3,929 research outputs found
Hypoxia activates IKK-NF-κB and the immune response in <em>Drosophila melanogaster</em>
No full textHypoxia, or low oxygen availability, is an important physiological and pathological stimulus for multicellular organisms. Molecularly, hypoxia activates a transcriptional programme directed at restoration of oxygen homoeostasis and cellular survival. In mammalian cells, hypoxia not only activates the HIF (hypoxia-inducible factor) family, but also additional transcription factors such as NF-?B (nuclear factor ?B). Here we show that hypoxia activates the IKK–NF-?B [I?B (inhibitor of nuclear factor ?B)–NF-?B] pathway and the immune response in Drosophila melanogaster. We show that NF-?B activation is required for organism survival in hypoxia. Finally, we identify a role for the tumour suppressor Cyld, as a negative regulator of NF-?B in response to hypoxia in Drosophila. The results indicate that hypoxia activation of the IKK–NF-?B pathway and the immune response is an important and evolutionary conserved response.</p
Development of a secreted cell-permeable NF-κB inhibitor to control inflammation
No full textPhDRheumatoid arthritis (RA) is an autoimmune chronic inflammatory disease, of
unknown aetiology. Several disease-modulating approaches have been developed in
the past years, however these are expensive, usually accompanied by unwanted
side-effects and 30% of the patients fail to respond. The transcription factor NF-kB is
a key factor in the development and perpetuation of the disease, as it regulates a
number of inflammatory genes. The activity of certain signalling pathways can be
modulated by delivering into cells inhibitors coupled to Protein Transduction Domains
(PTDs). The aim of this study was to develop a secretable PTD-fusion NF-κΒ inhibitor
that is produced and secreted by genetically engineered mammalian cells in sufficient
amounts to subsequently transduce and regulate NF-κΒ activity in neighbouring cells.
Such methodology could be useful for the management of RA by transplantation of
engineered cells or directly using gene delivery into the synovial joints.
In this study, PTD-fusion proteins were fused to the IL-2 secretion signal and
their ability to be secreted from mammalian cells was explored. Secretable forms of
TAT-IgG2A and TAT-eGFP were generated as control PTD-fusion proteins, and the
TAT-srIκΒα (super repressor IκBα, a NF-κΒ inhibitor) was generated as an NF-κΒ
PTD-fusion inhibitor. Western blotting analysis of supernatants from transiently
transfected 293T cells revealed that TAT-IgG2A, TAT-eGFP and TAT-srIκΒα are
secreted with variable efficiencies. When concentrated, PTD proteins were able to
transduce mammalian cells, as demonstrated with Jurkat cells by confocal
microscopy and western blotting analysis.
The TAT PTD domain was replaced to a more stable, furin cleavage-resistant
and less positively charged PTD domain, the TAT3 PTD domain, to ensure that PTDfusion
proteins will be secreted more efficiently. This change of the PTD domain did
not increase secretion levels of the srΙκBα. Subsequently, the Latent Associated
Peptide (LAP) of TGFβ, was fused to the TAT3-srIκΒα inhibitor, via a matrix
metalloproteinase (MMP) cleavage linker. This LAP-MMP-PTD-fusion NF-κΒ inhibitor
was again poorly secreted. In turn, the srIκΒα inhibitor was replaced with a small
synthetic NF-κΒ inhibitor, termed Nemo Binding Domain (NBD), in the form of LAP
MMP-TAT3-NBD NF-κΒ inhibitor. Western blotting analysis of supernatants from
transiently transfected 293T cells revealed that the LAP-MMP-TAT3-NBD was
efficiently secreted.
The ability of LAP-MMP-TAT3-NBD to inhibit NF-κΒ was tested in vitro with the
use of a cell-assay based on HeLa cells that are permanently transfected with the
luciferase gene driven by an NF-κB regulated promoter. In this assay, HeLa cells that
were treated with the secreted LAP-MMP-TAT3-NBD, showed reduced levels of
luciferase activity after IL-1β stimulation. Subsequently, using a replication-deficient
lentiviral vector, genetically engeneered DBA/1 fibroblasts (DTF) able to produce the
secreted LAP-MMP-TAT3-NBD were generated. The NF-κB inhibitory properties of
the secreted LAP-MMP-TAT3-NBD were tested in vivo in the Carrageenan-induced
paw oedema, Antigen Induced Arthritis and Air-Pouch acute inflammation models.
Paws of mice that were treated with engineered cells or lentivirus encoding LAPMMP-
TAT3-NBD demonstrated milder paw swelling, suggesting that LAP-MMPTAT3-
NBD had a protective role in the induction of inflammation. However, the LAPMMP-
TAT3-NBD did not demonstrate anti-inflammatory effects in the Air-Pouch
model.
