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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Pesquisa da mutação T1799A do gene BRAF e a presença de metástases linfáticas no carcinoma papilífero da tireoide / Analysis of the T1799A BRAF mutation and lymph node mestastases in papillary thyroid carcinoma

Simone Elisa Dutenhefner 11 October 2011 (has links)
Muitos pacientes submetidos à tireoidectomia por Carcinoma Papilífero da Tireoide (CPT) têm doença linfonodal subclínica no momento da cirurgia. A mutação BRAF T17799A (V600E) é um evento comum no CPT e alguns estudos demonstram correlação entre a mutação e características de maior agressividade tumoral, incluindo a presença de metástases linfonodais. O esvaziamento eletivo do compartimento central ganha aceitação, uma vez que alguns estudos evidenciam que a presença de metástases linfonodais aumenta o risco de recidiva e mortalidade. Devido ao grande potencial de complicações do esvaziamento do compartimento central, o objetivo deste trabalho foi avaliar a associação entre a presença da mutação BRAF T17799A (V600E), a presença de metástases linfonodais e fatores clínicos e histopatológicos de pior prognóstico. Métodos: 51 casos consecutivos de pacientes com CPT foram submetidos à tireoidectomia total e ao esvaziamento eletivo ou terapêutico do compartimento central. Em todos os pacientes foi pesquisada a mutação BRAF T17799A (V600E) no tecido tireoidiano com Carcinoma Papilífero de Tireoide. Resultados: Cinquenta e quatro por cento (54,9%) dos pacientes apresentaram metástases linfonodais. Seis pacientes apresentaram metástases laterais confirmadas por punção aspirativa por agulha fina no pré-operatório e 22 pacientes (43%) apresentaram metástases não detectadas no pré ou no intra operatório A mutação BRAF T17799A (V600E) foi encontrada em 15 pacientes portadores de CPT (29,4%). A presença da mutação não teve associação estatisticamente significante para sexo, idade, tamanho do tumor, extensão extratireoidiana, multicentricidade, embolização angiolinfática e metástases linfonodais. As metástases linfonodais se associaram à multifocalidade (p = 0,005) e invasão angiolinfática (p = 0,003) na análise univariada. Conclusão: A presença da mutação BRAF T17799A (V600E) não se associou à metástases linfonodais em nosso estudo. A multifocalidade e a detecção de invasão angiolinfática no CPT foram os fatores mais importantes na predição de metástases linfonodais / Background: Many patients undergoing thyroidectomy for Papillary Thyroid Carcinoma (PTC) have subclinical node disease at the time of surgery. The BRAF T17799A (V600E) mutation is a common event in PTC and some studies have demonstrated a correlation between the mutation and aggressive characteristics including lymph node metastasis. Prophylactic Central Node Dissection (CND) is gaining acceptance in the treatment of PTC as studies have shown nodal disease increases local recurrence and may alter mortality. Given the potential complications of CND, the aim of this study was to determine the correlation among BRAF mutation, lymph node metastasis and clinical and histopathological factors of worse prognosis. Methods: A total of 51 consecutive cases of patients with PTC underwent total thyroidectomy and routine prophylactic (CND) or therapeutic neck dissection when metastases were found. All patients were tested for the BRAF mutation. Results: Overall, positive lymph nodes were found in Fifty four per cent9% of patients. Six patients had lateral metastases confirmed by fine needle aspirative cytology and 22 patients (43%) had occult metastases. The BRAF mutation was found in 15 patients (29.4%). BRAF was not correlated with sex, age, size of tumor, multifocality, extrathyroid extension or lymph node metastases. Lymph node metastases were correlated with multifocality (p = 0.005) and angiolymphatic invasion (p = 0.003) in univariate. Conclusions: The BRAF mutation was not correlated with lymph node metastases in our study. Multifocality and angiolymphatic invasion were important factors for predicting lymph node metastases
42

Terroristorganisationer : En studie om terroristorganisationers mål, fiender, medel och organisationssätt.

