RESUMEN
Cellular senescence is characterized by an irreversible cell cycle arrest as well as a pro-inflammatory phenotype, thought to contribute to aging and age-related diseases. Neutrophils have essential roles in inflammatory responses; however, in certain contexts their abundance is associated with a number of age-related diseases, including liver disease. The relationship between neutrophils and cellular senescence is not well understood. Here, we show that telomeres in non-immune cells are highly susceptible to oxidative damage caused by neighboring neutrophils. Neutrophils cause telomere dysfunction both in vitro and ex vivo in a ROS-dependent manner. In a mouse model of acute liver injury, depletion of neutrophils reduces telomere dysfunction and senescence. Finally, we show that senescent cells mediate the recruitment of neutrophils to the aged liver and propose that this may be a mechanism by which senescence spreads to surrounding cells. Our results suggest that interventions that counteract neutrophil-induced senescence may be beneficial during aging and age-related disease.
Asunto(s)
Lesión Pulmonar Aguda/inmunología , Tetracloruro de Carbono/efectos adversos , Neutrófilos/citología , Especies Reactivas de Oxígeno/metabolismo , Acortamiento del Telómero , Lesión Pulmonar Aguda/inducido químicamente , Lesión Pulmonar Aguda/metabolismo , Animales , Línea Celular , Senescencia Celular , Técnicas de Cocultivo , Modelos Animales de Enfermedad , Femenino , Fibroblastos/citología , Fibroblastos/metabolismo , Humanos , Masculino , Ratones , Neutrófilos/metabolismo , Estrés Oxidativo , Comunicación ParacrinaRESUMEN
Age-related chronic inflammation promotes cellular senescence, chronic disease, cancer, and reduced lifespan. In this study, we wanted to explore the effects of a moderate exercise regimen on inflammatory liver disease and tumorigenesis. We used an established model of spontaneous inflammaging, steatosis, and cancer (nfkb1-/- mouse) to demonstrate whether 3 mo of moderate aerobic exercise was sufficient to suppress liver disease and cancer development. Interventional exercise when applied at a relatively late disease stage was effective at reducing tissue inflammation (liver, lung, and stomach), oxidative damage, and cellular senescence, and it reversed hepatic steatosis and prevented tumor development. Underlying these benefits were transcriptional changes in enzymes driving the conversion of tryptophan to NAD+, this leading to increased hepatic NAD+ and elevated activity of the NAD+-dependent deacetylase sirtuin. Increased SIRT activity was correlated with enhanced deacetylation of key transcriptional regulators of inflammation and metabolism, NF-κB (p65), and PGC-1α. We propose that moderate exercise can effectively reprogram pre-established inflammatory and metabolic pathologies in aging with the benefit of prevention of disease.
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Envejecimiento/inmunología , Carcinogénesis/inmunología , Hígado Graso/prevención & control , Neoplasias Hepáticas/prevención & control , Condicionamiento Físico Animal , Envejecimiento/genética , Envejecimiento/patología , Animales , Carcinogénesis/patología , Senescencia Celular/inmunología , Hígado Graso/inmunología , Hígado Graso/patología , Inflamación/genética , Inflamación/inmunología , Inflamación/patología , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/inmunología , Neoplasias Hepáticas/patología , Ratones , Ratones Noqueados , Subunidad p50 de NF-kappa B/genética , Subunidad p50 de NF-kappa B/inmunologíaRESUMEN
BACKGROUND: Irrespective of the underlying aetiology, 90% of hepatocellular carcinomas arise and progress on a background of chronic inflammation. We have explored the independent prognostic value of circulating inflammatory cells. METHODS: Peripheral blood count data sets from 583 consecutive patients presenting to a single UK centre (2000-2010) were analysed for associations with tumour stage, liver function, performance status (PST) and survival. Validation was in an independent Hong Kong cohort (585 patients; 2007-2013). RESULTS: In both UK and Hong Kong cohorts, neutrophils, platelets, lymphocytes, the neutrophil/lymphocyte ratio (NLR) and the Systemic Immune-Inflammation Index (SII) correlated stepwise, either increasing or decreasing (lymphocytes), with tumour node metastasis (TNM) and Childs-Pugh stage, PST and consequently with the combined Barcelona Clinic for Liver Cancer stage. Survival analyses confirmed the NLR and SII as highly significant prognostic biomarkers. Focused on individual cell types, only the neutrophil count was independently associated with both TNM stage and PST, as well as being significantly and independently associated with poorer survival. CONCLUSIONS: In this study of 1168 patients, neutrophils alone, rather than lymphocytes or platelets, were independently associated with outcome. These data support further characterisation of a potentially distinctive role for neutrophils as facilitators of tumour progression and deteriorating performance.
