Os primeiros vasos sanguíneos do embrião de vertebrados, formados de novo a partir de células originadas da mesoderme, originam os vasos linfáticos em um processo denominado vasculogênese. Já no adulto, novos vasos são formados principalmente através da angiogênese (ou linfoangiogênese) a partir da vasculatura pré-existente. Em indivíduos saudáveis, a arquitetura vascular é relativamente estática, sendo que o excesso ou a insuficiência de vasos são comumente relacionados à angiogênese patológica, vinculada a diversas doenças, como câncer, degeneração macular relacionada à idade, isquemia de membros e muitas outras. Dessa forma, o controle local da densidade de vasos sanguíneos torna-se interessante para o tratamento de condições patológicas visando melhoria de prognóstico e cura. Dentre os diversos fatores de crescimento conhecidos, o fator de crescimento endotelial vascular, VEGF, destaca-se como o principal regulador do processo de angiogênese através de isoformas pró-angiogênicas (VEGFxxx) e antiangiogênicas (VEGFxxxb) do gene VEGF-A. Consequentemente, as proteínas codificadas por esse gene constituem um alvo com alto potencial terapêutico. No presente estudo, propusemos a produção das isoformas proteicas recombinantes rhVEGF165, rhVEGF165b e rhVEGF121, oriundas do gene VEGF-A humano, visando à geração de biofármacos que podem ser utilizados para terapia molecular e engenharia tecidual. As sequências codificadoras das isoformas rhVEGF165 e rhVEGF121 foram amplificadas a partir do cDNA total sintetizado de amostras de RNA total de pulmão humano, enquanto que a da isoforma rhVEGF165b foi gerada através da mutação sítio-dirigida da sequência de rhVEGF165. As sequências foram clonadas no vetor de clonagem pGEM®-T Easy, sendo em seguida subclonadas no vetor pLV-eGFP, um vetor plasmidial de transferência lentiviral, que permite a expressão de transgenes em células de mamíferos e, também, da proteína repórter eGFP. Células humanas HEK293 em cultura aderente foram independentemente cotransfectadas com cada uma das construções geradas (pLV-rhVEGF165, pLV-rhVEGF165b e pLV-rhVEGFl21) juntamente com o vetor pTK-Hyg na proporção de 40:1 (m/m), viabilizando a seleção dos transfectantes com o antibiótico higromicina B, além da detecção de eGFP. Os clones celulares superprodutores das proteínas de interesse foram avaliados quanto à cinética de expressão em meio carente de soro e adaptados para a cultura em suspensão estática na presença de meio na ausência de componentes derivados de animais, demostrando a capacidade de expressão das isoformas rhVEGFs nestas condições de cultivo. Para o nosso conhecimento, este é o primeiro trabalho a descrever a expressão de isoformas de VEGF-A em células HEK293 mantidas em suspensão. As isoformas rhVEGF165 e rhVEGF165b foram purificadas por cromatografia de afinidade a heparina, a partir do meio condicionado pelos clones superprodutores gerados. Ensaios in vitro, utilizando o AngioPhaseTM Kit, e in vivo, através do ensaio da membrana corioalantoide em embriões de galinha (CAM Assay), ambos próprios para avaliação da atividade pró- e antiangiogênica de diferentes compostos, demonstraram que a isoforma rhVEGF165 possui atividade biológica, enquanto a isoforma rhVEGF165b não apresentou a atividade esperada (inibição da angiogênese). Estas isoformas foram testadas em modelo murino de engenharia tecidual do intestino curto, com indícios de que poderiam contribuir para o uso terapêutico neste contexto. A purificação da isoforma rhVEGF121, bem como as análises estruturais das proteínas produzidas, estão em processo de otimização. / The first blood vessels of the vertebrate embryo are formed de novo from mesoderm-derived cells and give rise to lymph vessels in a process termed vasculogenesis. In the adult, new blood vessels are formed mainly through angiogenesis (or lymphangiogenesis) from the pre-existing vasculature. In healthy individuals, the vascular architecture is fairly static, and both the excess and the insufficiency of vessels comprise a pathological angiogenic state, to which is credited the onset and/or progression of several diseases such as cancer, age-related macular degeneration, limb ischemia, and