Le cancer de la prostate (CaP) représente la deuxième cause de mortalité par cancer. La suppression d’androgène est la thérapie de référence, du fait de l’androgéno-dépendance de ce cancer. Toutefois, la maladie progresse quand même vers un stade androgéno-indépendant 2 à 3 ans après le début du traitement. Pour améliorer les thérapies du CaP, notre stratégie consiste à cibler les gènes activés par la privation d’androgènes. Récemment, nous avons identifié TCTP (Translationally controlled tumor protein) comme étant hautement surexprimé après privation d’androgènes. Nous avons développé et breveté un oligonucléotide antisense (ASO) ciblant TCTP. Durant ma thèse j’ai développé un ASO de 3ème génération par ajout d’une séquence lipidique TCTP-LASO pour améliorer la stabilité, la biodisponibilité et la délivrance de l’ASO TCTP. Ce LASO est capable de s’autonanovectoriser et permet une internalisation de l’ASO sans agent transfectant. J’ai montré dans les modèles animaux que cela conduit à une meilleure efficacité thérapeutique sans engendrer de toxicité. De plus cette séquence peut servir de nanovecteur pour encapsuler la chimiothérapie. / Prostate cancer (PC) represents one of the most common cancers in industrialized countries. Androgen ablation is used as first-line therapy in patients with advanced disease. While most patients initially respond to this hormonal therapy, they eventually become unresponsive and recur within 2 years as castration-resistant prostate cancer (CRPC). Our strategy to improve therapies involves targeting genes that are activated by androgen withdrawal, to prevent the emergence of CRCP. We have identified the Translationnaly controlled Tumor protein (TCTP) as highly over-expressed in CRPC. We developed and patented an oligonucleotide antisense (ASO) targeting TCTP. During my PhD I developed a 3rd generation ASO (TCTP-LASO) by using a lipid-conjugated oligonucleotides modification in order to improve stability, biodisponibility and delivery of the ASO. This LASO can autonanovectorize, which permits cellular uptake without transfecting agents. This autonanovectorization leads to enhanced tumor regression in vivo without toxicity in animal models. Finally, LASO can be used as a nanovector, in which chemotherapy can be encapsulated to promote its delivery.

A interação entre fragmentos de bicamada (BF) de brometo de dioctadecildimetilamônio (DODAB) e um mononucleotídeo-modelo (deoxiadenosina monofosfato, dAMP) ou um oligodeoxinucleotídeo-modelo (5\'- AAAAAAAAAA-3\', poli(dA)) ou um oligodeoxinucleotídeo terapêutico (5\'- TTGACGTTCG -3\', CpG) foi investigada por turbidimetria, espalhamento de luz dinâmico, espectroscopia de dicroísmo circular e de fluorescência e calorimetria diferencial de varredura (DSC). Respostas imunológicas foram caracterizadas com ensaio de hipersensibilidade tardia por inchamento de coxim patelar de camundongo, dosagem de anticorpos IgG1 e IgG2a e de citocinas secretadas por células de linfonodo em cultura. Poli(dA), em contraste com dAMP, induziu fusão máxima de DODAB BF a partir da neutralização de cargas, quando houve obtenção de um tamanho máximo e um potencial-zeta igual a zero para os arranjos. Para [poli(dA)] maiores do que aquela correspondente à neutralização de cargas, houve recuperação da estabilidade coloidal com reversão do potencial-zeta e com obtenção de tamanhos que foram aproximadamente o dobro daqueles determinados inicialmente para DODAB BF. A proporção molar de neutralização poli(dA): DODAB foi 1:10 para DODAB BF e 1:20 para vesículas grandes (LV) de DODAB, de acordo com as estruturas de bicamada aberta e fechada dessas duas dispersões de bicamada de DODAB. A fusão de DODAB BF induzida por poli(dA) foi extensiva aumentando o grau de empacotamento das bicamadas formadas conforme inferido a partir dos termogramas de DSC. Em condições de equivalencia de cargas, nucleotídeo não causou fusão de DODAB BF, mostrando a importância do caráter de polieletrólito do poli(dA) para induzir fusão. O sal divalente Na2HPO4 causou fusão e aumentou o empacotamento da bicamada graças à blindagem eficiente de