Potential antioxidant response to coffee - A matter of genotype?

In a human intervention trial, a coffee, combining nature green coffee bean constituents and dark roast products was studied towards its potential to activate the Nrf2/ARE-pathway in PBLs. The study coffee was identified as a strong inducer of Nrf2 and downstream GST1A1 and UGT1A1 gene transcription. However, the response of the participants was found to depend on the respective genotype. The -651 SNP in the Nrf2 gene as well as the heterozygote 6/7 sequence in the UGT1A1 gene significantly down-regulated the susceptibility to respond to coffee, proposing the existing genotype to be critical for the response to the coffee.

Hepatic Histopathological Characteristics and Antioxidant Response of Phytoplanktivorous Silver Carp Intraperitoneally Injected with Extracted Microcystins

Objective To investigate the hispathological characteristics and antioxidant responses in liver of silver carp after intraperitoneal administration of microcystins (MCs) for further understanding hepatic intoxication and antioxidation mechanism in fish. Methods Phytoplanktivorous silver carp was injected intraperitoneally (i.p.) with extracted hepatotoxic microcystins (mainly MC-RR and -LR) at a dose of 1000 mu g MC-LReq./kg body weight, and liver histopathological changes and antioxidant responses were studied at 1, 3, 12, 24, and 48 h, respectively, after injection. Results The damage to liver structure and the activities of hepatic antioxidant enzymes including catalase (CAT), superoxide dismutase (SOD), and glutathione peroxide (GPX) were increased in a time-dependent manner. Conclusion In terms of clinical and histological signs of intoxication and LD50 (i.p.) dose of MC-LR, silver carp appears rather resistant to MCs exposure than other fishes. Also, the significantly increased SOD activity in the liver of silver carp suggests a higher degree of response to MCs exposure than CAT and GPX.

The antioxidant response of the liver of male Swiss mice raised on a AIN 93 or commercial diet

Background: Reactive oxygen species (ROS) are formed under natural physiological conditions and are thought to play an important role in many human diseases. A wide range of antioxidants are involved in cellular defense mechanisms against ROS, which can be generated in excess during stressful conditions, these include enzymes and non-enzymatic antioxidants. The aim of this study was to evaluate the antioxidant responses of mice to two diets control, commercial and the purified AIN 93 diet, commonly used in experiments with rodents. Results: Malondialdehyde (MDA) and hydrogen peroxide (H2O2) concentrations and superoxide dismutase (SOD) and glutathione reductase (GR) activities determined in the liver were lower in the group of mice fed with the AIN 93 diet, while catalase (CAT) activity was higher in the same group, when compared to the group fed on the commercial diet. Liver glutathione peroxidase (GSH-Px) activity was similar in the groups fed on either AIN 93 or the commercial diets. Two SOD isoforms, Mn-SODII and a Cu/Zn-SODV, were specifically reduced in the liver of the AIN 93 diet fed animals. Conclusions: The clear differences in antioxidant responses observed in the livers of mice fed on the two diets suggest that the macro- and micro-nutrient components with antioxidant properties, including vitamin E, can promote changes in the activity of enzymes involved in the removal of the ROS generated by cell metabolism.

Nrf1 and Nrf2 positively and c-Fos and Fra1 negatively regulate the human antioxidant response element-mediated expression of NAD(P)H:quinone oxidoreductase1 gene

Twenty-four base pairs of the human antioxidant response element (hARE) are required for high basal transcription of the NAD(P)H:quinone oxidoreductase1 (NQO1) gene and its induction in response to xenobiotics and antioxidants. hARE is a unique cis-element that contains one perfect and one imperfect AP1 element arranged as inverse repeats separated by 3 bp, followed by a “GC” box. We report here that Jun, Fos, Fra, and Nrf nuclear transcription factors bind to the hARE. Overexpression of cDNA derived combinations of the nuclear proteins Jun and Fos or Jun and Fra1 repressed hARE-mediated chloramphenicol acetyltransferase (CAT) gene expression in transfected human hepatoblastoma (Hep-G2) cells. Further experiments suggested that this repression was due to overexpression of c-Fos and Fra1, but not due to Jun proteins. The Jun (c-Jun, Jun-B, and Jun-D) proteins in all the possible combinations were more or less ineffective in repression or upregulation of hARE-mediated gene expression. Interestingly, overexpression of Nrf1 and Nrf2 individually in Hep-G2 and monkey kidney (COS1) cells significantly increased CAT gene expression from reporter plasmid hARE-thymidine kinase-CAT in transfected cells that were inducible by β-naphthoflavone and tert-butyl hydroquinone. These results indicated that hARE-mediated expression of the NQO1 gene and its induction by xenobiotics and antioxidants are mediated by Nrf1 and Nrf2. The hARE-mediated basal expression, however, is repressed by overexpression of c-Fos and Fra1.