Asunto(s)
Carcinoma Hepatocelular/sangre , Neoplasias Hepáticas/sangre , Neutrófilos/patología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Plaquetas/inmunología , Plaquetas/patología , Carcinoma Hepatocelular/inmunología , Carcinoma Hepatocelular/patología , Estudios de Cohortes , Femenino , Hong Kong , Humanos , Estimación de Kaplan-Meier , Neoplasias Hepáticas/inmunología , Neoplasias Hepáticas/patología , Linfocitos/inmunología , Linfocitos/patología , Masculino , Persona de Mediana Edad , Estadificación de Neoplasias , Neutrófilos/inmunología , Pronóstico , Reino Unido , Adulto JovenRESUMEN
BACKGROUND & AIMS: Ubiquitination is a reversible protein modification involved in the major cellular processes that define cell phenotype and behaviour. Ubiquitin modifications are removed by a large family of proteases named deubiquitinases. The role of deubiquitinases in hepatic stellate cell (HSC) activation and their contribution to fibrogenesis are poorly defined. We have identified that the deubiquitinase ubiquitin C-terminal hydrolase 1 (UCHL1) is highly induced following HSC activation, determined its function in activated HSC and its potential as a therapeutic target for fibrosis. METHODS: Deubiquitinase expression was determined in day 0 and day 10 HSC. Increased UCHL1 expression was confirmed in human HSC and in an alcoholic liver disease (ALD) patient liver. The importance of UCHL1 in hepatic fibrosis was investigated in CCl4 and bile duct ligation injured mice using a pharmacological inhibitor (LDN 57444). The effects of UCHL1 inhibition on HSC proliferation were confirmed by Western blot and 3H thymidine incorporation. RESULTS: Here we report that pharmacological inhibition of UCHL1 blocks progression of established fibrosis in CCl4 injured mice. UCHL1 siRNA knockdown, LDN 57444 treatment, or HSC isolated from UCHL1(-/-) mice show attenuated proliferation in response to the mitogen, platelet-derived growth factor. Additionally, we observed changes in the phosphorylation of the cell cycle regulator retinoblastoma protein (Rb) in the absence of UCHL1 highlighting a potential mechanism for the reduced proliferative response. CONCLUSIONS: UCHL1 expression is highly upregulated upon HSC activation and is involved in the regulation of HSC proliferation. This study highlights therapeutic opportunities for pharmacological targeting of UCHL1 in chronic liver disease.
Asunto(s)
Hepatopatías/enzimología , Ubiquitina Tiolesterasa/metabolismo , Animales , Biomarcadores/metabolismo , Tetracloruro de Carbono/toxicidad , Proliferación Celular , Transdiferenciación Celular , Células Cultivadas , Enfermedad Crónica , Técnicas de Silenciamiento del Gen , Células Estrelladas Hepáticas/enzimología , Células Estrelladas Hepáticas/patología , Humanos , Cirrosis Hepática Experimental/enzimología , Cirrosis Hepática Experimental/patología , Hepatopatías/patología , Hepatopatías/terapia , Hepatopatías Alcohólicas/enzimología , Hepatopatías Alcohólicas/patología , Ratones , Ratones Noqueados , Miofibroblastos/enzimología , Miofibroblastos/patología , ARN Mensajero/genética , ARN Mensajero/metabolismo , Ratas , Ubiquitina Tiolesterasa/antagonistas & inhibidores , Ubiquitina Tiolesterasa/deficiencia , Ubiquitina Tiolesterasa/genética , Proteasas Ubiquitina-Específicas/genética , Proteasas Ubiquitina-Específicas/metabolismo , UbiquitinaciónRESUMEN
The majority of studies examining antigen-presenting cell (APC) function have focused on the capture and presentation of antigens released from pathogens or damaged cells. However, antigen-specific B cells are also capable of efficiently extracting antigens that are either tethered to, or integrally part of the plasma membrane of various target cells. In this study we show that B cells are also highly efficient at extracting integral components of the extracellular matrix (ECM) for subsequent presentation. In particular we demonstrate that B cells specific for aggrecan, an integral component of cartilage ECM, acquire this rheumatoid arthritis candidate autoantigen in both a B-cell-receptor-dependent and a contact-dependent manner. We also demonstrate that the subsequent presentation of aggregan from ECM leads to CD4(+) T-cell activation and effector cell formation. Recent studies have identified B-cell-mediated antigen presentation as essential for the development of autoimmunity, but a unique role for B cells compared with other APC has yet to be defined. Our findings lead us to propose that the acquisition of ECM-derived autoantigens represents a mechanism that defines the APC requirement for B cells in the development of autoimmunity.
