La Bruton tyrosine kinase ou Btk est une protéine dont le rôle dans la maturation des lymphocytes B est connu depuis plusieurs années. Par contre, son rôle dans le contrôle de l’immunité innée est moins établi. Nous avons montré que, en réponse à la voie des Toll like Receptors ou TLRs, Btk régule la stabilité de l’ARN messager du TNF-α par l’intermédiairede la protéine TTP ou Tristétraproline. Par ailleurs, nous avons montré que l’expression d’un microARN, le miR-346, régulait négativement la protéine Btk et donc la synthèse de TNF-α. L’amplification de l’expression de ce miR-346 par transfection permet d’avoir un effet anti-TNF-α et anti-Btk interessant notamment dans le modèle cellulaire de la polyarthrite rhumatoïde. Enfin, nous avons montré que, en réponse au TLRs, la modulation de l’expression du TNF-α en fonction de l’état de méthylation de l’ADN et d’acétylation des histones dépendait directement de l’expression du couple miR-346 et Btk. Btk est donc une protéine charnière dans le contrôle de l’inflammation par les mécanismes épigénétiques que sont les miARNs, la méthylation de l’ADN et l’acétylation des histones. Sur le plan thérapeutique, l’inhibition de cette protéine par ces différents mécanismes de régulation semble donc être très interessante, à la fois dans les maladies inflammatoires et néoplasiques. / Bruton tyrosine kinase, or Btk, is a protein whose role in the maturation of B cells has been known for several years. However, its role in the control of innate immunity is less established. We have shown that, in response to Toll like Receptors pathway or TLRs, Btk regulates the stability of the mRNA of TNF-α via the TTP or Tristetraprolin protein. Furthermore, we showed that the expression of microRNA, the miR-346, negatively regulated the Btk protein and thus the synthesis of TNF-α. Upregulation of miR-346 by transfection act as an anti-TNF-α and anti-Btk drugs, especially in the cellular model of rheumatoid arthritis.Finally, we showed that, in response to TLRs, the modulation of the expression of TNF-α according to the state of DNA methylation and histone acetylation depended directly on crosstalk beetween miR-346 and Btk. Btk is a key protein in the control of inflammation by epigenetic mechanisms such as miRNAs, DNA methylation and histone acetylation. As therapeutic interest, inhibition of Btk by those different regulatory mechanisms seems to be very interesting, both in inflammatory and neoplastic diseases.

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Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Base teórica: doenças linfoproliferativas crônicas de linhagem B (DLPC-B) são neoplasias clonais que afetam linfócitos B maduros. A tirosina quinase de Bruton (do inglês Bruton’s tyrosine kinase, BTK) é uma proteína essencial para o desenvolvimento, diferenciação e sinalização nos linfócitos B. Ki-67 é uma proteína nuclear associada à proliferação celular. A avaliação de proteínas envolvidas nas vias de sinalização oncogênicas pode levar ao aprimoramento do diagnóstico, tratamento e definição de prognóstico das DLPC-B. Objetivo: avaliar a expressão de BTK e Ki-67 em linfócitos de portadores de DLPC-B. Métodos: para avaliação de BTK foi realizado um estudo transversal; foi avaliada a expressão de BTK em amostras de pacientes saudáveis e de pacientes com diagnóstico de DLPC-B. Para avaliação de Ki-67 foi realizado um estudo transversal. As amostras foram marcadas com CD45 FITC e CD19 APC para identificação dos linfócitos B. Após a lise das hemácias, foi realizada marcação citoplasmática de BTK PE e/ou Ki-67 PerCP-Cy5.5. O percentual de expressão e a intensidade de fluorescência média (IFM) dos marcadores avaliados foram determinados nos linfócitos B. A análise estatística foi realizada com testes de correlação de Pearson e Spearman entre BTK ou Ki-67 e as demais variáveis clínicas e laboratoriais, e ANOVA seguido por teste post hoc de Bonferroni para comparações entre grupos. Foi considerado resultado significante quando P < 0,05. Resultados: não foram observadas diferenças na expressão de BTK e não houve associação entre a expressão de BTK e as variáveis clínicas avaliadas. A expressão de Ki-67 foi maior nos grupos linfoma do manto, linfoma de Burkitt e linfoma difuso de grandes células B em relação aos demais; após análise multivariada, a IFM de Ki-67 foi associada à IFM de CD38. Conclusão: no presente trabalho, a expressão de BTK em DLPC-B foi similar a de linfócitos B normais e a expressão de Ki-67 foi maior nas DLPC-B com curso clínico mais agressivo. / Background: mature B-cell neoplasms (MBCN) are clonal neoplasms that affect mature B-cell lymphocytes. Bruton’s tyrosine kinase (BTK) is an essential protein for the development, differentiation and signaling in B-cell lymphocytes. Ki-67 is a nuclear protein associated to cellular proliferation. Evaluation of proteins involved in oncogenic signaling pathways can lead to improvement in the diagnosis, treatment and prognosis definition in MBCN. Objective: to evaluate the expression of BTK and Ki-67 in lymphocytes of MBCN patients using flow cytometry. Methods: a cross-sectional study was conducted for BTK assessment; BTK expression was assessed on healthy patients samples and MBCN samples. For evaluation of Ki-67 a cross-sectional study was conducted. Samples were stained with CD45 FITC and CD19 APC for identification of B-cell lymphocytes. After lysis of red blood cells, cytoplasmic staining of BTK PE and/or Ki-67 PerCP-Cy5.5 was performed. Percentage of expression and mean fluorescence intensity (MFI) of the markers were determined in B-cell lymphocytes. Statistical analysis was performed with Pearson and Spearman correlation tests between BTK and Ki-67 and the other clinical and laboratory variables, and ANOVA followed by post-hoc Bonferroni test for comparisons between groups. Results were considered significant when P < 0.05. Results: no differences in BTK expression were identified and there was no association between BTK expression and clinical variables evaluated. Ki-67 expression was higher in mantle cell lymphoma, Burkitt lymphoma and diffuse large B-cell lymphoma cases; after multivariate analysis, MFI of Ki-67 was associated with MFI of CD38. Conclusions: in this study, BTK expression in B-cell neoplasms was similar to that of normal B-cell lymphocytes and Ki-67 expression was higher in MBCN with more aggressive clinical courses.

Major constituents of the venom of various animals are peptidogenic in nature. Marine snails belonging to the species Conus are venomous predators that use small, structurally constrained peptides present in their venom for prey capture and defense. It is known that ~500 Conus species are present in nature and the venom of each of these Conus species is a complex mixture of nearly 100 peptides accounting for > 50,000 peptides with little overlap among the different species. The peptides isolated from the venom of Conus species are commonly known as conotoxins or conopeptides. Some of the common targets of these peptides include the different ion channels like Na+, K+, and Ca2+, and receptor subtypes such as nicotinic acetylcholine and NMDA receptors. The ion channels and receptor subtypes were targeted by conopeptides with high degree of specificity and selectivity. The structural information on the peptides from cone snails can prove to be a valuable starting tool for the understanding of the function of different ion channels and hence in the design of neuropharmacologically active drugs. Conotoxins are disulfide-rich peptides and the number of disulfide generally ranges from two to five. Based on the arrangement of cysteines in their primary sequence, they are classified into different superfamilies. The signal sequences of the precursors belonging to a particular superfamily are highly conserved and hence the members within the same family have, in common, the unique disulfide arrangement and pharmacological activity. Conotoxins are classified into eleven superfamilies till date. In order to understand the underlying the principles involved in the action of these peptides on different ion channels, one needs to know the three-dimensional structures which, in potential, will help in the identification of the pharmacophores responsible for the observed pharmacological activity. With the aim of studying the structure-activity relationships found among the conotoxins, we have initiated a study on the peptides isolated from the marine snails found in the Indian coastal waters. This thesis is focused in the structural studies of the peptide toxins from marine cone snails and a terrestrial scorpion. The tool used for the structural studies of these peptide toxins is Nuclear Magnetic Resonance Spectroscopy. Chapter 1 provides an overview of the peptide toxins found among various animal species with more emphasis on conotoxins and scorpion toxins. In addition, the rationale behind the present study has also been explained. Chapter 2 describes the structure determination of two conopeptides isolated from Conus amadis, δ-Am2766 and Am2735, which are active on mammalian sodium channels. The structural aspects and comparison with other known conopeptides belonging to the same superfamily as that of these two peptides have also been described. Solution NMR studies of Ar1446 and Ar1248, two conopeptides isolated from the species Conus araneosus have also been studied using Homonuclear NMR methods. Ar1446 is a three disulfide-bonded peptide. Our studies have revealed that this peptide has a novel disulfide connectivity not previously observed in the M superfamily or any other superfamily of conotoxins. The structural features of Ar1446 will be described along with the NMR studies on two-disulfide bonded peptide, Ar1248, belonging to the A-superfamily of conotoxins. The main problem faced in the kind of study of peptides isolated from natural sources is the amount that can be isolated and purified to homogeneity. In order to obtain large quantities of peptides, we have successfully used Cytochrome b5 as fusion host to clone, over express and purify these peptides using recombinant methods. The use of recombinant methods has aided in the preparation of isotopically enriched peptides. The use of cyt b5 as fusion host for the large scale production of some of the peptides from Indian marine snails is described in Chapter 4. A novel pharmacologically active linear peptide, Mo1659 isolated from Conus monile, have been studied using Heteronuclear NMR methods. This peptide was cloned, over expressed and purified using Cytochrome b5 as a fusion host. Another linear peptide, Mo1692 (also from Conus monile), has been prepared using the same method and was studied using Homonuclear NMR methods. Both these peptides were liberated from the fusion host using cyanogen bromide cleavage and were subsequently purified using RP-HPLC. The results of the biosynthetic preparation and NMR studies of these two peptides have been described in Chapter 5. Chapter 6 describes the solution structure determination of a novel scorpion toxin characterized in the venom of the Indian red scorpion Buthus tamulus. The cloning, over expression, folding and purification of BTK-2 is described here. The structure and the function of this recombinantly produced BTK-2 will also be described.

