Dans le cadre de l’analyse des crises financières au sein des pays émergents, de nombreux travaux sont venus expliquer l’occurrence de ce genre de phénomènes. Pourtant, des faits nouveaux se manifestent sans pour autant s’inscrire dans les recherches déjà proposées (Brésil, Corée du Sud et pays d’Europe centrale et orientale principalement). En référence à cette littérature, la thèse pose en retour la question de l’incidence de la contagion financière sur la dégradation des fondamentaux macroéconomiques et macro-financiers de pays émergents susceptibles d’être initialement considérés comme « robustes ». La réponse passe par la mise en évidence des principales composantes des crises financières pour en extraire les limites face à l’hypothèse soulevée. La description des stratégies de rattrapage économique, par l’intégration au marché financier international, est à l’origine des vulnérabilités potentielles dans les effets de contagion. La structure instable de l’endettement international, à l’aide de l’Hypothèse d’Instabilité Financière de Minsky (1974), va offrir les éléments théoriques nécessaires à la modélisation des faits empiriques. Les premières générations de crises de change viendront conceptualiser la fuite des capitaux en attribuant la responsabilité de la contraction de la liquidité au reste du monde. Dans la transition qu’ils opèrent actuellement en vue de leur adhésion à l’UEM, les PECO ne peuvent être considérés comme étant à l’abri de la survenance de crises financières, et ce même s’ils bénéficient des impacts stabilisateurs favorables liés à leur appartenance à l’UE. Mais disposent-ils alors des facteurs de robustesse macroéconomique et macro-financière s / As part of the analysis of financial crises in emerging countries, many studies have come to explain the occurrence of such phenomena. However, developments occur without enrolling in research already available (Brazil, South Korea and countries in Central and Eastern Europe mainly). In reference to this literature, the thesis in turn raises the question of the impact of financial contagion on the degradation of macro-economic fundamentals and emerging countries' financial might initially be regarded as "robust." The answer lies in the identification of key components of financial crises to extract the limits against the hypothesis raised. The description of the strategies of economic recovery, by the international financial market integration, is the source of potential vulnerabilities in the contagion. The unstable structure of international debt, with the financial instability hypothesis of Minsky (1974), will provide the theoretical elements necessary for modeling of empirical facts. The first generation of currency crises will conceptualize capital flight by assigning responsibility for the liquidity squeeze in the world. In the transition they currently operate with a view to joining EMU, the Central and Eastern Europe countries cannot be considered safe from the occurrence of financial crises, even if they have favorable impacts associated with stabilizers membership in the EU. But then they have robust macroeconomic factors and macro-financial enough to ward off the economic impact of any pressure by contagion? The empirical part of the thesis should answer the question through analytical and econometric modeling

A hipóxia ocorre quando a demanda de oxigênio molecular necessário para gerar ATP é insuficiente. Os genes ativados por hipóxia compreendem o gene Hif-1a (Hipóxia-fator induzível 1a), Vegf-a (fator de crescimento endotelial vascular a), Arnt e Vhl (von Hippel-Lindau). Neste estudo foram utilizadas linhagens de camundongos geneticamente selecionados para alta (AIRmax) ou baixa (AIRmin) resposta inflamatória aguda (AIR). Foram realizados testes biológicos para caracterizar as reações inflamatórias produzidas por Biogel e TPA, bem como o tipo PAH cancerígeno. Testamos a expressão de mRNA de genes de hipóxia e caracterização de polimorfismo da região codificadora do Hif-1a no cromossomo 12. Camundongos AIRmax demonstraram uma maior reação inflamatória que os AIRmin para biogel e TPA enquanto o inverso foi observado com o DMBA. Os conjuntos de dados de fenótipos, expressão gênica e polimorfismo candidatam a região do cromossomo 12, que contém, entre outros, o gene Hif-1a, como participante da regulação da AIR. / Hypoxia occurs when the demand for molecular oxygen necessary to generate ATP is insufficient. Genes activated by hypoxia comprise the Hif-1a gene (Hypoxia-Inducible Factor 1a), Vegf-a (Vascular Endothelial Growth Factor a), Arnt and Vhl (von Hippel-Lindau). In this study we used lines of mice genetically selected for high (AIRmax) or low (AIRmin) acute inflammatory response (AIR). We conducted biological tests to characterize the inflammatory reactions produced by Biogel and TPA, and the type PAH carcinogen. We tested the mRNA expression of genes of hypoxia and characterization of polymorphism of the coding region of Hif-1a gene on chromosome 12. We found that the mice AIRmax had greater intensity of the inflammatory reaction that AIRmin to biogel and TPA while the reverse was observed with the DMBA. The data sets of phenotypes, gene expression and polymorphism applying the region of chromosome 12 that contains, among others, the gene Hif-1a, as part of the regulation of AIR.

