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1.
Sci Rep ; 13(1): 19614, 2023 11 10.
Artigo em Inglês | MEDLINE | ID: mdl-37950057

RESUMO

Ras guanine nucleotide exchange factor member 1b (RasGEF1b) of the RasGEF/CDC25 domain-containing family is preferentially expressed by macrophages. However, information is lacking about its role in macrophage function. In this study, we generated mice with ubiquitous deletion of Rasgef1b and used RNA-seq-based transcriptomics to compare the global gene expression in wild-type and knock-out primary bone-marrow-derived macrophages under basal conditions and after lipopolysaccharide (LPS) treatment. Transcriptional filtering identified several genes with significantly different transcript levels between wild-type and knock-out macrophages. In total, 49 and 37 differentially expressed genes were identified at baseline and in LPS-activated macrophages, respectively. Distinct biological processes were significantly linked to down-regulated genes at the basal condition only, and largely included chemotaxis, response to cytokines, and positive regulation of GTPase activity. Importantly, validation by RT-qPCR revealed that the expression of genes identified as down-regulated after LPS stimulation was also decreased in the knock-out cells under basal conditions. We used a luciferase-based reporter assay to showcase the capability of RasGEF1b in activating the Serpinb2 promoter. Notably, knockdown of RasGEF1b in RAW264.7 macrophages resulted in impaired transcriptional activation of the Serpinb2 promoter, both in constitutive and LPS-stimulated conditions. This study provides a small collection of genes that shows relative expression changes effected by the absence of RasGEF1b in macrophages. Thus, we present the first evidence that RasGEF1b mediates the regulation of both steady-state and signal-dependent expression of genes and propose that this GEF plays a role in the maintenance of the basal transcriptional level in macrophages.


Assuntos
Citocinas , Lipopolissacarídeos , Animais , Camundongos , Quimiotaxia , Citocinas/genética , Citocinas/metabolismo , Lipopolissacarídeos/farmacologia , Lipopolissacarídeos/metabolismo , Macrófagos/metabolismo , Transcriptoma
2.
Int J Obes (Lond) ; 46(1): 68-76, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34493775

RESUMO

BACKGROUND/OBJECTIVES: Platelet-activating factor receptor (PAFR) activation controls adipose tissue (AT) expansion in animal models. Our objective was twofold: (i) to check whether PAFR signaling is involved in human obesity and (ii) investigate the PAF pathway role in hematopoietic or non-hematopoietic cells to control adipocyte size. MATERIALS/SUBJECTS AND METHODS: Clinical parameters and adipose tissue gene expression were evaluated in subjects with obesity. Bone marrow (BM) transplantation from wild-type (WT) or PAFR-/- mice was performed to obtain chimeric PAFR-deficient mice predominantly in hematopoietic or non-hematopoietic-derived cells. A high carbohydrate diet (HC) was used to induce AT remodeling and evaluate in which cell compartment PAFR signaling modulates it. Also, 3T3-L1 cells were treated with PAF to evaluate fat accumulation and the expression of genes related to it. RESULTS: PAFR expression in omental AT from humans with obesity was negatively correlated to different corpulence parameters and more expressed in the stromal vascular fraction than adipocytes. Total PAFR-/- increased adiposity compared with WT independent of diet-induced obesity. Differently, WT mice receiving PAFR-/--BM exhibited similar adiposity gain as WT chimeras. PAFR-/- mice receiving WT-BM showed comparable augmentation in adiposity as total PAFR-/- mice, demonstrating that PAFR signaling modulates adipose tissue expansion through non-hematopoietic cells. Indeed, the PAF treatment in 3T3-L1 adipocytes reduced fat accumulation and expression of adipogenic genes. CONCLUSIONS: Therefore, decreased PAFR signaling may favor an AT accumulation in humans and animal models. Importantly, PAFR signaling, mainly in non-hematopoietic cells, especially in adipocytes, appears to play a significant role in regulating diet-induced AT expansion.