Solhjort, Stefan January 2008 (has links)
The aim with this study is to achieve an increased understanding and knowledge about terrorist groups. The factors that the study come to be focused around is the groups' objectives, their organization, which enemies they have and with which means that they use for there terrorism. In order to respond to this aim the four different terrorist groups, Colombian revolutionary armed forces (FARC), Baskien - our native country and our freedom (ETA), red Army fraction (RAF) and al Qaida is studied. To achieve the aim of this study the methods qualitative text analysis and comparative method is being used. It is designed also within the framework of this study a categorization model that is used as method in order to do a division of the studied groups based on their objective, enemies, organization and means. The model is also constructed to be used in order to analyze others terrorist groups than these current groups. The result of the study is presented in the categorization model on page 32 in the essay.
43

Genomweite Suche neuer Modulatoren der Signaltransduktion in kardialer Hypertrophie und Herzinsuffizienz / Genome wide cDNA library screen for new signaling associated modulators of cardiac hypertrophy and heart failure

Kramann, Nadine 18 January 2011 (has links)
No description available.
44

Terroristorganisationer : En studie om terroristorganisationers mål, fiender, medel och organisationssätt.

Solhjort, Stefan January 2008 (has links)
<p>The aim with this study is to achieve an increased understanding and knowledge about terrorist groups. The factors that the study come to be focused around is the groups' objectives, their organization, which enemies they have and with which means that they use for there terrorism. In order to respond to this aim the four different terrorist groups, Colombian revolutionary armed forces (FARC), Baskien - our native country and our freedom (ETA), red Army fraction (RAF) and al Qaida is studied.</p><p>To achieve the aim of this study the methods qualitative text analysis and comparative method is being used. It is designed also within the framework of this study a categorization model that is used as method in order to do a division of the studied groups based on their objective, enemies, organization and means. The model is also constructed to be used in order to analyze others terrorist groups than these current groups.</p><p>The result of the study is presented in the categorization model on page 32 in the essay.</p>
45

Inhibition de l'angiogenèse tumorale : criblage d'une chimiothèque et caractérisation d'un nouveau composé agissant sur la voie de signalisation Ras-ERK / Inhibition of tumor angiogenesis : screening of a chemical library and characterization of a new compound that targets the Ras-ERK signaling pathway

Castan, Agnès 03 October 2014 (has links)
Au cours des dernières années, des thérapies anti-cancéreuses ciblant l'angiogenèse tumorale ont été développées et ont démontré un bénéfice en terme de survie globale pour les patients atteints de certains cancers métastatiques. Cependant, dans de nombreux cas, les tumeurs acquièrent des résistances échappent au traitement. Le développement de nouveaux composés anti-angiogène est donc une réelle nécessité pour être proposés en seconde ligne thérapeutique. Dans ce travail, notre objectif était d'identifier de nouvelles molécules anti-angiogènes par le criblage à haut débit, de la chimiothèque académique de l'Université de Grenoble. Nous avons adapté le test de blessure sur cellules endothéliales au format des plaques de 96 puits et avons identifié une famille de molécules qui inhibent spécifiquement leur fermeture. L'activité anti-angiogène de la molécule leader (COB223) a été confirmée dans des modèles d'angiogenèse tridimensionnels in vitro, et, chez la souris, dans un modèle d'angiogenèse sous-cutanée. Nous avons testé l'activité anti-tumorale de COB223 dans un modèle de xénogreffe chez la souris et observé une diminution significative de la taille des tumeurs dans les souris traitées. A la recherche de son mécanisme d'action, nous avons observé que COB223 inhibe la prolifération cellulaire et diminue les phosphorylations de MEK et Raf, de ERK1/2 induites par le VEGF-A dans les cellules endothéliales. Nous avons également montré que COB223 n'inhibe pas les phosphorylations du VEGFR2 et de PLC. D'après ces résultats, nous proposons que la cible de COB est localisée dans la voie de signalisation VEGF/ PLC /PKC/ERK entre PKC et Ras. / Several anti-tumoral therapies targeting angiogenesis have been developed over the recent years and have demonstrated benefits for several metastatic cancers. However, in many cases, resistances to these treatments appear over time, allowing tumor escape. The development of new anti-angiogenic compounds is thus dramatically urged in order to propose second-line anti-angiogenic treatments. In this work, our aim was to identify new anti-angiogenic compounds through high throughput screening of the academic library from the University of Grenoble. We adapted the endothelial cell scratch assay to 96-well plates. We identified a family of molecules that specifically inhibited endothelial cell migration. The anti-angiogenic activity of the leader molecule (COB223) was confirmed in vitro in 3D cellular models of angiogenesis and in vivo using a mouse model of subcutaneous sponge implantation. We tested the anti-tumoral activity of COB223 on a mouse xenograft model. We observed that tumor growth was significantly reduced in treated mice correlated with decreased microvessel density. In search for its mechanism of action, we observed that COB223 inhibits cell proliferation and reduces VEGF-A-induced phosphorylation of MEK and ERK1/2 in endothelial cells. We also showed that COB223 did not affect VEGFR2 and PLC phosphorylation but reduces Raf phosphorylation responsible for its activity. These results allow us to propose that the molecular site of action of COB223 is located in the VEGF/ PLC /PKC/ERK pathway, between PKC and MEK.
46

CONTRIBUIÇÃO ANATÔMICA DO LENHO À TAXONOMIA DO ANTIGO GÊNERO ACACIA Mill. (Fabaceae) / CONTRIBUITION TO THE WOOD TAXONOMY OF THE FORMER GENUS ACACIA Mill. (Fabaceae)

Machado, Paulo Fernando dos Santos 26 February 2016 (has links)
Conselho Nacional de Desenvolvimento Científico e Tecnológico / This study aimed to describe the wood anatomy of ten species of the former genus Acacia Mill., as well as to conduct a quantitative agglomerative analysis with 25 species of the same genus, in order to recognize wood anatomical features of diagnostic value to the genera segregated from Acacia Mill. in 2005. The following species were investigated and described, according to IAWA Committee: Acacia acuminata A. Gray, Acacia cambagei R.T. Baker, ex Baker, Acacia harpophylla F. Muell. ex Benth., Acacia koa A. Gray, Acacia rhodoxylon Maiden, Acacia richii A. Gray, Senegalia martiusiana (Steud.) Seigler e Ebinger, Vachellia collinsii Saff., Vachellia nilotica (L.) P. J. H. Hurter e Mabb., e Vachellia planifrons (Wight e Arn.) Ragup., Seigler, Ebinger e Maslin. To the Cluster analysis, anatomical data of another 15 species were collected from the literature. All species share the following features of large occurrence in Fabaceae: diffuse-porous wood; simple perforation plates; vestured intervessel pits; paratracheal parenchyma; libriform fibers; and homogeneous rays. The presence of septate fibers allows to distinguish all the studied species of Senegalia Raf. The occurrence of conspicuous large rays, conjugated with abundant axial parenchyma allows to set apart all Vachellia species from the seven ones, that belongs to the genus Acacia Mill. / Este trabalho teve por objetivo a descrição anatômica de dez espécies de madeira do antigo gênero Acacia Mill., bem como a realização de uma análise quantitativa aglomerativa com dados de 25 espécies do mesmo gênero, com vistas a contribuir para o melhor conhecimento taxonômico, além de reconhecer, na estrutura do lenho, caracteres qualitativos e quantitativos de valor diagnóstico para os táxones segregados em 2005, a partir deste gênero botânico. As descrições basearam-se nas recomendações do IAWA Committee: Acacia acuminata A. Gray, Acacia cambagei R.T. Baker, ex Baker, Acacia harpophylla F. Muell. ex Benth., Acacia koa A. Gray, Acacia rhodoxylon Maiden, Acacia richii A. Gray, Senegalia martiusiana (Steud.) Seigler e Ebinger, Vachellia collinsii Saff., Vachellia nilotica (L.) P. J. H. Hurter e Mabb., e Vachellia planifrons (Wight e Arn.) Ragup., Seigler, Ebinger e Maslin. Na análise de Cluster foram utilizadas as espécies do presente estudo mais outras 15 colhidas na literatura. Todas as espécies apresentam os seguintes caracteres de ampla ocorrência em Fabaceae: porosidade difusa; placas de perfuração simples; elementos vasculares com pontoações ornamentadas; parênquima paratraqueal; fibras libriformes; e raios homogêneos. A presença de fibras septadas permite distinguir as espécies de Senegalia Raf. das demais. Por sua vez, a ocorrência de raios conspícuos, e a abundância de parênquima axial em Vachellia Wight e Arn. permite excluí-la das sete espécies do gênero.
47