Asunto(s)
Agrecanos/inmunología , Presentación de Antígeno , Autoantígenos/inmunología , Linfocitos B/inmunología , Linfocitos T CD4-Positivos/inmunología , Cartílago/inmunología , Matriz Extracelular/inmunología , Activación de Linfocitos , Animales , Artritis Reumatoide/inmunología , Artritis Reumatoide/patología , Linfocitos B/patología , Linfocitos T CD4-Positivos/patología , Cartílago/patología , Bovinos , Línea Celular Tumoral , Matriz Extracelular/patología , Humanos , RatonesRESUMEN
BACKGROUND & AIMS: Neutrophils are important immune effectors required for sterile and non-sterile inflammatory responses. However, neutrophils are associated with pathology in drug-induced liver injury, acute alcoholic liver disease, and ischemia-reperfusion injury. An understanding of the complex mechanisms that control neutrophil recruitment to the injured liver is desirable for developing strategies aimed at limiting neutrophil-mediated cellular damage. METHODS: Wt, tlr2(-/-), tlr4(-/-), and s100a9(-/-) mice were administered CCl4 either acutely (8, 24, 48, or 72 h) or chronically (8 weeks) and livers investigated by histological (IHC for neutrophils, fibrogenesis, proliferation, and chemotactic proteins) or molecular approaches (qRT-PCR for neutrophil chemoattractant chemokines and cytokines as well as pro-fibrogenic genes). RESULTS: Mice lacking TLR2 or S100A9 failed to recruit neutrophils to the injured liver and had a defective hepatic induction of the neutrophil chemokine CXCL-2. Hierarchy between TLR2 and S100A9 proved to be complex. While induction of S100A9 was dependent on TLR2 in isolated neutrophils, there was a more complicated two-way signalling cross-talk between TLR2 and S100A9 in whole liver. However, wound-healing and regenerative responses of the liver were unaffected in these genetic backgrounds as well as in wild type mice, in which neutrophils were depleted by infusion of Ly-6G antibody. CONCLUSIONS: We have identified TLR2 and S100A8/S100A9 as key regulators of hepatic CXCL-2 expression and neutrophil recruitment. This novel TLR2-S100A9-CXCL-2 pathway may be of use in development of new strategies for selectively manipulating neutrophils in liver disease without impairing normal wound healing and regenerative responses.
Asunto(s)
Calgranulina B/inmunología , Enfermedad Hepática Crónica Inducida por Sustancias y Drogas/inmunología , Enfermedad Hepática Inducida por Sustancias y Drogas/inmunología , Quimiocina CXCL2/inmunología , Infiltración Neutrófila/inmunología , Receptor Toll-Like 2/inmunología , Animales , Calgranulina A/inmunología , Calgranulina B/genética , Tetracloruro de Carbono/toxicidad , Enfermedad Hepática Inducida por Sustancias y Drogas/patología , Enfermedad Hepática Crónica Inducida por Sustancias y Drogas/patología , Quimiocina CXCL2/biosíntesis , Modelos Animales de Enfermedad , Humanos , Complejo de Antígeno L1 de Leucocito/inmunología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Transducción de Señal/inmunología , Receptor Toll-Like 2/deficiencia , Receptor Toll-Like 2/genética , Receptor Toll-Like 4/deficiencia , Receptor Toll-Like 4/genética , Receptor Toll-Like 4/inmunología , Cicatrización de Heridas/inmunologíaRESUMEN
UNLABELLED: Toll-like receptors (TLRs) function as key regulators of liver fibrosis and are able to modulate the fibrogenic actions of nonparenchymal liver cells. The fibrogenic signaling events downstream of TLRs on Kupffer cells (KCs) and hepatic stellate cells (HSCs) are poorly defined. Here, we describe the MAP3K tumor progression locus 2 (Tpl2) as being important for the activation of extracellular regulated kinase (ERK) signaling in KCs and HSCs responding to stimulation of TLR4 and TLR9. KCs lacking Tpl2 display defects with TLR induction of cytokines interleukin (IL)-1ß, IL-10, and IL-23. tpl2(-/-) HSCs were unable to increase expression of fibrogenic genes IL-1ß and tissue inhibitor of metalloproteinase 1 (TIMP-1), with the latter being the result of defective stimulation of TIMP-1 promoter activity by TLRs. To determine the in vivo relevance of Tpl2 signaling in liver fibrosis, we compared the fibrogenic responses of wild-type (WT) and tpl2(-/-) mice in three distinct models of chronic liver injury. In the carbon tetrachloride and methionine-choline-deficient diet models, we observed a significant reduction in fibrosis in mice lacking Tpl2, compared to WT controls. However, in the bile duct ligation model, there was no effect of tpl2 deletion, which may reflect a lesser role for HSCs in wounding response to biliary injury. CONCLUSION: We conclude that Tpl2 is an important signal transducer for TLR activation of gene expression in KCs and HSCs by the ERK pathway and that suppression of its catalytic activity may be a route toward suppressing fibrosis caused by hepatocellular injuries. (HEPATOLOGY 2013).
Asunto(s)
Células Estrelladas Hepáticas/fisiología , Cirrosis Hepática/metabolismo , Quinasas Quinasa Quinasa PAM/metabolismo , Sistema de Señalización de MAP Quinasas/fisiología , Proteínas Proto-Oncogénicas/metabolismo , Inhibidor Tisular de Metaloproteinasa-1/genética , Animales , Células Cultivadas , Citocinas/metabolismo , Células Estrelladas Hepáticas/citología , Hepatocitos/citología , Hepatocitos/fisiología , Macrófagos del Hígado/citología , Macrófagos del Hígado/fisiología , Cirrosis Hepática/genética , Cirrosis Hepática/patología , Quinasas Quinasa Quinasa PAM/genética , Macrófagos/citología , Macrófagos/fisiología , Masculino , Ratones , Ratones Noqueados , Proteínas Proto-Oncogénicas/genética , Inhibidor Tisular de Metaloproteinasa-1/metabolismo , Receptor Toll-Like 4/metabolismo , Receptor Toll-Like 9/metabolismo , Transcripción Genética/fisiologíaRESUMEN
Liver fibrosis is the excessive accumulation of extracellular matrix proteins that occurs in most types of chronic liver disease. At the cellular level, liver fibrosis is associated with the activation of hepatic stellate cells (HSCs) which transdifferentiate into a myofibroblast-like phenotype that is contractile, proliferative and profibrogenic. HSC transdifferentiation induces genome-wide changes in gene expression that enable the cell to adopt its profibrogenic functions. We have previously identified that the deubiquitinase ubiquitin C-terminal hydrolase 1 (UCHL1) is highly induced following HSC activation; however, the cellular targets of its deubiquitinating activity are poorly defined. Here, we describe a role for UCHL1 in regulating the levels and activity of hypoxia-inducible factor 1 (HIF1), an oxygen-sensitive transcription factor, during HSC activation and liver fibrosis. HIF1 is elevated during HSC activation and promotes the expression of profibrotic mediator HIF target genes. Increased HIF1α expression correlated with induction of UCHL1 mRNA and protein with HSC activation. Genetic deletion or chemical inhibition of UCHL1 impaired HIF activity through reduction of HIF1α levels. Furthermore, our mechanistic studies have shown that UCHL1 elevates HIF activity through specific cleavage of degradative ubiquitin chains, elevates levels of pro-fibrotic gene expression and increases proliferation rates. As we also show that UCHL1 inhibition blunts fibrogenesis in a pre-clinical 3D human liver slice model of fibrosis, these results demonstrate how small molecule inhibitors of DUBs can exert therapeutic effects through modulation of HIF transcription factors in liver disease. Furthermore, inhibition of HIF activity using UCHL1 inhibitors may represent a therapeutic opportunity with other HIF-related pathologies.
Asunto(s)
Células Estrelladas Hepáticas , Subunidad alfa del Factor 1 Inducible por Hipoxia , Cirrosis Hepática , Ubiquitina Tiolesterasa , Ubiquitina Tiolesterasa/genética , Ubiquitina Tiolesterasa/metabolismo , Cirrosis Hepática/genética , Cirrosis Hepática/patología , Cirrosis Hepática/metabolismo , Animales , Células Estrelladas Hepáticas/metabolismo , Células Estrelladas Hepáticas/patología , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Subunidad alfa del Factor 1 Inducible por Hipoxia/genética , Ratones , Humanos , Regulación de la Expresión Génica , Transdiferenciación Celular/genéticaRESUMEN
UNLABELLED: Transdifferentiation of hepatic stellate cells (HSCs) to a myofibroblast-like phenotype is the pivotal event in liver fibrosis. The dramatic change in phenotype associated with transdifferentiation is underpinned by a global change in gene expression. Orchestrated changes in gene expression take place at the level of chromatin packaging which is regulated by enzymatic activity of epigenetic regulators that in turn affect histone modifications. Using expression profiling of epigenetic regulators in quiescent and activated primary HSCs we found a number of histone methyltransferases including MLL1, MLL5, Set1 and ASH1 to be highly up-regulated during transdifferentiation of HSCs. All of these histone methyltransferases regulate methylation of lysine 4 of histone H3, which is a signature of actively transcribed genes. We therefore postulated that one or more of these enzymes may be involved in positively influencing expression of profibrogenic genes. CONCLUSION: We find that ASH1 directly binds to the regulatory regions of alpha smooth muscle actin (αSMA), collagen I, tissue inhibitor of metalloproteinase-1 (TIMP1) and transforming growth factor beta1 (TGFß1) in activated HSCs while depletion of ASH1 caused broad suppression of fibrogenic gene expression. We also discovered that MeCP2 positively regulates ASH1 expression and therefore identify ASH1 as a key transcriptional activator component of the MeCP2 epigenetic relay pathway that orchestrates coordinated induction of multiple profibrogenic genes.
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Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/fisiología , Transdiferenciación Celular/genética , N-Metiltransferasa de Histona-Lisina/fisiología , Miofibroblastos/citología , Transcripción Genética , Animales , Fibrosis/genética , Histona Metiltransferasas , Humanos , RatonesRESUMEN
Effective immune responses require antigen uptake by antigen-presenting cells (APC), followed by controlled endocytic proteolysis resulting in the generation of antigen-derived peptide fragments that associate with intracellular MHC class II molecules. The resultant peptide-MHC class II complexes then move to the APC surface where they activate CD4(+) T cells. Dendritic cells (DC), macrophages and B cells act as efficient APC. In many settings, including the T helper type 1 (Th1) -dependent, proteoglycan-induced arthritis model of rheumatoid arthritis, accumulating evidence demonstrates that antigen presentation by B cells is required for optimal CD4(+) T cell activation. The reasons behind this however, remain unclear. In this study we have compared the activation of CD4(+) T cells specific for the proteoglycan aggrecan following antigen presentation by DC, macrophages and B cells. We show that aggrecan-specific B cells are equally efficient APC as DC and macrophages and use similar intracellular antigen-processing pathways. Importantly, we also show that antigen presentation by aggrecan-specific B cells to TCR transgenic CD4(+) T cells results in enhanced CD4(+) T cell interferon-γ production and Th1 effector sub-set differentiation compared with that seen with DC. We conclude that preferential CD4(+) Th1 differentiation may define the requirement for B cell APC function in both proteoglycan-induced arthritis and rheumatoid arthritis.
Asunto(s)
Agrecanos/inmunología , Células Presentadoras de Antígenos/inmunología , Artritis Reumatoide/inmunología , Linfocitos B/inmunología , Diferenciación Celular , Linfocitos T Colaboradores-Inductores/citología , Agrecanos/química , Secuencia de Aminoácidos , Animales , Presentación de Antígeno/inmunología , Artritis Reumatoide/metabolismo , Autoantígenos/inmunología , Linfocitos T CD4-Positivos/citología , Linfocitos T CD4-Positivos/inmunología , Humanos , Activación de Linfocitos , Ratones , Ratones Endogámicos BALB C , Datos de Secuencia Molecular , Péptidos/síntesis química , Péptidos/química , Péptidos/inmunología , Linfocitos T Colaboradores-Inductores/inmunologíaRESUMEN
The synaptonemal complex (SC) is a supramolecular protein scaffold that mediates chromosome synapsis and facilitates crossing over during meiosis. In mammals, SC proteins are generally assumed to have no other function. Here, we show that SC protein TEX12 also localises to centrosomes during meiosis independently of chromosome synapsis. In somatic cells, ectopically expressed TEX12 similarly localises to centrosomes, where it is associated with centrosome amplification, a pathology correlated with cancer development. Indeed, TEX12 is identified as a cancer-testis antigen and proliferation of some cancer cells is TEX12-dependent. Moreover, somatic expression of TEX12 is aberrantly activated via retinoic acid signalling, which is commonly disregulated in cancer. Structure-function analysis reveals that phosphorylation of TEX12 on tyrosine 48 is important for centrosome amplification but not for recruitment of TEX12 to centrosomes. We conclude that TEX12 normally localises to meiotic centrosomes, but its misexpression in somatic cells can contribute to pathological amplification and dysfunction of centrosomes in cancers.