many others. Therefore, locally controlling the blood vessel density becomes interesting for the treatment of pathological conditions aiming at prognosis improvement and cure. Among the various known growth factors, the vascular endothelial growth factor, VEGF, stands out as the major regulator of the angiogenic process. This process is mediated through the action of pro- (VEGFxxx) and antiangiogenic (VEGFxxxb) isoforms, which are derived from the VEGF-A gene. Consequently, the proteins encoded by this gene are potential therapeutic targets. In this work, we set out to produce the recombinant protein isoforms rhVEGF165, rhVEGF165b, and rhVEGF121, which originate from the human VEGF-A gene, with the aim of generating biopharmaceuticals to be used for molecular therapy and tissue engineering. The rhVEGF165 and rhVEGF121 coding sequences were amplified from total cDNA sythesized from human lung total RNA. Conversely, the rhVEGF165b coding sequence was generated by site-directed mutagenesis of the rhVEGF165 sequence. The sequences were cloned into the pGEM®-T Easy cloning vector. These cDNAs were then subcloned into pLV-eGFP, a plasmid lentiviral transfer vector that allows for expression of transgenes and the eGFP reporter protein in mammalian cells. Human HEK293 cells cultivated under adherent conditions were independently co-transfected with each of the obtained constructs (pLV-rhVEGF165, pLV-rhVEGF165b, and pLV-rhVEGF121) and the pTK-Hyg vector at a proportion of 40:1 (m/m), enabling for the selection of transfectants with hygromycin B, apart from the detection of eGFP. The cell clones overexpressing the proteins of interest were evaluated for expression kinetics in serum-deprived conditioned media and adapted to static suspension culture in medium free of animal-derived components, demonstrating that expression of the protein isoforms was possible in these culture conditions. To the best of our knowledge, this is the first work that describes the expression of VEGF-A isoforms in HEK293 cells in suspension culture. The rhVEGF165 and rhVEGF165b isoforms were purified by affinity chromatography from media previously conditioned by the overexpressing cell clones. The biological activity of rhVEGF165 was demonstrated in vitro, by the AngioPhaseTM Kit assay, and in vivo with the CAM (chorioallantoic membrane) assay, both of which are suitable for evaluating the pro- and antiangiogenic activity of different compounds. The rhVEGF165b did not show the expected antiangiogenic activity. These isoforms were tested in a model of murine tissue-engineered small intestine, indicating a possible contribution to therapeutic use in this context. The purification of rhVEGF121, as well as the structural analysis of all three proteins, are in the process of being optimized.

In the beginning of this thesis is a short introduction into plasmid DNA which is in the form of a vector used in molecular biology. Plasmids can be used in the form of fluorescent probes to measure changes in membrane potential. Into their structure is added a dye called fluorophore. As an important representative of this thesis is a fluorescent probe ASAP1 which contains green fluorescent protein whose response to the membrane potential change is the decrease in the intensity of emitted light. The aim of this thesis was to make chemical transfection of this plasmid into the HEK293 cell line and carry out its characterization. In the work is also described the design of a method for the analysis of the time course of changes in fluorescence depending on the cell membrane depolarisation. In the end of this thesis is also desribed realized experiment including the discussion of aquired results.

Ziel dieser Arbeit war die elektrophysiologische Charakterisierung des vor kurzem erstmals von NIESLER et al. (2003) klonierten humanen 5-HT3A+E-Rezeptors. Da dieser Rezeptor-Subtyp ausschließlich im Gastrointestinaltrakt exprimiert wird, ist ein Einfluss auf Nausea und Emesis sehr wahrscheinlich. Es stellt sich demnach die Frage, ob funktionelle Unterschiede zum homomeren 5-HT3A-Rezeptor und zum heteromeren 5-HT3A+B-Rezeptor bestehen, und ob auf molekularer Ebene unterschiedliche Wirkungen emetogener bzw. antiemetischer Pharmaka festzustellen sind. Um die Wirkmechanismen und die Interaktionen eines Pharmakons mit den 5-HT3-Rezeptor-Subtypen beurteilen zu können, erfordert dies genaue Kenntnisse über das biophysikalische Verhalten und die pharmakologische Sensitivität der 5-HT3-Rezeptor-Untereinheiten. Die Experimente erfolgten in-vitro an heterolog in HEK293-Zellen exprimierten Rezeptoren, wobei alleinig die 5-HT3A-Untereinheit in der Lage ist, funktionelle homopentamere Rezeptoren auszubilden. Die 5-HT3E- und 5-HT3B-Untereinheiten können nur zusammen mit der 5-HT3A-Untereinheit an die Zelloberfläche exprimiert werden und funktionelle heteropentamere Rezeptoren bilden. Im Verlauf der Untersuchungen hat sich herausgestellt, dass bei der Transfektion die 5-HT3E- und die 5-HT3B-Untereinheiten im Verhältnis zur 5-HT3A-Untereinheit signifikant schwächer exprimiert werden. Mittels der experimentellen Methode der Patch-Clamp Technik im „excised-patch“ („outside-out“)- und im Ganzzell-Modus war es möglich, die biophysikalischen und pharmakologischen Eigenschaften des heteromeren 5-HT3A+E-Rezeptors im Vergleich mit dem homomeren 5-HT3A-Rezeptor und dem heteromeren 5-HT3A+B-Rezeptor zu analysieren. Bei den Experimenten zur Grundcharakterisierung des humanen 5-HT3A+E-Rezeptor-Subtyps zeigte die Agonisten-Konzentrations-Wirkungskurve mit einem Hill-Koeffizienten von 1,0 einen deutlichen flacheren Verlauf als die Kurve des 5-HT3A-Rezeptor-Subtyps, die einen Hill-Koeffizienten von 1,5 aufwies. Dies spricht für eine geringe Agonisten-Bindungskooperativität des 5-HT3A+E-Rezeptors. Kein Unterschied zeigte sich allerdings in der Affinität zu 5-HT, da die EC50-Werte von beiden Rezeptor-Subtypen im Bereich von ca. 7 µM lagen. Aus dem biphasischen Verlauf der Kurve konnte der Rückschluss gezogen werden, dass bei der Transfektion des heteromeren 5-HT3A+E-Rezeptors der homomere 5-HT3A-Rezeptor parallel exprimiert wird. Dasselbe Verhalten wurde auch schon für den heteromeren 5-HT3A+B-Rezeptor beschrieben (WALSTAB et al. 2008). Bei der Charakterisierung eines heteromeren Rezeptor-Subtyps ergibt sich dadurch die Schwierigkeit, dessen Eigenschaften nicht eindeutig von denen des homomeren Rezeptors unterscheiden zu können. Des Weiteren konnte im Vergleich zum homomeren 5-HT3A-Rezeptor eine schnellere Desensibilisierungszeitkonstante des heteromeren 5-HT3A+E-Rezeptors nachgewiesen werden. Insgesamt deuten die beschriebenen Ergebnisse auf eine erhöhte Sensitivität des Rezeptors für Serotonin hin. Da der 5-HT3A+E-Rezeptor ausschließlich im Gastrointestinaltrakt exprimiert wird, könnte dies ein Hinweis auf eine Beteiligung dieses Rezeptors bei der Vermittlung von Emesis sein. Bei der pharmakologischen Charakterisierung wurden der partielle 5-HT3-Rezeptoragonist Tryptamin, der volle 5-HT3-Rezeptorantagonisten Tropisetron sowie die partiellen 5-HT3-Rezeptorantagonisten Metoclopramid, Tubocurarin, Mirtazapin und der Cannabinoid-Rezeptoragonist Anandamid, welcher eine emetogene Wirkung aufweist, untersucht. Auffällig war ein deutlich flacherer Verlauf der Konzentrations-Wirkungskurve von Metoclopramid (5-HT3A+E-Rezeptor: Hill-Koeffizient = -0,8; 5-HT3A-Rezeptor: Hill-Koeffizient = -1,2) und von Mirtazapin (5-HT3A+E-Rezeptor: Hill-Koeffizient = -0,9; 5-HT3A-Rezeptor: Hill-Koeffizient = -1,3) am heteromeren 5-HT3A+E-Rezeptor. Des Weiteren konnte für Mirtazapin am 5-HT3A+E-Rezeptor ein IC50-Wert von 8,4 nM im Vergleich zu 25,4 nM am 5-HT3A-Rezeptor festgestellt werden. Diese deutlich höhere Potenz von Mirtazapin am untersuchten heteromeren Rezeptor-Subtyp sowie die geringere Bindungskooperativität von Mirtazapin und Metoclopramid am 5-HT3A+E-Rezeptor, stellen einen interessanten Ansatz für eine effektive Pharmakotherapie gastrointestinaler Erkrankungen dar. Die Ergebnisse dieser Arbeit zeigen erstmalig auf molekularer Ebene, die elektrophysiologischen Eigenschaften der humanen 5-HT3A+E-Rezeptoren sowie deren Beeinflussung durch emetogenen und antiemetische Pharmaka. Aufgrund der schwachen Expression der 5-HT3E-Untereinheit gilt es in Zukunft durch einen alternativen Weg der Transfektion, die Effizienz der Ausbeute von 5-HT3A+E-Rezeptoren zu erhöhen. / The