cargas. Reestabilização coloidal como aquela induzida por poli(dA) não ocorreu em presença de Na2HPO4, NaCl ou nucleotídeo. Para complexos DODAB BF/CpG em presença de ovalbumina (OVA) como antígenomodelo, a neutralização de cargas de DODAB BF/OVA por CpG reduziu a estabilidade coloidal, enquanto que supercompensação de cargas levou à reestabilização por repulsão eletrostática, como observado para a interação DODAB BF/poli(dA). Diferenças no tamanho e nas proporções de neutralização por CpG indicaram que os fragmentos são capazes de carregar mais moléculas de OVA do que de BSA. Na região de supercompensação de cargas com potenciais-zeta negativos, arranjos Al(OH)3/ OVA/ CpG são coloidalmente bem mais instáveis que DODAB BF/ OVA ou DODAB BF / OVA/ CpG. O complexo negativamente carregado DODAB (0,1 mM) / OVA (0,1mg/mL)/ CpG (0,020 mM) potencializou a resposta Th1 obtida com DODAB (0,1 mM)/ OVA (0,1 mg/mL). Houve um aumento de 25 % no inchamento do coxim patelar, de 36 % na produção de IFN-γ, de 60 % de IL-12 e produção sustentada de IgG2a ao longo de 35 dias pós-imunização, todos indícios fortes de potencialização da resposta Th1 por CpG. Arranjos negativamente carregados de oligonucleotídeos em fragmentos de bicamada de DODAB possuem excelente potencial para terapias baseadas em oligonucleotídeos e para produção de vacinas para diferentes antígenos de interesse. / The interaction between bilayer fragments (BF) of dioctadecyldimethylammonium bromide (DODAB) and a model nucleotide (deoxyadenosine monophosphate, dAMP) or a model oligodeoxynucleotide (5\'- AAAAAAAAAA-3\', poly(dA)) or a therapeutic oligodeoxynucleotide (5\'- TTGACGTTCG -3\', CpG) was investigated by means of turbidimetry, dynamic light scattering, circular dichroism and fluorescence spectroscopies and differential scanning calorimetry. Immune responses were characterized using footpad swelling delayed type hipersensitivity assay and antibody and cytokine measurements. In contrast to dAMP, poly(dA) induced maximal DODAB BF fusion from charge neutralization, where assemblies presented maximal size and zero zeta-potential. Above charge neutralization colloid stability was recovered with negative zeta-potentials and sizes that were about the double of those initially determined for DODAB BF. The poly(dA):DODAB molar ratio for neutralization was 1:10 for DODAB BF and 1:20 for DODAB LV, in agreement with the open and closed bilayer structures of these two DODAB bilayer dispersions. The poly(dA)-induced DODAB BF fusion was extensive and increased the packing of the formed bilayers, as inferred from DSC thermograms. In conditions of charge equivalence, nucleotide did not cause DODAB BF fusion, highlighting the importance of poly(dA)\'s polyelectrolyte character to induce fusion. Divalent Na2HPO4 salt caused fusion and increased bilayer packing due to efficient BF charge shielding. Colloid restabilization as induced by poly(dA) was not observed in presence of Na2HPO4, NaCl and nucleotide. For DODAB BF/CpG complexes in presence of the ovalbumin (OVA) model antigen, the charge neutralization of DODAB BF/OVA by CpG reduced colloid stability, while charge overcompensation led to restabilization due to electrostatic repulsion, as observed for DODAB BF/poly(dA) interaction. Differences in size and neutralization proportions by CpG indicate that BF are able to load more OVA than BSA molecules. In the charge overcompensation region with negative zeta-potentials, Al(OH)3/OVA/CpG assemblies are colloidally less stable than DODAB BF/OVA or DODAB BF/OVA/CpG. The negatively charged DODAB (0.1mM)/OVA (0.1mg/ml)/CpG (0.020mM) assembly enhanced the Th1 response obtained with DODAB (0.1mM)/OVA (0.1mg/ml). There was a 25% increase in footpad sweeling, a 36% and 60% increase in the production of IFN-γ and IL-12 and sustained IgG2a production for the 35-day period after immunization, all indicative of strong Th1 response enhancement by CpG. Negatively charged assemblies of oligonucleotides in DODAB bilayer fragments have excellent potential in oligonucleotidebased therapies and in vaccine production for different antigens of interest.

