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1.
Gut ; 66(10): 1829-1837, 2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-27196570

RESUMO

OBJECTIVE: As pathogen sensors, Toll-like receptors (TLR) play a role in the first defence line during HCV infection. However, the impact of the DNA sensor TLR9 on the natural course of HCV infection is unknown. To address this, TLR9 promoter polymorphisms (single nucleotide polymorphisms (SNPs)) rs187084 and rs5743836 were investigated for their effect on disease progression. DESIGN: Therefore, the TLR9 SNPs and the interferon lambda 4 (IFNL4) rs12979860 were genotyped in chronically HCV type 1 infected (n=333), in patients who spontaneously cleared the infection (n=161), in the Swiss HCV cohort (n=1057) and the well-characterised German (n=305) and Irish (n=198) 'anti-D' cohorts. Functional analyses were done with promoter reporter constructs of human TLR9 in B cells and assessing TLR9 mRNA levels in whole blood of healthy volunteers. RESULTS: The TLR9 rs187084 C allele was associated with spontaneous virus clearance in women of the study cohort (OR=2.15 (95% CI 1.18 to 3.90) p=0.012), of the Swiss HCV cohort (OR=2.06 (95% CI 1.02 to 4.18) p=0.044) and in both 'anti-D' cohorts (German: OR=2.01 (95% CI 1.14 to 3.55) p=0.016; Irish: OR=1.93 (95% CI 1.10 to 3.68) p=0.047). Multivariate analysis in the combined study and Swiss HCV cohorts supported the results (OR=1.99 (95% CI 1.30 to 3.05) p=0.002). Functional analyses revealed higher transcriptional activities for both TLR9 variants and an association of the C allele of rs5743836 with allele-specific TLR9 mRNA regulation by oestrogens in women. CONCLUSIONS: TLR9 promoter SNPs are associated with the natural course of HCV infection and show higher transcriptional activities. Our results imply the DNA sensor TLR9 in natural immunity against the RNA virus, HCV.


Assuntos
Hepatite C Crônica/genética , Interleucinas/genética , RNA Mensageiro/sangue , Receptor Toll-Like 9/genética , Adulto , Idoso , Alelos , Progressão da Doença , Feminino , Regulação da Expressão Gênica/genética , Alemanha , Haplótipos , Humanos , Irlanda , Masculino , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único , Regiões Promotoras Genéticas , Remissão Espontânea , Estudos Retrospectivos , Fatores Sexuais , Suíça , Transcrição Gênica
2.
Hepatology ; 62(5): 1375-87, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26250868

RESUMO

UNLABELLED: Patients carrying very rare loss-of-function mutations in interleukin-1 receptor-associated kinase 4 (IRAK4), a critical signaling mediator in Toll-like receptor signaling, are severely immunodeficient, highlighting the paramount role of IRAK kinases in innate immunity. We discovered a comparatively frequent coding variant of the enigmatic human IRAK2, L392V (rs3844283), which is found homozygously in ∼15% of Caucasians, to be associated with a reduced ability to induce interferon-alpha in primary human plasmacytoid dendritic cells in response to hepatitis C virus (HCV). Cytokine production in response to purified Toll-like receptor agonists was also impaired. Additionally, rs3844283 was epidemiologically associated with a chronic course of HCV infection in two independent HCV cohorts and emerged as an independent predictor of chronic HCV disease. Mechanistically, IRAK2 L392V showed intact binding to, but impaired ubiquitination of, tumor necrosis factor receptor-associated factor 6, a vital step in signal transduction. CONCLUSION: Our study highlights IRAK2 and its genetic variants as critical factors and potentially novel biomarkers for human antiviral innate immunity.


Assuntos
Hepatite C Crônica/imunologia , Quinases Associadas a Receptores de Interleucina-1/genética , Genótipo , Células HEK293 , Humanos , Interferon-alfa/biossíntese , Interferons , Quinases Associadas a Receptores de Interleucina-1/fisiologia , Interleucinas/genética , Polimorfismo de Nucleotídeo Único , Fator 6 Associado a Receptor de TNF/metabolismo , Receptores Toll-Like/fisiologia , Ubiquitinação
3.
J Immunol ; 192(3): 1171-83, 2014 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-24391214

