Among abiotic stresses, salinity is considered the main limiting stress that negatively affects plant growth and reduces productivity worldwide. To overcome this challenge, a sustainable solution such as plant growth-promoting bacteria (PGPB) can be used to meet the increasing demand for food. The desert microbe Enterobacter sp SA187, an endophytic PGPB, induces salt tolerance in both model plant and crops. The interaction between SA187 and the host plant triggers the sulfur pathway in the bacteria which then provides multiple sulfur-containing compounds to its host plant. However, the molecular sensor of these compounds in the host plant is not known. Here, we show that SA187 activates the plant target of rapamycin (TOR) pathway. The beneficial effect of SA187 was lost in TOR mutants like raptor, and by the application of TOR inhibitor AZD8055. Next, we show that SA187 modulates the one- carbon (1C) metabolism of the host plant consisting of methionine and folate cycles. The beneficial effect of SA187 was compromised by using chemical inhibitors of folate cycle like Methotrexate (MTX) and Sulfadiazine (SDZ). The intermediates of the 1C metabolism like Homocysteine and S-adenosyl methionine (SAM) showed similar beneficial effects as SA187 colonized plants. Finally, we showed that SA187 enhances 1C metabolism activity by increasing methylation index (SAM/SAH ratio) in the plants. Taken together, we could show that host TOR-1C axis is essential for plant salt tolerance by SA187.

Les Troubles du Spectre Autistique (TSA) sont caractérisés par deux principaux symptômes : des difficultés de communication sociale et des comportements stéréotypés et intérêts restreints. Les TSA touchent 5 fois plus les garçons que les filles et une augmentation de la prévalence exponentielle et continue a été observée aux États-Unis ces dernières décennies. Cette augmentation ne peut s’expliquer par les facteurs génétiques à eux seuls qui ne représentent que 5 à 15% des cas de TSA. Il est donc indispensable d’identifier de potentiels facteurs de risque environnementaux des TSA. Le but de ce travail est d’étudier différents facteurs environnementaux potentiellement modifiables dans le développement de phénotypes autistiques dans différents modèles précliniques des TSA. Les objectifs spécifiques sont : (i) caractériser les effets neurocomportementaux provoqués par une exposition périnatale simultanée à 5 perturbateurs endocriniens parmi les plus prévalent dans notre environnement quotidien (DEHP, DBP, DiNP, BDE-47, BDE-99) à de faibles doses pertinentes pour l’exposition humaine, (ii) identifier les effets neurocomportementaux associés à une altération périconceptionnelle du microbiote maternelle (iii) déterminer les effets neurocomportementaux associés à une altération périconceptionnelle du métabolisme monocarboné. Les résultats présentés dans cette thèse démontrent le potentiel de chacun de ces facteurs environnementaux d’altérer le développement cérébral fœtal. Chaque condition expérimentale a provoqué l’apparition de traits autistiques chez les rats, avec des spécificités comportementales pour chaque exposition développementale. Des déficits d’interactions sociales ont été observés dans chaque situation expérimentale, associés soit à de l’anxiété, de l’hyperactivité, des altérations d’intégration sensorimotrice, et/ou des stéréotypies. Cela nous force à considérer les TSA comme une pathologie aux multiples facettes où l’hétérogénéité des tableaux cliniques est représentative de l’hétérogénéité des causes possibles. La multitude des interactions environnementales courantes possibles avec l’épigénome pourrait être à la base de la grande diversité observée dans la sévérité des symptômes et / ou des comorbidités des TSA. Ce travail ouvre des perspectives futures de prévention ciblée des TSA fondées sur de potentielles modifications de l’environnement comme la réduction de l’exposition aux perturbateurs endocriniens, ou des supplémentations en donneurs monocarbonés (e.g. acide folique) et/ou probiotiques.