A interação entre fragmentos de bicamada (BF) de brometo de dioctadecildimetilamônio (DODAB) e um mononucleotídeo-modelo (deoxiadenosina monofosfato, dAMP) ou um oligodeoxinucleotídeo-modelo (5\'- AAAAAAAAAA-3\', poli(dA)) ou um oligodeoxinucleotídeo terapêutico (5\'- TTGACGTTCG -3\', CpG) foi investigada por turbidimetria, espalhamento de luz dinâmico, espectroscopia de dicroísmo circular e de fluorescência e calorimetria diferencial de varredura (DSC). Respostas imunológicas foram caracterizadas com ensaio de hipersensibilidade tardia por inchamento de coxim patelar de camundongo, dosagem de anticorpos IgG1 e IgG2a e de citocinas secretadas por células de linfonodo em cultura. Poli(dA), em contraste com dAMP, induziu fusão máxima de DODAB BF a partir da neutralização de cargas, quando houve obtenção de um tamanho máximo e um potencial-zeta igual a zero para os arranjos. Para [poli(dA)] maiores do que aquela correspondente à neutralização de cargas, houve recuperação da estabilidade coloidal com reversão do potencial-zeta e com obtenção de tamanhos que foram aproximadamente o dobro daqueles determinados inicialmente para DODAB BF. A proporção molar de neutralização poli(dA): DODAB foi 1:10 para DODAB BF e 1:20 para vesículas grandes (LV) de DODAB, de acordo com as estruturas de bicamada aberta e fechada dessas duas dispersões de bicamada de DODAB. A fusão de DODAB BF induzida por poli(dA) foi extensiva aumentando o grau de empacotamento das bicamadas formadas conforme inferido a partir dos termogramas de DSC. Em condições de equivalencia de cargas, nucleotídeo não causou fusão de DODAB BF, mostrando a importância do caráter de polieletrólito do poli(dA) para induzir fusão. O sal divalente Na2HPO4 causou fusão e aumentou o empacotamento da bicamada graças à blindagem eficiente de cargas. Reestabilização coloidal como aquela induzida por poli(dA) não ocorreu em presença de Na2HPO4, NaCl ou nucleotídeo. Para complexos DODAB BF/CpG em presença de ovalbumina (OVA) como antígenomodelo, a neutralização de cargas de DODAB BF/OVA por CpG reduziu a estabilidade coloidal, enquanto que supercompensação de cargas levou à reestabilização por repulsão eletrostática, como observado para a interação DODAB BF/poli(dA). Diferenças no tamanho e nas proporções de neutralização por CpG indicaram que os fragmentos são capazes de carregar mais moléculas de OVA do que de BSA. Na região de supercompensação de cargas com potenciais-zeta negativos, arranjos Al(OH)3/ OVA/ CpG são coloidalmente bem mais instáveis que DODAB BF/ OVA ou DODAB BF / OVA/ CpG. O complexo negativamente carregado DODAB (0,1 mM) / OVA (0,1mg/mL)/ CpG (0,020 mM) potencializou a resposta Th1 obtida com DODAB (0,1 mM)/ OVA (0,1 mg/mL). Houve um aumento de 25 % no inchamento do coxim patelar, de 36 % na produção de IFN-γ, de 60 % de IL-12 e produção sustentada de IgG2a ao longo de 35 dias pós-imunização, todos indícios fortes de potencialização da resposta Th1 por CpG. Arranjos negativamente carregados de oligonucleotídeos em fragmentos de bicamada de DODAB possuem excelente potencial para terapias baseadas em oligonucleotídeos e para produção de vacinas para diferentes antígenos de interesse. / The interaction between bilayer fragments (BF) of dioctadecyldimethylammonium bromide (DODAB) and a model nucleotide (deoxyadenosine monophosphate, dAMP) or a model oligodeoxynucleotide (5\'- AAAAAAAAAA-3\', poly(dA)) or a therapeutic oligodeoxynucleotide (5\'- TTGACGTTCG -3\', CpG) was investigated by means of turbidimetry, dynamic light scattering, circular dichroism and fluorescence spectroscopies and differential scanning calorimetry. Immune responses were characterized using footpad swelling delayed type hipersensitivity assay and antibody and cytokine measurements. In contrast to dAMP, poly(dA) induced maximal DODAB BF fusion from charge neutralization, where assemblies presented maximal size and zero zeta-potential. Above charge neutralization colloid stability was recovered with negative zeta-potentials and sizes that were about the double of those initially determined for DODAB BF. The poly(dA):DODAB molar ratio for neutralization was 1:10 for DODAB BF and 1:20 for DODAB LV, in agreement with the open and closed bilayer structures of these two DODAB bilayer dispersions. The poly(dA)-induced DODAB BF fusion was extensive and increased the packing of the formed bilayers, as inferred from DSC thermograms. In conditions of charge equivalence, nucleotide did not cause DODAB BF fusion, highlighting the importance of poly(dA)\'s polyelectrolyte character to induce fusion. Divalent Na2HPO4 salt caused fusion and increased bilayer packing due to efficient BF charge shielding. Colloid restabilization as induced by poly(dA) was not observed in presence of Na2HPO4, NaCl and nucleotide. For DODAB BF/CpG complexes in presence of the ovalbumin (OVA) model antigen, the charge neutralization of DODAB BF/OVA by CpG reduced colloid stability, while charge overcompensation led to restabilization due to electrostatic repulsion, as observed for DODAB BF/poly(dA) interaction. Differences in size and neutralization proportions by CpG indicate that BF are able to load more OVA than BSA molecules. In the charge overcompensation region with negative zeta-potentials, Al(OH)3/OVA/CpG assemblies are colloidally less stable than DODAB BF/OVA or DODAB BF/OVA/CpG. The negatively charged DODAB (0.1mM)/OVA (0.1mg/ml)/CpG (0.020mM) assembly enhanced the Th1 response obtained with DODAB (0.1mM)/OVA (0.1mg/ml). There was a 25% increase in footpad sweeling, a 36% and 60% increase in the production of IFN-γ and IL-12 and sustained IgG2a production for the 35-day period after immunization, all indicative of strong Th1 response enhancement by CpG. Negatively charged assemblies of oligonucleotides in DODAB bilayer fragments have excellent potential in oligonucleotidebased therapies and in vaccine production for different antigens of interest.