aim of this doctor thesis was the electrophysiological characterization of the human 5-HT3A+E receptor which was recently cloned for the first time by NIESLER et al. (2003). Since the expression of this receptor subtype takes place exclusively in gastrointestinal tract, an influence on nausea and emesis is very likely. The question is if functional differences exist between homomeric 5-HT3A receptors and heteromeric 5-HT3A+B receptors, and whether different effects from emetic and antiemetic drugs can be detected at the molecular level. To assess the mechanisms and the interactions of a drug with the 5-HT3 receptor subtypes, knowledge of the biophysical characteristics and the pharmacological sensitivity of the 5-HT3 receptor subunit is required. The experiments were developed in-vitro on heterologous expressed receptors in HEK293-cells, whereat only the 5-HT3A subunit is able to form functional homopentameric receptors. The 5-HT3E and the 5-HT3B subunit can only be expressed on the cell surface and build functional heteropentameric receptors in combination with the 5-HT3A subunit. In the course of the investigations it became obvious that during transfection the 5-HT3E subunit and the 5-HT3B subunit are significantly lesser expressed than the 5-HT3A subunit. Using the patch-clamp technique in the excised-patch (outside-out) and whole-cell configuration it was possible to analyse the pharmacological and biophysical properties of the heteromeric 5-HT3A+E receptor compared with the homomeric 5-HT3A-receptor and the heteromeric 5-HT3A+B receptor. During the characterisation of the human 5-HT3A+E receptor subtype, the agonist concentration-response curve with the hillslope of 1,0 showed a significant flatter course than the graph of the 5-HT3A receptor subtype with a hillslope of 1,5. This indicates a diminished agonist binding-cooperativeness of the 5-HT3A+E receptor. No difference could be detected in the affinity to 5-HT, since the EC50 values of both receptor-subtypes were at the range of 7 µM. The biphasic course of the graph showed that by transfection of the heteromeric 5-HT3A+E receptor the homomeric 5-HT3A-receptor is expressed parallel. The same properties were described also for the 5-HT3A+B receptor (WALSTAB et al. 2008). Therefore it is difficult to distinguish the properties of a homomeric receptor by characterisation of a heteromeric receptor subtype. Furthermore, a faster desensitization of the heteromeric 5-HT3A+E-receptor could be demonstrated in comparison to homomeric 5-HT3A-receptor. Overall, the results described above indicate an increased sensitivity to the receptor for serotonin. As the 5-HT3A+E receptor is expressed exclusively in the gastro-intestinal tract, this could be an indication of involvement of this receptor in the mediation of emesis. During the pharmacological characterisation the partial 5-HT3 receptor agonist tryptamine, the full 5-HT3 receptor antagonist tropisetron as well as the partial 5-HT3 receptor antagonists metoclopramide, tubocurarin, mirtazapin and the cannabinoid receptor agonist anandamide, which has an emetic effect, were examined. The agonist concentration-response curve of metoclopramide (5-HT3A+E receptor: hillslope = -0,8; 5-HT3A receptor: hillslope = -1,2) and of mirtazapin (5-HT3A+E receptor: hillslope = -0,9; 5-HT3A receptor: hillslope = -1,3) showed a significant flatter course at the 5-HT3A+E receptor. Mirtazapin has an IC50 value of 8,4 nM at the 5-HT3A+E receptor in comparison to 25,4 nM at the 5-HT3A receptor. This significant higher potency of mirtazapin at the heteromeric 5-HT3 receptor subtype and the decreased binding-cooperativeness of mirtazapin and meteclopramide at the 5-HT3A+E receptor represent interesting approaches for an effective pharmacotherapy for gastrointestinal diseases. For the first time the results of this thesis showed the electrophysiological properties of the human 5-HT3A+E receptors and their interference by emetic and antiemetic drugs on the molecular level. Due to the decreased expression of 5-HT3E subunit, the goal for the future is to find an alternative way of transfection which increases the rate of yield for the 5-HT3A+E receptors.