Assuntos
Tecido Adiposo/fisiopatologia , Obesidade/complicações , Glicoproteínas da Membrana de Plaquetas/farmacologia , Tecido Adiposo/metabolismo , Adulto , Animais , Modelos Animais de Doenças , Feminino , Humanos , Masculino , Camundongos , Camundongos Knockout , Pessoa de Meia-Idade , Obesidade/fisiopatologia , Paris , Receptores Acoplados a Proteínas G , Transdução de Sinais/fisiologia
3.
J Med Food ; 24(12): 1323-1330, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34491843

RESUMO

Brazilian Cerrado is the second largest biome in South America and contains many unstudied valuable plant species rich in bioactive substances. In this study we investigated the phenolic content and proliferative effects on cultured fibroblasts of 32 extracts of different polarities prepared from 11 plants found in Cerrado regions. Eight extracts from six species increased cell proliferation and significantly induced ATP production by the cells. Four of these extracts were obtained from plants used as food, specifically from its fruits or seeds. A high phenolic content for these eight extracts, which directly correlated with the induction of cell proliferation, was corroborated by mass spectrometry analysis. We suggest that the bioactive substance content of these species shows an interesting potential use in cosmetic and food industry, which can contribute to the conservation and sustainable development of this region.


Assuntos
Frutas , Fenóis , Brasil , Fibroblastos , Frutas/química , Fenóis/análise , Extratos Vegetais/farmacologia , Plantas Comestíveis
4.
Int Rev Cell Mol Biol ; 361: 211-243, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34074495

RESUMO

Toll-like receptor (TLR) signaling induces substantial changes in the phosphoproteome of innate immune cells, mainly in the form of increased phosphorylation of signaling intermediaries. Loss of constitutive phosphorylation occurs simultaneously, but these transitions from a stable, phosphorylated state in resting cells to a sustained underphosphorylated state in activated cells have received far less attention. This review provides an overview of phosphorylation sites downregulated during TLR-mediated signaling, with a particular focus on TLR4 activation by lipopolysaccharide (LPS). Energy homeostasis, the cell cycle, mitochondrial fission, and gene regulation are among the biological events in macrophages that are regulated through the downregulation of phosphoproteins as part of intracellular signaling events. Phosphoproteomics studies on innate immune cells have identified hundreds of hitherto uncharacterized phosphorylation sites that are lost upon stimulation, indicating that protein hypophosphorylation is a significant, largely unexplored layer of complexity in the TLR4 pathway.


Assuntos
Doença , Saúde , Macrófagos/metabolismo , Transdução de Sinais , Receptores Toll-Like/metabolismo , Animais , Humanos , Fosforilação
5.
Int J Biochem Cell Biol ; 127: 105840, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32866686

RESUMO

Ras Guanine Exchange Factor (RasGEF) domain family member 1b is encoded by a Toll-like receptor (TLR)-inducible gene expressed in macrophages, but transcriptional mechanisms that govern its expression are still unknown. Here, we have functionally characterized the 5' flanking Rasgef1b sequence and analyzed its transcriptional activation. We have identified that the inflammation-responsive promoter is contained within a short sequence (-183 to +119) surrounding the transcriptional start site. The promoter sequence is evolutionarily conserved and harbors a cluster of five NF-κB binding sites. Luciferase reporter gene assay showed that the promoter is responsive to TLR activation and RelA or cRel, but not RelB, transcription factors. Besides, site-directed mutagenesis showed that the κB binding sites are required for maximal promoter activation induced by LPS. Analysis by Assay for Transposase-Accessible Chromatin using sequencing (ATAC-seq) revealed that the promoter is located in an accessible chromatin region. More important, Chromatin Immunoprecipitation sequencing (ChIP-seq) showed that RelA is recruited to the promoter region upon LPS stimulation of bone marrow-derived macrophages. Finally, studies with Rela-deficient macrophages or pharmacological inhibition by Bay11-7082 showed that NF-κB is required for optimal Rasgef1b expression induced by TLR agonists. Our data provide evidence of the regulatory mechanism mediated by NF-κB that facilitates Rasgef1b expression after TLR activation in macrophages.


Assuntos
Macrófagos/metabolismo , NF-kappa B/metabolismo , Receptores Toll-Like/metabolismo , Fatores ras de Troca de Nucleotídeo Guanina/biossíntese , Animais , Células Cultivadas , Lipopolissacarídeos/farmacologia , Macrófagos/efeitos dos fármacos , Macrófagos/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , NF-kappa B/genética , Regiões Promotoras Genéticas , Ativação Transcricional , Fatores ras de Troca de Nucleotídeo Guanina/genética , Fatores ras de Troca de Nucleotídeo Guanina/metabolismo
6.
Cell Microbiol ; 22(6): e13179, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32017324

RESUMO

Cryptococcus gattii (Cg) is one of the agents of cryptococcosis, a severe systemic mycosis with a higher prevalence in men than women, but the influence of the female sex hormone, 17-ß-estradiol (E2), on cryptococcosis remains unclear. Our study shows that female mice presented delayed mortality, increased neutrophil recruitment in bronchoalveolar lavage fluid, and reduced fungal load after 24 hr of infection compared to male and ovariectomised female mice (OVX). E2 replacement restored OVX female survival. Female macrophages have more efficient fungicidal activity, which was increased by E2 and reversed by the antagonist of G-protein-coupled oestrogen receptor (GPER), which negatively modulates PI3K activation. Furthermore, E2 induces a reduction in Cg cell diameter, cell charge, and antioxidant peroxidase activity. In conclusion, female mice present improved control of Cg infection, and GPER is important for E2 modulation of the female response.