Base teórica: doenças linfoproliferativas crônicas de linhagem B (DLPC-B) são neoplasias clonais que afetam linfócitos B maduros. A tirosina quinase de Bruton (do inglês Bruton’s tyrosine kinase, BTK) é uma proteína essencial para o desenvolvimento, diferenciação e sinalização nos linfócitos B. Ki-67 é uma proteína nuclear associada à proliferação celular. A avaliação de proteínas envolvidas nas vias de sinalização oncogênicas pode levar ao aprimoramento do diagnóstico, tratamento e definição de prognóstico das DLPC-B. Objetivo: avaliar a expressão de BTK e Ki-67 em linfócitos de portadores de DLPC-B. Métodos: para avaliação de BTK foi realizado um estudo transversal; foi avaliada a expressão de BTK em amostras de pacientes saudáveis e de pacientes com diagnóstico de DLPC-B. Para avaliação de Ki-67 foi realizado um estudo transversal. As amostras foram marcadas com CD45 FITC e CD19 APC para identificação dos linfócitos B. Após a lise das hemácias, foi realizada marcação citoplasmática de BTK PE e/ou Ki-67 PerCP-Cy5.5. O percentual de expressão e a intensidade de fluorescência média (IFM) dos marcadores avaliados foram determinados nos linfócitos B. A análise estatística foi realizada com testes de correlação de Pearson e Spearman entre BTK ou Ki-67 e as demais variáveis clínicas e laboratoriais, e ANOVA seguido por teste post hoc de Bonferroni para comparações entre grupos. Foi considerado resultado significante quando P < 0,05. Resultados: não foram observadas diferenças na expressão de BTK e não houve associação entre a expressão de BTK e as variáveis clínicas avaliadas. A expressão de Ki-67 foi maior nos grupos linfoma do manto, linfoma de Burkitt e linfoma difuso de grandes células B em relação aos demais; após análise multivariada, a IFM de Ki-67 foi associada à IFM de CD38. Conclusão: no presente trabalho, a expressão de BTK em DLPC-B foi similar a de linfócitos B normais e a expressão de Ki-67 foi maior nas DLPC-B com curso clínico mais agressivo. / Background: mature B-cell neoplasms (MBCN) are clonal neoplasms that affect mature B-cell lymphocytes. Bruton’s tyrosine kinase (BTK) is an essential protein for the development, differentiation and signaling in B-cell lymphocytes. Ki-67 is a nuclear protein associated to cellular proliferation. Evaluation of proteins involved in oncogenic signaling pathways can lead to improvement in the diagnosis, treatment and prognosis definition in MBCN. Objective: to evaluate the expression of BTK and Ki-67 in lymphocytes of MBCN patients using flow cytometry. Methods: a cross-sectional study was conducted for BTK assessment; BTK expression was assessed on healthy patients samples and MBCN samples. For evaluation of Ki-67 a cross-sectional study was conducted. Samples were stained with CD45 FITC and CD19 APC for identification of B-cell lymphocytes. After lysis of red blood cells, cytoplasmic staining of BTK PE and/or Ki-67 PerCP-Cy5.5 was performed. Percentage of expression and mean fluorescence intensity (MFI) of the markers were determined in B-cell lymphocytes. Statistical analysis was performed with Pearson and Spearman correlation tests between BTK and Ki-67 and the other clinical and laboratory variables, and ANOVA followed by post-hoc Bonferroni test for comparisons between groups. Results were considered significant when P < 0.05. Results: no differences in BTK expression were identified and there was no association between BTK expression and clinical variables evaluated. Ki-67 expression was higher in mantle cell lymphoma, Burkitt lymphoma and diffuse large B-cell lymphoma cases; after multivariate analysis, MFI of Ki-67 was associated with MFI of CD38. Conclusions: in this study, BTK expression in B-cell neoplasms was similar to that of normal B-cell lymphocytes and Ki-67 expression was higher in MBCN with more aggressive clinical courses.