Redução do crescimento de plantas de crisântemo e lisianthus em vaso / Reducing the growth of plants chrysanthemum and lisianthus cultured in pot

Mainardi, Jucelma de Cássia Camara Tolotti 08 February 2013 (has links)
The Chrysanthemum (Dendranthema grandiflora Tzvelev) and Lisianthus (Eustoma grandiflorum Raf.) are species of ornamental plants of great prominence in the Brazilian and international floriculture. In the cultivation of ornamental plants in pots, is usually performed chemical control of plant growth seeking its standardization. This research aimed to evaluate the responses of these two species to plant growth retardant, sprayed on cutting cultivars conducted in pots in order to obtain a differentiated product, and also define the optimal dose for producing quality plant pots suited to commercial standards. The survey consists of tests in a randomized design. Lisianthus in the model is 3 x 5 factorial, with three cultivars ('Echo Pure White', 'Mariachi Misty Pink' and 'Echo Yellow') and five doses of Paclobutrazol (0, 16, 32, 48 and 64 mg.L-1) applied in spraying. The Chrysanthemum uses 2 x 4 factorial design, frequency of application being tested weekly and biweekly and plant growth retardant Daminozide (0, 2.000, 4.000 and 6.000 mg.L-1) on the cultivar 'Yellow Spithoven'. The results show that the cultivar of Lisianthus 'Echo Yellow' is the most suitable for growing in pots and the best fit is achieved with these commercial spraying of 64 mg.L-1 of Paclobutrazol. The cultivar of Chrysanthemum 'Yellow Spithoven' has driven its growth Daminozide and can be grown in pots, and 2.000 mg L-1 produces the weekly sprayed potted plants of better quality. / O Crisântemo (Dendranthema grandiflora Tzvelev) e o Lisianthus (Eustoma grandiflorum Raf.) são espécies de plantas ornamentais de grande destaque na floricultura brasileira e internacional. Nos cultivos de plantas ornamentais em vaso, normalmente é realizado o controle químico do crescimento da planta buscando a sua padronização. Esta pesquisa teve como objetivos avaliar as respostas dessas duas espécies a retardantes de crescimento de plantas, pulverizados sobre cultivares de corte conduzidas em vaso, visando obter-se um produto diferenciado, e ainda, definir a melhor dose para produção de vasos com plantas de qualidade adequados aos padrões de comercialização. A pesquisa foi constituída de ensaios, no delineamento inteiramente casualizado. No Lisianthus, o modelo foi bifatorial 3 x 5, com três cultivares ( Echo Pure White‟, Mariachi Misty Pink‟ e Echo Yellow‟) e cinco doses de Paclobutrazol (0, 16, 32, 48 e 64 mg.L-1) aplicadas em pulverização. Com o Crisântemo utilizou-se o modelo bifatorial 2 x 4, sendo testada a freqüência de aplicação semanal e bissemanal e o retardante de crescimento vegetal Daminozide (0, 2.000, 4.000 e 6.000 mg.L-1) sobre a cultivar Yellow Spithoven‟. Os resultados evidenciaram que, das cultivares de Lisianthus, a Echo Yellow‟ é a mais apropriada para o cultivo em vaso e a melhor adequação comercial destes é conseguida com a pulverização de 64 mg.L-1 de Paclobutrazol. A cultivar de Crisântemo Yellow Spithoven‟ tem seu crescimento controlado por Daminozide, podendo ser cultivada em vaso, e 2.000 mg.L-1 pulverizados semanalmente produziram os vasos com plantas de melhor qualidade.
48

Development of Dual-Pathway Inhibitors of Raf/MEK/ERK and PI3K/Akt Signaling Pathways.