Assuntos
Criptococose/tratamento farmacológico , Cryptococcus gattii/efeitos dos fármacos , Estradiol/farmacologia , Proteínas de Ligação ao GTP/metabolismo , Macrófagos/efeitos dos fármacos , Receptores de Estrogênio/metabolismo , Animais , Antifúngicos/farmacologia , Antioxidantes , Criptococose/imunologia , Modelos Animais de Doenças , Feminino , Macrófagos/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL
7.
Data Brief ; 24: 103965, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31193517

RESUMO

We present here the data to support the understanding of the implication of Rap2a GTPase in LPS-induced innate immune response and NF-κB activation. The data presented are related to molecular tools that were generated, acquired, optimized or validated to investigate Rap2a expression, activation and its effects in mammalian cells including RAW264.7 macrophages and THP-1 monocytes under inflammatory conditions. These data supplement important technical and biological information on immune function of Rap2a in macrophages activated by LPS, recently reported by us (Carvalho et al., 2019) [1].

8.
Mol Immunol ; 109: 27-37, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30851634

RESUMO

Small Ras GTPases are key molecules that regulate a variety of cellular responses in different cell types. Rap1 plays important functions in the regulation of macrophage biology during inflammation triggered by toll-like receptors (TLRs). However, despite sharing a relatively high degree of similarity with Rap1, no studies concerning Rap2 in macrophages and innate immunity have been reported yet. In this work, we show that either way alterations in the levels of Rap2a hampers proper macrophages response to TLR stimulation. Rap2a is activated by LPS in macrophages, and although putative activator TLR-inducible Ras guanine exchange factor RasGEF1b was sufficient to induce, it was not fully required for Rap2a activation. Silencing of Rap2a impaired LPS-induced production of IL-6 cytokine and KC/Cxcl1 chemokine, and also NF-κB activity as measured by reporter gene studies. Surprisingly, overexpression of Rap2a did also lead to marked inhibition of NF-κB activation induced by LPS, Pam3CSK4 and downstream TLR signaling molecules. We also found that Rap2a can inhibit the LPS-induced phosphorylation of the NF-κB subunit p65 at serine 536. Collectively, our data suggest that expression levels of Rap2a in macrophages might be tightly regulated to avoid unbalanced immune response. Our results implicate Rap2a in TLR-mediated responses by contributing to balanced NF-κB activity status in macrophages.


Assuntos
Regulação da Expressão Gênica , Inflamação/genética , Macrófagos/enzimologia , NF-kappa B/metabolismo , Proteínas rap de Ligação ao GTP/metabolismo , Animais , Quimiocina CXCL1/metabolismo , Técnicas de Silenciamento de Genes , Células HEK293 , Humanos , Inflamação/patologia , Mediadores da Inflamação/metabolismo , Interleucina-6/metabolismo , Lipopolissacarídeos , Macrófagos/patologia , Camundongos , Células RAW 264.7 , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptores Toll-Like/agonistas , Receptores Toll-Like/metabolismo , Proteínas rap de Ligação ao GTP/genética , Fatores ras de Troca de Nucleotídeo Guanina
9.
Sci Rep ; 8(1): 4281, 2018 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-29511271