The hTREX complex mediates cellular bulk mRNA nuclear export by recruiting the nuclear export factor, TAP, via a direct interaction with the export adaptor, Aly. Intriguingly however, depletion of Aly only leads to a modest reduction in cellular mRNA nuclear export, suggesting the existence of additional mRNA nuclear export adaptor proteins. In order to efficiently export Kaposi's sarcoma-associated herpesvirus (KSHV) intronless mRNAs from the nucleus, the KSHV ORF57 protein recruits hTREX onto viral intronless mRNAs allowing access to the TAP-mediated export pathway. Similarly however, depletion of Aly only leads to a modest reduction in the nuclear export of KSHV intronless mRNAs. Herein, we identify a novel interaction between ORF57 and the cellular protein, UIF. We provide the first evidence that the ORF57-UIF interaction enables the recruitment of hTREX and TAP to KSHV intronless mRNAs in Aly-depleted cells. Strikingly, depletion of both Aly and UIF inhibits the formation of an ORF57-mediated nuclear export competent ribonucleoprotein particle and consequently prevents ORF57-mediated mRNA nuclear export and KSHV protein production. Importantly, these findings highlight that redundancy exists in the eukaryotic system for certain hTREX components involved in the mRNA nuclear export of intronless KSHV mRNAs.

La possibilité de programmer une cellule dans le but de produire une protéine d’intérêt est apparue au début des années 1970 avec l’essor du génie génétique. Environ dix années plus tard, l’insuline issue de la plateforme de production microbienne Escherichia coli, fut la première protéine recombinante (r-protéine) humaine commercialisée. Les défis associés à la production de r-protéines plus complexes et glycosylées ont amené l’industrie biopharmaceutique à développer des systèmes d’expression en cellules de mammifères. Ces derniers permettent d’obtenir des protéines humaines correctement repliées et de ce fait, biologiquement actives. Afin de transférer le gène d’intérêt dans les cellules de mammifères, le polyéthylènimine (PEI) est certainement un des vecteurs synthétiques le plus utilisé en raison de son efficacité, mais aussi sa simplicité d’élaboration, son faible coût et sa stabilité en solution qui facilite son utilisation. Il est donc largement employé dans le contexte de la production de r-protéines à grande échelle et fait l’objet d’intenses recherches dans le domaine de la thérapie génique non virale. Le PEI est capable de condenser efficacement l’ADN plasmidique (vecteur d’expression contenant le gène d’intérêt) pour former des complexes de petites tailles appelés polyplexes. Ces derniers doivent contourner plusieurs étapes limitantes afin de délivrer le gène d’intérêt au noyau de la cellule hôte. Dans les conditions optimales du transfert de gène par le PEI, les polyplexes arborent une charge positive nette interagissant de manière électrostatique avec les protéoglycanes à héparane sulfate (HSPG) qui décorent la surface cellulaire. On observe deux familles d’HSPG exprimés en abondance à la surface des cellules de mammifères : les syndécanes (4 membres, SDC1-4) et les glypicanes (6 membres, GPC1-6). Si l’implication des HSPG dans l’attachement cellulaire des polyplexes est aujourd’hui largement acceptée, leur rôle individuel vis-à-vis de cet attachement et des étapes subséquentes du transfert de gène reste à confirmer. Après avoir optimisées les conditions de transfection des cellules de mammifères CHO et HEK293 dans le but de produire des r-protéines secrétées, nous avons entrepris des cinétiques de capture, d’internalisation des polyplexes et aussi d’expression du transgène afin de mieux comprendre le processus de transfert de gène. Nous avons pu observer des différences au niveau de ces paramètres de transfection dépendamment du système d’expression et des caractéristiques structurelles du PEI utilisé. Ces résultats présentés sous forme d’articles scientifiques constituent une base solide de l’enchaînement dans le temps des évènements essentiels à une transfection efficace des cellules CHO et HEK293 par le PEI. Chaque type cellulaire possède un profil d’expression des HSPG qui lui est propre, ces derniers étant plus ou moins permissifs au transfert de gène. En effet, une étude menée dans notre laboratoire montre que les SDC1 et SDC2 ont des rôles opposés vis-à-vis du transfert de gène. Alors que tous deux sont capables de lier les polyplexes, l’expression de SDC1 permet leur internalisation contrairement à l’expression de SDC2 qui l’inhibe. De plus, lorsque le SDC1 est exprimé à la surface des cellules HEK293, l’efficacité de transfection est augmentée de douze pourcents. En utilisant la capacité de SDC1 à induire l’internalisation des polyplexes, nous avons étudié le trafic intracellulaire des complexes SDC1 / polyplexes dans les cellules HEK293. De plus, nos observations suggèrent une nouvelle voie par laquelle les polyplexes pourraient atteindre efficacement le noyau cellulaire. Dans le contexte du transfert de gène, les HSPG sont essentiellement étudiés dans leur globalité. S’il est vrai que le rôle des syndécanes dans ce contexte est le sujet de quelques études, celui des glypicanes est inexploré. Grâce à une série de traitements chimiques et enzymatiques visant une approche « perte de fonction », l’importance de la sulfatation comme modification post-traductionnelle, l’effet des chaînes d’héparanes sulfates mais aussi des glypicanes sur l’attachement, l’internalisation des polyplexes, et l’expression du transgène ont été étudiés dans les cellules CHO et HEK293. L’ensemble de nos observations indique clairement que le rôle des HSPG dans le transfert de gène