RESUMO

Semliki Forest virus (SFV) requires RNA replication and Bax/Bak for efficient apoptosis induction. However, cells lacking Bax/Bak continue to die in a caspase-dependent manner. In this study, we show in both mouse and human cells that this Bax/Bak-independent pathway involves dsRNA-induced innate immune signaling via mitochondrial antiviral signaling (MAVS) and caspase-8. Bax/Bak-deficient or Bcl-2- or Bcl-xL-overexpressing cells lacking MAVS or caspase-8 expression are resistant to SFV-induced apoptosis. The signaling pathway triggered by SFV does neither involve death receptors nor the classical MAVS effectors TNFR-associated factor-2, IRF-3/7, or IFN-ß but the physical interaction of MAVS with caspase-8 on mitochondria in a FADD-independent manner. Consistently, caspase-8 and -3 activation are reduced in MAVS-deficient cells. Thus, after RNA virus infection MAVS does not only elicit a type I antiviral response but also recruits caspase-8 to mitochondria to mediate caspase-3 activation and apoptosis in a Bax/Bak-independent manner.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/fisiologia , Apoptose/fisiologia , Caspase 8/fisiologia , Efeito Citopatogênico Viral/fisiologia , Mitocôndrias/fisiologia , Vírus da Floresta de Semliki/fisiologia , Animais , Caspase 3/metabolismo , RNA Helicases DEAD-box/fisiologia , Ativação Enzimática , Proteína de Domínio de Morte Associada a Fas/fisiologia , Fibroblastos/virologia , Células HEK293/virologia , Células HeLa/virologia , Humanos , Helicase IFIH1 Induzida por Interferon , Camundongos , Mitocôndrias/enzimologia , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Interferência de RNA , RNA Viral/genética , Transdução de Sinais , Replicação Viral , Proteína bcl-X/metabolismo
4.
Sci Rep ; 9(1): 13168, 2019 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-31511529

RESUMO

Toll-like receptors (TLRs) are important sentinels of bacterial and viral infection and thus fulfil a critical sensory role in innate immunity. Polo-like kinases (PLKs), a five membered family of Ser/Thr protein kinases, have long been studied for their role in mitosis and thus represent attractive therapeutic targets in cancer therapy. Recently, PLKs were implicated in TLR signaling in mice but the role of PLKs in TLR signaling in untransformed primary immune cells has not been addressed, even though PLK inhibitors are in clinical trials. We here identified several phospho-serine and phospho-threonine residues in the known TLR pathway kinases, Interleukin-1 receptor-associated kinase (IRAK) 2 and IRAK4. These sites lie in canonical polo-box motifs (PBM), sequence motifs known to direct recruitment of PLKs to client proteins. Interestingly, PLK1 was phosphorylated and PLK 2 and 3 mRNA induced upon TLR stimulation in primary immune cells, respectively. In whole blood, PLK inhibition disparately affected TLR mediated cytokine responses in a donor- and inhibitor-dependent fashion. Collectively, PLKs may thus potentially interface with TLR signaling in humans. We propose that temporary PLK inhibitor-mediated blockade of TLR-signaling in certain patients receiving such inhibitors during cancer treatment may cause adverse effects such as an increased risk of infections due to a then compromised ability of the TLR recognition system to sense and initiate cytokine responses to invading microbes.


Assuntos
Proteínas de Ciclo Celular/metabolismo , Quinases Associadas a Receptores de Interleucina-1/metabolismo , Monócitos/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Receptores Toll-Like/metabolismo , Benzimidazóis/farmacologia , Sítios de Ligação/genética , Proteínas de Ciclo Celular/antagonistas & inibidores , Proteínas de Ciclo Celular/genética , Citocinas/metabolismo , Expressão Gênica , Células HEK293 , Humanos , Quinases Associadas a Receptores de Interleucina-1/genética , Monócitos/citologia , Monócitos/efeitos dos fármacos , Fosforilação , Ligação Proteica , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Proteínas Serina-Treonina Quinases/genética , Proteínas Proto-Oncogênicas/antagonistas & inibidores , Proteínas Proto-Oncogênicas/genética , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Células THP-1 , Tiofenos/farmacologia , Receptores Toll-Like/genética , Quinase 1 Polo-Like
5.
Eur J Med Chem ; 42(2): 243-7, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17084000

RESUMO

An efficient synthesis of dialkylsubstituted maleic anhydrides 1a-j is described. The inhibitory potential of these original anhydride derivatives was tested toward the three human isoforms A, B and C of dual specific phosphatases Cdc25. A micromolar range inhibition of Cdc25s was observed with the maleic anhydrides bearing simple alkyl side chains longer than C(9), to reach the optimal activity with a C(17) chain length.