RESUMO

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

10.
Microbiology (Reading) ; 164(3): 349-358, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29458690

RESUMO

Lactobacilli are the dominant bacteria of the vaginal tract of healthy women and they play a major role in the maintenance of mucosal homeostasis, preventing genital infections, such as bacterial vaginosis (BV) and vulvovaginal candidiasis (VVC). It is now known that one mechanism of this protection is the influence that lactobacilli can exert on host immune responses. In this context, we evaluated two Lactobacillus strains (L. plantarum 59 and L. fermentum 137) for their immunomodulatory properties in response to Gardnerella vaginalis (BV) or Candida albicans (VVC) infections in a HeLa cell infection model. G. vaginalis and C. albicans triggered the secretion of pro-inflammatory cytokines (TNF-α, IL-1ß, IL-6 and IL-8) and the activation of NF-κB in HeLa cells, in contrast to L. plantarum 59 and L. fermentum 137. Treatments with the Lactobacillus strains or their cell-free supernatants before (pre-treatment) or after (post-treatment) the challenge with the pathogens resulted in decreased secretion of pro-inflammatory cytokines and decreased activation of NF-κB. The treatments with Lactobacillus strains not only decreased the secretion of IL-8, but also its expression, as confirmed by gene reporter luciferase assay, suggesting transcription-level control by lactobacilli. In conclusion, L. plantarum 59 and L. fermentum 137 were confirmed to have an anti-inflammatory effect against G. vaginalis and C. albicans and they were able to influence signalling in NF-κB pathway, making them interesting candidates as probiotics for the prevention or treatment of BV and VVC.


Assuntos
Anti-Inflamatórios/farmacologia , Candida albicans/efeitos dos fármacos , Gardnerella vaginalis/efeitos dos fármacos , Lactobacillus plantarum/fisiologia , Limosilactobacillus fermentum/fisiologia , Probióticos/farmacologia , Candida albicans/crescimento & desenvolvimento , Técnicas de Cocultura , Meios de Cultivo Condicionados , Citocinas/genética , Citocinas/metabolismo , Feminino , Gardnerella vaginalis/crescimento & desenvolvimento , Células HeLa , Humanos , Fator de Transcrição RelA/metabolismo , Transcrição Gênica/efeitos dos fármacos
11.
Sci Rep ; 7(1): 9190, 2017 08 23.
Artigo em Inglês | MEDLINE | ID: mdl-28835710

RESUMO

In response to ER stress, activating transcription factor 6 (ATF6) traffics from ER to Golgi apparatus where it is activated by cleavage before being translocated as transcription factor to the cell nucleus. In this work we describe ATF6α as a newly target of the aspirin metabolite sodium salicylate (NaSal). NaSal treatment of cells induces increases in ATF6α mRNA and protein levels, but these events are not accompanied by ATF6 activation. Conversely, NaSal inhibited ATF6 transactivating activity elicited by various ER stress-inducing stimuli in different cell types. This resulted in reduced expression of a subset of ATF6α target genes. Mechanistically, exposure of cells to NaSal results in ATF6α trapping at the Golgi apparatus, thus preventing nuclear translocation. This study provides evidence that NaSal compound restrains the activity of ATF6α, thereby preventing activation of a specific subset of ER-stress responsive genes implicated in different cellular responses.

12.
Dig Dis Sci ; 61(1): 107-16, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26391267

RESUMO

BACKGROUND: Gastric adenocarcinoma is associated with chronic infection by Helicobacter pylori and with the host inflammatory response triggered by it, with substantial inter-person variation in the immune response profile due to host genetic factors. AIM: To investigate the diversity of the proinflammatory genes IL8, its receptors and PTGS2 in Amerindians; to test whether candidate SNPs in these genes are associated with gastric cancer in an admixed population with high Amerindian ancestry from Lima, Peru; and to assess whether an IL8RB promoter-derived haplotype affects gene expression. METHODS: We performed a Sanger-resequencing population survey, a candidate-gene association study (220 cases, 288 controls) and meta-analyses. We also performed an in vitro validation by a reporter gene assay of IL8RB promoter. RESULTS: The diversity of the promoter of studied genes in Native Americans is similar to Europeans. Although an association between candidate SNPs and gastric cancer was not found in Peruvians, trend in our data is consistent with meta-analyses results that suggest PTGS2-rs689466-A is associated with H. pylori-associated gastric cancer in East Asia. IL8RB promoter-derived haplotype (rs3890158-A/rs4674258-T), common in Peruvians, was up-regulated by TNF-α unlike the ancestral haplotype (rs3890158-G/rs4674258-C). Bioinformatics analysis suggests that this effect stemmed from creation of a binding site for the FOXO3 transcription factor by rs3890158G>A. CONCLUSIONS: Our updated meta-analysis reinforces the role of PTGS2-rs689466-A in gastric cancer in Asians, although more studies that control for ancestry are necessary to clarify its role in Latin Americans. Finally, we suggest that IL8RB-rs3890158G>A is a cis-regulatory SNP.


