RESUMO
Innate immune cells generate a multifaceted antitumor immune response, including the conservation of essential nutrients such as iron. These cells can be modulated by commensal bacteria; however, identifying and understanding how this occurs is a challenge. Here we show that the food commensal Lactiplantibacillus plantarum IMB19 augments antitumor immunity in syngeneic and xenograft mouse tumor models. Its capsular heteropolysaccharide is the major effector molecule, functioning as a ligand for TLR2. In a two-pronged manner, it skews tumor-associated macrophages to a classically active phenotype, leading to generation of a sustained CD8+ T cell response, and triggers macrophage 'nutritional immunity' to deploy the high-affinity iron transporter lipocalin-2 for capturing and sequestering iron in the tumor microenvironment. This process induces a cycle of tumor cell death, epitope expansion and subsequent tumor clearance. Together these data indicate that food commensals might be identified and developed into 'oncobiotics' for a multi-layered approach to cancer therapy.
Assuntos
Ferro , Microambiente Tumoral , Animais , Ferro/metabolismo , Camundongos , Microambiente Tumoral/imunologia , Humanos , Macrófagos Associados a Tumor/imunologia , Macrófagos Associados a Tumor/metabolismo , Linfócitos T CD8-Positivos/imunologia , Linhagem Celular Tumoral , Receptor 2 Toll-Like/metabolismo , Receptor 2 Toll-Like/imunologia , Camundongos Endogâmicos C57BL , Lipocalina-2/metabolismo , Lipocalina-2/imunologia , Feminino , Simbiose/imunologia , Macrófagos/imunologia , Macrófagos/metabolismo , Ativação de Macrófagos/imunologia , Camundongos KnockoutRESUMO
Single-nucleotide polymorphisms in ETS1 are associated with systemic lupus erythematosus (SLE). Ets1-/- mice develop SLE-like symptoms, suggesting that dysregulation of this transcription factor is important to the onset or progression of SLE. We used conditional deletion approaches to examine the impact of Ets1 expression in different immune cell types. Ets1 deletion on CD4+ T cells, but not B cells or dendritic cells, resulted in the SLE autoimmunity, and this was associated with the spontaneous expansion of T follicular helper type 2 (Tfh2) cells. Ets1-/- Tfh2 cells exhibited increased expression of GATA-3 and interleukin-4 (IL-4), which induced IgE isotype switching in B cells. Neutralization of IL-4 reduced Tfh2 cell frequencies and ameliorated disease parameters. Mechanistically, Ets1 suppressed signature Tfh and Th2 cell genes, including Cxcr5, Bcl6, and Il4ra, thus curbing the terminal Tfh2 cell differentiation process. Tfh2 cell frequencies in SLE patients correlated with disease parameters, providing evidence for the relevance of these findings to human disease.
Assuntos
Diferenciação Celular/imunologia , Lúpus Eritematoso Sistêmico/imunologia , Proteína Proto-Oncogênica c-ets-1/imunologia , Células Th2/imunologia , Animais , Autoimunidade/genética , Autoimunidade/imunologia , Linfócitos B/imunologia , Linfócitos B/metabolismo , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD4-Positivos/metabolismo , Diferenciação Celular/genética , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/genética , Expressão Gênica/imunologia , Perfilação da Expressão Gênica , Humanos , Lúpus Eritematoso Sistêmico/genética , Lúpus Eritematoso Sistêmico/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Proteína Proto-Oncogênica c-ets-1/genética , Proteína Proto-Oncogênica c-ets-1/metabolismo , Células Th2/metabolismoRESUMO
Intestinal microbiota and selected strains of commensal bacteria influence regulatory T (Treg) cell functionality in the colon. Nevertheless, whether and how microbiota changes the transcriptome profile and TCR specificities of colonic Tregs remain to be precisely defined. In this study, we have employed single-cell RNA sequencing and comparatively analyzed colonic Tregs from specific pathogen-free and germ-free (GF) mice. We found that microbiota shifts the activation trajectory of colonic Tregs toward a distinct phenotypic subset enriched in specific pathogen-free but not in GF mice. Moreover, microbiota induced the expansion of specific Treg clonotypes with shared transcriptional specificities. The microbiota-induced subset of colonic Tregs, identified as PD-1- CXCR3+ Tregs, displayed enhanced suppressive capabilities compared with colonic Tregs derived from GF mice, enhanced production of IL-10, and were the primary regulators of enteric inflammation in dextran sodium sulfate-induced colitis. These findings identify a hitherto unknown gut microbiota and immune cell interaction module that could contribute to the development of a therapeutic modality for intestinal inflammatory diseases.