Assuntos
Anidridos Maleicos/síntese química , Fosfatases cdc25/antagonistas & inibidores , Fosfatase Alcalina/antagonistas & inibidores , Fosfatase Alcalina/química , Animais , Cavalos , Humanos , Isoenzimas/antagonistas & inibidores , Isoenzimas/química , Fígado/enzimologia , Anidridos Maleicos/química , Nitrofenóis/química , Compostos Organofosforados/química , Relação Estrutura-Atividade , Fosfatases cdc25/química
6.
PLoS One ; 10(6): e0126645, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26030884

RESUMO

Viruses can trigger apoptosis of infected host cells if not counteracted by cellular or viral anti-apoptotic proteins. These protective proteins either inhibit the activation of caspases or they act as Bcl-2 homologs to prevent Bax/Bak-mediated outer mitochondrial membrane permeabilization (MOMP). The exact mechanism by which viruses trigger MOMP has however remained enigmatic. Here we use two distinct types of viruses, a double stranded DNA virus, herpes simplex virus-1 (HSV-1) and a positive sense, single stranded RNA virus, Semliki Forest virus (SFV) to show that the BH3-only protein Puma is the major mediator of virus-induced Bax/Bak activation and MOMP induction. Indeed, when Puma was genetically deleted or downregulated by shRNA, mouse embryonic fibroblasts and IL-3-dependent monocytes as well as human colon carcinoma cells were as resistant to virus-induced apoptosis as their Bax/Bak double deficient counterparts (Bax/Bak-/-). Puma protein expression started to augment after 2 h postinfection with both viruses. Puma mRNA levels increased as well, but this occurred after apoptosis initiation (MOMP) because it was blocked in cells lacking Bax/Bak or overexpressing Bcl-xL. Moreover, none of the classical Puma transcription factors such as p53, p73 or p65 NFκB were involved in HSV-1-induced apoptosis. Our data suggest that viruses use a Puma protein-dependent mechanism to trigger MOMP and apoptosis in host cells.


Assuntos
Proteínas Reguladoras de Apoptose/metabolismo , Apoptose , Herpesvirus Humano 1/metabolismo , Filogenia , Proteínas Proto-Oncogênicas/metabolismo , Vírus da Floresta de Semliki/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Proteína Killer-Antagonista Homóloga a bcl-2/metabolismo , Proteína X Associada a bcl-2/metabolismo , Animais , Proteínas Reguladoras de Apoptose/genética , Caspase 3/metabolismo , Citocromos c/metabolismo , Ativação Enzimática , Proteína Ligante Fas/metabolismo , Fibroblastos/metabolismo , Células HCT116 , Humanos , Camundongos , Complexo de Proteínas Formadoras de Poros Nucleares , Proteínas Proto-Oncogênicas/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteínas de Ligação a RNA , Proteína Serina-Treonina Quinases de Interação com Receptores/metabolismo , Ligante Indutor de Apoptose Relacionado a TNF/metabolismo , Proteínas Supressoras de Tumor/genética , Células U937 , Replicação Viral
7.
Virus Res ; 209: 45-55, 2015 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-25736565

RESUMO

There is no doubt that viruses require cells to successfully reproduce and effectively infect the next host. The question is what is the fate of the infected cells? All eukaryotic cells can "sense" viral infections and exhibit defence strategies to oppose viral replication and spread. This often leads to the elimination of the infected cells by programmed cell death or apoptosis. This "sacrifice" of infected cells represents the most primordial response of multicellular organisms to viruses. Subverting host cell apoptosis, at least for some time, is therefore a crucial strategy of viruses to ensure their replication, the production of essential viral proteins, virus assembly and the spreading to new hosts. For that reason many viruses harbor apoptosis inhibitory genes, which once inside infected cells are expressed to circumvent apoptosis induction during the virus reproduction phase. On the other hand, viruses can take advantage of stimulating apoptosis to (i) facilitate shedding and hence dissemination, (ii) to prevent infected cells from presenting viral antigens to the immune system or (iii) to kill non-infected bystander and immune cells which would limit viral propagation. Hence the decision whether an infected host cell undergoes apoptosis or not depends on virus type and pathogenicity, its capacity to oppose antiviral responses of the infected cells and/or to evade any attack from immune cells. Viral genomes have therefore been adapted throughout evolution to satisfy the need of a particular virus to induce or inhibit apoptosis during its life cycle. Here we review the different strategies used by viruses to interfere with the two major apoptosis as well as with the innate immune signaling pathways in mammalian cells. We will focus on the intrinsic mitochondrial pathway and discuss new ideas about how particular viruses could activately engage mitochondria to induce apoptosis of their host.


Assuntos
Apoptose , Interações Hospedeiro-Patógeno , Imunidade Inata , Mitocôndrias/metabolismo , Replicação Viral , Vírus/crescimento & desenvolvimento , Vírus/imunologia , Humanos
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