Assuntos
Adenocarcinoma/etnologia , Adenocarcinoma/genética , Biomarcadores Tumorais/genética , Ciclo-Oxigenase 2/genética , Indígenas Sul-Americanos/genética , Interleucina-8/genética , Polimorfismo de Nucleotídeo Único , Neoplasias Gástricas/etnologia , Neoplasias Gástricas/genética , Adenocarcinoma/metabolismo , Povo Asiático/genética , Sítios de Ligação , População Negra/genética , Estudos de Casos e Controles , Biologia Computacional , Proteína Forkhead Box O3 , Fatores de Transcrição Forkhead/genética , Fatores de Transcrição Forkhead/metabolismo , Regulação Neoplásica da Expressão Gênica , Frequência do Gene , Estudos de Associação Genética , Predisposição Genética para Doença , Células HEK293 , Haplótipos , Humanos , Peru/epidemiologia , Fenótipo , Regiões Promotoras Genéticas , Fatores de Risco , Neoplasias Gástricas/metabolismo , Transfecção , População Branca/genética
13.
Immunobiology ; 220(4): 437-44, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25466588

RESUMO

The protozoan parasite Leishmania infects and replicates in macrophages, causing a spectrum of diseases in the human host, varying from cutaneous to visceral clinical forms. It is known that cytokines modulate the immunological response against Leishmania and are relevant for infection resolution. Here, we report that Interleukin (IL)-27 increases Leishmania amazonensis replication in human and murine macrophages and that the blockage of the IL-10 receptor on the surface of infected cells abolished the IL-27-mediated enhancement of Leishmania growth. IL-27 induced the activation/phosphorylation of protein kinase R (PKR) in macrophages, and PKR blockage or PKR gene deletion abrogated the enhancement of the parasite growth driven by IL-27, as well as the L. amazonensis-induced macrophage production of IL-27. We also observed that L. amazonensis-induced expression of IL-27 depends on type I interferon signaling and the engagement of Toll-like receptor 2. Treatment of Leishmania-infected mice with IL-27 increased lesion size and parasite loads in the footpad and lymph nodes of infected animals, indicating that this cytokine exerts a local and a systemic effect on parasite growth and propagation. In conclusion, we show that IL-27 is a L. amazonensis-enhancing factor and that the PKR/IFN1 axis and IL-10 are critical mediators of this IL-27 induced effect.


Assuntos
Interleucina-10/metabolismo , Interleucina-27/metabolismo , Leishmania mexicana , Leishmaniose Cutânea/metabolismo , Transdução de Sinais , eIF-2 Quinase/metabolismo , Animais , Linhagem Celular , Humanos , Interferon Tipo I/metabolismo , Interleucina-27/farmacologia , Leishmaniose Cutânea/genética , Leishmaniose Cutânea/parasitologia , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Macrófagos/parasitologia , Masculino , Camundongos , Camundongos Knockout , Transdução de Sinais/efeitos dos fármacos , Receptor 2 Toll-Like/metabolismo , eIF-2 Quinase/genética
14.
PLoS One ; 8(12): e82988, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24376622

RESUMO

In a previous study we had shown that membrane cholesterol removal induced unregulated lysosomal exocytosis events leading to the depletion of lysosomes located at cell periphery. However, the mechanism by which cholesterol triggered these exocytic events had not been uncovered. In this study we investigated the importance of cholesterol in controlling mechanical properties of cells and its connection with lysosomal exocytosis. Tether extraction with optical tweezers and defocusing microscopy were used to assess cell dynamics in mouse fibroblasts. These assays showed that bending modulus and surface tension increased when cholesterol was extracted from fibroblasts plasma membrane upon incubation with MßCD, and that the membrane-cytoskeleton relaxation time increased at the beginning of MßCD treatment and decreased at the end. We also showed for the first time that the amplitude of membrane-cytoskeleton fluctuation decreased during cholesterol sequestration, showing that these cells become stiffer. These changes in membrane dynamics involved not only rearrangement of the actin cytoskeleton, but also de novo actin polymerization and stress fiber formation through Rho activation. We found that these mechanical changes observed after cholesterol sequestration were involved in triggering lysosomal exocytosis. Exocytosis occurred even in the absence of the lysosomal calcium sensor synaptotagmin VII, and was associated with actin polymerization induced by MßCD. Notably, exocytosis triggered by cholesterol removal led to the secretion of a unique population of lysosomes, different from the pool mobilized by actin depolymerizing drugs such as Latrunculin-A. These data support the existence of at least two different pools of lysosomes with different exocytosis dynamics, one of which is directly mobilized for plasma membrane fusion after cholesterol removal.


