CD19/imunologia , Linfócitos B/imunologia , Linfócitos B/metabolismo , Criança , Feminino , Humanos , Imunoglobulina G/imunologia , Imunoglobulina M/imunologia , Síndromes de Imunodeficiência/imunologia , Síndromes de Imunodeficiência/terapia , Imunofenotipagem , Masculino , Linhagem , Polimorfismo de Nucleotídeo Único , Isoformas de Proteínas/genética , Isoformas de Proteínas/imunologia , Proteína Quinase C-delta/imunologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA