RESUMO
BACKGROUND: The present study aimed to investigate the underlying role of interferon-regulatory factor 2 (IRF2)-inositol polyphosphate-4-phosphatase, type-II (INPP4B) axis in the regulation of autophagy in acute myeloid leukemia (AML) cells. METHODS: Quantitative real time PCR (QRT-PCR) and western blot were performed to determine the expression levels of IRF2, INPP4B and autophagy-related markers in AML cell lines. Autophagy was assessed by elevated Beclin-1 expression, the conversion of light chain 3 (LC3)-I to LC3-II, downregulated p62 expression and green fluorescent protein (GFP)-LC3 puncta formation. The colony formation and apoptosis assays were performed to determine the effects of IRF2 and INPP4B on the growth of AML cells. RESULTS: IRF2 and INPP4B were highly expressed in AML cell lines, and were positively correlated with autophagy-related proteins. Overexpression of IRF2 or INPP4B stimulated autophagy of AML cells, whereas inhibition of IRF2 or INPP4B resulted in the attenuation of autophagy. More importantly, IRF2 or INPP4B overexpression reversed autophagy inhibitor, 3-methyladenine (3-MA)-induced proliferation-inhibitory and pro-apoptotic effects, while IRF2 or INPP4B silencing overturned the proliferation-promoting and anti-apoptotic effects of autophagy activator rapamycin. CONCLUSION: IRF2-INPP4B signaling axis attenuated apoptosis through induction of autophagy in AML cells.
Assuntos
Apoptose , Autofagia , Fator Regulador 2 de Interferon/metabolismo , Leucemia Mieloide Aguda/metabolismo , Monoéster Fosfórico Hidrolases/metabolismo , Western Blotting , Linhagem Celular Tumoral , Proliferação de Células , Imunofluorescência , Humanos , Leucemia Mieloide Aguda/patologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Transdução de SinaisRESUMO
BACKGROUND: The present study aimed to investigate the underlying role of interferon-regulatory factor 2 (IRF2)-inositol polyphosphate-4-phosphatase, type-II (INPP4B) axis in the regulation of autophagy in acute myeloid leukemia (AML) cells. METHODS: Quantitative real time PCR (QRT-PCR) and western blot were performed to determine the expression levels of IRF2, INPP4B and autophagy-related markers in AML cell lines. Autophagy was assessed by elevated Beclin-1 expression, the conversion of light chain 3 (LC3)-I to LC3-II, downregulated p62 expression and green fluorescent protein (GFP)-LC3 puncta formation. The colony formation and apoptosis assays were performed to determine the effects of IRF2 and INPP4B on the growth of AML cells. RESULTS: IRF2 and INPP4B were highly expressed in AML cell lines, and were positively correlated with autophagy-related proteins. Overexpression of IRF2 or INPP4B stimulated autophagy of AML cells, whereas inhibition of IRF2 or INPP4B resulted in the attenuation of autophagy. More importantly, IRF2 or INPP4B overexpression reversed autophagy inhibitor, 3-methyladenine (3-MA)-induced proliferation-inhibitory and pro-apoptotic effects, while IRF2 or INPP4B silencing overturned the proliferation-promoting and anti-apoptotic effects of autophagy activator rapamycin. CONCLUSION: IRF2-INPP4B signaling axis attenuated apoptosis through induction of autophagy in AML cells.
Assuntos
Humanos , Autofagia , Leucemia Mieloide Aguda/metabolismo , Apoptose , Monoéster Fosfórico Hidrolases/metabolismo , Fator Regulador 2 de Interferon/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Leucemia Mieloide Aguda/patologia , Transdução de Sinais , Western Blotting , Imunofluorescência , Linhagem Celular Tumoral , Proliferação de Células , Reação em Cadeia da Polimerase em Tempo RealRESUMO
Brazilian Guidelines to HCV treatment (2007) recommended that the first choice treatment for patients with chronic hepatitis C (CHC) and genotype 2 or 3 is interferon alpha (IFN) plus ribavirin (RBV) for 24 weeks. The aim of this study is compare the cost and effectiveness to Hepatitis C treatment in patients with genotype 2 or 3 of peginterferon alpha (PEG) as the first choice of treatment within PEG for those that do not respond to IFN. The target population is CHC patients with genotype 2 or 3 in Brazil. The interventions are: PEG-SEC (first IFN plus RBV for 24 weeks, after, for non-responders and relapsers subsequently PEG plus RBV for 48 weeks); PEG-FIRST24 (PEG+RBV for 24 weeks). The type of the study is cost-effectiveness analysis. The data sources are: Effectiveness data from meta-analysis conducted on the Brazilian population. Treatment cost from Brazilian micro costing study is converted into USD (2010). The perspective is the Public Health System. The outcome measurements are Sustained Viral Response (SVR) and costs. PEG-FIRST24 (SVR: 87.8%, costs: USD 8,338.27) was more effective and more costly than PEG-SEC (SVR: 79.2%, costs: USD 5,852.99). The sensitivity analyses are: When SVR rates with IFN was less than 30% PEG-FIRST is dominant. On the other hand, when SVR with IFN was more then 75% PEG-SEC is dominant (SVR=88.2% and costs USD $ 3,753.00). PEG-SEC is also dominant when SVR to PEG24 weeks was less than 54%. In the Brazilian context, PEG-FIRST is more effective and more expensive than PEG-SEC. PEG-SEC could be dominant when rates of IFN therapy are higher than 75% or rates of PEG24 therapy are lower than 54%.
O protocolo brasileiro de tratamento da Hepatite C (2007) recomendava como primeira escolha para pacientes com hepatite C crônica e portadores de genótipo 2 ou 3 o tratamento com interferona alfa (IFN) associada à ribavirina (RBV), por 24 semanas. O objetivo deste estudo é comparar o custo e a efetividade para pacientes com hepatite C crônica e portadores do genótipo 2 ou 3 o uso de peguinterferon (PEG) como primeiro escolha com o PEG como secunda escolha para aqueles que não responderam ao tratamento com IFN. A população alvo compreende pacientes com hepatite C crônica portadores de genótipo 2 ou 3 no Brasil. As intervenções são: PEG-SEC (IFN + RBV por 24 semanas, para os não respondedores e recidivantes tratamento subsequente com PEG + RBV por 48 semanas; PEG-FIRST24 (PEG + RBV por 24 semanas). O tipo de estudo envolvido é Análise de Custo Efetividade. Os dados de efetividade são provenientes de um metanálise de estudos brasileiros e os dados de custo do tratamento de um estudo de custo do contexto brasileiro. A perspectiva é o Sistema Público de Saúde. Os desfechos avaliados foram Resposta Viral Sustentada (RVS) e Custos. PEG-FIRST24 (RVS: 87,8%, costs: USD 8.338,27) foi mais efetivo e apresentou maior custo que PEG-SEC (RVS: 79,2%, custo USD 5.852,99). A análise de sensibilidade demonstrou que PEG-SEC é dominado por PEG-FIRST24 quando RVS com IFN for menor que 30%. Por outro lado, quando RVS com IFN for maior que 75% PEG-SEC é dominante (RVS=88.2% e custo USD $ 3.753,00). PEG-SEC é também dominante quando RVS para PEG24 for menor que 54%. Conclusão: No contexto brasileiro, PEG-FIRST é mais efetivo e mais custoso que PEG-SEC. PEG-SEC poderia ser dominante quando as taxas de RVS do tratamento com IFN forem superiores a 75% ou as taxas de PEG24 forem inferiores a 54%.
Assuntos
Terapêutica/economia , Análise Custo-Benefício/estatística & dados numéricos , Hepatite C Crônica/classificação , Genótipo , Custos e Análise de Custo/classificação , Fator Regulador 2 de Interferon/classificação , Fator Regulador 3 de InterferonRESUMO
The nuclear factor of activated T cells (NFAT) family of transcription factors is expressed in a wide range of cell types and regulates genes involved in cell cycle, differentiation, and apoptosis. NFAT proteins share two well-conserved regions, the regulatory domain and the DNA binding domain. The N- and C-terminal ends are transactivation sites and show less sequence similarity, whereas their molecular functions remain poorly understood. Here, we identified a transcriptional repressor, interferon regulatory factor 2 binding protein 2 (IRF-2BP2), which specifically interacts with the C-terminal domain of NFAT1 among the NFAT family members. IRF-2BP2 was described as a corepressor by inhibiting both enhancer-activated and basal transcription. Gene reporter assays demonstrated that IRF-2BP2 represses the NFAT1-dependent transactivation of NFAT-responsive promoters. The ectopic expression of IRF-2BP2 in CD4 T cells resulted in decreased interleukin-2 (IL-2) and IL-4 production, supporting a repressive function of IRF-2BP2 for NFAT target genes. Furthermore, NFAT1 and IRF-2BP2 colocalized in the nucleus in activated cells, and the mutation of a newly identified nuclear localization signal in the IRF-2BP2 rendered it cytoplasmic, abolishing its repressive effect on NFAT1 activity. Collectively, our data demonstrate that IRF-2BP2 is a negative regulator of the NFAT1 transcription factor and suggest that NFAT1 repression occurs at the transcriptional level.
Assuntos
Proteínas de Transporte/metabolismo , Regulação da Expressão Gênica , Fator Regulador 2 de Interferon/metabolismo , Fatores de Transcrição NFATC/metabolismo , Proteínas Nucleares/metabolismo , Transcrição Gênica , Sequência de Aminoácidos , Animais , Linfócitos T CD4-Positivos/citologia , Linfócitos T CD4-Positivos/metabolismo , Proteínas de Transporte/genética , Células Cultivadas , Proteínas de Ligação a DNA , Células HEK293 , Humanos , Fator Regulador 2 de Interferon/genética , Camundongos , Dados de Sequência Molecular , Fatores de Transcrição NFATC/genética , Sinais de Localização Nuclear , Proteínas Nucleares/genética , Ligação Proteica , Alinhamento de Sequência , Fatores de Transcrição , Técnicas do Sistema de Duplo-HíbridoRESUMO
We had previously observed that HPV-16 E7 disturbs the Guanylate Binding Protein (GBP)-ISRE reporter activation by IFN-gamma thus suggesting an alteration of the IRF-1 function. In this study we examined the mechanism by which E7 affects the IFN-gamma signals driving the activation of gene transcription. Using 14/2 BRK cells containing dexamethasone-inducible HPV-16 E7 gene, we observed a large inhibition of the IRF-1 DNA binding activity upon E7 induction. Concomitantly, there was no significant change in the levels of IRF-1, indicating that this was not due to reduced levels of IRF-1 expression. Likewise, in vitro translated E7 did not affect the IRF-1 DNA binding activity in nuclear extracts derived from IFN-induced cells, thus indicating that the effects of E7 are upstream of IRF-1's binding to its DNA recognition site. Finally, NFkappaB DNA binding activity was also inhibited under conditional expression of E7. These data indicate that HPV-16 E7 inhibits the IRF-1 and NFkappaB function and this could lead to the impairment of the IFN response in HPV-infected cells. Furthermore, the findings suggest that different events of the IFN inducible signal cascade seem to be target for HPV-16 E7.
Assuntos
Proteínas de Ligação a DNA/metabolismo , Proteínas Oncogênicas Virais/metabolismo , Papillomaviridae/metabolismo , Fosfoproteínas/metabolismo , Proteínas Repressoras , Fatores de Transcrição , Linhagem Celular , Dexametasona/farmacologia , Humanos , Fator Regulador 1 de Interferon , Fator Regulador 2 de Interferon , Interferon gama/metabolismo , Interferon gama/farmacologia , NF-kappa B/metabolismo , Proteínas E7 de Papillomavirus , Proteínas Recombinantes , Fator de Transcrição STAT1 , Transativadores/metabolismoRESUMO
To investigate the roles of type I interferon (IFN-alpha/beta) and other mediators of innate immune responses (e.g., inducible nitric oxide synthase [iNOS]) in early dissemination of Venezuelan equine encephalitis virus (VEE) infection, we used mice with targeted deletions in either their IFN-alpha/beta-receptor (IFNAR-1-/-) or interferon regulatory factor 2 (IRF-2-/-) genes. Following footpad infection, both IFNAR-1-/- and IRF-2-/- mice were more susceptible than control mice to VEE. The IFNAR-1-/- mice also exhibit accelerated VEE dissemination to serum, spleen, and brain, and compared with control mice, they evidenced faster kinetics in the upregulation of proinflammatory genes. In contrast, in IRF-2-/- mice, iNOS gene induction was completely absent following peripheral virulent VEE infection. In evaluating the role of cells involved in iNOS production, primary microglial cell cultures were found to be highly permissive to VEE infection. Moreover, VEE infection increased levels of nitric oxide (NO) in resting microglial cultures but decreased NO production in IFN-gamma-stimulated microglia. Thus, these findings suggest that reactive nitrogen species play an important contributory role in VEE dissemination and survival of the host. Our results further suggest the necessity for a carefully balanced host response that follows a middle course between immunopathology and insufficient inflammatory response to VEE infection.