RESUMO
The transcription factor Foxp3 is indispensible for the differentiation and function of regulatory T cells (T(reg) cells). To gain insights into the molecular mechanisms of Foxp3-mediated gene expression, we purified Foxp3 complexes and explored their composition. Biochemical and mass-spectrometric analyses revealed that Foxp3 forms multiprotein complexes of 400-800 kDa or larger and identified 361 associated proteins, â¼30% of which were transcription related. Foxp3 directly regulated expression of a large proportion of the genes encoding its cofactors. Some transcription factor partners of Foxp3 facilitated its expression. Functional analysis of the cooperation of Foxp3 with one such partner, GATA-3, provided additional evidence for a network of transcriptional regulation afforded by Foxp3 and its associates to control distinct aspects of T(reg) cell biology.
Assuntos
Fatores de Transcrição Forkhead/metabolismo , Regulação da Expressão Gênica , Redes Reguladoras de Genes , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/metabolismo , Animais , Diferenciação Celular , Fatores de Transcrição Forkhead/genética , Fator de Transcrição GATA3/genética , Fator de Transcrição GATA3/metabolismo , Humanos , Camundongos , Camundongos Transgênicos , Estrutura Terciária de Proteína , ProteômicaRESUMO
In this issue of Molecular Cell, Albert et al. (2016) demonstrate how the production of rRNA and ribosomal proteins is coordinated through a two-step response to stress that requires cross-talk between a dedicated transcription factor and a ribosome assembly factor.
Assuntos
Proteínas Ribossômicas/genética , Ribossomos/genética , Crime , RNA RibossômicoRESUMO
The transcription factor Foxp3 has an indispensable role in establishing stable transcriptional and functional programs of regulatory T cells (T(reg) cells). Loss of Foxp3 expression in mature T(reg) cells results in a failure of suppressor function, yet the molecular mechanisms that ensure steady, heritable Foxp3 expression in the T(reg) cell lineage remain unknown. Using T(reg) cell-specific gene targeting, we found that complexes of the transcription factors Runx and CBFbeta were required for maintenance of Foxp3 mRNA and protein expression in T(reg) cells. Consequently, mice lacking CBFbetab exclusively in the T(reg) cell lineage had a moderate lymphoproliferative syndrome. Thus, Runx-CBFbeta complexes maintain stable high expression of Foxp3 and serve as an essential determinant of T(reg) cell lineage stability.
Assuntos
Subunidade beta de Fator de Ligação ao Core/imunologia , Fatores de Transcrição Forkhead/imunologia , Regulação da Expressão Gênica , Linfócitos T Reguladores/imunologia , Transferência Adotiva , Animais , Transplante de Medula Óssea , Linhagem da Célula/imunologia , Subunidade beta de Fator de Ligação ao Core/metabolismo , Feminino , Fatores de Transcrição Forkhead/metabolismo , Marcação de Genes , Linfonodos/citologia , Linfonodos/imunologia , Linfonodos/patologia , Transtornos Linfoproliferativos/imunologia , Transtornos Linfoproliferativos/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Baço/citologia , Baço/imunologia , Baço/patologia , Linfócitos T Reguladores/metabolismo , Timo/citologia , Timo/imunologiaRESUMO
Maintenance of lymphoid homeostasis in a number of immunological and inflammatory contexts is served by a variety of regulatory T (Treg) cell subtypes and depends on interaction of the transcription factor FoxP3 with specific transcriptional cofactors. We report that a commonly used insertional mutant of FoxP3 (GFP-Foxp3) modified its molecular interactions, blocking HIF-1α but increasing IRF4 interactions. The transcriptional profile of these Treg cells was subtly altered, with an overrepresentation of IRF4-dependent transcripts. In keeping with IRF4-dependent function of Treg cells to preferentially suppress T cell help to B cells and Th2 and Th17 cell-type differentiation, GFP-FoxP3 mice showed a divergent susceptibility to autoimmune disease: protection against antibody-mediated arthritis in the K/BxN model, but greater susceptibility to diabetes on the NOD background. Thus, specific subfunctions of Treg cells and the immune diseases they regulate can be influenced by FoxP3's molecular interactions, which result in divergent immunoregulation.