Numerous studies have investigated how bulk lipid metabolism is influenced in obesity and in particular how the composition of triglycerides found in the cytosol change with increased adipocyte expansion. However, in part reflecting the analytical challenge the composition of cell membranes, and in particular glycerophospholipids, an important membrane component, have been seldom investigated. Cell membrane components contribute to a variety of cellular processes including maintaining organelle functionality, providing an optimized environment for numerous proteins and providing important pools for metabolites, such as choline for one-carbon metabolism and S-adenosylmethionine for DNA methylation. Here, I have conducted a comprehensive lipidomic and transcriptomic study of white adipose tissue in mice that become obese either through genetic modification (ob/ob genotype), diet (high-fat diet) or a combination of the two across the life course. Specifically, I demonstrated that the changes in triglyceride metabolism that dominate the overall lipid composition of white adipose tissue were distinct from the compositional changes of glycerophospholipids. These latter lipids became more unsaturated to maintain the fluidity and normal function of the membrane in the initiation of obesity but then turned saturated after long-term administration of HFD and aging. This suggests that while triglycerides within the adipose tissue may be a relatively inert store of lipids, the compositional changes occur in cell membranes with more far-reaching functional consequences in both obesity and aging. The two-phase change of phospholipids can be correlated well with transcriptional and one-carbon metabolic changes within the adipocytes. The transcriptomic study demonstrated that the lipid metabolic pathways regulated by the peroxisome, AMPK, insulin and PPARγ signaling were activated in the initiation of obesity but inhibited in the adipose tissue of old ob/ob mice along with up-regulated inflammation pathways. The brown and white adipose tissue of PPARα-knock-out mice were also studied by lipidomic tools to get a deeper understanding of the effect of the peroxisome and PPAR system on adipose tissue and lipid metabolism during obesity. Most of the lipids were increased and became more saturated and shorter in adipose tissues of PPARα null mice, which is in good accordance with the results of the former animal study. In conclusion, my work using different rodent models and multi-omics techniques demonstrated a protective metabolic mechanism activated in the initiation but impaired at the end of the processes of obesity and aging, which could be an explanation of the similarity of obesity and aging in terms of high incidence of the metabolic syndrome and related diseases.

Cells must regulate their metabolism in order to grow, adapt to changes in nutrient availability and maintain homeostasis. Flux, or the turnover of metabolites, through the metabolic network can be regulated at the allosteric and transcriptional levels. While study of allosteric regulation is limited to biochemical examination of individual proteins, transcriptional control of metabolism can be explored at a systems level. We endeavored to elucidate transcriptional mechanisms of metabolic flux regulation in the model organism Caenorhabditis elegans (C. elegans). We also worked to create a visual tool to explore metabolic pathways that will support future efforts in the research of metabolic gene regulation. C. elegans is a small, free-living nematode that feeds on bacteria and experiences a high level of diversity in nutrient level and composition. Previously, we identified a mechanism by which the essential cofactor, vitamin B12, regulates the expression of genes involved in the degradation of propionate, referred to as B12‑mechanism‑I. This mechanism functions to prevent the toxic accumulation of propionate and requires the TFs NHR-10 and NHR-68. Using genetic screens as well as transcriptomic and metabolomic approaches, we discover a second mechanism by which vitamin B12 regulates metabolic gene expression: B12-mechanism-II. Unlike B12-mechanism-I, B12-mechanism-II is independent of propionate, requires the transcription factor NHR-114 and functions to maintain the metabolic activity of the Methionine/S-adenosylmethionine cycle in a tightly regulated regime. We also present WormPaths, an online resource that allows visualization of C. elegans metabolic pathways and enables metabolic pathway enrichment of user-uploaded transcriptomic data.

Prostate cancer is the most common cancer among men. The purpose of this quantitative, meta-analysis study was to examine one-carbon metabolism gene polymorphisms in a group of genes to determine their association with prostate cancer risk. The genetic epidemiology theory provided the framework for the study. The data collected were from published articles. From over 2,800 individual studies, 20 articles were retained for results and data abstraction, following the title, abstract screen, and full text screening in the second phase. The data were analyzed by a meta-analysis statistical method, combining the results from selected studies to estimate the overall association. According to study results by the adjusted p-values of fixed model, there was a significant association between decreased risk of prostate cancer and the variant of Allele T, Genotype TT, and the recessive model of C667T polymorphism. In the random model, the adjusted p-values show a significant association between decreased risk of prostate cancer, the variant of Genotype TT, and recessive model. There was an increased risk of prostate cancer in A1298C polymorphism by adjusted p-value on the variant of Genotype AC, in the fixed model. This study leads to positive social change by providing information on an optimization surveillance strategy to ensure valid screening test for prostate disease reporting. Future studies with a greater number of samples are needed, including gene-gene and gene-environment interaction to verify study results.