Fraser, Sasha 13 December 2011 (has links)
In the present study, we designed a new chemical template that contains an oxindole moiety as potential dual-pathway inhibitors of the Raf/MEK/ERK and PI3K/Akt signaling pathways. The design hypothesis is to evaluate whether the oxindole ring system will approximately orient functional groups in a similar manner to the thiazolidinedione moiety, and thus maintain biological activity as dual-pathway inhibitors of the Raf/MEK/ERK and PI3K/Akt signaling pathways. Furthermore, the oxindole ring will provide the flexibility to allow the introduction of various substituents on the oxindole moiety, thereby facilitating comprehensive SAR studies to further explore the biological activity.
49

Obraz československých válečných letců v Rudém právu v letech 1945-1950 a ve vybraných ročnících 60. let. / The Image of Czechoslovak War Pilots in Rudé Právo between 1945-1950 and in the Selected Years of 1960s

Holeček, Martin January 2017 (has links)
The aim of diploma thesis The Image of Czechoslovak War Pilots in Rudé Právo between 1945-1950 and in the Selected Years of 1960s is to present the media image of this social group in the view of Rudé právo newspaper. Considering the topic chosen, the author concentrated on the post-war years between 1945-1947, 1948-1950 and the selected years of 1960s (1963, 1965 and 1968). This paper is based on complementation method which combines media history and theory, historical context and complex content analysis of Rudé právo articles in the given years. For content analysis, the author of the paper used a method of text coding depending on the topics suitable for sufficient presentation of the image of Czechoslovak war pilots as well as of the topics and events that contributed to that image. The primary source of this thesis was Rudé právo newspaper which also supplied material for content analysis. Secondary sources contain professional literature concerning media history and air or war environment. The author also uses internet sources and some of them are even archived by the National Library of the Czech Republic because of their content.
50

The Role of Protein-Protein Interactions in the Activation Cycle of RAF Kinases / Die Rolle von Protein-Protein Interaktionen im Aktivierungszyklus der RAF Kinasen