Assuntos
Artrite/genética , Diabetes Mellitus Tipo 1/genética , Fatores de Transcrição Forkhead/genética , Mutação , Fatores de Transcrição/genética , Animais , Artrite/imunologia , Artrite/metabolismo , Doenças Autoimunes/genética , Doenças Autoimunes/imunologia , Doenças Autoimunes/metabolismo , Linfócitos B/imunologia , Linfócitos B/metabolismo , Diferenciação Celular/genética , Diferenciação Celular/imunologia , Diabetes Mellitus Tipo 1/imunologia , Diabetes Mellitus Tipo 1/metabolismo , Fatores de Transcrição Forkhead/imunologia , Fatores de Transcrição Forkhead/metabolismo , Homeostase/genética , Homeostase/imunologia , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Subunidade alfa do Fator 1 Induzível por Hipóxia/imunologia , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Fatores Reguladores de Interferon/genética , Fatores Reguladores de Interferon/imunologia , Fatores Reguladores de Interferon/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos NOD , Domínios e Motivos de Interação entre Proteínas/genética , Domínios e Motivos de Interação entre Proteínas/imunologia , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/metabolismo , Células Th17/imunologia , Células Th17/metabolismo , Células Th2/imunologia , Células Th2/metabolismo , Fatores de Transcrição/imunologia , Fatores de Transcrição/metabolismoRESUMO
IL-10 is a pleiotropic cytokine with multifaceted functions in establishing immune homeostasis. Although expressed by Th1 and Th2 cells, conventional Th1 cells produce marginal levels of IL-10 compared with their Th2 counterparts. In this study, we investigated the epigenetic mechanisms of Il-10 gene expression in Th1 cells. Bioinformatics EMBOSS CpG plot analysis and bisulfite pyrosequencing revealed three CpG DNA methylation sites in the Il-10 gene locus. Progressive DNA methylation at all of the CpG regions of interest (ROIs) established a repressive program of Il-10 gene expression in Th1 cells. Interestingly, Th1 cells treated with IL-12 and IL-27 cytokines, thereby mimicking a chronic inflammatory condition in vivo, displayed a significant increase in IL-10 production that was accompanied by selective DNA demethylation at ROI 3 located in intron 3. IL-10-producing T cells isolated from lymphocytic choriomeningitis virus-infected mice also showed enhanced DNA demethylation at ROI 3. Binding of STAT1 and STAT3 to demethylated ROI 3 enhanced IL-10 expression in an IL-12/IL-27-dependent manner. Accordingly, CD4+ T cells isolated from STAT1- or STAT3-knockout mice were significantly defective in IL-10 production. Our data suggest that, although stably maintained DNA methylation at the promoter may repress IL-10 expression in Th1 cells, locus-specific reversible DNA demethylation may serve as a threshold platform to control transient Il-10 gene expression.
Assuntos
Metilação de DNA/genética , Interleucina-10/genética , Células Th1/fisiologia , Animais , Linfócitos T CD4-Positivos/fisiologia , Linhagem Celular , Ilhas de CpG/genética , Epigênese Genética/genética , Células HEK293 , Humanos , Interleucina-27/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Regiões Promotoras Genéticas/genética , Fator de Transcrição STAT3/genética , Células Th2/fisiologiaRESUMO
IL-31 is a key mediator of itching in atopic dermatitis (AD) and is preferentially produced by activated CD4(+) T cells and Th2 cells. Although pathophysiological functions of IL-31 have been suggested in diverse immune disorders, the molecular events underlying IL-31 gene regulation are still unclear. In this study we identified the transcription start site and functional promoter involved in IL-31 gene regulation in mouse CD4(+) T cells. TCR stimulation-dependent IL-31 expression was found to be closely linked with in vivo binding of NFAT1 and JunB to the IL-31 promoter. Although NFAT1 alone enhanced IL-31 promoter activity, it was further enhanced in the presence of JunB. Conversely, knockdown of either NFAT1 or JunB resulted in reduced IL-31 expression. NFAT1-deficient CD4(+) T cells showed a significant defect in IL-31 expression compared with wild-type CD4(+) T cells. In agreement with these findings, mice subjected to atopic conditions showed much higher levels of IL-31, which were closely correlated with a significant increase in the number of infiltrated NFAT1(+)CD4(+) T cells into the AD ears. Amelioration of AD progression by cyclosporin A treatment was well correlated with downregulation of IL-31 expressions in CD4(+) T cells and total ear residual cells. In summary, our results suggest a functional cooperation between NFAT1 and JunB in mediating IL-31 gene expression in CD4(+) T cells and indicate that interference with this interaction or their activity has the potential of reducing IL-31-mediated AD symptoms.