No description available.

Le cancer du pancréas est l’un des plus chimiorésistants, avec un taux de survie sur 5 ans inférieur à 5%. La chimiorésistance pourrait être due à la présence de cellules initiatrices de tumeur (TICs), une petite sous-population des cellules tumorales possédant la capacité de régénérer une nouvelle tumeur. Il a été démontré que la metformine cible les TICs par un mécanisme non élucidé. Il est connu que la metformine affecte le métabolisme du carbone. Il a également été démontré que le métabolisme du carbone, plus précisément la glycine décarboxylase (GLDC), est à la fois nécessaire et suffisant à l’acquisition de propriétés d’initiation tumorale. Nous proposons que la metformine cible les cellules initiatrices de tumeur en affectant le métabolisme du carbone. Nous avons utilisé des lignées cellulaires dérivées d’un modèle murin de cancer du pancréas pour comparer l’expression génique de lésions bénignes versus malignes. Les cellules malignes surexpriment Gldc. La metformine diminue l’expression de Gldc, et la surexpression de Gldc diminue la sensibilité à la metformine dans un essai de sphères tumorales. La metformine induit une augmentation du ratio NADP+/NADPH, et la surexpression de Gldc empêche cette augmentation. Nous proposons que la metformine diminue l’expression de Gldc, ce qui cause une diminution du flux du métabolisme du carbone, et donc une diminution de la production de NADPH par ce dernier. L’augmentation du ratio NADP+/NADPH inhibe la synthèse des acides gras et la régénération de la glutathione, ce qui pourrait expliquer la diminution de la formation de sphères tumorales sous traitement metformine. / Pancreatic cancer is one of the most chemoresistant cancers, with a 5-year survival rate lesser than 5%. Chemoresistance might be due to the presence of tumor-initiating cells (TICs), a small subpopulation of tumor cells with stem-like characteristics which possess the unique ability to self-renew and to generate a new tumor. Metformin has been shown to affect TICs in various cancer types, but the mechanism through which it does so is unclear. It is known that metformin affects one-carbon metabolism. It has also been shown that one-carbon metabolism, more precisely the glycine decarboxylase (GLDC) enzyme, is both necessary and sufficient to the acquisition of tumor-initiating properties. Considering this, we propose that metformin affects TICs by targeting one-carbon metabolism. Using cell lines derived from a genetically engineered mouse model of pancreatic cancer, we compared gene expression data from cells derived from benign pancreatic neoplasia with cells derived from pancreatic ductal adenocarcinoma (PDAC), and found that PDAC cells exhibited a dramatic increase in Gldc expression. Metformin treatment decreases Gldc expression in PDAC cell lines, and Gldc overexpression greatly decreases metformin sensitivity in a tumor sphere assay. Metformin induces an increase in NADP+/NADPH ratio, which is rescued by Gldc overexpression. We propose a model in which metformin decreases Gldc expression, which causes reduced flux through mitochondrial one-carbon metabolism. This results in decreased NADPH production by this pathway. This increase in NADP+/NADPH ratio impairs fatty acid biosynthesis and glutathione regeneration. Together these effects might explain the decrease of tumor sphere formation under metformin treatment.