Assuntos
Membrana Celular/efeitos dos fármacos , Colesterol/química , Fibroblastos/efeitos dos fármacos , Lisossomos/metabolismo , beta-Ciclodextrinas/farmacologia , Actinas/genética , Actinas/metabolismo , Animais , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Linhagem Celular , Membrana Celular/ultraestrutura , Colesterol/deficiência , Citoesqueleto/efeitos dos fármacos , Citoesqueleto/ultraestrutura , Exocitose/efeitos dos fármacos , Fibroblastos/citologia , Fibroblastos/metabolismo , Expressão Gênica , Lisossomos/classificação , Fluidez de Membrana/efeitos dos fármacos , Camundongos , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Sinaptotagminas/antagonistas & inibidores , Sinaptotagminas/genética , Sinaptotagminas/metabolismo , Tiazolidinas/farmacologia , Proteínas rho de Ligação ao GTP/genética , Proteínas rho de Ligação ao GTP/metabolismo
15.
Cell Metab ; 18(6): 831-43, 2013 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-24315369

RESUMO

Alzheimer's disease (AD) and type 2 diabetes appear to share similar pathogenic mechanisms. dsRNA-dependent protein kinase (PKR) underlies peripheral insulin resistance in metabolic disorders. PKR phosphorylates eukaryotic translation initiation factor 2α (eIF2α-P), and AD brains exhibit elevated phospho-PKR and eIF2α-P levels. Whether and how PKR and eIF2α-P participate in defective brain insulin signaling and cognitive impairment in AD are unknown. We report that ß-amyloid oligomers, AD-associated toxins, activate PKR in a tumor necrosis factor α (TNF-α)-dependent manner, resulting in eIF2α-P, neuronal insulin receptor substrate (IRS-1) inhibition, synapse loss, and memory impairment. Brain phospho-PKR and eIF2α-P were elevated in AD animal models, including monkeys given intracerebroventricular oligomer infusions. Oligomers failed to trigger eIF2α-P and cognitive impairment in PKR(-/-) and TNFR1(-/-) mice. Bolstering insulin signaling rescued phospho-PKR and eIF2α-P. Results reveal pathogenic mechanisms shared by AD and diabetes and establish that proinflammatory signaling mediates oligomer-induced IRS-1 inhibition and PKR-dependent synapse and memory loss.


Assuntos
Peptídeos beta-Amiloides/toxicidade , Encéfalo/efeitos dos fármacos , Proteínas Substratos do Receptor de Insulina/metabolismo , Polímeros/toxicidade , Fator de Necrose Tumoral alfa/metabolismo , eIF-2 Quinase/metabolismo , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/química , Animais , Encéfalo/metabolismo , Modelos Animais de Doenças , Haplorrinos/metabolismo , Hipoglicemiantes/farmacologia , Proteínas Substratos do Receptor de Insulina/antagonistas & inibidores , Transtornos da Memória/metabolismo , Transtornos da Memória/patologia , Camundongos , Camundongos Knockout , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Fosforilação/efeitos dos fármacos , Polímeros/química , Receptores Tipo I de Fatores de Necrose Tumoral/deficiência , Receptores Tipo I de Fatores de Necrose Tumoral/genética , Receptores Tipo I de Fatores de Necrose Tumoral/metabolismo , Transdução de Sinais/efeitos dos fármacos , Sinapses/efeitos dos fármacos , Sinapses/metabolismo , Fator de Necrose Tumoral alfa/antagonistas & inibidores , eIF-2 Quinase/deficiência , eIF-2 Quinase/genética
16.
Infect Immun ; 81(5): 1654-62, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23460520

RESUMO

Brucella abortus is recognized by several Toll-like receptor (TLR)-associated pathways triggering proinflammatory responses that affect both the nature and intensity of the immune response. Previously, we demonstrated that B. abortus-mediated dendritic cell (DC) maturation and control of infection are dependent on the adaptor molecule MyD88. However, the involvement of all TLRs in response to B. abortus infection is not completely understood. Therefore, we decided to evaluate the requirement for TLR6 in host resistance to B. abortus. Here, we demonstrated that TLR6 is an important component for triggering an innate immune response against B. abortus. An in vitro luciferase assay indicated that TLR6 cooperates with TLR2 to sense Brucella and further activates NF-κB signaling. However, in vivo analysis showed that TLR6, not TLR2, is required for the efficient control of B. abortus infection. Additionally, B. abortus-infected dendritic cells require TLR6 to induce tumor necrosis factor alpha (TNF-α) and interleukin-12 (IL-12). Furthermore, our findings demonstrated that the mitogen-activated protein kinase (MAPK) signaling pathway is impaired in TLR2, TLR6, and TLR2/6 knockout (KO) DCs when infected with B. abortus, which may account for the lower proinflammatory cytokine production observed in TLR6 KO mouse dendritic cells. In summary, the results presented here indicate that TLR6 is required to trigger innate immune responses against B. abortus in vivo and is required for the full activation of DCs to induce robust proinflammatory cytokine production.