Assuntos
Linfócitos T CD4-Positivos/imunologia , Dermatite Atópica/imunologia , Regulação da Expressão Gênica/imunologia , Interleucinas/biossíntese , Fatores de Transcrição NFATC/imunologia , Fatores de Transcrição/imunologia , Animais , Imunoprecipitação da Cromatina , Dermatite Atópica/genética , Dermatite Atópica/metabolismo , Modelos Animais de Doenças , Feminino , Imuno-Histoquímica , Interleucinas/genética , Interleucinas/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Mutagênese Sítio-Dirigida , Fatores de Transcrição NFATC/genética , RNA Interferente Pequeno , Reação em Cadeia da Polimerase em Tempo Real , Fatores de Transcrição/genética , Transcriptoma , TransfecçãoRESUMO
E and inhibitor of DNA binding (ID) proteins are involved in various cellular developmental processes and effector activities in T cells. Recent findings indicate that E and ID proteins are not only responsible for regulating thymic T cell development but also modulate the differentiation, function, and fate of peripheral T cells in multiple immune compartments. Based on the well-established E and ID protein axis (E-ID axis), it has been recognized that ID proteins interfere with the dimerization of E proteins, thus restricting their transcriptional activities. Given this close molecular relationship, the extent of expression or stability of these two protein families can dynamically affect the expression of specific target genes involved in multiple aspects of T cell biology. Therefore, it is essential to understand the endogenous proteins or extrinsic signaling pathways that can influence the dynamics of the E-ID axis in a cell-specific and context-dependent manner. Here, we provide an overview of E and ID proteins and the functional outcomes of the E-ID axis in the activation and function of multiple peripheral T cell subsets, including effector and memory T cell populations. Further, we review the mechanisms by which endogenous proteins and signaling pathways alter the E-ID axis in various T cell subsets influencing T cell function and fate at steady-state and in pathological settings. A comprehensive understanding of the functions of E and ID proteins in T cell biology can be instrumental in T cell-specific targeting of the E-ID axis to develop novel therapeutic modalities in the context of autoimmunity and cancer.
Assuntos
Ativação Linfocitária , Fatores de Transcrição , Diferenciação Celular , Transdução de Sinais , Subpopulações de Linfócitos TRESUMO
Multifaceted functions displayed by both pro- and anti-inflammatory properties of chitosan hinder its effective development as an immunomodulatory agent. Herein, the contributions of the bending stiffness of chitosan with regard to its immune regulatory properties toward inflammation are investigated. The anti-inflammatory properties of chitosan molecular weight (MW) with a shorter (≈1 kDa) or longer (≈15 kDa) than the persistent length (LP ) are compared using immunological assays and nanomechanics-based experiments on the surface forces apparatus (SFA). Interestingly, 1 kDa chitosan significantly enhances the generation of anti-inflammatory regulatory T cells (Tregs) through the Dectin-1-dependent pattern recognition receptor (PRR) on antigen-presenting cells. SFA analyses also show a similar trend of interaction forces between chitosan and diverse PRRs depending on their MW. The results obtained in the immunological and nanomechanical experiments are consistent and imply that the binding features of PRRs vary depending on the MW of chitosan, which may alter immune activity. In accordance, in vivo administration of only 1 kDa represses inflammatory responses and suppresses the progression of experimental colitis. This study elucidates a previously unexplored bending stiffness-dependent immune regulatory property of chitosan and suggests the applicability of low MW (rod-like) chitosan as a pharmaceutical ingredient to treat diverse inflammatory disorders.