Oligonucleotides are popular recognition-based biomaterials assembly and disassembly tools due to their specificity and ease of control. Their susceptibility to degradation by nucleases and false positive signals under certain conditions, however, has led to great interest in chemically modified oligonucleotides such as locked nucleic acids (LNA) that enhance both nuclease resistance and target specificity. This dissertation extends prior work with DNA sequences to investigate incorporating locked nucleic acid (LNA), a synthetic oligonucleotide, in isothermal colloidal assembly and disassembly schemes as well as on hybridization kinetics between single-stranded and double-stranded probes immobilized on microspheres. Incorporation of LNA nucleotides into DNA sequences is of particular interest as a means of enhancing the performance of DNA in a biomaterials context due to the increased resistance of LNA to nuclease degradation, its greater intrinsic affinity for oligonucleotide targets, and low cytotoxicity effects. The effects of LNA modification, target sequence length, sequence fidelity, and salt concentration are key variables explored. After providing an overview of DNA and its properties, synthetic oligonucleotides, colloidal particles, and previous applications of DNA and LNA in colloidal assembly schemes, this work then discusses the selection and characteristics of appropriate pairs of hybridization partners for reversible colloidal assembly scenarios. A comparative investigation of the in situ primary hybridization kinetics between select LNA or DNA targets and single-stranded probes immobilized on colloidal surfaces is performed. To support the disassembly studies, the in situ competitive displacement kinetics of hybridized LNA primary targets by either LNA or DNA secondary targets is discussed. For these in situ studies, flow cytometry was used to quantify the hybridization reactions as they occur on microsphere surfaces. While comparable rate constants were typically observed between target and single-stranded probes, LNA typically exhibited more extensive primary and secondary hybridization activity. Optimizing hybridization parameters, such as duplex concentration, sequence fidelity, and LNA content in the probe and target strands, allows for the extent of colloidal disassembly to be tuned, an important step in developing a multifunctional colloid-based biomaterial system.

The fundamental element of life known to man is the gene. The information contained in genes regulates all cellular functions, in health and disease. The ability to selectively alter genes or their transcript intermediates with designed molecular tools, as synthetic oligonucleotides, represents a paradigm shift in human medicine. The full potential of oligonucleotide therapeutics is however dependent on the development of efficient delivery vectors, due to their intrinsic characteristics, as size, charge and low bioavailability. Cell-penetrating peptides are short sequences of amino acids that are capable of mediating the transport of most types of oligonucleotide therapeutics to the cell interior. It is the interaction of cell-penetrating peptides with oligonucleotides and the transport of their non-covalently formed complexes across the cellular membrane, that constitutes the main subject of this thesis. In Paper I we studied the effects of different types of oligonucleotide cargo in the capacity of cationic and amphipathic peptides to interact with lipid membranes. We found that indeed the cargo sequesters some of the peptide’s capacity to interact with membranes. In Paper II we revealed the simultaneous interaction of different molecular and supramolecular peptide and peptide/oligonucleotide species in equilibrium, with the cellular membrane. In Paper III we developed a series of peptides with improved affinity for oligonucleotide cargo as well as enhanced endosomal release and consequently better delivery capacity. In Paper IV we investigated the effect of saturated fatty acid modifications to a cationic cell-penetrating peptide. The varying amphipathicity of the peptide correlated with the complex physicochemical properties and with its delivery efficiency. This thesis contributes to the field with a set of characterized mechanisms and physicochemical properties for the components of the ternary system – cell-penetrating peptide, oligonucleotide and cell membrane – that should be considered for the future development of gene therapy. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 2: Manuscript.</p>