Activation of heat shock and antioxidant responses by the natural product celastrol: transcriptional signatures of a thiol-targeted molecule.

Stress response pathways allow cells to sense and respond to environmental changes and adverse pathophysiological states. Pharmacological modulation of cellular stress pathways has implications in the treatment of human diseases, including neurodegenerative disorders, cardiovascular disease, and cancer. The quinone methide triterpene celastrol, derived from a traditional Chinese medicinal herb, has numerous pharmacological properties, and it is a potent activator of the mammalian heat shock transcription factor HSF1. However, its mode of action and spectrum of cellular targets are poorly understood. We show here that celastrol activates Hsf1 in Saccharomyces cerevisiae at a similar effective concentration seen in mammalian cells. Transcriptional profiling revealed that celastrol treatment induces a battery of oxidant defense genes in addition to heat shock genes. Celastrol activated the yeast Yap1 oxidant defense transcription factor via the carboxy-terminal redox center that responds to electrophilic compounds. Antioxidant response genes were likewise induced in mammalian cells, demonstrating that the activation of two major cell stress pathways by celastrol is conserved. We report that celastrol's biological effects, including inhibition of glucocorticoid receptor activity, can be blocked by the addition of excess free thiol, suggesting a chemical mechanism for biological activity based on modification of key reactive thiols by this natural product.

Shotgun proteomics reveals physiological response to ocean acidification in Crassostrea gigas

Background. Ocean acidification as a result of increased anthropogenic CO2 emissions is occurring in marine and estuarine environments worldwide. The coastal ocean experiences additional daily and seasonal fluctuations in pH that can be lower than projected end of century open ocean pH reductions. Projected and current ocean acidification have wide-ranging effects on many aquatic organisms, however the exact mechanisms of the impacts of ocean acidification on many of these animals remains to be characterized. Methods. In order to assess the impact of ocean acidification on marine invertebrates, Pacific oysters (Crassostrea gigas) were exposed to one of four different pCO2 levels for four weeks: 400 µatm (pH 8.0), 800 µatm (pH 7.7), 1000 µatm (pH 7.6), or 2800 µatm (pH 7.3). At the end of 4 weeks a variety of physiological parameters were measured to assess the impacts of ocean acidification: tissue glycogen content and fatty acid profile, shell micromechanical properties, and response to acute heat shock. To determine the effects of ocean acidification on the underlying molecular physiology of oysters and their stress response, some of the oysters from 400 µatm and 2800 µatm were exposed to an additional mechanical stress and shotgun proteomics were done on oysters from high and low pCO2 and from with and without mechanical stress. Results. At the end of the four week exposure period, oysters in all four pCO2 environments deposited new shell, but growth rate was not different among the treatments. However, micromechanical properties of the new shell were compromised by elevated pCO2. Elevated pCO2 affected neither whole body fatty acid composition, nor glycogen content, nor mortality rate associated with acute heat shock. Shotgun proteomics revealed that several physiological pathways were significantly affected by ocean acidification, including antioxidant response, carbohydrate metabolism, and transcription and translation. Additionally, the proteomic response to a second stress differed with pCO2, with numerous processes significantly affected by mechanical stimulation at high versus low pCO2 (all proteomics data are available in the ProteomeXchange under the identifier PXD000835). Discussion. Oyster physiology is significantly altered by exposure to elevated pCO2, indicating changes in energy resource use. This is especially apparent in the assessment of the effects of pCO2 on the proteomic response to a second stress. The altered stress response illustrates that ocean acidification may impact how oysters respond to other changes in their environment. These data contribute to an integrative view of the effects of ocean acidification on oysters as well as physiological trade-offs during environmental stress.