Assuntos
Quitosana , Células Apresentadoras de Antígenos , Quitosana/química , Imunidade , Peso Molecular , Receptores de Reconhecimento de PadrãoRESUMO
Yeast is an integral part of mammalian microbiome, and like commensal bacteria, has the potential of being harnessed to influence immunity in clinical settings. However, functional specificities of yeast-derived immunoregulatory molecules remain elusive. Here we find that while under steady state, ß-1,3-glucan-containing polysaccharides potentiate pro-inflammatory properties, a relatively less abundant class of cell surface polysaccharides, dubbed mannan/ß-1,6-glucan-containing polysaccharides (MGCP), is capable of exerting potent anti-inflammatory effects to the immune system. MGCP, in contrast to previously identified microbial cell surface polysaccharides, through a Dectin1-Cox2 signaling axis in dendritic cells, facilitates regulatory T (Treg) cell induction from naïve T cells. Furthermore, through a TLR2-dependent mechanism, it restrains Th1 differentiation of effector T cells by suppressing IFN-γ expression. As a result, administration of MGCP display robust suppressive capacity towards experimental inflammatory disease models of colitis and experimental autoimmune encephalomyelitis (EAE) in mice, thereby highlighting its potential therapeutic utility against clinically relevant autoimmune diseases.
Assuntos
Imunomodulação/efeitos dos fármacos , Imunomodulação/imunologia , Polissacarídeos/imunologia , Saccharomyces cerevisiae/metabolismo , beta-Glucanas/imunologia , Animais , Linfócitos T CD4-Positivos , Diferenciação Celular/efeitos dos fármacos , Colite/imunologia , Colite/patologia , Ciclo-Oxigenase 2 , Células Dendríticas/imunologia , Encefalomielite Autoimune Experimental , Glucanos , Proteínas de Homeodomínio/genética , Imunidade , Lectinas Tipo C , Mananas , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Polissacarídeos/metabolismo , Polissacarídeos/farmacologia , Saccharomyces cerevisiae/genética , Linfócitos T Reguladores/efeitos dos fármacos , Linfócitos T Reguladores/imunologia , Células Th1 , Zimosan , beta-Glucanas/metabolismo , beta-Glucanas/farmacologiaRESUMO
It has become clear that in Saccharomyces cerevisiae the transcription of ribosomal protein genes, which makes up a major proportion of the total transcription by RNA polymerase II, is controlled by the interaction of three transcription factors, Rap1, Fhl1, and Ifh1. Of these, only Rap1 binds directly to DNA and only Ifh1 is absent when transcription is repressed. We have examined further the nature of this interaction and find that Ifh1 is actually associated with at least two complexes. In addition to its association with Rap1 and Fhl1, Ifh1 forms a complex (CURI) with casein kinase 2 (CK2), Utp22, and Rrp7. Fhl1 is loosely associated with the CURI complex; its absence partially destabilizes the complex. The CK2 within the complex phosphorylates Ifh1 in vitro but no other members of the complex. Two major components of this complex, Utp22 and Rrp7, are essential participants in the processing of pre-rRNA. Depletion of either protein, but not of other proteins in the early processing steps, brings about a substantial increase in ribosomal protein mRNA. We propose a model in which the CURI complex is a key mediator between the two parallel pathways necessary for ribosome synthesis: the transcription and processing of pre-rRNA and the transcription of ribosomal protein genes.
Assuntos
Precursores de RNA/metabolismo , Processamento Pós-Transcricional do RNA , Proteínas Ribossômicas/biossíntese , Saccharomyces cerevisiae/metabolismo , Caseína Quinase II/metabolismo , Modelos Biológicos , Peso Molecular , Complexos Multiproteicos/metabolismo , Fosforilação , Ligação Proteica , Proteínas de Saccharomyces cerevisiae/metabolismo , Termodinâmica , Transcrição GênicaRESUMO
ETS1 has shown dichotomous roles as an oncogene and a tumor suppressor gene in diverse cancers, but its functionality in breast cancer tumorigenesis still remains unclear. We utilized the Cancer Genome Atlas (TCGA) database to analyze comprehensive functions of ETS1 in human breast cancer (BRCA) patients by investigating its expression patterns and methylation status in relation to clinical prognosis. ETS1 expression was significantly diminished by hyper-methylation of the ETS1 promoter region in specimens from BRCA patients compared to a healthy control group. Moreover, ETS1 high BRCA patients showed better prognosis and longer survival compared to ETS1 low BRCA patients. Consistent with clinical evidence, comparative transcriptome analysis combined with CRISPR/Cas9 or shRNA based perturbation of ETS1 expression revealed direct as well as indirect mechanisms of ETS1 that hinder tumorigenesis of BRCA cells. Taken together, our study enlightens a novel function of ETS1 as a tumor suppressor in breast cancer cells.