Les interactions entre les sucres et les lectines sont généralement l'étape clé dans de nombreux phénomènes biologiques et pathologiques. Malgré leu r importance cruciale, ces interactions sont paradoxalement caractérisées par des constantes d'affinité faibles et nécessite une multiprésentation des motifs saccharidiques pour être significatives. Cette augmentation est appelée "effet cluster". En outre, les techniques d'analyse actuellement utilisées en laboratoire nécessitent des quantités importantes de produits, ce qui est difficilement compatible avec les méthodes de synthèse actuelle. Pour pallier ces difficultés, une approche originale basée sur l'utilisation conjointe de glycooligonucléotide et de puces à ADN a été proposée. Les glycoconjugués basés sur des squelettes phosphodiesters et couplés à des séquences d'ADN ont été synthétisés en utilisant la chimie des oligonucléotides, couplée à la "click chemistry". La séquence d'ADN quant à elle a permis l'ancrage sur une puce à ADN et donc la mesure de leur affinité vis-à-vis de différentes lectines. Ce manuscrit rapporte le développement des nouvelles méthodologies de synthèse des glycooligonucléotides ainsi que la préparation de nombreux glycoconjugués originaux, dont l'affinité pour différentes lectines a été mesurée via l'utilisation de la puce à ADN. L'influence de plusieurs paramètres a été étudiée: le nombre de résidus, l'arrangement spatial, la lipophilie etc. Il s'avère que l'arrangement spatial semble être l'un des points les plus importants dans la mise au point d'un glycoconjugué. / The interactions between carbohydrates and lectins are generally the "key step" in many biological and pathological phenomena. Despite their importance, these interactions are paradoxically characterized by low affinity constants and requires multipresence of saccharide to be significant. This increase is called "cluster effect". In addition, the analysis techniques currently used in the laboratory requires large quantities of products, which is hardly compatible with the current methods of synthesis. To circumvent these difficulties, a original approach based on the combined use of glycooligonucleotides and DNA microarrays has been proposed. Glycoconjugates based on phosphodiester skeletons linked to DNA sequences have been synthesized using the chemistry of oligonucleotides, coupled with the "click chemistry". The DNA sequence has allowed the anchoring on a DNA chip and therefore the measurement of their affinity versus different lectins.This manuscript reports the development of new synthetic methodologies for the glycooligonucleotides synthesis and the preparation of many original glycoconjugates, whose affinity for various lectins was measured through the use of DNA microarray. The influence of several parameters was studied: the number of residues, the spatial arrangement, etc. lipophilicity. The spatial arrangement appears to be one of the most important parameters in the development of a glycoconjugate.

Le Tumor Necrosis Factor alpha (TNF-[alpha]) est une cytokine pro-inflammatoire qui occupe un rôle central dans la physiopathologie de nombreuses pathologies inflammatoires et particulièrement l'arthrite. La neutralisation de cette cytokine par l'utilisation d'anticorps anti-TNF-[alpha] a montré son efficacité dans la polyarthrite rhumatoïde et est aujourd'hui le traitement de référence pour la prise en charge de cette pathologie. Cependant, un tiers des patients traités par anticorps anti-TNF restent réfractaires ou ne répondent pas à ce traitement. Dans ce contexte, il apparait nécessaire de développer des approches nouvelles ou complémentaires pour renforcer l'arsenal thérapeutique actuellement disponible. L'utilisation d'oligonucléotides triple hélice (TFO) permet de moduler l'expression génique de manière spécifique par interaction avec la double hélice d'ADN. Dans cette étude, nous avons évalué les potentialités anti-inflammatoires d'un TFO anti-TNF-[alpha] in vitro sur les synoviocytes et chondrocytes articulaires et in vivo dans deux modèles d'arthrite expérimentale. Ce TFO interagit avec le promoteur du gène du