Pathogen-Induced Changes in the Antioxidant Status of the Apoplast in Barley Leaves

Leaves of two barley (Hordeum vulgare L.) isolines, Alg-R, which has the dominant Mla1 allele conferring hypersensitive race-specific resistance to avirulent races of Blumeria graminis, and Alg-S, which has the recessive mla1 allele for susceptibility to attack, were inoculated with B. graminis f. sp. hordei. Total leaf and apoplastic antioxidants were measured 24 h after inoculation when maximum numbers of attacked cells showed hypersensitive death in Alg-R. Cytoplasmic contamination of the apoplastic extracts, judged by the marker enzyme glucose-6-phosphate dehydrogenase, was very low (less than 2%) even in inoculated plants. Dehydroascorbate, glutathione, superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase, monodehydroascorbate reductase, and dehydroascorbate reductase were present in the apoplast. Inoculation had no effect on the total foliar ascorbate pool size or the redox state. The glutathione content of Alg-S leaves and apoplast decreased, whereas that of Alg-R leaves and apoplast increased after pathogen attack, but the redox state was unchanged in both cases. Large increases in foliar catalase activity were observed in Alg-S but not in Alg-R leaves. Pathogen-induced increases in the apoplastic antioxidant enzyme activities were observed. We conclude that sustained oxidation does not occur and that differential strategies of antioxidant response in Alg-S and Alg-R may contribute to pathogen sensitivity.

The antioxidant enzyme peroxiredoxin-2 is depleted in lymphocytes seven days after ultra-endurance exercise

Purpose: Peroxiredoxin-2 (PRDX-2) is an antioxidant and chaperone-like protein critical for cell function. This study examined whether the levels of lymphocyte PRDX-2 are altered over one month following ultra-endurance exercise. Methods: Nine middle-aged men undertook a single-stage, multi-day 233 km (145 mile) ultra-endurance running race. Blood was collected immediately before (PRE), upon completion/retirement (POST), and following the race at DAY 1, DAY 7 and DAY 28. Lymphocyte lysates were examined for PRDX-2 by reducing SDS-PAGE and western blotting. In a sub-group of men who completed the race (n = 4) PRDX-2 oligomeric state (indicative of redox status) was investigated. Results: Ultra-endurance exercise caused significant changes in lymphocyte PRDX-2 (F (4,32) 3.409, p=0.020, ?(2) =0.299): seven-days after the race, PRDX-2 levels in lymphocytes had fallen to 30% of pre-race values (p=0.013) and returned to near-normal levels at DAY 28. Non-reducing gels demonstrated that dimeric PRDX-2 (intracellular reduced PRDX-2 monomers) was increased in 3 of 4 race completers immediately post-race, indicative of an "antioxidant response". Moreover, monomeric PRDX-2 was also increased immediately post-race in 2 of 4 race-completing subjects, indicative of oxidative damage, which was not detectable by DAY 7. Conclusions: Lymphocyte PRDX-2 was decreased below normal levels 7 days after ultra-endurance exercise. Excessive accumulation of reactive oxygen species induced by ultra-endurance exercise may underlie depletion of lymphocyte PRDX-2 by triggering its turnover after oxidation. Low levels of lymphocyte PRDX-2 could influence cell function and might, in part, explain reports of dysregulated immunity following ultra-endurance exercise.

Potential Mechanisms Underlying Response to Effects of the Fungicide Pyrimethanil from Gene Expression Profiling inSaccharomyces cerevisiae

Pyrimethanil is a fungicide mostly applied in vineyards. When misused, residue levels detected in grape must or in the environment may be of concern. The present work aimed to analyze mechanisms underlying response to deleterious effects of pyrimethanil in the eukaryotic model Saccharomyces cerevisiae. Pyrimethanil concentration-dependent effects at phenotypic (inhibition of growth) and transcriptomic levels were examined. For transcriptional profiling, analysis focused on two sublethal exposure conditions that inhibited yeast growth by 20% or 50% compared with control cells not exposed to the fungicide. Gene expression modifications increased with the magnitude of growth inhibition, in numbers and fold-change of differentially expressed genes and in diversity of over-represented functional categories. These included mostly biosynthesis of arginine and sulfur amino acids metabolism, as well as energy conservation, antioxidant response, and multidrug transport. Several pyrimethanil-responsive genes encoded proteins sharing significant homology with proteins from phytopathogenic fungi and ecologically relevant higher eukaryotes.