devrait être investigué individuellement plutôt que collectivement. En effet, le rôle spécifique de chaque membre des HSPG sur la capture des polyplexes et leur permissivité à l’expression génique demeure encore inconnu. En exprimant de manière transitoire chaque membre des syndécanes et glypicanes à la surface des cellules CHO, nous avons déterminé leur effet inhibiteur ou activateur sur la capture des polyplexes sans pouvoir conclure quant à l’effet de cette surexpression sur l’efficacité de transfection. Par contre, lorsqu’ils sont présents dans le milieu de culture, le domaine extracellulaire des HSPG réduit l’efficacité de transfection des cellules CHO sans induire la dissociation des polyplexes. Curieusement, lorsque chaque HSPG est exprimé de manière stable dans les cellules CHO, seulement une légère modulation de l’expression du transgène a pu être observée. Ces travaux ont contribué à la compréhension des mécanismes d'action du vecteur polycationique polyéthylènimine et à préciser le rôle des protéoglycanes à héparane sulfate dans le transfert de gène des cellules CHO et HEK293. / With the aim to express a protein of interest, the transfer of exogenous genetic material into host cells was established in early 70s with the development of genetic engineering. Approximately ten years later, insulin was the first human recombinant protein (r-protein) produced at large scale in Escherichia coli and commercialized. Challenges associated with the production of more complex and glycosylated r-proteins brought the pharmaceutical industry to develop mammalian expression platforms. Thus, the expressed r-proteins are correctly folded and biologically actives. As a means to transfer genetic materials of interest into mammalian cells, the synthetic vector polyethylenimine (PEI) is probably the most popular due to its efficacy, ease of use, cost-effectiveness and stability in solution. Consequently, PEI is largely employed for the production of r-proteins by large scale and extensively studied in the context of non-viral gene therapy. PEI is capable to efficiently condense plasmid DNA (expression vector containing the gene of interest) to form small nanoparticles termed polyplexes. The latter must circumvent several steps to deliver the gene of interest to the cell nucleus. When formed at the optimum conditions, polyplexes exhibit a net positive charge which can interact electrostatically with negatively charged heparan sulfate proteoglycans (HSPG) located at the cell surface. There are two major families of HSPG that are largely expressed at the surface of mammalian cells: the syndecans (4 members, SDC1-4) and the glypicans (6 members, GPC1-6). Although it is generally accepted that HSPG are involved in the binding of polyplexes, their individual role toward polyplex binding and the subsequent phases of gene transfer need to be confirmed. Following optimization of the mammalian CHO and HEK293 cells transfection conditions, we undertook an in-depth study of polyplexes uptake, internalization kinetics, as well as transgene expression kinetics with the aim to better understand the mechanisms underlying gene transfer. We observed several contrasting differences between the two cell lines and the type of PEI used. Our results presented as a scientific article, establish strong basis of the gene transfer process over-time. Every cell type possesses its own expression profile of HSPG which can display individual potency toward gene transfer. Indeed, a preliminary study conducted in our laboratory showed that SDC1 and SDC2 have distinct features with regard to gene transfer. While both are capable to bind polyplexes at the cell surface, the expression of SDC1 enhances polyplexes internalization whereas the expression of SDC2 drastically inhibits it. Furthermore, when SDC1 is expressed at the surface of HEK293 cells, the transfection efficiency is increased by twelve percent compared to control cells. By using the ability of SDC1 to mediate efficient internalization of polyplexes, we have studied the intracellular traffic of SDC1 / polyplexes complexes. Our conclusions lead to new insights concerning the path by which polyplexes can mediate efficient transfection. In the context of gene transfer, HSPG have been essentially studied in their entirety. Although the role of syndecans is the subject of some studies, that of glypicans is unexplored. Thanks to a series of chemical and enzymatic treatments leading to « loss of functions », the importance of sulfation as post-translational modification, the effect of HS chains and of glypicans on the attachment, internalization of polyplexes as well as transgene expression were investigated in CHO and HEK293 cells. Taken together, our observations indicate clearly that the role of HSPG should be investigated individually instead of collectively. Consequently, the individual potency of each HSPG member regarding gene transfer remains to be defined. We demonstrated that, in fact, the transient expression of some HSPG in CHO cells have a beneficial effect on polyplexes uptake while others have a negative effect. Unfortunately, this method did not allow concluding about their effect on transfection efficacy. However, when present in the culture medium, the extracellular domain of HSPG decreases transfection efficacy of CHO cells without inducing polyplexes dissociation. Strangely, when each HSPG is stably expressed in CHO cells, only subtle modulations of the gene expression level were observed. This study contributed to a better understanding of the mechanisms underlying PEI mediated gene transfer in CHO and HEK293 cells and clarify the role of HSPG in gene transfer.