Fischer, Andreas January 2010 (has links) (PDF)
Members of the RAF protein kinase family are key regulators of diverse cellular processes. The need for isoform-specific regulation is reflected by the fact that all RAFs not only display a different degree of activity but also perform isoform-specific functions at diverse cellular compartments. Protein-protein-interactions and phosphorylation events are essential for the signal propagation along the Ras-RAF-MEK-ERK cascade. More than 40 interaction partners of RAF kinases have been described so far. Two of the most important regulators of RAF activity, namely Ras and 14-3-3 proteins, are subject of this work. So far, coupling of RAF with its upstream modulator protein Ras has only been investigated using truncated versions of RAF and regardless of the lipidation status of Ras. We quantitatively analyzed the binding properties of full-length B- and C-RAF to farnesylated H-Ras in presence and absence of membrane lipids. While the isolated Ras-binding domain of RAF exhibit a high binding affinity to both, farnesylated and nonfarnesylated H-Ras, the full-length RAF kinases demonstrate crucial differences in their affinity to Ras. In contrast to C-RAF that requires carboxyterminal farnesylated H-Ras for interaction at the plasma membrane, B-RAF also binds to nonfarnesylated H-Ras in the cytosol. For identification of the potential farnesyl binding site we used several fragments of the regulatory domain of C-RAF and found that the binding of farnesylated H-Ras is considerably increased in the presence of the cysteine-rich domain of RAF. In B-RAF a sequence of 98 amino acids at the extreme N terminus enables binding of Ras independent of its farnesylation status. The deletion of this region altered Ras binding as well as kinase properties of B-RAF to resemble C-RAF. Immunofluorescence studies in mammalian cells revealed essential differences between B- and C-RAF regarding the colocalization with Ras. In conclusion, our data suggest that that B-RAF, in contrast to C-RAF, is also accessible for nonfarnesylated Ras in the cytosolic environment due to its prolonged N terminus. Therefore, the activation of B-RAF may take place both at the plasma membrane and in the cytosolic environment. Furthermore, the interaction of RAF isoforms with Ras at different subcellular sites may also be governed by the complex formation with 14-3-3 proteins. 14-3-3 adapter proteins play a crucial role in the activation of RAF kinases, but so far no information about the selectivity of the seven mammalian isoforms concerning RAF association and activation is available. We analyzed the composition of in vivo RAF/14-3-3 complexes isolated from mammalian cells with mass spectrometry and found that B-RAF associates with a greater variety of 14-3-3 proteins than C- and A-RAF. In vitro binding assays with purified proteins supported this observation since B-RAF showed highest affinity to all seven 14-3-3 isoforms, whereas C-RAF exhibited reduced affinity to some and A-RAF did not bind to the 14-3-3 isoforms epsilon, sigma, and tau. To further examine this isoform specificity we addressed the question of whether both homo- and heterodimeric forms of 14-3-3 proteins participate in RAF signaling. By deleting one of the two 14-3-3 isoforms in Saccharomyces cerevisiae we were able to show that homodimeric 14-3-3 proteins are sufficient for functional activation of B- and C-RAF. In this context, the diverging effect of the internal, inhibiting and the activating C-terminal 14-3-3 binding domain in RAF could be demonstrated. Furthermore, we unveil that prohibitin stimulates C-RAF activity by interfering with 14-3-3 at the internal binding site. This region of C-RAF is also target of phosphorylation as part of a negative feedback loop. Using tandem MS we were able to identify so far unknown phosphorylation sites at serines 296 and 301. Phosphorylation of these sites in vivo, mediated by activated ERK, leads to inhibition of C-RAF kinase activity. The relationship of prohibitin interference with 14-3-3 binding and phosphorylation of adjacent sites has to be further elucidated. Taken together, our results provide important new information on the isoform-specific regulation of RAF kinases by differential interaction with Ras and 14-3-3 proteins and shed more light on the complex mechanism of RAF kinase activation. / RAF Protein Kinasen sind essentielle Regulatoren verschiedener zellulärer Prozesse. Unterschiedlich starke Aktivitäten und Lokalisation der drei RAF Isoformen erfordern eine isoform-spezifische