TNF-[alpha], et son activité inhibitrice a été comparée à celle d'une approche par ARN interférence in vitro. Dans les modèles d'arthrite aigue et chronique, l'injection intra-articulaire préventive de TFO anti-TNF-[alpha] permet une amélioration significative des symptômes arthritiques. Particulièrement, le traitement par le TFO diminue sensiblement l'inflammation synoviale et les lésions ostéocartilagineuses articulaires. Ces résultats sont les premiers à montrer la possibilité d'utiliser un TFO in vivo et offrent d'intéressantes perspectives thérapeutiques / Tumor necrosis factor alpha (TNF-[alpha]), a pro-inflammatory cytokine, plays a key role in the pathogenesis of many inflammatory diseases, including arthritis. Neutralization of this cytokine by anti-TNF-[alpha] antibodies has shown its efficacy in rheumatoid arthritis and is now widely used. Nevertheless, some patients currently treated with anti-TNF-[alpha] remain refractory or become non-responder to these treatments. In this context, there is a need for new or complementary therapeutic strategies. Triplex forming oligonucleotides (TFO) can inhibit gene expression with high sequence-specificity by interacting with the DNA double-strand. In this study, we investigated if an anti-TNF-[alpha] TFO had a therapeutic activity on inflammatory processes in vitro and in vivo, as judged from effects on two rat arthritis models. This TFO interacted with the TNF-[alpha] gene promoter, and its inhibitory activity was verified and compared to that of siRNA in vitro. A local intra-articular preventive injection of TFO in both acute and chronic arthritis models significantly reduced the development of the disease. Furthermore, the TFO efficiently blocked synovitis and cartilage and bone destruction in the joints. The results presented here provide the first evidence that gene targeting by anti-TNF-[alpha] TFO modulates arthritis in vivo, thus providing proof of concept that it could be used as therapeutic tool for TNF-[alpha]-dependent chronic inflammatory disorders

No presente trabalho foi investigado o efeito do oligonucleotídeo-modelo 5-AAAAAAAAAA-3(ODN) sobre a estabilidade e estrutura de vesículas catiônicas de brometo de dioctadecildimetilamônio (DODAB), extrusadas através filtros de 100 nm, em dispersão aquosa, com as técnicas de espalhamento de luz dinâmico (DLS), medidas de potencial de superfície (potencial zeta), calorimetria diferencial de varredura (DSC), espalhamento de raios-X a baixos ângulos (SAXS), espectroscopias de absorção óptica e de fluorescência do estado estacionário da sonda Laurdan incorporada a vesículas de DODAB-ODN. Este fluoróforo monitora a polaridade e estrutura da superfície da membrana de DODAB. Variando a concentração de ODN, três diferentes regimes foram observados. Para baixas concentrações de ODN, ([ODN]/[DODAB]) 0.025 mM, a dispersão é estável, límpida, apesar do diâmetro médio das vesículas aumentar, um aumento de turbidez ser observado por medidas de Absorbância, e o SAXS já acusar a presença de algumas poucas multilamelas. As vesículas mistas apresentam potencial de superfície positivo, semelhante ao potencial medido para vesículas de puro DODAB. A calorimetria mostra a coexistência de regiões da bicamada de puro DODAB, e regiões mistas, com DODAB-ODN, sendo estas últimas mais estáveis, apresentando maior temperatura de transição gel-fluido. A forma e posição da banda de fluorescência do Laurdan incorporado às vesículas não são alteradas pela presença do oligonucleotídeo, indicando pouca variação na polaridade e estrutura da superfície da membrana mista monitorada pela sonda. Um segundo regime é observado para ([ODN]/[DODAB]) 0.05 mM, onde não é mais observado por calorimetria a presença significativa de domínios de puro DODAB, e a dispersão mostra-se instável, turva, com agregação/fusão das vesículas. Finalmente, o terceiro regime, para altas concentrações de ODN, ([ODN]/[DODAB]) 0.075 mM, onde é observado um potencial de superfície negativo, portanto, com predominância da carga do oligonucleotídeo, e a dispersão volta a ser estável, apresentando baixa turbidez. Neste regime, a calorimetria indica uma grande estabilidade da fase gel, medidas de SAXS mostram a formação de estruturas multilamelares, porém DLS indica a presença de vesículas pequenas, com dimensões às observadas para DODAB puro. Neste