Les vitamines B et les facteurs liés au métabolisme monocarboné (C1) aident à maintenir la synthèse de l'ADN, régulent l'expression des gènes, et peuvent affecter le risque de cancer. L'objectif général de cette thèse est d'étudier l'importance des biomarqueurs du C1 dans l'étiologie de trois cancers distincts qui diffèrent dans leur force d'association avec le tabagisme. Les articles inclus dans cette thèse ont été conduits au sein de deux études prospectives : l'étude prospective européenne sur la nutrition et le cancer (EPIC) et le consortium de cohortes du cancer du poumon (LC3). Dans l'article 1, nous avons étudié la relation entre les biomarqueurs du C1 et l'incidence ainsi que le pronostic du cancer de la sphère oto-rhino-laryngée (ORL) et de l'oesophage au sein de l'étude EPIC. Nous avons observé que les sujets ayant des concentrations élevées d'homocystéine avaient un risque accru de développer un cancer de la sphère ORL. Dans l'article 2, nous avons examiné la relation entre les biomarqueurs du C1 et l'incidence ainsi que le pronostic du carcinome à cellules rénales (CCR) au sein de l'étude EPIC. Nous avons constaté que les participants ayant des concentrations de vitamine B6 élevées avaient une diminution du risque de CCR avec un effet dose-réponse ainsi qu'une amélioration de la survie post-diagnostic. Dans l'article 3, nous avons étudié si les biomarqueurs du C1 sont associés au risque de cancer du poumon au sein de l'étude LC3. Dans l'ensemble, nous avons mis en exergue une faible association inverse, sans tendance claire, entre les concentrations de vitamine B6 et de folate et le risque du cancer du poumon. La principale conclusion de nos études est que les concentrations élevées de vitamine B6 sont associées à un risque plus faible de développer un CCR, et également à un meilleur pronostic chez les patients atteints de cette pathologie. Davantage d'études sont nécessaires afin d'évaluer si la vitamine B6 exerce une influence causale sur l'étiologie et la mortalité du CCR, ou si d'autres facteurs métaboliques sont impliqués / B-vitamins and factors related to one-carbon metabolism (OCM) pathway help to maintain DNA synthesis and regulate gene expression and may affect cancer risk. The overarching aim of this thesis is to investigate the importance of OCM biomarkers in the etiology of three distinct cancer sites that differed in their strength of association with smoking. Papers included in this thesis were conducted within two prospective studies, the European Prospective Investigation into nutrition and Cancer (EPIC) study and the Lung Cancer Cohort Consortium (LC3). In paper 1, we investigated if OCM biomarkers are associated with incidence and survival of cancer of the head and neck and esophagus in the EPIC study. We observed that subjects with higher concentrations of homocysteine had increased risk of developing head and neck cancer. In paper 2, we investigated if OCM biomarkers are associated with incidence and survival of renal cell carcinoma (RCC) in the EPIC study. We observed that study subjects with elevated vitamin B6 concentrations had lower risk of RCC in a dose-response fashion and improved survival following diagnosis. In paper 3, we investigated whether OCM factors are associated with lung cancer risk in the LC3 study. Overall, we observed a weak inverse association, with no clear trend, between concentrations of vitamin B6 and folate and risk of lung cancer. The most important conclusion is that elevated vitamin B6 concentrations are associated with lower risk of developing RCC, and also better prognosis among RCC cases. Further studies are warranted to evaluate if vitamin B6 exerts a causal influence on RCC etiology and mortality, or if other metabolic factors are involved