Submitted by Ubirajara Cruz (ubirajara.cruz@gmail.com) on 2017-03-28T13:31:49Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese_Giseli_Ritterbusch.pdf: 1007939 bytes, checksum: 6829555e6aeec4b59e73c9a7f0f29087 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2017-03-28T20:59:38Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese_Giseli_Ritterbusch.pdf: 1007939 bytes, checksum: 6829555e6aeec4b59e73c9a7f0f29087 (MD5) / Made available in DSpace on 2017-03-28T20:59:38Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese_Giseli_Ritterbusch.pdf: 1007939 bytes, checksum: 6829555e6aeec4b59e73c9a7f0f29087 (MD5) Previous issue date: 2015-01-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / O vírus da bronquite infecciosa das galinhas (VBI) é o agente etiológico da Bronquite Infecciosa (BI), uma enfermidade altamente contagiosa que causa grandes perdas econômicas na avicultura. O VBI é um vírus envelopado, que possui genoma constituído de RNA fita simples, que codifica 4 proteínas estruturais, dentre elas a Nucleoproteína (N), que é produzida em grande quantidade na infecção viral e é reconhecidamente imunogênica. O controle da BI se faz com a imunização das aves através da aplicação de vacinas vivas atenuadas, seguidas de vacinação utilizando antígeno inativado, sendo o sorotipo Massachusetts o único liberado para uso no Brasil. Um dos objetivos do presente trabalho foi realizar um estudo exploratório, afim de conhecer a opinião de diferentes segmentos da avicultura sobre a situação atual da ocorrência de BI nos planteis brasileiros e os custos que ela representa. Diante disso, surge então a necessidade do desenvolvimento de vacinas alternativas e seguras para controle da BI, entre elas a utilização de vacinas vetoriais. Dessa forma, com o objetivo de desenvolver uma vacina efetiva no controle da BI, amostras variantes de VBI foram clonadas em adenovírus humano recombinante e utilizadas para transfectar células HEK293, originando adenovírus recombinantes carreadores do gene N do VBI. Estes vírus foram purificados e utilizados como vacinas recombinantes para imunização de aves SPF. Com base nos dados obtidos, observou-se que apesar das diferentes estratégias de vacinação, a BI ainda é considerada uma doença de alta prevalência que continua causando significativas perdas econômicas na produção avícola de corte e postura no Brasil. Os resultados obtidos demonstraram que a vacina recombinante não induziu uma resposta sorológica detectável pelo teste de Elisa comercial utilizado, bem como não reduziu os escores de lesões nos tecidos das aves vacinadas e desafiadas. Assim, a vacina recombinante carreada por adenovírus defectivo expressando o gene N do VBI foi construída e caracterizada, porém se mostrou ineficaz e não induziu suficiente proteção às aves experimentalmente imunizadas frente ao desafio com VBI. / The infectious bronchitis virus (IBV) is the etiologic agent of Infectious bronchitis (IB), a highly contagious disease that causes great economic losses in the poultry industry. The IBV is an enveloped virus that has RNA single strand genome, encoding four structural proteins, among them Nucleoprotein (N), which is produced abundantly in viral infection and is known immunogenic. The IB control is done by immunization of birds by applying live attenuated vaccine, followed by vaccination using inactivated antigen, wherein the Massachusetts serotype is the only released for use in Brazil. One of the goals of the present work was to conduct an exploratory study in order to know the opinion of different segments of the poultry industry on the current situation of the occurrence of BI in Brazilian squads and the costs that it represents. Therefore, the development of alternative and safe vaccines to BI control is necessary, including the use of vectors. In order to develop an effective vaccine to IB control, samples from IBV field variants were cloned into recombinant human adenovirus and used to transfect HEK293 cells, resulting in recombinant adenovirus carriers of the N gene of the IBV. These recombinant viruses were purified and used as vaccines to immunization of SPF chickens. Based on the obtained data, it was observed that despite the different vaccination strategies, IB is still considered highly prevalent disease that causes significant economic losses in Brazilian poultry industry. The results here obtained showed that the recombinant vaccine does not causes detectable positive serological responses by commercial Elisa test in vaccinated chickens and does not reduce the tissues damage in vaccinated and challenged chickens. Thus, the recombinant vaccine carried by defective adenovirus expressing N gene of IBV was constructed and characterized, but seemed to be ineffective and did not induce sufficient protection to experimentally immunized chickens against IBV challenge.