L’hadronthérapie par ions carbone est une alternative à la radiothérapie photonique dans le traitement des cancers des VADS, en raison d’une balistique précise et d’une efficacité biologique élevée, y compris au sein des zones tumorales hypoxiques. Ces cancers sont de mauvais pronostic en raison d’un risque élevé de récidives liées à la présence de cellules souches cancéreuses (CSCs). L’objectif de ce travail était de déterminer les spécificités moléculaires de la réponse aux ions carbone par rapport aux photons dans deux lignées cellulaires de cancer des VADS et leur sous-population CSCs en hypoxie et normoxie. Il s’est focalisé sur le rôle de la protéine HIF-1α dans la survie cellulaire, dans la mesure où l’hypoxie favorise sa stabilisation mais également la radiorésistance; sur la transition épithélio-mésenchymateuse (EMT) et la détection-réparation des cassures double-brin (CDBs) de l’ADN. HIF-1α est stabilisée plus précocement dans les CSCs par rapport aux non-CSCs. Son activation, tout comme celle des voies de l’EMT (STAT3, MEK/p38/JNK et Akt/mTOR) est dépendante des radicaux libres oxygénés (RLO), dont la production est homogène dans la cellule en réponse aux photons. Par contre, les RLO produits dans la trace des ions carbone ne permettent pas d’activer HIF-1α et les voies de l’EMT. Sous hypoxie, une relation a été établie entre l’activation d’HIF-1α et celles des voies de détection (ATM) et de réparation (Rad51) des CDBs (Recombinaison Homologue). Ces travaux démontrent que l’avantage thérapeutique des ions carbone repose sur la répartition spatiale des RLO à l’échelle nanométrique et consécutivement sur la non-activation de voies clés de la défense cellulaire tumorale / Hadrontherapy using carbon ions is an alternative to photon irradiation in the treatment of Head and Neck cancers, because of accurate ballistics and high biological efficiency, including hypoxic tumor areas. These cancers are of poor prognosis because of a high risk of recurrences related to the presence of cancer stem cells (CSCs).The aim of this work was to determine the molecular specificities of the response to carbon ion irradiations compared to photons in two cancer cell lines and their CSCs’ subpopulation, in hypoxic and normoxic conditions. This work focused on the role of the HIF-1α protein in cell survival, since hypoxia promotes its stabilization, but also in the radioresistance; the epithelial-mesenchymal transition (EMT) and the detection and repair of DNA double-strand breaks (DSBs). HIF-1α is stabilized earlier in CSCs compared to non-CSCs. Its activation, as well as the EMT pathways (STAT3, MEK/p38/JNK and Akt/mTOR), are dependent on reactive oxygen species (ROS), whose production is homogeneous in response to photons. At the opposite, the ROS produced in the carbon ion tracks are insufficient to activate HIF-1α and the upstream EMT pathways. Under hypoxic conditions, a relationship has been established between HIF-1α activation and that of the DSBs detection (ATM) and repair (Rad51) pathways (Homologous Recombination). These studies demonstrate that the therapeutic advantage of carbon ions is based on the spatial ROS distribution at the nanoscale and consequently on the non-activation of key pathways involved in tumor cell defense

