Many molecules and the complex interactions between them underlie plasticity in the cerebellum. However, the exact relationship between cerebellar plasticity and the different signalling cascades remains unclear. Calcium-calmodulin dependent protein kinase II (CaMKII) regulates many forms of synaptic plasticity, but very little is known about its function during plasticity induction in the cerebellum. The aim of this thesis is to contribute to a better understanding of the molecular mechanisms that regulate the induction of synaptic plasticity in cerebellar Purkinje cells (PCs). The focus of the thesis is to investigate the role of CaMKII isoforms in the bidirectional modulation of plasticity induction at parallel fibre (PF)-PC synapses. For this investigation, computational models that represent the CaMKII activation and the signalling network that mediates plasticity induction at these synapses were constructed. The model of CaMKII activation by calcium-calmodulin developed by Dupont et al (2003) replicates the experiments by De Koninck and Schulman (1998). Both theoretical and experimental studies have argued that the phosphorylation and activation of CaMKII depends on the frequency of calcium oscillations. Using a simplified version of the Dupont model, it was demonstrated that the CaMKII phosphorylation is mostly determined by the average calcium-calmodulin concentration, and therefore depends only indirectly on the actual frequency of calcium oscillations. I have shown that a pulsed application of calcium-calmodulin is, in fact, not required at all. These findings strongly indicate that the activation of CaMKII depends on the average calcium-calmodulin concentration and not on the oscillation frequency per se as asserted in those studies. This thesis also presents the first model of AMPA receptor phosphorylation that simulates the induction of long-term depression (LTD) and potentiation (LTP) at the PF-PC synapse. The results of computer simulations of a simple mathematical model suggest that the balance of CaMKII-mediated phosphorylation and protein phosphatase 2B (PP2B)-mediated dephosphorylation of AMPA receptors determines whether LTD or LTP occurs in cerebellar PCs. This model replicates the experimental observations by Van Woerden et al (2009) that indicate that CaMKII controls the direction of plasticity at PF-PC synapses. My computer simulations support Van Woerden et al’s original suggestion that filamentous actin binding can enable CaMKII to regulate bidirectional plasticity at these synapses. The computational models of intracellular signalling constructed in this thesis advance the understanding of the mechanisms of synaptic plasticity induction in the cerebellum. These simple models are significant tools for future research by the scientific community.

El adenocarcinoma ductal pancreático (PDAC) es la quinta causa de muerte por cáncer en los países desarrollados y uno de los tumores humanos más agresivos. A pesar del papel clave de la angiogénesis -la formación de nuevos vasos a partir de otros preexistentes- en la progresión y metástasis de muchos tumores, su papel en PDAC ha sido poco caracterizado. El activador tisular del plasminógeno (tPA), una proteína multifuncional que regula numerosas funciones celulares, ejerce efectos proangiogénicos en modelos in vivo de PDAC, aunque no se han analizado los mecanismos moleculares responsables de estos efectos. Esta tesis trata de identificar el papel de tPA en la angiogénesis del PDAC, así como de descubrir los factores responsables de la sobreexpresión de tPA en cáncer de páncreas. En primer lugar, hemos demostrado que los efectos pro-angiogénicos de tPA pueden ser tanto directos como indirectos. Por un lado, aunque tPA no cambia los niveles de moléculas pro-angiogénicas como VEGF, TGF-b, IL-1 o IL-8 producidas por las células tumorales o endoteliales, sí que induce la sobreexpresión y activación de MMP-9, una metaloproteasa implicada en promover angiogénesis, sugiriendo por tanto que esta proteína puede mediar de forma indirecta los efectos proangiogénicos de tPA. Por otro lado, hemos encontrado que tPA, de forma independiente de su actividad catalítica, promueve directamente la proliferación, migración y tubulogénesis de las células endoteliales. Estos efectos son mediados por la activación en estas células de las rutas de señalización ERK1/2, AKT y JNK. Además, mediante siRNA o inhibidores químicos, hemos encontrado que Annexina A2, Galectina-1 y EGFR son necesarios para la activación de la señalización inducida por tPA en células endoteliales. Finalmente, hemos visto que citoquinas inflamatorias e hipoxia, dos eventos asociados a PDAC y además inductores de angiogénesis, dan lugar a un fuerte incremento de los niveles de tPA en células tumorales pancreáticos. Todos estos datos apoyan un mecanismo de retroalimentación positiva entre estímulos proangiogénicos presentes en las células tumorales y el estroma, y el incremento de la molécula proangiogénica tPA. / Pancreatic ductal adenocarcinoma (PDAC) is the fifth leading cause of cancer death in the developed countries and one of the most aggressive human tumors. Despite the key contribution of angiogenesis – the growth of new vessels from pre-existing ones- to the progression and spread of many cancers, its role in PDAC has been poorly characterized. Tissue plasminogen activator (tPA), a multifunctional protein regulating a broad range of cellular functions, has been reported to exert pro-angiogenic effects in in vivo models of PDAC, although the underlying molecular mechanism has not been analyzed. This work aims to elucidate the role of tPA in the angiogenesis of PDAC as well as to identify the factors responsible for tPA increase in pancreatic cancer. First, we demonstrated that tPA pro-angiogenic effects are both indirect and direct. On the one hand, tPA does not change the levels of the pro-angiogenic molecules VEGF, TGF-b, IL-1 or IL-8 produced by pancreatic tumoral cells or endothelial cells, but it is involved in MMP-9 –a potent stimulator of angiogenesis- upregulation and activation in pancreatic and endothelial cells, suggesting that this matrix metalloproteinase can indirectly mediate tPA angiogenic effects. On the other hand, we found that tPA, in a catalytic-independent way, directly promotes endothelial cell proliferation, migration and tubulogenesis. These direct effects of tPA are mediated by activation of ERK1/2, AKT and JNK signaling pathways in endothelial cells. In addition, using siRNA technology or chemical inhibitors, we found that AnnexinA2, Galectin-1 and EGFR are required for tPA-mediated signaling activation in endothelium. Finally, we found that inflammatory cytokines and hypoxia, two hallmarks of PDAC and also angiogenic stimuli, lead to a sharp increase in tPA levels in pancreatic tumoral cells. These data support a feed-back loop between proangiogenic stimuli present in both tumoral and stromal cells and the increase of the proangiogenic molecule tPA.

La déficience intellectuelle (DI) est souvent associée à d’autres signes cliniques morphologiques et psychiatriques mais cette comorbidité est peu caractérisée pour la DI associée à un gène donné. Ainsi les mutations du gène p21-activated kinase 3 (PAK3) sont responsable d’un large spectre clinique, allant de la DI légère à des DI sévères associées parfois à des malformations du cerveau. Nous avançons l’hypothèse que les différentes mutations d’un même gène peuvent affecter divers paramètres biochimiques et affecter de manière différentielle les voies de signalisation impliquées dans la plasticité synaptique et dans le développement du cerveau. Pour valider notre hypothèse, nous avons caractérisé une nouvelle mutation responsable d’une déficience intellectuelle sévère associée à une agénésie du corps calleux et une microcéphalie. Cette mutation supprime l’activité kinase, n’affecte pas la stabilité de la protéine et augmente l’interaction avec un GEF de la famille PIX. Ces derniers résultats identifient une nouvelle voie de signalisation impactée par certaines mutations de PAK3. L’expression de ce variant modifie la morphologie cellulaire et la dynamique des adhésions focales, ainsi que les propriétés migratoires des cellules, ce qui pourraient relier les défauts biochimiques aux défauts de certaines fonctions cellulaires. De manière intéressante, ces caractéristiques sont aussi retrouvées pour un autre variant responsable d’une clinique également très sévère. Nous avons également caractérisé d’autres mutations associées à des phénotypes moins sévères. La synthèse de nos résultats nous permet ici de proposer un modèle explicatif de la relation génotype-phénotype pour les mutations de déficience intellectuelle liées au gène PAK3, intégrant des défauts neurodéveloppementaux et de plasticité synaptique. / Intellectual Disability (ID) is often associated with other morphological and psychiatric clinical signs, but this comorbidity is poorly characterized for ID associated with a given gene. Thus mutations of the p21-activated kinase 3 (PAK3) gene are responsible for a broad clinical spectrum, ranging from mild ID to severe ID, sometimes associated with brain malformations. We hypothesize that different mutations of the same gene may affect various biochemical parameters and differentially affect the signaling pathways involved in synaptic plasticity and brain development. To validate our hypothesis, we characterized a new mutation responsible for a severe intellectual disability associated with agenesis of the corpus callosum and microcephaly. This mutation suppresses kinase activity, does not affect protein stability and increases the interaction with a GEF of the PIX family. These latest results identify a new signaling pathway impacted by certain PAK3 mutations. The expression of this variant modifies the cellular morphology and the dynamics of the focal adhesions, as well as cell migratory properties, which could link the biochemical defects to those of certain cell functions. Interestingly, these features are also found for another variant responsible for a very similar severe clinical spectrum. We have also characterized other mutations associated with less severe phenotypes. The synthesis of our results allows us to propose an explanatory model of the genotype-phenotype relationship integrating neurodevelopmental and synaptic plasticity defects for intellectual disability and other clinical traits associated to the PAK3 gene mutations.