Regulation. Der Einfluss von Protein-Protein Interaktionen und Phosphorylierungen ist dabei mitentscheidend für die Signalweiterleitung entlang der Ras-RAF-MEK-ERK Kaskade. Mehr als 40 Interaktionspartner der RAF Kinasen wurden bereits beschrieben von denen zwei der wichtigsten, Ras und 14-3-3 Proteine, Gegenstand der vorliegenden Arbeit sind. Die Interaktion von RAF mit seinem vorgeschaltetem Modulatorprotein Ras wurde bislang nur mit verkürzten RAF-Proteinen und ohne Rücksicht auf den Lipidierungsgrad von Ras untersucht. Wir haben die Bindeeigenschaften von B- und C-RAF in voller, nativer Länge zu farnesyliertem H-Ras in Gegenwart und Abwesenheit von Membranlipiden quantifiziert. Während die isolierte Ras-Bindungsdomäne eine hohe Affinität sowohl zu farnesyliertem als auch nicht-farnesyliertem H-Ras aufweist, zeigen die RAF Proteine in voller Länge entscheidende Unterschiede in ihrem Bindeverhalten zu Ras. C-RAF benötigt für eine effiziente Interaktion mit H-Ras dessen C-terminale Farnesylgruppe, wobei B-RAF auch an nicht-farnesyliertes H-Ras im Cytosol bindet. Um die verantwortliche Farnesylbinderegion zu identifizieren haben wir verschiedene Fragmente der regulatorischen Domäne von C-RAF eingesetzt. Dadurch konnten wir zeigen, dass die Affinität zu farnesyliertem Ras in Gegenwart der sogenannten Cystein-reichen Domäne von RAF beträchtlich erhöht war. In B-RAF ist eine Sequenz von 98 Aminosäuren am N-Terminus verantwortlich für die Ras-Bindung unabhängig von dessen Farnesylierungszustand. Die Deletion dieser Sequenz von B-RAF veränderte die Ras-Bindungseigenschaften sowie die Kinaseaktivität vergleichbar mit C-RAF. Durch Immunfluoreszenzversuche in Säugerzellen konnten darüber hinaus Unterschiede in der Kolokalisation von B- und C-RAF mit Ras beobachtet werden. Zusammenfassend deuten unsere Ergebnisse darauf hin, dass B-RAF, im Gegensatz zu C-RAF, aufgrund seines verlängerten N-Terminus in der Lage ist bereits im Cytosol auch mit unfarnesyliertem Ras zu interagieren, wodurch die Aktivierung von B-RAF sowohl im Cytosol als auch an der Plasmamenbran erfolgen kann. Die Interaktion der RAF-Isoformen mit Ras in unterschiedlichen zellulären Kompartimenten kann aber auch durch die Komplexbildung mit 14-3-3 Proteinen beeinflusst werden. Die 14-3-3 Adapter Proteine spielen eine entscheidende Rolle im Aktivierungszyklus der RAF Proteine. Bislang waren jedoch keine Details bezüglich der Selektivität der sieben 14-3-3 Isoformen aus Säugerzellen hinsichtlich der Assoziation mit und Aktivierung der RAF Kinasen bekannt. Wir haben RAF/14-3-3 Komplexe aus Säugerzellen isoliert und durch Massenspektrometrie analysiert. Dadurch konnten wir zeigen, dass B-RAF mit einer größeren Vielfalt an 14-3-3 Isoformen bindet als C- und A-RAF. In vitro Bindungsversuche mit gereinigten Proteinen bestätigten die höhere Affinität von B-RAF zu allen sieben Säuger-14-3-3 Proteinen. C-RAF dagegen zeigte eine deutlich reduzierte Affinität, während für A-RAF keine Bindung zu den 14-3-3 Isoformen epsilon, sigma, und tau festgestellt wurde. Um diese Isoformspezifität weiter aufzuklären haben wir untersucht, ob sowohl Homo- als auch Heterodimere von 14-3-3 in der Lage sind die RAF-Signaltransduktion zu beeinflussen. Durch die Deletion einer der beiden 14-3-3 Isoformen aus Saccharomyces cerevisiae konnten wir zeigen, dass bereits ein 14-3-3 Homodimer für die korrekte Aktivierung von B- und C-RAF ausreichend ist. In diesem Zusammenhang konnte auch die Rolle der internen, inhibierenden 14-3-3 Bindestelle in RAF gegenüber der C-terminalen, aktivierenden Stelle dargelegt werden. Zusätzlich zeigen wir, dass Prohibitin seinen aktivierenden Einfluss gegenüber C-RAF durch die Beeinträchtigung der 14-3-3 Bindung an der internen Stelle in RAF ausübt. Diese Region in C-RAF ist das Ziel von Phosphorylierungen im Zuge eines negativen Rückkopplungsmechanismus. Durch den Einsatz von Tandem-Massenspektrometrie konnten wir bislang unbekannte Phosphorylierungsstellen an den Serinen 296 und 301 identifizieren deren ERK-vermittelte Phosphorylierung in vivo eine Inaktivierung der C-RAF bewirkt. Der Zusammenhang zwischen der Behinderung der 14-3-3 Anlagerung durch Prohibitin und die Phosphorylierung in unmittelbarer Nachbarschaft bedarf weiterer Untersuchungen. Zusammengefasst liefern unsere Ergebnisse wichtige Informationen bezüglich der isoform-spezifischen Regulation der RAF Kinasen durch die Interaktion mit Ras und 14-3-3 Proteinen und helfen die komplexen Mechanismen der RAF Aktivierung weiter aufzuklären.

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