Asunto(s)
Proteínas de Ciclo Celular/genética , Centrosoma/fisiología , Expresión Génica , Complejo Sinaptonémico/metabolismo , Animales , Proteínas de Ciclo Celular/metabolismo , Línea Celular Tumoral , Humanos , RatonesRESUMEN
Non-alcoholic fatty liver disease ranges from steatosis to non-alcoholic steatohepatitis (NASH), potentially progressing to cirrhosis and hepatocellular carcinoma (HCC). Here, we show that platelet number, platelet activation and platelet aggregation are increased in NASH but not in steatosis or insulin resistance. Antiplatelet therapy (APT; aspirin/clopidogrel, ticagrelor) but not nonsteroidal anti-inflammatory drug (NSAID) treatment with sulindac prevented NASH and subsequent HCC development. Intravital microscopy showed that liver colonization by platelets depended primarily on Kupffer cells at early and late stages of NASH, involving hyaluronan-CD44 binding. APT reduced intrahepatic platelet accumulation and the frequency of platelet-immune cell interaction, thereby limiting hepatic immune cell trafficking. Consequently, intrahepatic cytokine and chemokine release, macrovesicular steatosis and liver damage were attenuated. Platelet cargo, platelet adhesion and platelet activation but not platelet aggregation were identified as pivotal for NASH and subsequent hepatocarcinogenesis. In particular, platelet-derived GPIbα proved critical for development of NASH and subsequent HCC, independent of its reported cognate ligands vWF, P-selectin or Mac-1, offering a potential target against NASH.
Asunto(s)
Plaquetas/metabolismo , Neoplasias Hepáticas/sangre , Neoplasias Hepáticas/tratamiento farmacológico , Enfermedad del Hígado Graso no Alcohólico/sangre , Enfermedad del Hígado Graso no Alcohólico/tratamiento farmacológico , Complejo GPIb-IX de Glicoproteína Plaquetaria/metabolismo , Animales , Plaquetas/efectos de los fármacos , Peso Corporal/efectos de los fármacos , Citocinas/metabolismo , Gránulos Citoplasmáticos/efectos de los fármacos , Gránulos Citoplasmáticos/metabolismo , Endotelio/efectos de los fármacos , Endotelio/metabolismo , Hepatocitos/efectos de los fármacos , Hepatocitos/patología , Humanos , Receptores de Hialuranos/metabolismo , Ácido Hialurónico/metabolismo , Macrófagos del Hígado/efectos de los fármacos , Macrófagos del Hígado/metabolismo , Hígado/efectos de los fármacos , Hígado/metabolismo , Hígado/patología , Ratones Transgénicos , Agregación Plaquetaria/efectos de los fármacos , Inhibidores de Agregación Plaquetaria/farmacología , Recuento de PlaquetasRESUMEN
Current evidence strongly suggests that aberrant activation of the NF-κB signalling pathway is associated with carcinogenesis. A number of key cellular processes are governed by the effectors of this pathway, including immune responses and apoptosis, both crucial in the development of cancer. Therefore, it is not surprising that dysregulated and chronic NF-κB signalling can have a profound impact on cellular homeostasis. Here we discuss NFKB1 (p105/p50), one of the five subunits of NF-κB, widely implicated in carcinogenesis, in some cases driving cancer progression and in others acting as a tumour-suppressor. The complexity of the role of this subunit lies in the multiple dimeric combination possibilities as well as the different interacting co-factors, which dictate whether gene transcription is activated or repressed, in a cell and organ-specific manner. This review highlights the multiple roles of NFKB1 in the development and progression of different cancers, and the considerations to make when attempting to manipulate NF-κB as a potential cancer therapy.