Posttranslational modifications are of great importance in the mediation of transcriptional effects, necessary for signalling in cancer. A characteristic example of such modifications is acetylation of the p53 tumour suppressor, a transcription factor involved in several crucial cellular functions including cell-cycle arrest and apoptosis. p53 is stabilised under hypoxic and DNA damaging-conditions. However, only in the latter scenario is p53 fully capable of inducing the expression of its proapoptotic targets through acetylation. The hypoxia inducible factor 1 (HIF-1) transcription factor is stabilised at low oxygen levels to mediate a cellular adaptive response under these conditions, promoting cell survival. As these two opposing transcription factors share a common transcriptional regulator, p300/CBP, this study focused on deciphering the p300/CBP complex components under differential stress to determine its composition required for cellular responses elicited in response to DNA damage or hypoxia, in an effort to investigate a possible link between differential posttranslational modifications and the resulting cell fate. Hence, the aim of this study was to investigate the roles of p300/CBP components in dictating transcriptional regulation of both HIF-1 and p53 in hypoxic conditions. To carry out this study, the proapoptotic BID gene was the system used, as its promoter contains a p53 response element and a HIF-1 response element (HRE). The p300/CBP associated factors PCAF and Strap were appointed as potent candidates for posttranslational modifications under differential conditions, as they are stress-responsive cofactors. Under DNA damage, PCAF acetylates p53 at K320 and Strap augments p300 binding to p53, both of which amplify the p53 response. Evidence from this study demonstrates that under hypoxia-mimicking conditions PCAF-mediated p53 acetylation at K320 is reduced to a greater extent compared to p300/CBP acetylation at K382. The limited amounts of acetylated p53 at K320 are preferentially recruited to the promoter of the cell cycle arrest p21WAF-1/CIP-1 gene that appears to be unaffected by hypoxia, but fail to be recruited to the BID promoter, rendering p53 incapable of upregulating proapoptotic BID in hypoxic conditions. In addition, under the same conditions, PCAF was found to acetylate, and direct HIF-1 to a particular subset of its targets, leading to alterations in the net physiological effect. Moreover, the intrinsic acetyl transferase activity of PCAF was shown to increase the stability of HIF-1. An additional role was attributed to PCAF in relation to apoptosis, albeit from another angle. BID protein translocation to the cytoplasm in hypoxic conditions was facilitated by ectopically expressed PCAF.Strap was found to be preferentially recruited to the HRE of the BID promoter in hypoxic conditions, and to exert a transrepression effect that appeared to be p53-dependent. Strap also interacted with specific PCAF isoforms depending on the type of cellular stress. Contrary to PCAF, ectopically expressed Strap did not have any effect on BID subcellular distribution. This study has provided additional insight in the mechanisms by which cofactors are involved in cell fate, either by affecting activity and stability of HIF-1 and p53, or having a direct effect on Bcl-2 member subcellular distribution.

Many fish face low oxygen concentrations (hypoxia) in their natural environments, and they respond to hypoxia through a variety of behavioral, physiological, and cellular mechanisms. Some of these responses involve changes in gene expression. In mammals, the hypoxia inducible factor (HIF) family of transcription factors are the “master regulators” of gene expression during hypoxia, but the study of HIF in fish has been hampered by the lack of reagents to detect this protein in non-mammalian vertebrates. The goals of this thesis are to affinity purify antibodies against HIF from the killifish Fundulus heteroclitus and use them to recover and quantify HIF from killifish cells and tissues. The purified, validated antibodies represent a critical reagent for future studies of the role of HIF in the molecular response of this and other fish to fluctuations in oxygen in their natural environments.