Hydrogenasen sind komplexe Enzyme, die die reversible Oxidation von molekularem Wasserstoff zu Protonen und Elektronen katalysieren. Diese Enzyme erlauben ihrem Wirtsorganismus das Wachstum unter chemolithoautotrophen Bedingungen. Der Modellorganismus Ralstonia eutropha besitzt drei gut charakterisierte Hydrogenasen der [NiFe]-Klasse, die sich durch ihre Sauerstofftoleranz auszeichnen. Ihr aktives Zentrum besteht aus einer komplexen prosthetischen Gruppe, welche aus einem Nickel- und einem Eisenatom besteht. Letzteres koordiniert drei diatomare Liganden, zwei Cyanide und ein CO. Die Synthese der gesamten Ni(SR)2(µ-SR)2Fe(CN)2(CO)-Gruppe ist ein komplexer Prozess. Die sogenannte Maturation benötigt wenigstens sechs akzessorische Proteine, die sogenannten Hyp-Proteine. Das umfassende Verständnis dieser Maturationsprozesse ermöglicht eine Vielzahl von biotechnologischen Anwendungen. Die vorliegende Arbeit untersucht die Maturation unter verschiedenen Gesichtspunkten. Zentrale, offene Fragen sind die Herkunft des Carbonylliganden sowie die Prozesse, die zur Ligandierung des katalytischen Eisens führen. Dazu wurden molekularbiologische, biochemische und spektroskopische Methoden in Verbindung mit Isotopenmarkierung eingesetzt. Unter anderem konnte dabei gezeigt werden, dass das katalytische Eisen alle seine Liganden bereits im HypCD-Komplex, dem zentralen Element der Maturation, erhält. Ferner konnte in dieser Arbeit, erstmalig für [NiFe]-Hydrogenasen, eine konkrete Biosynthese des seltenen und toxischen diatomaren CO-Liganden beschrieben werden. Ausgehend vom Alpha-Kohlenstoff von Glycin wird der Tetrahydrofolat (THF)-abhängige C1-Metabolismus mit C1-Einheiten versorgt. Durch die enzymatische Aktivität von HypX wird die Formylgruppe von N10-Formyl-THF zu CO umgesetzt. / Hydrogenases are complex enzymes that catalyze the reversible oxidation of molecular hydrogen into protons and electrons. These enzymes allow their host organism to grow under chemolithoautotrophic conditions. The model organism Ralstonia eutropha has three well-characterized [NiFe]-hydrogenases, which exhibit an extraordinary high oxygen tolerance. Its active center is a complex prosthetic group which consists of a nickel and iron atom. The latter coordinates three diatomic ligands, two cyanides and one CO. The biosynthesis of the whole Ni(SR)2(μ-SR)2Fe(CN)2(CO)-group is a complex process. This so-called maturation process needs the activity of at least six accessory proteins, the Hyp-proteins. Understanding the maturation allows a variety of biotechnological applications. The present study examines the maturation of [NiFe]-hydrogenases under different aspects. The major questions concern the origin of the carbonyl ligand as well as the processes that lead to ligandation of the designated catalytic iron. To adress these tasks, molecular biological, biochemical and spectroscopic methods in combination with isotopic labeling were employed. Inter alia, it could be shown that the catalytic iron in the HypCD-complex, the central element of the maturation process, contains all three diatomic ligands. Furthermore, this study describes, for the first time in [NiFe]-hydrogenases, a specific biosynthetic route of the rare and toxic diatomic CO-ligand. Starting from the alpha-carbon of glycine the tetrahydrofolate (THF)-dependent one-carbon metabolism is replenished with one-carbon units. Subsequently the formyl group from N10-formyl-THF is hydrolyzed by the enzymatic activity from HypX and further converted to carbon monoxide as determined by isotopic labeling and infrared spectroscopy.

Introdução - Os hábitos alimentares e os nutrientes da via metabólica do folato e homocisteína possuem grande importância na manutenção da saúde. Objetivo - Investigar a relação entre padrões alimentares (PAs) e os nutrientes envolvidos nessa via metabólica, com medidas antropométricas do recém-nascido, duração da infecção por HPV em homens e concentrações de homocisteína (Hcy) em adultos. Métodos - Foram utilizados dados dos estudos de coorte ProcriAr (Influência dos fatores nutricionais e poluentes atmosféricos urbanos na saúde pulmonar de crianças: um estudo de coorte com gestantes da zona oeste do município de São Paulo, n=299); e HIM (História natural da infecção por HPV em homens, n=1.194); e do estudo transversal ISA-Capital 2008 (Inquérito de saúde do estado de São Paulo, n=281). Os padrões alimentares foram derivados por análise fatorial por componentes principais nos estudos ProcriAr e ISA-Capital 2008 e utilizando reduced rank regression (RRR) no estudo HIM. Modelos multivariados de regressão de Poisson e lineares foram utilizados nos estudos ProcriAr e HIM para identificar a relação entre PAs e medidas antropométricas do recém-nascido e duração da infecção por HPV em homens, respectivamente. Utilizando modelo de equação estrutural, investigou-se a relação entre PAs, concentrações bioquímicas de folato, vitamina B12 e ácido docosahexaenoico (DHA) e concentrações de homocisteína em adultos do estudo ISA-Capital, considerando polimorfismo da enzima metilenotetrahidrofolato