In this study, I present a method to design PTD-fusion proteins that can be
efficiently secreted from mammalian cells and I demonstrate a novel gene therapy
approach for the local delivery of a therapeutic agent
Aberrant NF-kappaB expression in autism spectrum condition : a mechanism for neuroinflammation
No full textAutism spectrum condition (ASC) is recognized as having an inflammatory component. Post-mortem brain samples from patients with ASC display neuroglial activation and inflammatory markers in cerebrospinal fluid, although little is known about the underlying molecular mechanisms. Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) is a protein found in almost all cell types and mediates regulation of immune response by inducing the expression of inflammatory cytokines and chemokines, establishing a feedback mechanism that can produce chronic or excessive inflammation. This article describes immunodetection and immunofluorescence measurements of NF-κB in human post-mortem samples of orbitofrontal cortex tissue donated to two independent centers: London Brain Bank, Kings College London, UK (ASC: n = 3, controls: n = 4) and Autism Tissue Program, Harvard Brain Bank, USA (ASC: n = 6, controls: n = 5). The hypothesis was that concentrations of NF-κB would be elevated, especially in activated microglia in ASC, and pH would be concomitantly reduced (i.e., acidification). Neurons, astrocytes, and microglia all demonstrated increased extranuclear and nuclear translocated NF-κB p65 expression in brain tissue from ASC donors relative to samples from matched controls. These between-groups differences were increased in astrocytes and microglia relative to neurons, but particularly pronounced for highly mature microglia. Measurement of pH in homogenized samples demonstrated a 0.98-unit difference in means and a strong (F = 98.3; p = 0.00018) linear relationship to the expression of nuclear translocated NF-κB in mature microglia. Acridine orange staining localized pH reductions to lysosomal compartments. In summary, NF-κB is aberrantly expressed in orbitofrontal cortex in patients with ASC, as part of a putative molecular cascade leading to inflammation, especially of resident immune cells in brain regions associated with the behavioral and clinical symptoms of ASC.Peer reviewe
NF-κB translocation assay ImageJ macro
No full textThis is ImageJ macro used to determine the degree of NF-κB translocation in cells stained for NF-κB and nuclear signal. It is a part of publication entitled "Plasma extracellular vesicles signal spleen fibroblasts facilitating Plasmodium vivax adherence". Please see the publication for full author details.</p
Translocação nuclear de NF-KB e de receptores de glicocorticoides em células musculares lisas: envolvimento do óxido nítrico e do peroxinitrito
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Biológicas, Programa de Pós-Graduação em Farmacologia, Florianópolis, 2011O lipopolissacarídeo (LPS) é um componente da parede de bactérias Gram-negativas capaz de induzir respostas inflamatórias sistêmicas pela capacidade de ativar o fator de transcrição nuclear .B (NF-.B). Além do LPS, a presença de citocinas como IFN-., também promovem a ativação do NF-.B. Uma vez que este fator é ativado, inúmeros genes pró-inflamatórios são transcritos, elevando a expressão de citocinas como TNF-a, IL-1, IL-6, IFN-. e a enzima NOS-2. Um dos mecanismos endógenos anti-inflamatórios mais importantes é a ativação de receptores de glicocorticoides (GR). Utilizando um modelo in vitro baseado em aspectos relevantes da sepse, uma doença de cunho inflamatório, mostrou-se que células musculares lisas (CML) de aorta de rato da linhagem A7r5 são ativadas pelo estímulo LPS/IFN produzindo NO, dosado na forma do seu metabólito, nitrito. De forma inédita, observou-se que a ativação das CML depende de um pulso inicial de NO oriundo de NOS constitutivas, uma vez que a inibição do mesmo diminui substancialmente a ativação celular. Além do pulso de NO, ocorre também uma rápida produção de EROs após estimulação das células com LPS. A caracterização e presença de GR funcionais nestas células permitiram o acompanhamento da sua dinâmica após estimulação com LPS/IFN. Surpreendentemente, a estimulação com LPS/IFN induz um aumento na translocação nuclear destes receptores de forma concomitante com a translocação nuclear do NF-.B, cuja intensidade de translocação é parcialmente regulada pelo NO. Outro fator que parece intermediar a translocação nuclear de GR e NF-.B e exercer um papel fundamental no curso da ativação celular é o peroxinitrito, que pode estar sendo formado imediatamente após a estimulação das células pela reação do pulso de NO com o ânion superóxido. Os resultados mostram que o NO e seus derivados desempenham um papel fundamental no início da ativação celular e na translocação nuclear de GR, contribuindo para o entendimento do início do processo de ativação celular