regime, a sonda Laurdan monitora variações na superfície da membrana, possivelmente indicando a diminuição da quantidade de moléculas de água na superfície e/ou um enrijecimento da bicamada. Os estudos aqui apresentados fazem parte de um amplo esforço para entender as características estruturais de agregados lipídio-material genético, com o objetivo de seu uso futuro em terapias gênicas. / In the present work the effect of 5\'-AAAAAAAAAA-3 \'oligonucleotide model (ODN) was investigated on the stability and structure of dioctadecyldimethylammonium bromide (DODAB) cationic vesicles, extruded through 100 nm filters in aqueous dispersion, with dynamic scattering techniques (DLS), surface potential measurements (zeta potential), differential scanning calorimetry (DSC), small angle X-ray scattering (SAXS), optical absorption spectrometry and stationary-state fluorescence spectroscopy of Laurdan incorporated into DODAB-ODN vesicles. This fluorophore monitors the polarity and surface structure of the DODAB membrane. Varying the ODN concentration, three different behaviors were observed. For low concentrations of ODN, ([ODN] / [DODAB]) 0.025 mM, the dispersion is stable, clear, although the mean diameter of the vesicles increases, an increase in turbidity is observed by Absorbance measurements, and SAXS already shows the presence of a few multilamellar structure. The mixed vesicles present positive surface potential, similar to the potential measured for pure DODAB vesicles. Calorimetry shows the coexistence of regions of the pure DODAB bilayer, and mixed regions, with DODAB-ODN, the latter being more stable, presenting a higher gel-fluid transition temperature. The shape and position of the Laurdan fluorescence band incorporated into the vesicles are not altered by the presence of the oligonucleotide, indicating minor variation in the polarity and surface structure of the mixed membrane monitored by the probe. A second behavior is observed for ([ODN] / [DODAB]) 0.05 mM, where the presence of pure DODAB domains is no longer detected by calorimetry, and the dispersion is unstable, cloudy, displaying vesicle aggregation/fusion. Finally, the third behavior is detected at high concentrations of ODN, ([ODN] / [DODAB]) 0.075 mM, where a negative surface potential is observed, therefore, with predominance of the charge of the oligonucleotide, and the dispersion is stable, exibiting low turbidity. In this regime, the calorimetry indicates a great stability of the gel phase, SAXS measurements show the formation of multilamellar structures, however DLS indicates the presence of small vesicles, with dimensions to those observed for pure DODAB. In this region, the Laurdan probe monitors variations at the surface of the membrane, possibly indicating the decrease in the amount of water molecules on the surface and/or a stiffening of the bilayer. The studies presented here are part of a broad effort to understand the structural characteristics of \"lipid-genetic material\", aggregates, with the aim of their future use in gene therapies.

by Ray, Kit Ng. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 112-121). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgments --- p.iv / Abbreviations --- p.x / List of Figures --- p.xii / List of Tables --- p.xiv / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Hepatitis B Virus (HBV) --- p.1 / Chapter 1.2 --- Hepatitis B Virus X Protein (HBx) --- p.5 / Chapter 1.2.1 --- The Genomic Structure of HBx --- p.5 / Chapter 1.2.2 --- The HBx Protein Structure --- p.6 / Chapter 1.2.3 --- Subcellular Localization of HBx --- p.7 / Chapter 1.2.4 --- Possible Functions of HBx --- p.8 / Chapter 1.3 --- Etiology of Hepatocellular Carcinoma (HCC) --- p.12 / Chapter 1.4 --- Relationship between HCC and HBx --- p.13 / Chapter 1.5 --- Aims of Study --- p.14 / Chapter 1.6 --- The Basis of Tet-On System --- p.15 / Chapter 1.7 --- The Basis of DNA Microarray --- p.18 / Chapter 1.8 --- The Basis of Two-Dimensional Electrophoresis --- p.20 / Chapter Chapter 2 --- Materials and Methods / Chapter 2.1 --- Construction of a Tet-On HBx Expressing Cell Model --- p.22 / Chapter 2.1.1 --- Cloning of HBx Gene into pTRE2 Vector --- p.22 / Chapter 2.1.1.1 --- PCR of HBx Gene --- p.22 / Chapter 2.1.1.2 --- Purification of the PCR Product --- p.23 / Chapter 2.1.1.3 --- Restriction Enzyme