RESUMO
Retinal dehydrogenase (RALDH) enzymatic activities catalyze the conversion of vitamin A to its metabolite Retinoic acid (RA) in intestinal dendritic cells (DCs) and promote immunological tolerance. However, precise understanding of the exogenous factors that act as initial trigger of RALDH activity in these cells is still evolving. By using germ-free (GF) mice raised on an antigen free (AF) elemental diet, we find that certain components in diet are critically required to establish optimal RALDH expression and activity, most prominently in small intestinal CD103+CD11b+ DCs (siLP-DCs) right from the beginning of their lives. Surprisingly, systematic screens using modified diets devoid of individual dietary components indicate that proteins, starch and minerals are dispensable for this activity. On the other hand, in depth comparison between subtle differences in dietary composition among different dietary regimes reveal that adequate glucose concentration in diet is a critical determinant for establishing RALDH activity specifically in siLP-DCs. Consequently, pre-treatment of siLP-DCs, and not mesenteric lymph node derived MLNDCs with glucose, results in significant enhancement in the in vitro generation of induced Regulatory T (iTreg) cells. Our findings reveal previously underappreciated role of dietary glucose concentration in establishing regulatory properties in intestinal DCs, thereby extending a potential therapeutic module against intestinal inflammation.
Assuntos
Antígenos CD/metabolismo , Antígeno CD11b/metabolismo , Células Dendríticas/efeitos dos fármacos , Açúcares da Dieta/administração & dosagem , Glucose/administração & dosagem , Cadeias alfa de Integrinas/metabolismo , Intestino Delgado/efeitos dos fármacos , Retinal Desidrogenase/metabolismo , Ração Animal , Animais , Antígenos CD/imunologia , Antígeno CD11b/imunologia , Células Cultivadas , Técnicas de Cocultura , Células Dendríticas/enzimologia , Células Dendríticas/imunologia , Cadeias alfa de Integrinas/imunologia , Intestino Delgado/enzimologia , Intestino Delgado/imunologia , Camundongos Endogâmicos C57BL , Retinal Desidrogenase/imunologia , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/metabolismoRESUMO
The ribosomal protein genes of Saccharomyces cerevisiae, responsible for nearly 40% of the polymerase II transcription initiation events, are characterized by the constitutive tight binding of the transcription factor Rap1. Rap1 binds at many places in the yeast genome, including glycolytic enzyme genes, the silent MAT loci, and telomeres, its specificity arising from specific cofactors recruited at the appropriate genes. At the ribosomal protein genes two such cofactors have recently been identified as Fhl1 and Ifh1. We have now characterized the interaction of these factors at a bidirectional ribosomal protein promoter by replacing the Rap1 sites with LexA operator sites. LexA-Gal4(AD) drives active transcription at this modified promoter, although not always at the correct initiation site. Tethering Rap1 to the promoter neither drives transcription nor recruits Fhl1 or Ifh1, showing that Rap1 function requires direct DNA binding. Tethering Fhl1 also fails to activate transcription, even though it does recruit Ifh1, suggesting that Fhl1 does more than simply provide a platform for Ifh1. Tethering Ifh1 to the promoter leads to low-level transcription, at the correct initiation sites. Remarkably, activation by tethered LexA-Gal4(AD) is strongly reduced when TOR kinase is inhibited by rapamycin. Thus, TOR can act independently of Fhl1/Ifh1 at ribosomal protein promoters. We also show that, in our strain background, the response of ribosomal protein promoters to TOR inhibition is independent of the Ifh1-related protein Crf1, indicating that the role of this corepressor is strain specific. Fine-structure chromatin mapping of several ribosomal protein promoters revealed that histones are essentially absent from the Rap1 sites, while Fhl1 and Ifh1 are coincident with each other but distinct from Rap1.