Base teórica: doenças linfoproliferativas crônicas de linhagem B (DLPC-B) são neoplasias clonais que afetam linfócitos B maduros. A tirosina quinase de Bruton (do inglês Bruton’s tyrosine kinase, BTK) é uma proteína essencial para o desenvolvimento, diferenciação e sinalização nos linfócitos B. Ki-67 é uma proteína nuclear associada à proliferação celular. A avaliação de proteínas envolvidas nas vias de sinalização oncogênicas pode levar ao aprimoramento do diagnóstico, tratamento e definição de prognóstico das DLPC-B. Objetivo: avaliar a expressão de BTK e Ki-67 em linfócitos de portadores de DLPC-B. Métodos: para avaliação de BTK foi realizado um estudo transversal; foi avaliada a expressão de BTK em amostras de pacientes saudáveis e de pacientes com diagnóstico de DLPC-B. Para avaliação de Ki-67 foi realizado um estudo transversal. As amostras foram marcadas com CD45 FITC e CD19 APC para identificação dos linfócitos B. Após a lise das hemácias, foi realizada marcação citoplasmática de BTK PE e/ou Ki-67 PerCP-Cy5.5. O percentual de expressão e a intensidade de fluorescência média (IFM) dos marcadores avaliados foram determinados nos linfócitos B. A análise estatística foi realizada com testes de correlação de Pearson e Spearman entre BTK ou Ki-67 e as demais variáveis clínicas e laboratoriais, e ANOVA seguido por teste post hoc de Bonferroni para comparações entre grupos. Foi considerado resultado significante quando P < 0,05. Resultados: não foram observadas diferenças na expressão de BTK e não houve associação entre a expressão de BTK e as variáveis clínicas avaliadas. A expressão de Ki-67 foi maior nos grupos linfoma do manto, linfoma de Burkitt e linfoma difuso de grandes células B em relação aos demais; após análise multivariada, a IFM de Ki-67 foi associada à IFM de CD38. Conclusão: no presente trabalho, a expressão de BTK em DLPC-B foi similar a de linfócitos B normais e a expressão de Ki-67 foi maior nas DLPC-B com curso clínico mais agressivo. / Background: mature B-cell neoplasms (MBCN) are clonal neoplasms that affect mature B-cell lymphocytes. Bruton’s tyrosine kinase (BTK) is an essential protein for the development, differentiation and signaling in B-cell lymphocytes. Ki-67 is a nuclear protein associated to cellular proliferation. Evaluation of proteins involved in oncogenic signaling pathways can lead to improvement in the diagnosis, treatment and prognosis definition in MBCN. Objective: to evaluate the expression of BTK and Ki-67 in lymphocytes of MBCN patients using flow cytometry. Methods: a cross-sectional study was conducted for BTK assessment; BTK expression was assessed on healthy patients samples and MBCN samples. For evaluation of Ki-67 a cross-sectional study was conducted. Samples were stained with CD45 FITC and CD19 APC for identification of B-cell lymphocytes. After lysis of red blood cells, cytoplasmic staining of BTK PE and/or Ki-67 PerCP-Cy5.5 was performed. Percentage of expression and mean fluorescence intensity (MFI) of the markers were determined in B-cell lymphocytes. Statistical analysis was performed with Pearson and Spearman correlation tests between BTK and Ki-67 and the other clinical and laboratory variables, and ANOVA followed by post-hoc Bonferroni test for comparisons between groups. Results were considered significant when P < 0.05. Results: no differences in BTK expression were identified and there was no association between BTK expression and clinical variables evaluated. Ki-67 expression was higher in mantle cell lymphoma, Burkitt lymphoma and diffuse large B-cell lymphoma cases; after multivariate analysis, MFI of Ki-67 was associated with MFI of CD38. Conclusions: in this study, BTK expression in B-cell neoplasms was similar to that of normal B-cell lymphocytes and Ki-67 expression was higher in MBCN with more aggressive clinical courses.