Orientador: Antonio Carlos Cicogna / Resumo: Introdução - A estenose aórtica supravalvar (EAo) experimental é utilizada para induzir a remodelação cardíaca (RC) patológica; esse modelo provoca, inicialmente disfunção diastólica e, posteriormente, distúrbio sistólico e insuficiência cardíaca (IC). Diferentes fatores podem contribuir para essa alteração funcional como, déficit de oxigênio (O2). O principal regulador da homeostase do O2 é o fator induzível por hipóxia-1α (HIF-1α) que na condição normóxia é sintetizado e degradado. No coração hipertrofiado, isquêmico, o HIF-1α torna-se estável e regula a transcrição de vários genes que aumentam a disponibilidade de O2. Além disso, aumenta a expressão das proteínas da via da glicose, com a finalidade de aumentar a oferta de energia. Embora, existam trabalhos que mostraram alteração do HIF-1 α, metabolismo de glicose e função cardíaca, não encontramos na literatura pesquisas que analisaram o comportamento e a associação do HIF-1α com o metabolismo glicídico, estrutura e função ventricular durante a evolução da remodelação por EAo. Objetivos gerais – Analisar durante o processo de evolução da RC o comportamento do HIF-1α, metabolismo da glicose, estrutura e função ventricular e a associação entre o HIF-1α e estas variáveis. Material e métodos – Foram utilizados dois grupos de ratos Wistar: controle operado (Sham, n=48) e EAo (n=48): os animais foram submetidos a cirurgia e no grupo EAo foi implantado um clipe de 0,60 mm de diâmetro na raiz da aorta. Os ratos foram avaliados no... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Introduction - The experimental supravalvar aortic stenosis (AS) is used to induce pathological cardiac remodeling (CR); this model causes, initially, diastolic dysfunction and, later, systolic disorder and heart failure (HF). Different factors may contribute to these cardiac functional alterations, such as oxygen (O2) deficiency. The main regulator of O2 is hypoxia-inducible transcription factor (HIF-1α) that in normoxia condition is synthesized and degraded. In the hypertrophied, ischemic heart, HIF-1α becomes stable and regulates the transcription of several genes that increase O2 availability. In addition, it increases the expression of the glucose pathway proteins, in order to increase energy supply. Although there are studies that have shown alterations in HIF-1α, glucose metabolism and cardiac function, we have not found in the literature studies that investigated the behavior and association of HIF-1α with glucose metabolism, ventricular structure and function during the evolution of CR by AS.Objective - To analyze, during the course of CR evolution, the behavior of HIF-1α, glucose metabolism, ventricular structure and function, and the association between HIF-1α and these variables. Material and methods - Two groups of rats were studied: operated control (Sham, n=48) and supravalvar aortic stenosis (AS, n=48): the animals underwent surgery and in the AS group a clip of 0.60 mm diameter was placed at the aorta’s root. The rats were evaluated at 2, 6, 18 weeks after su... (Complete abstract click electronic access below) / Doutor

The diverse outcomes of ubiquitination primarily relate to the flexibility of ubiquitin in forming homo- or heterotypic chains on each of its seven lysine residues which in turn stimulate distinct downstream signaling pathways. These ubiquitin signals must be selectively initiated on the substrate protein and subsequently decoded to facilitate the desired cellular function. These initiation and decoding steps often involve additional post-translational modifications and ubiquitin receptor proteins, but the enzymes and ubiquitin chains involved for many ubiquitinated substrates are not clear. Here, I have explored the initiation and decoding of ubiquitin signals, focusing on lysine-11 (K11) linked polyubiquitin chains and their role in protein degradation. I established in vitro assays to understand how K11-chains are decoded and whether these chains act as a signal for proteasome-mediated degradation. Pure homotypic K11-chains did not bind the proteasome or its associated ubiquitin binding proteins, but did bind to the mitophagy ubiquitin receptors, MyosinVI and TAX1BP1. Heterotypic K11/K48 linkages not only bound the proteasome but also stimulated degradation of the cell cycle substrate, cyclin B1. To further explore the functions of K11-chains I focused on the hypoxia inducible transcription factor (HIF) pathway, as K11-ubiquitination had been implicated in proteasome-independent degradation of the transcription factor. I established an in vitro assay to initiate HIF ubiquitination, via prolyl hydroxylation, and determine the type of ubiquitin chains involved. Recombinant HIF isoforms were rapidly hydroxylated when incubated with cell extracts. Moreover, the levels of iron and small molecule metabolites within the lysates regulated HIF hydroxylation. However, this hydroxylation was insufficient to reproducibly promote HIF ubiquitination or determine the ubiquitin chains involved. While the nature of the polyubiquitin chains formed in the HIF pathway remain elusive, my studies identify distinct roles for homotypic and heterotypic K11-polyubiquitination in proteasome-mediated degradation.