Assuntos
Regulação Fúngica da Expressão Gênica , Proteínas Ribossômicas/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/genética , Proteínas de Ligação a Telômeros/metabolismo , Transativadores/metabolismo , Fatores de Transcrição/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Fatores de Transcrição Forkhead , Regiões Promotoras Genéticas/efeitos dos fármacos , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Serina Endopeptidases/genética , Serina Endopeptidases/metabolismo , Complexo Shelterina , Sirolimo/farmacologia , Proteínas de Ligação a Telômeros/genética , Transativadores/genética , Fatores de Transcrição/genética , Transcrição GênicaRESUMO
With the advent of the concept of dominant tolerance and the subsequent discovery of CD4+ regulatory T cells expressing the transcription factor FOXP3 (Tregs), almost all productive as well as nonproductive immune responses can be compartmentalized to a binary of immune effector T cells and immune regulatory Treg populations. A beneficial immune response warrants the timely regulation by Tregs, whereas a nonproductive immune response indicates insufficient effector functions or an outright failure of tolerance. There are ample reports supporting role of Tregs in suppressing spontaneous auto-immune diseases as well as promoting immune evasion by cancers. To top up their importance, several non-immune functions like tissue homeostasis and regeneration are also being attributed to Tregs. Hence, after being in the center stage of basic and translational immunological research, Tregs are making the next jump towards clinical studies. Therefore, newer small molecules, biologics as well as adoptive cell therapy (ACT) approaches are being tested to augment or undermine Treg responses in the context of autoimmunity and cancer. In this brief review, we present the strategies to modulate Tregs towards a favorable clinical outcome.
Assuntos
Imunomodulação , Imunoterapia Adotiva , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/metabolismo , Animais , Biomarcadores , Ensaios Clínicos como Assunto , Terapia Combinada , Humanos , Tolerância Imunológica , Imunoterapia Adotiva/métodos , Terapia de Alvo Molecular , Neoplasias/imunologia , Neoplasias/metabolismo , Neoplasias/terapia , Resultado do TratamentoRESUMO
Foxp3 and its protein partners establish a regulatory T (Treg) cell transcription profile and promote immunological tolerance. However, molecular features contributing to a Treg-specific gene expression program are still incompletely understood. We find that the transcription factor Bcl11b is a prominent Foxp3 cofactor with multifaceted functions in Treg biology. Optimal genomic recruitment of Foxp3 and Bcl11b is critically interdependent. Genome-wide occupancy studies coupled with gene expression profiling reveal that Bcl11b, in association with Foxp3, is primarily responsible in establishing a Treg-specific gene activation program. Furthermore, Bcl11b restricts misdirected recruitment of Foxp3 to sites, which would otherwise result in an altered Treg transcriptome profile. Consequently, Treg-specific ablation of Bcl11b results in marked breakdown of immune tolerance, leading to aggressive systemic autoimmunity. Our study provides previously underappreciated mechanistic insights into molecular events contributing to basic aspects of Treg function. Furthermore, it establishes a therapeutic target with potential implications in autoimmunity and cancer.
Assuntos
Autoimunidade , Regulação da Expressão Gênica , Proteínas Repressoras/metabolismo , Linfócitos T Reguladores/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Animais , Sítios de Ligação , Linfócitos T CD4-Positivos/citologia , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD4-Positivos/metabolismo , Colite/imunologia , Colite/patologia , Feminino , Fatores de Transcrição Forkhead/metabolismo , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Ligação Proteica , Proteínas Repressoras/deficiência , Proteínas Repressoras/genética , Linfócitos T Reguladores/citologia , Linfócitos T Reguladores/imunologia , Proteínas Supressoras de Tumor/deficiência , Proteínas Supressoras de Tumor/genéticaRESUMO
Several gut commensals have been shown to modulate host immune response. Recently, many food derived microbes have also been reported to affect the immune system. However, a mechanism to identify immunostimulatory and immunoregulatory microbes is needed. Here, we successfully established an in vitro screening system and identified an immunoregulatory bacterium, Lactobacillus pentosus KF340 (LP340), present in various fermented foods. LP340 induced a regulatory phenotype in mice Ag presenting cells which, in turn, induced IL-10 and IFN-γ producing Type 1 regulatory T cells (Tr1 cells) from naïve CD4+ T cells. Naïve CD4+ T cells co-cultured with LP340 treated dendritic cells highly expressed cytokine receptor IL-27R and were CD49b and lymphocyte-activation gene 3 double positive. Oral administration of LP340 in mice with atopic dermatitis reduced cellular infiltration in affected ear lobes and serum IgE levels, thus, ameliorating the disease symptoms. This suggests a systemic immunoregulatory effect of LP340. These findings demonstrate that LP340, a bacterium derived from food, prevents systemic inflammation through the induction of IL-10 producing Tr1 cells.