Assuntos
Brucella abortus/imunologia , Brucelose/imunologia , Imunidade Inata/fisiologia , Receptor 6 Toll-Like/fisiologia , Análise de Variância , Animais , Citocinas/metabolismo , Células Dendríticas/metabolismo , Modelos Animais de Doenças , Macrófagos/metabolismo , Camundongos , Camundongos Knockout , Quinases de Proteína Quinase Ativadas por Mitógeno/fisiologia , NF-kappa B/metabolismo , Transdução de Sinais/imunologia , Baço/microbiologia , Receptor 2 Toll-Like/fisiologia , Receptor 6 Toll-Like/deficiência
17.
J Interferon Cytokine Res ; 32(10): 495-504, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22873641

RESUMO

Double-stranded RNA dependent protein kinase (PKR) is a host defense enzyme whose expression is up-regulated in response to interferons (IFNs) and during viral infections. Increased levels of PKR can result in its activation, which, in turn, inhibits global cellular protein synthesis. Despite growing evidence suggesting the involvement of PKR in bacterial infections, little is known about its expression, regulation and cellular role in nonviral infections. The aim of this work was to determine the expression and regulation of PKR in response to stimulation of human THP-1 monocytes with bacterial agonists of TLR2/4. Treatment of cells with Pam3CSK4 or lipopolyssacharide (LPS) resulted in an increase in PKR mRNA and protein levels. Robust PKR expression at later times correlated with a decrease in global protein synthesis. PKR was also required to regulate the inhibition of protein synthesis triggered by LPS in mouse splenocytes. Surprisingly, no increase of IFN-ß or IFN-α mRNA levels was detected after treatment of THP-1 cells with toll-like receptor (TLR) agonists. In accordance with this, the supernatants from LPS or Pam3CSK4-treated cells lacked the ability to activate the PKR and ISG56 promoters in gene reporter assays carried out in HEK293T cells. The expression of PKR induced by TLRs agonists was dramatically impaired when cells were treated in the presence of tosyl-phenylalanyl chloromethylketone or Mithramycin, suggesting that NF-κB and Sp1 transcription factors, but not those activated by IFNs, regulate the expression of PKR in human monocytes.


Assuntos
Infecções Bacterianas/imunologia , Monócitos/imunologia , NF-kappa B/metabolismo , Fator de Transcrição Sp1/metabolismo , Receptor 2 Toll-Like/agonistas , Receptor 4 Toll-Like/agonistas , eIF-2 Quinase/metabolismo , Proteínas Adaptadoras de Transdução de Sinal , Animais , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Regulação Bacteriana da Expressão Gênica/genética , Células HEK293 , Humanos , Interferons/imunologia , Lipopeptídeos/farmacologia , Lipopolissacarídeos/farmacologia , Camundongos , Camundongos Knockout , Monócitos/efeitos dos fármacos , Monócitos/microbiologia , NF-kappa B/genética , Plicamicina/farmacologia , Inibidores da Síntese de Proteínas/farmacologia , Proteínas de Ligação a RNA , Fator de Transcrição Sp1/genética , Tosilfenilalanil Clorometil Cetona/farmacologia , Fatores de Transcrição/genética , eIF-2 Quinase/genética
18.
PLoS One ; 6(8): e23135, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21829705

RESUMO

Type I interferons (IFNs) are cytokines that orchestrate diverse immune responses to viral and bacterial infections. Although typically considered to be most important molecules in response to viruses, type I IFNs are also induced by most, if not all, bacterial pathogens. In this study, we addressed the role of type I IFN signaling during Brucella abortus infection, a facultative intracellular bacterial pathogen that causes abortion in domestic animals and undulant fever in humans. Herein, we have shown that B. abortus induced IFN-ß in macrophages and splenocytes. Further, IFN-ß induction by Brucella was mediated by IRF3 signaling pathway and activates IFN-stimulated genes via STAT1 phosphorylation. In addition, IFN-ß expression induced by Brucella is independent of TLRs and TRIF signaling but MyD88-dependent, a pathway not yet described for Gram-negative bacteria. Furthermore, we have identified Brucella DNA as the major bacterial component to induce IFN-ß and our study revealed that this molecule operates through a mechanism dependent on RNA polymerase III to be sensed probably by an unknown receptor via the adaptor molecule STING. Finally, we have demonstrated that IFN-αßR KO mice are more resistant to infection suggesting that type I IFN signaling is detrimental to host control of Brucella. This resistance phenotype is accompanied by increased IFN-γ and NO production by IFN-αßR KO spleen cells and reduced apoptosis.