Angiogenesis is the formation of new blood vessels from pre-existing ones. Unregulated angiogenesis is associated with several diseases such as diabetic retinopathy and tumour growth. Many signal transduction pathways have been implicated in the regulation of angiogenesis such as p38 mitogen-activated protein kinase (MAPK), phosphatidylinositol-3 kinase (PI3K), extracellular signal-related kinase 1/2 (Erk1/2) and of particular interest the calcineurin/nuclear factor of activated T-cell (NFAT) pathway. Inhibition of calcineurin activity by the drug cyclopsorin A (CsA) has been shown to inhibit processes required for successful angiogenesis such as in vitro cell migration, tube formation and additionally attenuates corneal angiogenesis in vivo. CsA is associated with severe side effects and therefore the identification of an endogenous regulator of this pathway would be beneficial. One possibility is the plasma membrane calcium ATPases (PMCAs). These high affinity calcium extrusion pumps have been shown to interact with calcineurin in mammalian cells and cardiomyocytes and down-regulate the calcineurin/NFAT pathway. This is hypothesised to be due to the interaction between the two proteins which maintains calcineurin in a low calcium micro-environment generated by the calcium removal function of the pump. Interestingly, PMCA4 has been shown to interact with calcineurin in endothelial cells. The aim of our study was to further our understanding of PMCA4s regulation of the calcineurin/NFAT pathway specifically in endothelial cells and establish if PMCA4 has a role in the regulation of angiogenesis. ‘Gain of function’ by adenoviral over-expression of PMCA4 and ‘loss of function’ by either si-RNA mediated knockdown of PMCA4 or isolation of PMCA4-/- MLEC were used as models. Over-expression of PMCA4 in HUVEC resulted in inhibition of the calcineurin/NFAT pathway with the opposite result occurring in the case of the knockout of PMCA4, identifying PMCA4 as a negative-regulator of the calcineurin/NFAT pathway in endothelial cells. Over-expression of PMCA4 significantly attenuated VEGF-induced protein and mRNA expression of the pro-angiogenic proteins RCAN1.4 and Cox-2, endothelial cell migration and in vitro and in vivo tube formation with the opposite result occurring in knockdown or knockout studies, confirming PMCA4 as a down-regulator of angiogenesis. Interestingly, over-expression or knockdown of PMCA4 had no effect on VEGF-induced HUVEC proliferation or Erk1/2 phopshorylation proposing PMCA4 may be a potential inhibitor of angiogenesis without compromising cell survival. Disruption of the interaction between PMCA4 and calcineurin by generation and ectopic expression of an adenovirus encoding the region of PMCA4 that interacts with calcineurin (428-651) (Ad-ID4) resulted in an increase in NFAT activity, RCAN1.4 protein expression and in vitro tube formation. These results identify the mechanism of PMCA4s inhibitory effect of the calcineurin/NFAT pathway and consequently angiogenesis is a result of the interaction between the two proteins. The novel findings of this study establish PMCA4 as a negative-regulator of the calcineurin/NFAT pathway in endothelial cells and angiogenesis. These results are far reaching and highlight a potential role for PMCA4 as a therapeutic target in a variety of diseases that are associated with pathological angiogenesis.