The potential role of lycopene for the prevention and therapy of prostate cancer : from molecular mechanisms to clinical evidence

Lycopene is a phytochemical that belongs to a group of pigments known as carotenoids. It is red, lipophilic and naturally occurring in many fruits and vegetables, with tomatoes and tomato-based products containing the highest concentrations of bioavailable lycopene. Several epidemiological studies have linked increased lycopene consumption with decreased prostate cancer risk. These findings are supported by in vitro and in vivo experiments showing that lycopene not only enhances the antioxidant response of prostate cells, but that it is even able to inhibit proliferation, induce apoptosis and decrease the metastatic capacity of prostate cancer cells. However, there is still no clearly proven clinical evidence supporting the use of lycopene in the prevention or treatment of prostate cancer, due to the only limited number of published randomized clinical trials and the varying quality of existing studies. The scope of this article is to discuss the potential impact of lycopene on prostate cancer by giving an overview about its molecular mechanisms and clinical effects. © 2013 by the authors; licensee MDPI, Basel, Switzerland.

Ativação do estresse oxidativo e da resposta antioxidante por ExoU de Pseudomonas aeruginosa

ExoU, uma citotoxina produzida pelo patógeno oportunista Pseudomonas aeruginosa e translocada para o citosol de células hospedeiras via sistema de secreção do tipo III, é associada à gravidade de infecções agudas. No presente trabalho, o efeito de ExoU na ativação do estresse oxidativo e da resposta antioxidante foi avaliado em culturas de células epiteliais respiratórias humanas infectadas com a cepa PA103 de P. aeruginosa (produtora de ExoU), com a mutante deletada no gene exoU, PA103∆exoU, ou com a mutante complementada com exoU sem atividade tipo fosfolipase A2, PA103∆UT/S142A. Análises das dosagens de hidroperóxidos lipídicos e isoprostanos, considerados marcadores de estresse oxidativo, revelaram que ExoU promoveu um aumento em suas concentrações. Foi observado, também, que ExoU estimulou a produção de espécies reativas de oxigênio, óxido nítrico e peroxinitrito nas células infectadas, assim como a expressão de iNOS e eNOS, mas não de nNOS. Além disso, ExoU foi responsável pelo aumento da atividade de SOD1 e pela redução dos níveis de GSH, mas não afetou a atividade da catalase ou de NQO1. No modelo in vivo, a dosagem de malondialdeído, um subproduto da lipoperoxidação de membranas, evidenciou uma maior produção deste composto no pulmão de camundongos infectados pela cepa produtora de ExoU, em comparação ao pulmão de camundongos infectados pela cepa mutante. Em conjunto, estes resultados mostram que ExoU ativa a produção de espécies reativas de oxigênio e nitrogênio, levando à peroxidação lipídica e modulando o sistema de defesa antioxidante