Digestion --- p.23 / Chapter 2.1.1.4 --- Ligation of HBx into pTRE Vector --- p.24 / Chapter 2.1.1.5 --- Transformation of the Ligation Product into Competent Cells --- p.24 / Chapter 2.1.2 --- Preparation of the Plasmid DNA --- p.24 / Chapter 2.1.2.1 --- DNA Sequencing of the Cloned Plasmid DNA --- p.25 / Chapter 2.1.3 --- Cell Culture of AML12 Cell Line --- p.26 / Chapter 2.1.4 --- Transfection of pTet-On Vector into AML12 Cells --- p.26 / Chapter 2.1.5 --- Selection of the Transfected AML12 Cells by G418 --- p.27 / Chapter 2.1.6 --- Single Clone Isolation --- p.27 / Chapter 2.1.6.1 --- Luciferase Assay for Selection of Highly Inducible Clones --- p.28 / Chapter 2.1.7 --- Second Transfection of pTRE-HBx Plasmid --- p.28 / Chapter 2.1.8 --- Selection of the Transfected Cells by Hygromycin --- p.29 / Chapter 2.1.9 --- Second Single Clone Isolation --- p.29 / Chapter 2.1.10 --- Total RNA Isolation --- p.29 / Chapter 2.1.11 --- DNase I Digestion --- p.30 / Chapter 2.1.12 --- First-Strand cDNA Synthesis --- p.31 / Chapter 2.1.13 --- RT-PCR of HBx Gene --- p.31 / Chapter 2.1.14 --- Northern Blotting --- p.32 / Chapter 2.1.15 --- Preparation of the Probe --- p.33 / Chapter 2.1.16 --- Northern Blot Hybridization --- p.33 / Chapter 2.1.17 --- 3H-Thymidine Incorporation Assay --- p.34 / Chapter 2.1.18 --- Analysis of Cell Cycle by Flow Cytometry --- p.35 / Chapter 2.2 --- Microarray Analysis of Differential Gene Expression upon HBx Induction --- p.35 / Chapter 2.2.1 --- Sample Preparation for Microarray Analysis --- p.35 / Chapter 2.2.2 --- Probe Labelling --- p.36 / Chapter 2.2.3 --- Microarray Hybridization --- p.37 / Chapter 2.2.4 --- RT-PCR of the Candidate Genes --- p.38 / Chapter 2.2.5 --- Northern Blot Analysis of the Candidate Genes --- p.39 / Chapter 2.3 --- Two-Dimensional (2D) Gel Electrophoretic Analysis --- p.40 / Chapter 2.3.1 --- Protein Sample Preparation for 2D Gel Electrophoresis --- p.40 / Chapter 2.3.2 --- First-Dimension Isoelectric Focusing (IEF) --- p.40 / Chapter 2.3.3 --- Second-Dimension SDS-PAGE --- p.41 / Chapter 2.3.4 --- Silver Stain of 2D Gel --- p.42 / Chapter 2.3.5 --- Mass Spectroscopic Analysis --- p.43 / Chapter 2.4 --- Subcellular Localization of HBx --- p.44 / Chapter 2.4.1 --- Cloning of HBx into Green Fluorescent Protein (GFP) Expression Vector --- p.44 / Chapter 2.4.2 --- Transfection of GFP-HBx --- p.44 / Chapter 2.4.3 --- Propidium Iodide (PI) Staining --- p.45 / Chapter 2.4.4 --- Mitochondria Staining --- p.45 / Chapter 2.4.5 --- Subcellular Localization Study using Epi-Fluorescent Microscopy --- p.45 / Chapter 2.5 --- Analysis of Mitochondrial Transmembrane Potential --- p.46 / Chapter Chapter 3 --- Results / Chapter 3.1 --- Construction of Tet-On AML12 Cell Line of HBx Gene --- p.47 / Chapter 3.2 --- Characterization of the HBx-Expressing Cell Model --- p.53 / Chapter 3.2.1 --- 3H-Thymidine Proliferation Assay --- p.53 / Chapter 3.2.2 --- Cell Cycle Analysis --- p.55 / Chapter 3.3 --- Microarray Analysis of Differential Gene Expression Pattern upon HBx Induction --- p.57 / Chapter 3.4 --- Northern Blot Analysis and RT-PCR of the Candidate Genes --- p.65 / Chapter 3.5 --- Differential Protein Expression Pattern under HBx Induction --- p.70 / Chapter 3.6 --- Subcellular Localization of HBx --- p.77 / Chapter 3.7 --- Analysis of Mitochondrial Transmembrane Potential --- p.83 / Chapter Chapter 4 --- Discussion / Chapter 4.1 --- Conditional HBx-Expressing Cell Model --- p.84 / Chapter 4.2 --- The Effects of HBx in Clone X18 --- p.86 / Chapter 4.2.1 --- Proliferative Effect of HBx --- p.86 / Chapter 4.2.2 --- Deregulation of G2/M Checkpoint by HBx --- p.86 / Chapter 4.3 --- Early Differential Gene Expression due to HBx Induction --- p.88 / Chapter 4.4 --- The Relationship of the Potential Candidate Genes and Cancer Development --- p.90 / Chapter 4.5 --- The Protein Expression Pattern due to HBx Induction --- p.93 / Chapter 4.6 --- The Subcellular Localization of HBx --- p.96 / Chapter 4.7 --- The Possible Involvement of HBx in Mitochondrial Transmembrane Potential --- p.98 / Chapter 4.8 --- Conclusions --- p.101 / Chapter 4.9 --- Future Prospects --- p.104 / Appendix --- p.107 / References --- p.112

by Zhang Yanbo. / "December 2003." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (p. 163-185). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.