Thesis (PhD)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Introduction: The anthracyclines (ACs), daunorubicin (DNR) and doxorubicin (DXR) are two of the most effective drugs known for the treatment of systemic neoplasms and solid tumours. However, their clinical use is often hampered by their dosedependent cumulative cardiotoxicity, which leads to irreversible and fatal druginduced congestive heart failure. The mechanism by which ACs induces heart damage is not fully understood. Recent reports have indicated that DXR activates autophagy and ubiquitin proteasome-mediated degradation of specific transcription factors, however, no reports exists on the effect of ACs on the E3 ubiquitin ligases, MuRF-1 and MAFbx. The aim of the first part of the study was therefore to investigate the effect of DNR treatment on the protein and organelle degradation systems in the heart and to elucidate the signalling mechanisms involved. Although this model was ideal in allowing the investigation of the signalling pathways which are affected by DNR, it did not allow for further exploration or manipulation of signalling pathways that may be of potential benefit in this context. The in vitro model was therefore used to validate the hypothesis that increased autophagy alleviates AC-induced cardiotoxicity and delays the onset of cardiomyocyte death. The aims for the second part of the study were (i) to characterize the effect of DXR in H9C2 cells, (ii) to determine whether the induction/inhibition of autophagy in combination with DXR alleviates cytotoxicity and (iii) to investigate the influence of increased/decreased autophagy in combination with DXR on reactive oxygen species (ROS) production, mitochondrial function, endoplasmic reticulum (ER) stress and the ubiquitin proteasome pathway. In the final part of this study, an in vivo model was used to assess the potential benefit of autophagy in a novel GFP-LC-3 tumour bearing mouse model of acute DXR-induced cardiotoxicity. Material and Methods: Adult rats were divided into two groups where one group received six intraperitoneal injections of 2 mg/kg DNR on alternate days and the other group received saline injections as control. Hearts were excised and perfused on a working heart system the day after the last injection and freeze clamped for biochemical analysis. H9C2s were cultured and treated with Bafilomycin A1 (10 nM, inhibitor of autophagy) for 6 hrs, Rapamycin (50 μM, inducer of autophagy) for 24 hrs, DXR (3 μM) for 24 hrs or a combination of these drugs. Following treatment, cells were harvested and assessed for cell death, proteolytic activity and oxidative stress using western blotting, fluorescence microscopy and flow cytometry. In the final phase of the study, twenty-four female mice were injected at 8 weeks with a mouse breast cancer cell line (EO771) and after observation of tumour growth, animals were either treated with one injection (i.p.) of Rapamycin (4 mg/kg), two injections (i.p.) of DXR (10 mg/kg) or a combination of the two drugs. After the experimental protocol, mice were terminated and their hearts were rapidly excised. The hearts were divided cross-sectionally and utilized for biochemical and histological analyses. Results and Discussion: DNR treatment significantly attenuated myocardial function and increased apoptosis in the ex vivo heart model. DNR-induced cardiac cytotoxicity was associated with the upregulation of two E3 ubiquitin ligases, MuRF-1 and MAFbx as well as a significant increase in two markers of autophagy, beclin-1 and LC-3. These changes observed in the heart were also associated with attenuation of the PI3-kinase/Akt signalling pathway. The augmentation of autophagy with rapamycin before DXR treatment significantly reduced cell death in the in vitro model. Indeed, rapamycin treatment demonstrated to be a vital survival mechanism for acute DXR-induced cardiotoxicity as it decreased cellular ROS production, improved mitochondrial function and prevented nuclear translocation of DXR. Moreover, these changes in cardiomyocytes were also associated with a reduction in the ubiquitin-proteasome pathway (UPP). In the final part of this study, a novel tumour bearing GFP-LC3 mouse model was developed to confirm the results obtained in the in vitro study. It was demonstrated that acute DXR-induced cardiotoxicity resulted in increased apoptosis, the inhibition of autophagy and increased proteolysis via the UPP. These findings were associated with a reduction in body weight and cardiomyocyte cross-sectional area. The cardiotoxic effects of DXR were substantially reduced when autophagy was induced with rapamycin. Taken together, our data strongly indicates that it is possible to attenuate the cardiotoxic effects of doxorubicin in cancer patients by carefully controlling the levels of autophagy using rapamycin as adjuvant therapy. / AFRIKAANSE OPSOMMING: Inleiding: Die antrasikliene (AC’s), daunorubisien (DNR) en doksorubisien (DKS), is twee van die mees effektiewe AC wat bekend is vir die behandeling van sistemiese neoplasmas en soliede tumore. Hulle kliniese gebruik word egter deur dosis afhanklike kumulatiewe kardiotoksisiteit benadeel, wat tot onomkeerbare en dodelike kongestiewe hartversaking kan lei. Die meganisme waardeur AC’s hartversaking kan veroorsaak, word nog nie ten volle verstaan nie. Onlangse navorsing het aangetoon dat DKS autofagie en die ubikwitienproteosoom-bemiddelde degradasie van spesifieke transkripsie faktore aktiveer. Daar is egter geen literatuur wat die effek van AC’s op die E3-ubikwitienligases, MuRF-1 en MAFbx beskryfnie. Die doel van hierdie eerste afdeling van die studie is om die effek van DNR behandeling op die proteïen- en organel degradasie sisteme in die hart te ondersoek en om van die betrokke seinmeganismes te bepaal. Alhoewel hierdie model ideaal is om sommige seinweë wat deur DNR geaffekteer word, te ondersoek, kon seinoordragpaaie wat potensieël voordelig in hierdie konteks is, nie in bg. model gemanipuleer word nie. Die in vitro model is gebruik om die hipotese dat verhoogde outofagie AC-geïnduseerde kardiotoksisiteit verlaag en sodoende seldood verminder, te bevestig. Die doel van hierdie afdeling van die studie was: (i) om die effek van DKS op H9C2 selle te karakteriseer, (ii) om te bepaal of die induksie/inhibisie van outofagie in kombinasie met DKS kardiotoksisiteit verbeter (iii) om die invloed van verhoogde/verlaagde outofagie in kombinasie met DKS op reaktiwe suurstof species (ROS), mitokondriale funksie, endoplasmiese retikulum (ER) stress en die ubikwitienproteosoompad te ondersoek. In die finale deel van hierdie studie, is ‘n in vivo model gebruik om die moontlike voordelige effek van verhoogde outofagie in ‘n GFP-LC-3 tumor-draende muismodel met akute DKSgeïnduseerde kardiotoksisiteit, ondersoek. Materiaal en Metodes: Volwasse rotte is in twee groepe verdeel waar een groep ses intraperitoneale inspuitings van 2 mg/kg DNR op afwissellende dae ontvang het en die andergroep as ‘n kontrole, ‘n soutoplossing gekry het. Die harte is verwyder en geperfuseer op ‘n werkende hartsisteem een dag na die laaste inspuiting en gevriesklamp vir biochemiese analises. H9C2 selle is vir 6 uurgekweek en behandel met Bafilomisien A1 (10 nM, ‘n autofagie inhibitor), 24 uur met Rapamisien (50 μM, ‘n autofagie induseerder), 24 uur met DKS (3 μM) of ‘n kombinasie van hierdie middels. Na behandeling is selle ge-oes vir analises in seldood, proteolitiese aktiwiteit en oksidatiewe stress deur van westelike kladtegniek, fluoresensie mikroskopie en vloeisitometrie gebruik te maak. In die finale fase van hierdie studie is vier en twintig, agt weke oue wyfie muise ingespuit met ‘n muisborskankersellyn (E0771) en is tumorgroei waargeneem; die diere is of behandel met een rapamisien inspuiting (i.p) (4 mg/kg), of twee DKS inspuitings (i.p.) (10 mg/kg) of ‘n kombinasie van die twee middels. Na die eksperimentele protokol, is die muise van kant gemaak en hulle harte vinnig verwyder. Die harte is in twee verdeel en gebruik vir biochemiese- en histologiese analises. Resultate en Bespreking: DNR behandeling het kardiale funksie betekenisvol verswak en apoptose in die hart verhoog. DNR-geïnduseerde kardiotoksisiteit is geassosieer met die opregulering van E3-ligases, MuRF-1 en MAFbx en het ook ‘n betekenisvolle toename in twee outofagie merkers, beclin-1 en LC-3 veroorsaak. Hierdie veranderinge wat in die hart waargeneem is, is ook geassosieer met ‘n onderdrukking van die PI3-kinase/Akt seinweg. Die toename in outofagie met rapamisien voor DKS behandeling het seldood in die vorm van apoptose betekenisvol verlaag. Daarmee saam het verhoogde outofagie ‘n noodsaaklike oorlewings meganisme vir akute DKS-geïnduseerde kardiotoksisiteit gedemonstreer. Die rede hiervoor is dat dit ROS produksie verlaag het, mitokondriale funksie verbeter het en DKS translokasie vanuit die sitoplasma tot binne die nukleus verhoed het. Hierdie veranderinge in kardiomiosiete is ook met ‘n afname in die ubikwitienproteosoomseinweg (EPS) geassosieer. In die finale deel van hierdie studie, is ‘n nuwe tumor-draende muismodel ontwikkel om die resultate wat in die in vitro studie gekry is, te bevestig. Daar is bewys dat akute DKS-geïnduseerde kardiomiotoksisiteit aanleiding gegee het tot verhoogde apoptose, outofagie inhibisie en verhoogde proteolise via die EPS. Hierdie bevindinge is geassosieer met ‘n verlaging in liggaamsgewig en kardiomiosiet dwarssnit area. Die kardiotoksiese effekte van DKS is insiggewend verminder as autofagiege ïnduseer is met rapamisien. Om saam te vat: Ons data bevestig dat dit moontlik is om die kardiotoksiese effekte van DKS in kanker pasiënte te verminder deur outofagie vlakke te monitor en te kontroleer deur middel van rapamisien behandeling as bykomende terapie.