Aluminium toxicity in wheat and rye

Com o presente trabalho pretendeu-se determinar e compreender melhor quais os alvos do Alumínio (Al) nas plantas, e contribuir para um melhor entendimento dos mecanismos de tolerância presentes em genótipos com elevado grau de tolerância ao Al. O Al é um dos maiores constituintes do solo e torna-se biodisponível em solos com baixo pH. Nesses casos, a exposição ao Al afecta negativamente o crescimento das plantas conduzindo a uma diminuição da produção. Estes factos são especialmente visíveis nos cereais, sendo a exposição ao Al uma das principais causas das quebras de produção nestas espécies. O Capítulo I consiste numa revisão geral sobre a toxicidade do Al nas plantas, apontando os seus principais alvos. Apresenta também os mecanismos de resistência, que inclui Al-destoxificação externa e interna, em diferentes espécies. O Capítulo II aborda os estudos sobre a exposição de curto prazo ao Al em duas espécies de cereais: Triticum aestivum L. e Secale cereale L., tendo-se sempre utilizado um genótipo Al-tolerante e um Al-sensível para cada espécie. Este capítulo está dividido em três estudos: no Capítulo II.1 realça-se o efeito da exposição a 185 μM de Al no equilíbrio nutricional em trigo. Verificou-se que em ambos os genótipos (sensível e tolerante) o perfil de macro e micro nutrientes se alterou, tendo uma interferência negativa, sobretudo no nível de P, Mg e K. Além disso, registaram-se diferenças na diferenciação da endoderme consoante o grau de tolerância/sensibilidade do genótipo. No Capítulo II.2 apresenta-se uma visão mais abrangente dos efeitos da exposição a 185 μM de Al em trigo, incluindo parâmetros fisiológicos, estruturais, citológicos e genotóxicos. Demonstra-se, pela primeira vez, que a progressão do ciclo celular é diferentemente regulada, dependendo da tolerância/sensibilidade do genótipo e que, mesmo em zonas já diferenciadas da raiz a exposição ao Al leva à deposição de calose. O Capítulo II.3 aborda os efeitos da exposição de 1.1 mM de Al em centeio, numa perspectiva bastante alargada. Apresenta-se o desequilíbrio nutricional, sobretudo no genótipo sensível, assim como a translocação de Al para a parte aérea nesse mesmo genótipo. Analisa-se também o comportamento de ambos os genótipos no que se refere ao ciclo celular, diferenciação da endoderme, crescimento radicular, reservas de hidratos de carbono, entre outros. Os resultados apontam para estratégias bem definidas adoptadas pelo genótipo tolerante de forma a minimizar a acção do Al no sistema radicular. O Capítulo III compreende a exposição longa ao Al. Dois genótipos de centeio com diferentes graus de tolerância ao Al foram expostos a 1.11 mM e 1.85 mM de Al durante 21 dias, tendo sido usados dois pontos de amostragem (15 e 21 dias). Este capítulo está dividido em dois estudos: No Capítulo III. 1 analisamse os mecanismos antioxidantes (folhas e raízes) como resposta à exposição ao Al, dando-se especial atenção ao ciclo do ascorbato-glutationas. A exposição ao Al levou a stress oxidativo e a alterações na actividade de enzimas antioxidantes e no conteúdo de antioxidantes não-enzimáticos. Demonstra-se que os dois órgãos apresentam respostas diferentes à exposição ao Al e que a capacidade de sobreviver em ambientes ricos em Al depende da eficácia da resposta antioxidante. Para além disso, a resposta do ciclo ascorbato-glutationas parece estar dependente do tipo de órgão, grau de tolerância e do tempo de exposição ao Al. No Capítulo III. 2 analisam-se os efeitos da exposição ao Al na fotossíntese. Verificou-se que o Al afecta negativamente a taxa fotossintética em ambos os genótipos, embora as alterações que o Al provoca nas trocas gasosas e no Ciclo de Calvin sejam dependentes do genótipo. Verificou-se também que os danos no genótipo sensível surgem mais cedo do que no genótipo tolerante, mas que ambos apresentam susceptibilidade ao Al após exposição de longo termo. Por fim, no Capítulo IV são apresentadas as conclusões da Tese de Doutoramento.

Investigating the role of Annexin A2 in Epidermal Growth Factor (EGF) induced signalling in cancer

Dissertação de mestrado, Qualidade em Análises, Faculdade de Ciências e Tecnologia, Universidade do Algarve; Universitat de Barcelona; Gdansk University of Technology, Universidad de Cádiz, Universitas Bergensis; 2015

Cellular polarity in aging: role of redox regulation and nutrition

Cellular polarity concerns the spatial asymmetric organization of cellular components and structures. Such organization is important not only for biological behavior at the individual cell level, but also for the 3D organization of tissues and organs in living organisms. Processes like cell migration and motility, asymmetric inheritance, and spatial organization of daughter cells in tissues are all dependent of cell polarity. Many of these processes are compromised during aging and cellular senescence. For example, permeability epithelium barriers are leakier during aging; elderly people have impaired vascular function and increased frequency of cancer, and asymmetrical inheritance is compromised in senescent cells, including stem cells. Here, we review the cellular regulation of polarity, as well as the signaling mechanisms and respective redox regulation of the pathways involved in defining cellular polarity. Emphasis will be put on the role of cytoskeleton and the AMP-activated protein kinase pathway. We also discuss how nutrients can affect polarity-dependent processes, both by direct exposure of the gastrointestinal epithelium to nutrients and by indirect effects elicited by the metabolism of nutrients, such as activation of antioxidant response and phase-II detoxification enzymes through the transcription factor nuclear factor (erythroid-derived 2)-like 2 (Nrf2). In summary, cellular polarity emerges as a key process whose redox deregulation is hypothesized to have a central role in aging and cellular senescence.