N-methyl-D-aspartate (NMDA) receptors are a subclass of glutamate receptors that play an essential role in mediating excitatory neurotransmission and synaptic plasticity in the mammalian central nervous system (CNS). The activation of NMDA receptors plays a key role in brain development and memory formation. Abnormal regulation of NMDA receptors plays a critical role in the etiology of many neuropsychiatric disorders. NMDA receptors form a heterotetrameric complex composed of GluN1, GluN2(A-D) and GluN3(A, B) subunits. The NMDA receptors surface expression is regulated at multiple levels including early processing (synthesis, subunit assembly, endoplasmic reticulum (ER) processing, intracellular trafficking to the cell surface), internalization, recycling and degradation. NMDA receptors are regulated by the availability of GluN subunits within the ER, the presence of ER retention and export signals, and posttranslational modifications including phosphorylation and palmitoylation. However, the role of N-glycosylation in regulating of NMDA receptor processing has not been studied in detail. The aim of this study was to clarify the mechanisms of regulation of surface expression and functional properties of NMDA receptors. We used a combination of molecular biology, microscopy, biochemistry and...

No / Phosphorylation or SUMOylation of the kainate receptor (KAR) subunit GluK2 have both individually been shown to regulate KAR surface expression. However, it is unknown whether phosphorylation and SUMOylation of GluK2 are important for activity-dependent KAR synaptic plasticity. We found that protein kinase C-mediated phosphorylation of GluK2 at serine 868 promotes GluK2 SUMOylation at lysine 886 and that both of these events are necessary for the internalization of GluK2-containing KARs that occurs during long-term depression of KAR-mediated synaptic transmission at rat hippocampal mossy fiber synapses. Conversely, phosphorylation of GluK2 at serine 868 in the absence of SUMOylation led to an increase in KAR surface expression by facilitating receptor recycling between endosomal compartments and the plasma membrane. Our results suggest a role for the dynamic control of synaptic SUMOylation in the regulation of KAR synaptic transmission and plasticity.

No / The surface expression and regulated endocytosis of kainate (KA) receptors (KARs) plays a critical role in neuronal function. PKC can modulate KAR trafficking, but the sites of action and molecular consequences have not been fully characterized. Small ubiquitin-like modifier (SUMO) modification of the KAR subunit GluK2 mediates agonist-evoked internalization, but how KAR activation leads to GluK2 SUMOylation is unclear. Here we show that KA stimulation causes rapid phosphorylation of GluK2 by PKC, and that PKC activation increases GluK2 SUMOylation both in vitro and in neurons. The intracellular C-terminal domain of GluK2 contains two predicted PKC phosphorylation sites, S846 and S868, both of which are phosphorylated in response to KA. Phosphomimetic mutagenesis of S868 increased GluK2 SUMOylation, and mutation of S868 to a nonphosphorylatable alanine prevented KA-induced SUMOylation and endocytosis in neurons. Infusion of SUMO-1 dramatically reduced KAR-mediated currents in HEK293 cells expressing WT GluK2 or nonphosphorylatable S846A mutant, but had no effect on currents mediated by the S868A mutant. These data demonstrate that agonist activation of GluK2 promotes PKC-dependent phosphorylation of S846 and S868, but that only S868 phosphorylation is required to enhance GluK2 SUMOylation and promote endocytosis. Thus, direct phosphorylation by PKC and GluK2 SUMOylation are intimately linked in regulating the surface expression and function of GluK2-containing KARs.