Organisms such as mammals need tissue renewal as an important process for maintenance of their viability. Because proliferation is essential also for tumourigenesis, cells need tumour-suppressor mechanisms to protect organism against cancer. Cellular senescence, the permanent state of cell-cycle arrest, features one of these intrinsic barriers against tumourigenesis after DNA damage and understanding of this process may lead to finding of novel therapeutic targets and to optimization of chemotherapy for patients with cancer. In the first part of the PhD thesis, we investigated activation of JAK/STAT signalling pathway in drug-induced senescence. We used genotoxic drugs like aphidicolin, camptothecine, 5-bromo- 2'-doexyuridin, etoposide or thymidine to induce premature senescence in normal and cancer cells. All this chemicals were able to persistently activate JAK/STAT signalling in monitored cells. Activation of STATs was accompanied with up-regulation of expression of interferon-stimulated genes (ISGs), such as MX1, IRF1, IRF7 and PML. Since IRF1 and IRF7 can be directly involved in stimulation of the IFN genes, we show activated expression as well as secretion of IFNbeta and IFNgamma, but not IFNalpha in drug-induced senescent cells. Furthermore, an inhibition of JAK1 as a major kinase of STAT...

O câncer de endométrio tem incidência crescente, principalmente nos países desenvolvidos, devido ao estilo de vida moderno, aumento de casos de obesidade e diabetes, e diversos outros fatores que, em conjunto, estão tornando esta neoplasia na mais comum no trato reprodutor feminino. Ele é bastante influenciado pelo estado hormonal e por fatores reprodutivos das pacientes. Assim, é mais frequente no período pós-menopausa, quando pode ocorrer um desequilíbrio na sinalização do estrogênio. A diabetes e a obesidade são causadas, principalmente, pelo excesso de triglicerídeos e glicose circulantes, e pela resistência à insulina. A hiperglicemia leva à produção excessiva de insulina e do fator de crescimento semelhante à insulina tipo 1 (IGF1), sendo que estes hormônios são considerados antiapoptóticos e promotores da proliferação celular. Sabe-se que eles agem por vias semelhantes e que, provavelmente, o mecanismo responsável pela proliferação provocada por eles está associado à via PI3K/Akt/mTOR. Desta forma, avaliamos a expressão gênica de 92 genes na rota de sinalização do IGF1R em câncer de endométrio (n=3) e endométrio normal (n=2), através da técnica de qRT-PCR (ensaio TaqMan® Array Human IGF1R Signaling). Dentro destes genes, alguns estão envolvidos diretamente com a via PI3K/Akt/MAPK, outros estão implicados em processos como proliferação, diferenciação, tumorigênese, apoptose, resposta imune, síntese proteica, entre outros. Avaliamos, também, os níveis proteicos do receptor do fator de crescimento semelhante à insulina (IGF1R), IGF1 e receptor da insulina (IR) pela técnica de imunohistoquímica, além da funcionalidade geral dos 4 genes mais diferencialmente expressos no câncer de endométrio Observamos que, dos 92 genes, 26 foram expressos somente no grupo câncer - CACNA1H, CRK, EIF2B5, ELK1, FRAP1 (MTOR), GYS1, HRAS, IGF2, IKBKB, IKBKE, ITPR3, KRAS, NFAT5, NFATC1, NFKB1, NFKBIB, NFKBIE, PIK3CA, PIK3CB, PLCB1, PLCB2, PLCG2, PRKCZ, RELB, SHC1 e YWHAZ; 46 tiveram expressão aumentada no grupo câncer de endométrio - AKT1, AKT2, ARAF, ATF4, BAD, BRAF, CACNA1C, CALM1, CALM2, CALM3, CREB1, EIF4E, FOXO3, GSK3B, IGF1, IGF1R, IKBKG, IRS1, MAP2K1, MAP2K2, MAPK3, MEF2C, MEF2D, NFATC2, NFATC3. NFKB2, NFKBIA, NRAS, PDPK1, PIK3CD, PIK3R1, PIK3R2, PLCG1, PPP3CA, PPP3R1, PRKCI, RAF1, RAPGEF1, RELA, RPS6, RPS6KB1, SOS1, YWHAB, YWHAE, YWHAH e YWHAQ, um não apresentou expressão em nenhum dos grupos (SLC2A4) e não foi possível analisar os restantes 20 genes, pois não foram expressos em todas as amostras. Quanto à expressão das proteínas IGF1R, IGF1 e IR, todas se mostraram mais expressas no câncer de endométrio e que se encontram localizadas principalmente no citoplasma das células. Assim, este trabalho mostra que a sinalização do IGF1R pode ter participação importante na aquisição do fenótipo maligno das células endometriais, e que o aumento das moléculas efetoras desta via no câncer de endométrio provavelmente está relacionado ao seu papel mitogênico. / Endometrial cancer has a growing incidence, especially in developed countries, because of the modern lifestyle, increased cases of obesity and diabetes, and several other factors that together make this