Monitoring of abnormal events in a distribution feeder by using a single technique is a challenging task. Many abnormal events can cause unsafe operation, including a high impedance fault (HIF) caused by a downed conductor touch ground surface, an incipient fault (IF) caused by partial breakdown to a cable insulation, and a circuit breaker (CB) malfunction due to capacitor bank de-energization to cause current restrikes. These abnormal events are not detectable by conventional protection schemes. In this dissertation, a new technique to identify distribution feeder events is proposed based on the complex Morlet wavelet (CMW) and on a decision tree (DT) classifier. First, the event is detected using CMW. Subsequently, a DT using event signatures classifies the event as normal operation, continuous and non-continuous arcing events (C.A.E. and N.C.A.E.). Additional information from the supervisory control and data acquisition (SCADA) can be used to precisely identify the event. The proposed method is meticulously tested on the IEEE 13- and IEEE 34-bus systems and has shown to correctly classify those events. Furthermore, the proposed method is capable of detecting very high impedance incipient faults (IFs) and CB restrikes at the substation level with relatively short detection time. The proposed method uses only current measurements at a low sampling rate of 1440 Hz yielding an improvement of existing methods that require much higher sampling rates.

Submitted by PAULA GRIPPA SANT'ANA null (paulagrippa@yahoo.com.br) on 2018-03-28T13:33:43Z No. of bitstreams: 1 Tese Doutorado Paula Grippa Sant Ana.pdf: 2655001 bytes, checksum: d70cef401afff8d2daed0e55b5009291 (MD5) / Approved for entry into archive by ROSANGELA APARECIDA LOBO null (rosangelalobo@btu.unesp.br) on 2018-03-29T17:06:19Z (GMT) No. of bitstreams: 1 santana_pg_dr_bot.pdf: 2655001 bytes, checksum: d70cef401afff8d2daed0e55b5009291 (MD5) / Made available in DSpace on 2018-03-29T17:06:19Z (GMT). No. of bitstreams: 1 santana_pg_dr_bot.pdf: 2655001 bytes, checksum: d70cef401afff8d2daed0e55b5009291 (MD5) Previous issue date: 2018-02-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Introdução - A estenose aórtica supravalvar (EAo) experimental é utilizada para induzir a remodelação cardíaca (RC) patológica; esse modelo provoca, inicialmente disfunção diastólica e, posteriormente, distúrbio sistólico e insuficiência cardíaca (IC). Diferentes fatores podem contribuir para essa alteração funcional como, déficit de oxigênio (O2). O principal regulador da homeostase do O2 é o fator induzível por hipóxia-1α (HIF-1α) que na condição normóxia é sintetizado e degradado. No coração hipertrofiado, isquêmico, o HIF-1α torna-se estável e regula a transcrição de vários genes que aumentam a disponibilidade de O2. Além disso, aumenta a expressão das proteínas da via da glicose, com a finalidade de aumentar a oferta de energia. Embora, existam trabalhos que mostraram alteração do HIF-1 α, metabolismo de glicose e função cardíaca, não encontramos na literatura pesquisas que analisaram o comportamento e a associação do HIF-1α com o metabolismo glicídico, estrutura e função ventricular durante a evolução da remodelação por EAo. Objetivos gerais – Analisar durante o processo de evolução da RC o comportamento do HIF-1α, metabolismo da glicose, estrutura e função ventricular e a associação entre o HIF-1α e estas variáveis. Material e métodos – Foram utilizados dois grupos de ratos Wistar: controle operado (Sham, n=48) e EAo (n=48): os animais foram submetidos a cirurgia e no grupo EAo foi implantado um clipe de 0,60 mm de diâmetro na raiz da aorta. Os ratos foram