Assuntos
Brucella abortus/isolamento & purificação , Brucelose/metabolismo , Fator Regulador 3 de Interferon/fisiologia , Interferon beta/biossíntese , Proteínas de Membrana/metabolismo , Fator 88 de Diferenciação Mieloide/metabolismo , Animais , Brucella abortus/genética , Brucelose/microbiologia , Linhagem Celular , DNA Bacteriano/genética , Macrófagos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fosforilação , RNA Polimerase III/metabolismo , Fator de Transcrição STAT1/metabolismo , Baço/citologia , Baço/metabolismo , Ligante Indutor de Apoptose Relacionado a TNF/metabolismo
19.
Cell Microbiol ; 13(10): 1518-29, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21749603

RESUMO

At the site of infection, pro-inflammatory cytokines locally produced by macrophages infected with Trypanosoma cruzi can activate surrounding non-professional phagocytes such as fibroblasts, epithelial and endothelial cells, which can be further invaded by the parasite. The effect of secreted soluble factors on the invasion of these cells remains, however, to be established. We show here that two epithelial cell lines become significantly susceptible to the infection by the Y strain of T. cruzi after tumour necrosis factor (TNF) treatment. The increase in the invasion was correlated with the increasing concentration of recombinant TNF added to cultures of HEK293T or LLC-MK2 cells. Supernatants taken from PMA-differentiated human monocytes infected with T. cruzi also increased the permissiveness of epithelial cells to subsequent infection with the parasite, which was inhibited by a TNF monoclonal antibody. Furthermore, the permissiveness induced by TNF was inhibited by TPCK, and led to significant decrease in the number of intracellular parasites, providing evidence that activation of NF-κB induced by TNF favours the invasion of the epithelial cell lines by T. cruzi through yet an unidentified mechanism. Our data indicate that soluble factors released from macrophages early in the infection favours T. cruzi invasion of non-professional phagocytic cells.


Assuntos
Células Epiteliais/imunologia , Células Epiteliais/parasitologia , NF-kappa B/metabolismo , Fagocitose , Trypanosoma cruzi/patogenicidade , Fator de Necrose Tumoral alfa/metabolismo , Animais , Linhagem Celular , Haplorrinos , Humanos
20.
Mem Inst Oswaldo Cruz ; 105(7): 895-8, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21120359

RESUMO

The aim of this work was to establish a modified pre-diagnostic polymerase chain reaction (PCR) protocol using a single primer set that enables successful amplification of a highly conserved mammalian sequence in order to determine overall sample DNA quality for multiple mammalian species that inhabit areas endemic for leishmaniasis. The gene encoding interphotoreceptor retinoid-binding protein (IRBP), but not other conserved genes, was efficiently amplified in DNA samples from tail skin, ear skin, bone marrow, liver and spleen from all of the species tested. In tissue samples that were PCR-positive for Leishmania, we found that DNA from 100%, 55% and 22% of the samples tested resulted in a positive PCR reaction for the IRBP, beta-actin and beta-globin genes, respectively. Nucleotide sequencing of an IRBP amplicon resolved any questions regarding the taxonomical classification of a rodent, which was previously based simply on the morphological features of the animal. Therefore, PCR amplification and analysis of the IRBP amplicon are suitable for pre-diagnostically assessing DNA quality and identifying mammalian species living in areas endemic to leishmaniasis and other diseases.


Assuntos
Actinas/genética , DNA de Protozoário/genética , Proteínas do Olho/genética , Leishmaniose/veterinária , Reação em Cadeia da Polimerase/veterinária , Proteínas de Ligação ao Retinol/genética , Globinas beta/genética , Actinas/análise , Animais , Primers do DNA/genética , Cães , Doenças Endêmicas , Proteínas do Olho/análise , Leishmaniose/parasitologia , Marsupiais , Reação em Cadeia da Polimerase/métodos , Proteínas de Ligação ao Retinol/análise , Roedores , Globinas beta/análise
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