disease the most common in the female reproductive tract. Endometrial cancer is strongly influenced by the hormonal state and by the reproductive factors of the patients. Thus, it is attributed to the postmenopausal period, when estrogen signaling can be unbalanced, and consequently lead to malignant proliferative patterns. Diabetes and obesity are caused mainly by the excess of circulating triglycerides and glucose, and by insulin resistance. Hyperglycemia leads to excessive production of insulin and IGF1.These hormones are considered to have antiapoptotic effects and to promote cell proliferation. It is known that they are very similar pathways, and the mechanism responsible for this proliferation is associated with the PI3K/Akt/mTOR pathway. Thus, we evaluated the expression of 92 genes in IGF1R signaling pathway in endometrial cancer (n = 3) and normal endometrium (n = 2), using qRT-PCR (TaqMan® Array Human IGF1R Signaling test). Within these genes, some are in the PI3K/Akt/MAPK pathways, others are involved in proliferation, differentiation, tumorigenesis, apoptosis, immune response, protein synthesis, among others We also evaluated the protein levels of IGF1R, IGF1 and IR by immunohistochemistry, as well as the general functionality of the 4 most differentially expressed genes in endometrial cancer. We found that 26 genes were expressed only in endometrial cancer - CACNA1H, CRK, EIF2B5, ELK1, FRAP1 (mTOR), GYS1, HRAS, IGF2, IKBKB, IKBKE, ITPR3, KRAS, NFAT5, NFATc1, NFKB1, NFKBIB, NFKBIE, PIK3CA, PIK3CB, PLCB1, PLCB2, PLCG2, PRKCZ, RELB, SHC1 and YWHAZ; 46 had increased expression in endometrial cancer, when compared to control group - AKT1, AKT2, ARAF, ATF4, BAD, BRAF, CACNA1C, CALM1, CALM2, CALM3, CREB1, eIF4E, FOXO3, GSK3B, IGF1, IGF1R IKBKG, IRS1, MAP2K1, MAP2K2, MAPK3 , MEF2C, MEF2D, NFATC2, NFATC3. NFKB2, NFKBIA, PIK3R1, PIK3R2, PLCG1, PPP3CA, PPP3R1, PRKCI, RAF1, RAPGEF1, RELA, RPS6, RPS6KB1, SOS1, YWHAB, YWHAE, YWHAH and YWHAQ, one showed no expression in neither groups (SLC2A4) and the other 20 were not expressed in all samples, so we decided not to analyze them. As for the expression of IGF1R, IGF1 and IR proteins, all them showed increased expression in endometrial cancer and were localized in the citoplasm. Thus, this work shows that IGF1R signaling may play an important role in the acquisition of a malignant phenotype by endometrial cells, and that the increase of these effectors in endometrial cancer is related to its mitogenic effects.

L'objectif principal de ma thèse a été la caractérisation de l'histoire évolutive des voies de signalisation au travers d'une double approche: (i) l'analyse phylogénétique de leurs composés; et (ii) l'identification et la caractérisation de leurs interactions par l'analyse des interactomes d'organismes modèles. Or, bien que de nombreux outils soient disponibles pour la reconstruction d'arbres de gènes individuels, peu de méthodes ont été développées pour l'étude d'un ensemble de protéines impliquées dans un même processus cellulaire. Pourtant, au sein de la cellule, la plupart des protéines agissent en interaction avec d'autres protéines. Dans un premier temps, j'ai étudié l'histoire évolutive de la famille des PI3K (Phosphatidylinositol 3-kinases). Cette première analyse phylogénétique détaillée m'a permis de mettre en place une méthodologie applicable aux voies de signalisation. Un problème important rencontré dans cette étude a consisté en la sélection de transcrits alternatifs et ceci m'a conduit à développer un logiciel dédié nommé BATfinder (\Best Aligned Transcript finder). Dans le but d'étudier la voie de signalisation AKT/mTOR, j'ai effectué l'implémentation de la méthodologie validée avec les PI3K. Cette implémentation a pris la forme d'un pipeline automatique nommé EPINe (Easy Phylogenetics for Interaction Networks). Ce pipeline est théoriquement utilisable pour l'analyse phylogénétique de tout réseau métabolique eucaryote / The main goal of my thesis was the characterization of the evolutionary history of signalling pathways through a twofold approach: (i) the phylogenetic analysis of their components; and (ii) the identification and characterization of their interactions by the analysis of model organisms interactomes. While many tools are available for single genes tree reconstruction, only a few methods have been developed for the study of a set of proteins involved in the same cellular process. However, inside the cell, most of proteins interact with others.Initially, I