avaliados nos momentos de 2, 6, 18 semanas após cirurgia e na fase de IC grave. Os subgrupos Sham2, 6, 18, IC, e EAo2, 6, 18, IC foram constituídos por 12 animais. A estrutura e função cardíaca foram analisadas por ecocardiograma. A hipertrofia cardíaca foi também avaliada, post mortem. No miocárdico foram analisadas a expressão do HIF-1α, das proteínas da glicólise [hexoquinaseII (HKII), fosfofrutoquinase-2 (PFK-2)], via aeróbica [piruvato desidrogenase (PDH)], via anaeróbica [lactato desidrogenase (LDH)], da captação de glicose [transportador de glicose 1 e 4 (GLUT1 e GLUT4), do receptor de insulina (IR), do fosfatoinositol-3- quinase (PI3K) e quinase ativada pela adenosina monofosfato (AMPK)] pela técnica de Western Blot. As atividades das HK, PK, LDH, citrato sintase (CS) e a concentração de lactato foram analisadas por ensaio enzimático. Análise estatística foi realizada pela técnica de variância (ANOVA) para o esquema fatorial 2x4, complementada com teste de comparações múltiplas de Tukey (paramétrico) e Dunn (não paramétrico). Aassociação entre o HIF-1α e os conjuntos de variáveis foi estudada por meio da correlação canônica. Todas as conclusões estatísticas foram discutidas ao nível de 5% de significância. Resultados: Os principais achados significativos deste estudo foram: a) acentuação da hipertrofia ventricular esquerda durante a evolução da RC, alteração precoce na função diastólica e severa disfunção sistólica e diastólica na fase de IC grave; b) aumento do HIF-1α no início da RC e agravamento na fase de IC ; c) alteração precoce no metabolismo da glicose, com acentuação da via glicolítica e desvio para a via anaeróbica a partir da 6ª semana de EAo; d) associação significativa entre o HIF-1α e alteração estrutural, função diastólica e metabolismo da glicose. Conclusões: a) há aumento do HIF-1α e reprogramação do metabolismo da glicose, hipertrofia e disfunção diastólica a partir da 2ª semana de EAo; b) durante a evolução da RC ocorre elevação do HIF-1α, das proteínas da captação de glicose e via glicolítica com desvio para via anaeróbia; c) há associação canônica entre o conjunto do HIF-1α com o agrupamento das variáveis relacionadas com a via da glicose, estrutura e função diastólica cardíaca. / Introduction - The experimental supravalvar aortic stenosis (AS) is used to induce pathological cardiac remodeling (CR); this model causes, initially, diastolic dysfunction and, later, systolic disorder and heart failure (HF). Different factors may contribute to these cardiac functional alterations, such as oxygen (O2) deficiency. The main regulator of O2 is hypoxia-inducible transcription factor (HIF-1α) that in normoxia condition is synthesized and degraded. In the hypertrophied, ischemic heart, HIF-1α becomes stable and regulates the transcription of several genes that increase O2 availability. In addition, it increases the expression of the glucose pathway proteins, in order to increase energy supply. Although there are studies that have shown alterations in HIF-1α, glucose metabolism and cardiac function, we have not found in the literature studies that investigated the behavior and association of HIF-1α with glucose metabolism, ventricular structure and function during the evolution of CR by AS.Objective - To analyze, during the course of CR evolution, the behavior of HIF-1α, glucose metabolism, ventricular structure and function, and the association between HIF-1α and these variables. Material and methods - Two groups of rats were studied: operated control (Sham, n=48) and supravalvar aortic stenosis (AS, n=48): the animals underwent surgery and in the AS group a clip of 0.60 mm diameter