Tyrphostine stellen eine Klasse synthetischer Protein-Tyrosin-Kinase (PTK)-Hemmer, die sich strukturell vom Tyrosin ableiten und dazu dienen, spezifisch Substratphosphorylierungen zu verhindern. Tyrphostin AG126 zeigte entzündungshemmende Eigenschaften in zahlreichen Tiermodellen von Erkrankungen. Dies schließt den septischen Schock ein, der durch Lipopolysaccharid (LPS) Gram-negativer Bakterien induziert werden kann, sowie die durch Zellwandstrukturen Gram-positiver Bakterien ausgelöste bakterielle Meningitis. Wir zeigen nun positive AG126-Effekte in einer weiteren ZNS-Komplikation, der experimentellen autoimmunen Enzephalomyelitis (EAE) als einem Modell der Multiplen Sklerose, wo AG126-Behandlung die klinischen Symptome und Myelinschäden mildert. Auf zellulärer Ebene beeinflusst AG126 eine Vielzahl von Funktionen der Mikroglia, der ZNS-Makrophagen, die durch Aktivierung von Toll-like-Rezeptoren (TLR s) ausgelöst werden. Diese Rezeptoren der angeborenen Immunität erkennen mikrobielle Strukturen sowie Faktoren, die durch Gewebeverletzungen generiert werden. Mit dem Fokus auf Mikroglia untersuchte die vorliegende Arbeit erstmals molekulare Zielstrukturen und Mechanismen des AG126. AG126 beeinflusst besonders Geninduktionen, die vom Adaptorprotein MyD88, einem der zwei TLR-Signalwege, abhängen. Bruton s Tyrosin-Kinase (BTK), eine MyD88-assoziierte PTK, kann von AG126 in molekularen und zellbasierten Assays gehemmt werden. Diese Hemmung kann allerdings nicht das gesamte Spektrum der AG126-Effekte erklären. Daher müssen alternative, sogar PTK-unabhängige Mechanismen, in Betracht gezogen werden, basierend auf strukturellen und funktionellen Ähnlichkeiten zu Tyrosin-abgeleiteten und/oder mikrogliaaktiven Molekülen. Diese alternativen Mechanismen umfassen Prinzipien, die für Antioxidantien, adrenerge Agonisten, Glukokortikoide oder Entkoppler der oxidativen Phosphorylierung bekannt sind. Tatsächlich zeigen Analysen auf der Grundlage von Kernspinresonanzspektroskopie, dass AG126 in die Hauptprodukte 3-Hydroxy-4-Nitroben zaldehyd (BZ) und Malononitril (MN) zerfallen kann, von denen MN, aber nicht BZ, die AG126-Effekte in Mikroglia imitiert. Ein ähnliches Verhalten zeigen weitere Tyrphostine, die ebenfalls das kritische MN-Strukturmotiv aufweisen. Tierexperimente zeigen schließlich, dass nur AG126 als Ausgangstruktur, nicht aber MN oder BZ, das Gesamtspektrum protektiver Effekte in der EAE vermittelt. Die Identifizierung des eigentlichen von AG126 bzw. von MN beeinflussten Targets könnte somit einen wesentlichen Mechanismus für die Entwicklung von entzündungshemmenden Verbindungen offenlegen.

La Bruton tyrosine kinase ou Btk est une protéine dont le rôle dans la maturation des lymphocytes B est connu depuis plusieurs années. Par contre, son rôle dans le contrôle de l'immunité innée est moins établi. Nous avons montré que, en réponse à la voie des Toll like Receptors ou TLRs, Btk régule la stabilité de l'ARN messager du TNF-α par l'intermédiairede la protéine TTP ou Tristétraproline. Par ailleurs, nous avons montré que l'expression d'un microARN, le miR-346, régulait négativement la protéine Btk et donc la synthèse de TNF-α. L'amplification de l'expression de ce miR-346 par transfection permet d'avoir un effet anti-TNF-α et anti-Btk interessant notamment dans le modèle cellulaire de la polyarthrite rhumatoïde. Enfin, nous avons montré que, en réponse au TLRs, la modulation de l'expression du TNF-α en fonction de l'état de méthylation de l'ADN et d'acétylation des histones dépendait directement de l'expression du couple miR-346 et Btk. Btk est donc une protéine charnière dans le contrôle de l'inflammation par les mécanismes épigénétiques que sont les miARNs, la méthylation de l'ADN et l'acétylation des histones. Sur le plan thérapeutique, l'inhibition de cette protéine par ces différents mécanismes de régulation semble donc être très interessante, à la fois dans les maladies inflammatoires et néoplasiques.