Assuntos
Encéfalo/enzimologia , Encéfalo/imunologia , Encefalomielite Equina Venezuelana/enzimologia , Encefalomielite Equina Venezuelana/imunologia , Interferon Tipo I/genética , Óxido Nítrico Sintase/genética , Proteínas Repressoras , Fatores de Transcrição , Animais , Encéfalo/virologia , Células Cultivadas , Cricetinae , Proteínas de Ligação a DNA/genética , Vírus da Encefalite Equina Venezuelana/patogenicidade , Vírus da Encefalite Equina Venezuelana/fisiologia , Encefalomielite Equina Venezuelana/genética , Fator Regulador 2 de Interferon , Proteínas de Membrana , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microglia/imunologia , Microglia/virologia , Óxido Nítrico/biossíntese , Óxido Nítrico Sintase Tipo II , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos , Receptor de Interferon alfa e beta , Receptores de Interferon/genética , Regulação para Cima , Virulência , Replicação ViralRESUMO
To investigate the role of type I interferon (IFN) and its regulatory transacting proteins, interferon regulatory factors (IRF-1 and IRF-2), in early protection against infection with virulent Venezuelan equine encephalitis virus (VEE), we utilized mice with targeted mutations in the IFN-alpha/beta receptor, IRF-1, or IRF-2 genes. IFN-alpha/beta-receptor knockout mice are highly susceptible to peripheral infection with virulent or attenuated VEE, resulting in their death within 24 and 48 h, respectively. Treatment of normal macrophages with anti-IFN-alpha/beta antibody prior to and during infection with molecularly cloned virulent VEE resulted in increased VEE replication. However, treatment with high doses of IFN or IFN-inducing agents failed to alter percentage mortality or average survival times in mice challenged with a low dose of virulent VEE. In IRF-1 and IRF-2 knockout mice (IRF-1(-/-) and IRF-2(-/-)), the 100% protection against virulent VEE that is conferred by attenuated VEE within 24 h in control C57BL/6 mice was completely absent in IRF-2(-/-) mice, whereas 50% of IRF-1(-/-) mice were protected. IRF-2(-/-) mice were deficient in clearing VEE virus from the spleen and the brain compared to the heterozygous IRF-2(+/-) knockout or C57BL/6 (+/+) mice. Furthermore, a distinct pattern of histopathological changes was observed in brains of IRF-2(-/-) mice after VEE exposure. Taken together, these findings imply that the altered immune response in IRF-1 and IRF-2 knockout mice results in altered virus dissemination, altered virus clearance, and altered virus-induced pathology. Thus, type I interferon, as well as IRF-1 and IRF-2, appears to play an important and necessary role in the pathogenesis of, and protection against, VEE infection.
Assuntos
Proteínas de Ligação a DNA/fisiologia , Vírus da Encefalite Equina Venezuelana/patogenicidade , Encefalomielite Equina Venezuelana/prevenção & controle , Interferons/fisiologia , Fosfoproteínas/fisiologia , Proteínas Repressoras/fisiologia , Fatores de Transcrição/fisiologia , Animais , Proteínas de Ligação a DNA/genética , Marcação de Genes , Fator Regulador 1 de Interferon , Fator Regulador 2 de Interferon , Interferon Tipo I/genética , Interferon Tipo I/fisiologia , Interferon gama/genética , Interferon gama/fisiologia , Interferons/genética , Macrófagos Peritoneais/virologia , Camundongos , Fosfoproteínas/genética , Proteínas Repressoras/genética , Fatores de Transcrição/genéticaRESUMO
Analysis of gene expression in peripheral blood lymphocytes is of special interest because it could reflect physiological conditions. We have examined the expression and compared the relative amounts of specific mRNAs for interferons (IFN-alpha and IFN-beta), tumor necrosis factor-alpha (TNF-alpha) and interferon regulatory factors (IRF-1 and IRF-2) from interferon primed and Sendai virus induced peripheral blood leukocytes. Results obtained showed that IRF-1 was highly inducible by IFN treatment, IFN-alpha, TNF-alpha and IRF-2 were weakly induced by IFN treatment, and IFN-beta was not inducible by priming the cells with recombinant human IFN-alpha 2b. The IFN-alpha, IFN-beta, IRF-2 and TNF-alpha transcripts increased upon viral infection. The IRF-1 mRNA was rapidly induced by IFN treatment and decreased after Sendai virus infection. Our results show that, in peripheral blood lymphocytes, IFN-alpha and -beta genes have a different response to IFN induction, thus suggesting different regulatory mechanisms for IFN induction of type I IFN genes in peripheral blood lymphocytes.