was placed at the aorta’s root. The rats were evaluated at 2, 6, 18 weeks after surgery and at the severe HF phase. The subgroups Sham2, 6, 18, HF and AS2, 6, 18, HF were composed of 12 animals/group. Cardiac structure and function were analyzed by echocardiogram. Cardiac hypertrophy was also evaluated, post mortem. The expression of myocardial: HIF-1α; glycolytic proteins [hexokinase II (HKII), phosphofructokinase-2 (PFK-2), pyruvate dehydrogenase (PDH) and lactate dehydrogenase (LDH)]; glucose uptake proteins [intracellular glucose transporters (GLUT1 and GLUT4)]; insulin receptor (IR); phosphateinositol-3-kinase (PI3K) and adenosine monophosphate-activated protein kinase (AMPK) were analyzed by Western Blot. The activities of HKII, pyruvate kinase (PK), LDH and citrate synthase (CS) were also analyzed by enzymatic assays, and lactate concentration was also measured. Statistical analysis was performed by analysis of variance (ANOVA) technique for the 2x4 factorial scheme, complemented with Tukey's (parametric) or Dunn’s (non-parametric) multiple comparisons test. The association between HIF-1α and the sets of variables was analyzed through canonical correlation. All statistical conclusions were discussed at the 5% significance level. Results - The main significant findings of this study were: a) accentuation of left ventricular hypertrophy during the course of CR, early alteration in diastolic function and severe systolic and diastolic dysfunction in the phase of severe heart failure; b) increased HIF-1α at the onset of CR and worsening in severe HF phase; c) early changes in glucose metabolism, with enhancement of the glycolytic pathway and switch to the anaerobic pathway from the 6th week of AS; d) significant association between HIF-1α and cardiac structural alteration, diastolic function and glucose metabolism. Conclusions - a) there is an increase in HIF-1α, reprogramming of glucose metabolism, hypertrophy and diastolic dysfunction from the 2 nd week of AS; b) during the evolution of CR, there is an elevation in HIF-1α, in glucose uptake and glycolytic pathway proteins with switch to the anaerobic pathway; c) there is an association between HIF-1α and the grouping of variables related to the glucose pathway, cardiac structure and diastolic function. / CNPQ 442822/2014-6

Abstract Oxygen homeostasis is critical to all animals, as both excess (hyperoxia) and reduced (hypoxia) levels of oxygen can result in pathological changes and ultimately in the loss of cellular and organismal viability. Complex systems have evolved to sense and adapt to changes in cellular oxygen availability, and the hypoxia-inducible factor HIF plays a pivotal role in this elaborate molecular network. In normoxic conditions the α-subunit of HIF becomes hydroxylated by HIF prolyl 4-hydroxylases (HIF-P4Hs 1-3), earmarking HIF-α for proteasomal degradation. Additionally, in the presence of oxygen the hydroxylation of an asparagine residue by the HIF asparaginyl hydroxylase FIH inhibits the transactivation of HIF-target genes by blocking the interaction of HIF-α with a transcriptional coactivator. In addition to being a feature of an organism’s normal life, hypoxia is also characteristic of many common diseases such as severe anemia and myocardial infarction, and it notably decreases these hydroxylation reactions, as HIF-P4Hs and FIH have an absolute requirement for oxygen as a cosubstrate. HIF-α thus escapes degradation and translocates into the nucleus, where it dimerizes with HIF-β and recruits transcriptional coactivators to the hypoxia-response elements of target genes, inducing their transcription and triggering the