RESUMEN
The NF-?B p50 subunit is an important regulator of inflammation, with recent experimental evidence to support it also having a tumor suppressor role. Classically, p50 functions in heterodimeric form with the RelA (p65) NF-?B subunit to activate inflammatory genes. However, p50 also forms homodimers which actively repress NF-?B-dependent inflammatory gene expression and exert an important brake on the inflammatory process. This repressive activity of p50:p50 is thought to be in part mediated by an interaction with the epigenetic repressor protein Histone Deacetylase 1 (HDAC1). However, neither the interaction of p50 with HDAC1 nor the requirement of HDAC1 for the repressive activities of p50 has been well defined. Here we employed in silico prediction with in vitro assays to map sites of interaction of HDAC1 on the p50 protein. Directed mutagenesis of one such region resulted in almost complete loss of HDAC1 binding to p50. Transfected mutant p50 protein lacking the putative HDAC1 docking motif resulted in enhanced cytokine and chemokine expression when compared with cells expressing a transfected wild type p50. In addition, expression of this mutant p50 was associated with enhanced chemoattraction of neutrophils and acetylation of known inflammatory genes demonstrating the likely importance of the p50:HDAC1 interaction for controlling inflammation. These new insights provide an advance on current knowledge of the mechanisms by which NF-?B-dependent gene transcription are regulated and highlight the potential for manipulation of p50:HDAC1 interactions to bring about experimental modulation of chronic inflammation and pathologies associated with dysregulated neutrophil accumulation and activation.
Asunto(s)
Histona Desacetilasa 1/metabolismo , Subunidad p50 de NF-kappa B/química , Subunidad p50 de NF-kappa B/metabolismo , Animales , Línea Celular , Quimiocinas/genética , Quimiotaxis , Ensamble y Desensamble de Cromatina , Expresión Génica , Histona Desacetilasa 1/química , Humanos , Mediadores de Inflamación/metabolismo , Ratones , Ratones Endogámicos C57BL , Mutación , Subunidad p50 de NF-kappa B/genética , Neutrófilos/inmunología , Señales de Localización NuclearRESUMEN
Novel insights into the epigenetic control of chronic liver diseases are now emerging. Recent advances in our understanding of the critical roles of DNA methylation, histone modifications and ncRNA may now be exploited to improve management of fibrosis/cirrhosis and cancer. Furthermore, improved technologies for the detection of epigenetic markers from patients' blood and tissues will vastly improve diagnosis, treatment options and prognostic tracking. The aim of this review is to present recent findings from the field of liver epigenetics and to explore their potential for translation into therapeutics to prevent disease promoting epigenome reprogramming and reverse epigenetic changes.
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Carcinoma Hepatocelular/genética , Reprogramación Celular/genética , Epigénesis Genética/genética , Cirrosis Hepática/genética , Neoplasias Hepáticas/genética , Animales , Carcinoma Hepatocelular/metabolismo , Carcinoma Hepatocelular/patología , Humanos , Cirrosis Hepática/metabolismo , Cirrosis Hepática/patología , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/patologíaRESUMEN
The NF-κB family of transcription factors is important for many cellular functions, in particular initiation and propagation of inflammatory and immune responses. However, recent data has suggested that different subunits of the NF-κB family can suppress the inflammatory response. NF-κB1, from the locus nfκb1, can inhibit transcription, acting as a brake to the recognised pro-inflammatory activity of other NF-κB subunits. We tested the function of NF-κB1 in an acute (nephrotoxic serum (NTS) nephritis) and a chronic (unilateral ureteric obstruction (UUO)) model of renal injury using NF-κB1 (nfκb1-/-) knockout mice. Deficiency in NF-κB1 increased the severity of glomerular injury in NTS-induced nephritis and was associated with greater proteinuria and persistent pro-inflammatory gene expression. Induction of disease in bone marrow chimeric mice demonstrated that the absence of NF-κB1 in either bone marrow or glomerular cells increased the severity of injury. Early after UUO (day 3) there was more severe histological injury in the nfκb1-/- mice but by day 10, disease severity was equivalent in wild type and nfκb1-/- mice. In conclusion, NF-κB1 modifies acute inflammatory renal injury but does not influence chronic fibrotic injury.