Deletion of vitamin D receptor leads to premature emphysema/COPD by increased matrix metalloproteinases and lymphoid aggregates formation
No full textDeficiency of vitamin D is associated with accelerated decline in lung function. Vitamin D is a ligand for nuclear hormone vitamin D receptor (VDR), and upon binding it modulates various cellular functions. The level of VDR is reduced in lungs of patients with chronic obstructive pulmonary disease (COPD) which led us to hypothesize that deficiency of VDR leads to significant alterations in lung phenotype that are characteristics of COPD/emphysema associated with increased inflammatory response. We found that VDR knock-out (VDR(-/-)) mice had increased influx of inflammatory cells, phospho-acetylation of nuclear factor-kappaB (NF-κB) associated with increased proinflammatory mediators, and up-regulation of matrix metalloproteinases (MMPs) MMP-2, MMP-9, and MMP-12 in the lung. This was associated with emphysema and decline in lung function associated with lymphoid aggregates formation compared to WT mice. These findings suggest that deficiency of VDR in mouse lung can lead to an early onset of emphysema/COPD because of chronic inflammation, immune dysregulation, and lung destruction
Current concepts on oxidative/carbonyl stress, inflammation and epigenetics in pathogenesis of chronic obstructive pulmonary disease
No full textChronic obstructive pulmonary disease (COPD) is a global health problem. The current therapies for COPD are poorly effective and the mainstays of pharmacotherapy are bronchodilators. A better understanding of the pathobiology of COPD is critical for the development of novel therapies. In the present review, we have discussed the roles of oxidative/aldehyde stress, inflammation/immunity, and chromatin remodeling in the pathogenesis of COPD. An imbalance of oxidants/antioxidants caused by cigarette smoke and other pollutants/biomass fuels plays an important role in the pathogenesis of COPD by regulating redox-sensitive transcription factors (e.g., NF-κB), autophagy and unfolded protein response leading to chronic lung inflammatory response. Cigarette smoke also activates canonical/alternative NF-κB pathways and their upstream kinases leading to sustained inflammatory response in lungs. Recently, epigenetic regulation has been shown to be critical for the development of COPD because the expression/activity of enzymes that regulate these epigenetic modifications have been reported to be abnormal in airways of COPD patients. Hence, the significant advances made in understanding the pathophysiology of COPD as described herein will identify novel therapeutic targets for intervention in COPD
Efeito citotóxico do óxido nítrico e do taxol em células linfoblásticas leucêmicas: envolvimento do fator de transcrição NF-kB e papel da glutationa
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Biológicas. Programa de Pós-Graduação em Farmacologia.O presente trabalho avaliou, através de técnicas moleculares, bioquímicas e farmacológicas, o efeito citotóxico do óxido nítrico (NO) e do taxol sobre células linfoblásticas leucêmicas. Foi investigado o envolvimento do NF-kB e a importância da glutationa na citotoxicidade causada pelo NO e pelo taxol. Os resultados obtidos, demonstraram que o efeito citotóxico do NO e do taxol sobre células leucêmicas linfoblásticas parecem atuar em vias muito semelhantes, ou seja, ambos apresentaram ações independentes de alterações no citoesqueleto, inibiram a atividade do NF-kB e depletaram os níveis de glutationa (GSH). Além disso, quando associados, apresentaram efeito citotóxico sinérgico. Sendo assim, concluímos que o NO e o taxol, além de diminuírem os níveis de glutationa intracelular, o que sensibiliza as células aos danos oxidativos e nitrosativos, também impedem o restabelecimento dos níveis normais de GSH intracelular, através da inibição da atividade do NF-kB
Pathogenetics mechanisms in celiac disease
No full textLa tesi di Dottorato, svolta presso il Dipartimento di Farmacologia Sperimentale, redatta in lingua inglese ed intitolata “PATHOGENETICS MECHANISMS IN CELIAC DISEASE” ha riguardato lo studio dei meccanismi molecolari coinvolti nella patogenesi della Celiachia.
I risultati della ricerca, condotta nel primo anno, ci hanno permesso di dimostrare che il fattore di trascrizione nuclear factor-B (NF-B) è attivato nella mucosa intestinale di pazienti celiaci indicando un ruolo per IB- nel regolare la persistente attivazione di NF-B in questa patologia. Le cellule epiteliali delle cripte e le cellule mononucleate della lamina propria di pazienti celiaci risultavano positive per p65 rispetto ai pazienti celiaci in remissione e di controllo. Inoltre, l'attivazione di NF-B era correlata con l'espressione della monossido d’azoto sintasi inducibile (iNOS) e della cicloossigenasi-2 (COX-2), enzimi che catalizzano la sintesi di monossido d’azoto (NO) e prostaglandine pro-infiammatorie.