redutase (MTHFR 677C>T). Os três estudos utilizaram questionário de frequência alimentar para avaliação do consumo alimentar. Resultados - No estudo ProcriAr, a maior adesão materna ao PA \"Snacks, sanduíches, doces e refrigerantes\", rico em energia, gordura, e folato sintético, esteve diretamente associada a ter um filho pequeno ao nascer (peso e/ou comprimento ao nascer, ajustado pela idade gestacional, abaixo do percentil 10 - INTERGOWTH-21st) (RR: 2,01; IC 95%: 1.13-3.57). No estudo HIM, homens com maior adesão ao \"PA3\" tiveram, em média, um aumento de 1,15 (IC95% 0,09-2,21) à 1,18 (IC95% 0,11-2,24) meses na duração da infecção por HPV. O \"PA3\" esteve positivamente correlacionado com vitamina B6 (r = 0,59), vitamina B12 (0,27) e DFE (0,07) e negativamente correlacionado com DHA (-0,37). No estudo ISA-Capital o PA \"Prudente\" esteve inversamente associado à concentração de Hcy (β = -0,12). O DHA esteve diretamente associado ao PA \"Prudente\"; composto por verduras e legumes, peixe, frutas, frango, suco natural e batata/mandioca/polenta (cozida ou assada). Conclusões - Os PAs estão associados às medidas antropométricas do recém-nascido, à duração da infecção por HPV em homens e às concentrações de homocisteína em adultos. Estes resultados reforçam a importância de estudos sobre alimentação e nutrição que considerem não somente nutrientes, mas principalmente o consumo de alimentos e suas combinações, servindo como base para a elaboração de estratégias e políticas públicas de promoção à saúde. / Introduction - The dietary habits and nutrients involved in one-carbon metabolism are of great importance in health. Objective - To investigate the relationship between dietary patterns (DP) and the nutrients involved in this metabolism, with newborn\'s anthropometric measurements, duration of HPV infection in men, and homocysteine (Hcy) levels in adults. Methods - Data from the cohort studies ProcriAr (Influence of nutritional factors and urban air pollutants on the pulmonary health of children: a cohort study with pregnant women from the western region of the city of São Paulo, n=299); and HIM (Natural history of HPV infection in men, n=1,194); and the cross-sectional study ISA-Capital 2008 (São Paulo State Health Survey, n=281) were used. The DP were estimated using factor analysis with principal component\'s estimation in ProcriAr and ISA-Capital 2008 studies and using reduced rank regression (RRR) in HIM study. Multivariate Poisson and linear regression models were used in the ProcriAr and HIM studies to identify the relationship between DP and newborn\'s anthropometric measurements and duration of HPV infection in men, respectively. Using a structural equation model, the relationship between DP, biochemical levels of folate, vitamin B12 and docosahexaenoic acid (DHA) and homocysteine levels was investigated in adults from the ISA-Capital 2008 study, considering the polymorphism of the enzyme methylenetetrahydrofolate reductase (MTHFR 677C>T). The three studies used a food frequency questionnaire to evaluate dietary intake. Results - In the ProcriAr study, the higher maternal adherence to the \"Snacks, sandwiches, sweets and soft drinks\" DP, which is a DP rich in energy, fat, and synthetic folate, was directly associated with having a child small at birth (weight and/or birth length by gestational age and sex below the 10th percentile - INTERGOWTH-21st) (RR: 2.01, 95% CI: 1.13-3.57). In the HIM study, men with higher adherence to \"DP3\" had, on average, an increase from 1.15 (95% CI 0.09-2.21) to 1.18 (95% CI 0.11-2.24) months in the duration of HPV infection. \"DP3\" was positively correlated with vitamin B6 (r = 0.59), vitamin B12 (0.27) and DFE (0.07) and negatively correlated with DHA (-0.37). In the ISA-Capital study, the \"Prudent\" DP was inversely associated with Hcy levels (β = -0.12). DHA was directly associated with \"Prudent\" DP; composed of vegetables, fish, fruits, chicken, natural juice and potato/cassava/polenta (cooked or roasted). Conclusions - Dietary patterns are associated with newborn\'s anthropometric measurements, duration of HPV infection in men, and Hcy levels in adults. These results reinforce the importance of studies on food and nutrition that consider not only nutrients, but mainly the consumption of foods and their combinations, serving as a basis for the elaboration of public health promotion strategies and policies.