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Enfermedades Renales/metabolismo , Factor de Transcripción ReIA/metabolismo , Animales , Células de la Médula Ósea/citología , Modelos Animales de Enfermedad , Fibrosis , Perfilación de la Expresión Génica , Homocigoto , Inflamación , Riñón/embriología , Riñón/lesiones , Glomérulos Renales/lesiones , Glomérulos Renales/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Nefritis/fisiopatología , Estrés Oxidativo , Fenotipo , Unión Proteica , Proteinuria/metabolismo , Factor de Transcripción ReIA/genéticaRESUMEN
The incidence of non-alcoholic fatty liver disease (NAFLD) increases with age. Cellular senescence refers to a state of irreversible cell-cycle arrest combined with the secretion of proinflammatory cytokines and mitochondrial dysfunction. Senescent cells contribute to age-related tissue degeneration. Here we show that the accumulation of senescent cells promotes hepatic fat accumulation and steatosis. We report a close correlation between hepatic fat accumulation and markers of hepatocyte senescence. The elimination of senescent cells by suicide gene-meditated ablation of p16Ink4a-expressing senescent cells in INK-ATTAC mice or by treatment with a combination of the senolytic drugs dasatinib and quercetin (D+Q) reduces overall hepatic steatosis. Conversely, inducing hepatocyte senescence promotes fat accumulation in vitro and in vivo. Mechanistically, we show that mitochondria in senescent cells lose the ability to metabolize fatty acids efficiently. Our study demonstrates that cellular senescence drives hepatic steatosis and elimination of senescent cells may be a novel therapeutic strategy to reduce steatosis.
Asunto(s)
Senescencia Celular/efectos de los fármacos , Dasatinib/química , Hígado Graso/patología , Inflamación , Quercetina/química , Animales , Apoptosis/efectos de los fármacos , Células Cultivadas , Inhibidor p16 de la Quinasa Dependiente de Ciclina/metabolismo , Hígado Graso/metabolismo , Fibroblastos/metabolismo , Hepatocitos/citología , Hígado/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Mitocondrias/metabolismo , Enfermedad del Hígado Graso no Alcohólico/metabolismo , Enfermedad del Hígado Graso no Alcohólico/patologíaRESUMEN
Toll-like Receptor 3 (TLR3) is a pathogen pattern recognition receptor that plays a key role in innate immunity. TLR3 signalling has numerous functions in liver, both in health and disease. Here we report that TLR3 is expressed by quiescent hepatic stellate cells (HSC) where it functions to induce transcription and secretion of functional interferons as well as a number of other cytokines and chemokines. Upon transdifferentiation into myofibroblasts, HSCs rapidly loose the ability to produce interferon gamma (IFNγ). Mechanistically, this gene silencing may be due to Polycomb complex mediated repression via methylation of histone H3 lysine 27. In contrast to wild type, quiescent HSC isolated from tlr3 knockout mice do not produce IFNγ in response to Poly(Iâ¶C) treatment. Therefore, quiescent HSC may contribute to induction of the hepatic innate immune system in response to injury or infection.
Asunto(s)
Ciclo Celular , Células Estrelladas Hepáticas/citología , Inmunidad Innata/inmunología , Hígado/citología , Hígado/inmunología , Receptor Toll-Like 3/metabolismo , Animales , Citocinas/biosíntesis , Células Estrelladas Hepáticas/inmunología , Interferones/metabolismo , Ligandos , Ratones , Ratones Noqueados , Proteínas del Grupo Polycomb/metabolismo , Ratas Sprague-Dawley , Transcripción GenéticaRESUMEN
Nuclear factor kappa B (NFκB) is a dimeric transcription factor comprised of five family members RelA (p65), RelB, c-Rel, p50 and p52. NFκB signalling is complex and controls a myriad of normal cellular functions. However, constitutive or aberrant activation of this pathway is associated with disease progression and cancer in multiple organs. The diverse array of biological responses is modulated by many factors, including the activating stimulus, recruitment of co-regulatory molecules, consensus DNA binding sequence, dimer composition and post-translational modifications. Each subunit has very different biological functions and in the context of disease the individual subunits forming the NFκB dimer can have a profound effect, causing a shift in the balance from normal to pathogenic signalling. Here we discuss the role of c-Rel dependant signalling in normal physiology and its contribution to disease both inside and outside of the immune system.