hypoxia response aimed at restoring cellular oxygen homeostasis. In this study we generated a genetically modified HIF-P4H-2 hypomorphic mouse line that expresses only 8% of the wild-type HIF-P4H-2 mRNA in the heart. We showed that chronic cardiac HIF-P4H-2 deficiency leads to stabilization of HIF-1α and HIF-2α and protects the heart against acute ischemia-reperfusion injury without causing any adverse effects. Furthermore, we identified and cloned a novel human transmembrane prolyl 4-hydroxylase P4H-TM and showed that it regulates HIF-1α protein levels in cellulo and hydroxylates HIF-1α in vitro similarly to the HIF-P4Hs, but may also have other physiological substrates. Using forward genetic tools we showed that lack of P4H-TM during development leads to basement membrane defects and compromised kidney function in zebrafish embryos. Finally, we demonstrated that FIH displays substrate selectivity in terms of hydroxylation and binding of HIF-1α and novel substrates Notch1-3. We showed that FIH has higher affinity for oxygen with Notch1 than with HIF-1α as a substrate, implying that FIH-mediated hydroxylation of Notch can continue in oxygen concentrations where HIF-1α hydroxylation would be markedly reduced. / Tiivistelmä Happitasapainon ylläpito on edellytys elimistön normaalille toiminnalle, koska sekä liian korkea (hyperoksia) että liian matala (hypoksia) happipitoisuus ovat elimistölle stressitiloja ja johtavat pitkittyessään haitallisiin seurauksiin. Happipitoisuuden muutosten havaitsemiseksi ja niihin reagoimiseksi onkin elimistössä kehittynyt monimutkainen säätelyjärjestelmä, jossa avainasemassa on hypoksia-indusoituva tekijä HIF. Solun happipitoisuuden ollessa normaali yksi kolmesta HIF prolyyli 4-hydroksylaasi-isoentsyymistä (HIF-P4Ht 1-3) katalysoi kahden proliinitähteen hydroksylaation HIF-α-alayksikössä. 4-hydroksiproliini toimii signaalina HIF-α:n nopealle proteasomaaliselle hajotukselle. Lisäksi HIF asparaginyyli hydroksylaasi FIH:n katalysoima HIF-α:n asparagiinitähteen hydroksylaatio estää transaktivaatiovaikutuksen. Koska HIF-P4Ht ja FIH tarvitsevat kosubstraatikseen happea, nämä hydroksylaatioreaktiot vähenevät happipitoisuuden laskiessa, jolloin HIF-α stabiloituu ja siirtyy solun tumaan, jossa se muodostaa kompleksin HIF-β-alayksikön kanssa ja houkuttelee paikalle tarvittavat kofaktorit. HIF-kompleksi tehostaa hypoksiavasteessa tarvittavien geenien luentaa sitoutumalla tumassa niiden promoottoreihin ja pyrkii näin palauttamaan solun happipitoisuuden normaaliksi. Tässä työssä luotiin geneettisesti muunneltu HIF-P4H-2 hypomorfi-hiirilinja, jonka sydämissä tuottuu vain 8 % normaalista HIF-P4H-2 lähetti-RNA:n määrästä. HIF-P4H-2:n puutoksen havaittiin johtavan HIF-1α:n ja HIF-2α:n stabiloitumiseen sydämessä ja suojaavan sydäntä kudosvaurioilta iskemian ja reperfuusion aikana aiheuttamatta haitallisia vaikutuksia. Tässä väitöskirjassa karakterisoitiin aiemmin tuntematon ihmisen transmembraaninen prolyyli 4-hydroksylaasi, P4H-TM. Sen osoitettiin säätelevän HIF-1α:n määrää soluissa ja katalysoivan HIF-1α:n kahden proliinitähteen hydroksylaatiota in vitro-olosuhteissa HIF-P4H-entsyymien tavoin. Seeprakalamallin avulla näytettiin, että P4H-TM:n puutos kalan kehityksen aikana aiheuttaa tyvikalvopoikkeavuuksia ja johtaa vakavaan munuaisen toiminnan häiriintymiseen seeprakalan poikasissa. FIH:n katalysoiman hydroksylaatioreaktion kineettisiä ominaisuuksia verrattiin tässä tutkimuksessa ensimmäistä kertaa aiemmin tunnetun HIF-α substraatin ja uusien Notch substraattien kesken. Tulokset osoittivat, että substraatin sitomisessa ja hydroksylaatiossa on merkittäviä eroja eri substraattien välillä.