Queste osservazioni potrebbero essere di una certa rilevanza clinica poichè una sostenuta attivazione di NF-B nella mucosa intestinale di pazienti celiaci conduce ad una prolungata induzione dell'espressione di geni pro-infiammatori perpetuando in tal modo il processo infiammatorio cronico.
I risultati della ricerca, condotta nel secondo e terzo anno, ci hanno permesso di approfondire alcuni meccanismi dell’interazione diretta della gliadina (un peptide del glutine) con i macrofagi murini RAW 264.7 stimolati con IFN-. In particolare, la gliadina in associazione con IFN- incrementava la produzione di NO, l’espressione della iNOS, l’attività di legame dei fattori di trascrizione NF-B, IRF-1 (interferon regulatory factor-1) e STAT-1 (signal transducer and activator of transcription-1 al DNA rispetto all’IFN- da solo. Questi effetti erano inibiti significativamente da pirrolidina ditiocarbammato, genisteina e tirfostina B42, rispettivamente, inibitori dell’attivazione di NF-B, IRF-1 e STAT-1. Approfondendo questi studi, è stato possibile accertare che la gliadina era in grado di aumentare i livelli di mRNA e l’attività del promotore del gene della iNOS nei macrofagi RAW 264.7 stimolati con IFN-per 1, 6 e 24 ore Questi effetti erano inibiti significativamente da genisteina e tirfostina B42 a 1 ora e da pirrolidina ditiocarbammato a 6 e 24 ore. E’ interessante osservare che le cinetiche di inibizione dell’espressione del gene della iNOS da parte di pirrolidina ditiocarbammato, genisteina e tirfostina B42 erano correlate con l’induzione dei livelli di mRNA dei fattori di trascrizione NF-B/p65, IRF-1 e STAT-1.
Questi risultati suggeriscono che la gliadina può modulare l’espressione del gene della iNOS come co-segnale con l’IFN- attraverso IRF-1 e STAT-1 nelle fasi precoci e NF-B nelle fasi tardive dell’induzione.
In conclusione, le nostre osservazioni possono contribuire ad una maggiore comprensione dei meccanismi molecolari della patogenesi della celiachia delineando nuove vie per il trattamento di questo disordine
Functional interactions of the Tax and p13 proteins of Human T-cell Leukemia Virus Type I
No full textHuman T-cell leukemia virus type 1 (HTLV-1) establishes a lifelong persistent infection in humans. Approximately 3% of the infected individuals will develop adult T-cell leukemia/lymphoma (ATLL), an aggressive malignancy of mature CD4+ T-cells. The viral protein Tax plays a major role in HTLV-1 pathogenicity by activating the NF-κB pathway. Tax activates both the canonical and non-canonical NF-κB pathways, promoting NF-κB translocation to the nucleus and transcription of genes that favour T-cell proliferation and survival. Our previous studies showed that the p13 protein of HTLV-1 enhances mitochondrial ROS production, resulting in activation of normal T-cells. ROS constitute a homeostatic rheostat that controls the activity of several key pathways, including the NF-κB pathway.Thus, we hypothesized that the effects of p13 on ROS production could affect the activation of the NF-κB pathway by Tax in primary T-cells.
The work described in the present thesis was aimed at testing the hypothesis that Tax and p13 might act in concert to activate the NF-κB signal transduction pathway in primary T-cells. To this end, we optimized a transfection protocol for primary T-cells using an innovative approach based on the electroporation of in vitro-transcribed RNA. Activation of the NF-κB pathway was then analysed by measuring expression of the NF-κB target genes CD25 and 4-1BB.
Results showed that the co-transfection of Tax and p13 resulted in a synergistic activation of the NF-κB pathway in primary T-cells measured as an increase in the expression levels of both CD25 and 4-1BB. In addition to being a transcriptional target of NF-κB, CD25 is also an early marker of T-cell activation. To further test the effects of Tax and p13 on cell activation, we measured CD38 expression by flow cytometry. Jurkat T-cells, which exhibit a constitutively activated CD38 positive phenotype, were used as a control. Results of this analysis confirmed the synergy of Tax and p13, although the effect was not so prominent as that observed for the CD25 marker, suggesting that, within the time frame of our experiments, Tax and p13 drove T-cells to an early-intermediate stage of activation.
Taken together, these findings suggest that, in contrast to the well-established role of Tax as an activator of the NF-κB pathway in tumor cell lines, in the context of normal T-cells, the induction of NF-κB target genes requires the concerted action of Tax and p13.
Current studies are aimed at verifying the ROS-dependence of this effect and testing the functional interaction of Tax and p13 in the context of the complete HTLV-1 genome using wild type HTLV-1 and a p13-knock-out HTLV-1 molecular clone. These experiments will be carried out in primary T-cells as well as in dendritic cells, which have recently emerged as an important target of the virus in vivo
- …