studied the evolutionary history of the PI3K family (Phosphati-dylinositol 3-kinases). This first detailed phylogenetic analysis allowed me to set up a methodology suitable for signalling pathways. One of the important problems encountered in this study was the selection of alternative transcripts and this led me to develop a software called BATfinder (Best Aligned Transcript finder ). In order to study the AKT/mTOR signalling pathway, I have implemented the methodology previously validated with PI3Ks. This implementation was carried out as an automated pipeline called EPINe (Easy Phylogenetics for Interaction Networks). This pipeline is theoretically usable for the phylogenetic analysis of any eukaryotic metabolic network

In this thesis, I discuss two main subjects coming from biology and I propose two models that mimic the behaviours of the biological networks studied. The first part of the thesis deals with intracellular transport of molecules. Proteins, RNA and, generally, any kind of cargo molecules move freely in the cytoplasm: intracellular transport as a consequence of Brownian motion is classically modelled as a diffusion process. Some specific proteins, like the tumour suppressor p53, use microtubules to facilitate their way towards the nucleus. Microtubules are a dense network of filaments that point towards the cell centre. Motor proteins bind to these filaments and move along, bearing a cargo bound to them. I propose a simplified bi-dimensional model of nucleocytoplasmic transport taking into account the kinetic processes linked to microtubule transport. Unlike in other models we know, I represented the position of a single MT filament. This model is given by a system of partial differential equations which are cast in different dimensions and connected by suitable exchange rules. A numerical scheme is introduced and several scenarios are presented and discussed to answer to the question of which proteins benefit from microtubule transport, depending on their diffusion coefficients. In the second part of the thesis, I design and analyse a physiologically based model representing the accumulation of protein p53 in the nucleus after triggering of the sentinel protein ATM by DNA damage. The p53 protein plays an essential role in the physiological maintenance of healthy tissue integrity in multicellular organisms (regulation of cell cycle arrest, repair pathways and apoptosis). Firstly, I developed a compartmental ODE model to represent the temporal dynamics of the protein. Since the p53 protein is known for its oscillatory behaviour, I performed a numerical bifurcation study to verify the existence, in the model, of stable periodic solutions. Next, I have expanded the model by the addition of a spatial variable and analysed the spatio-temporal dynamics of p53. After checking the existence of oscillations in the spatial setting, I have analysed the robustness of the system under spatial variations (diffusion and permeability coefficients, cell shape and size).

Flüssigkeitssekretion und Proteinsekretion werden in Speicheldrüsen von Insekten über Hormone und Neurotransmitter gesteuert. Diese entfalten ihre physiologische Wirkung in den sekretorischen Drüsenzellen hauptsächlich über den zyklischen Adenosinmonophosphat (cAMP)-Signalweg und den Inositoltrisphosphat (IP<SUB>3</SUB>) / Ca²⁺-Signalweg. Die Mechanismen möglicher Wechselwirkungen zwischen diesen Signalwegen und ihre physiologischen Auswirkungen sind unzureichend bekannt.<p> Im Mittelpunkt dieser Arbeit stand die Frage, ob und wie sich der Ca²⁺-Signalweg und der cAMP-Signalweg in der Speicheldrüse der Diptere <I>Calliphora vicina</I> beeinflussen. Substanzen wie 5-Fluoro-α-Methyltryptamin und Histamin wurden in früheren Arbei-ten als Agonisten genutzt, um in den Speicheldrüsen von <I>C. vicina</I> selektiv den cAMP-Signalweg (getrennt vom IP<SUB>3</SUB>/Ca²⁺-Signalweg) zu aktivieren. Es zeigte sich in transepithelialen Potentialmessungen und mikrofluorometrischen Ca²⁺-Untersuchungen, dass beide Substanzen sowohl den cAMP-Weg als auch den Ca²⁺-Signalweg aktivierten. Die physiologischen Ursachen der Histamin-induzierten Ca²⁺-Erhöhung wurden genauer untersucht. <p> Zusammengefasst zeigten diese Untersuchungen, dass Histamin wie 5-HT den cAMP-Weg und die Phosphoinositidkaskade aktivierte. Im Gegensatz zu den 5-HT-induzierten Ca²⁺-Oszillationen, welche durch interzelluläre Ca²⁺-Wellen synchronisiert werden, verursachte Histamin bei niedrigen Konzentrationen lokale Ca²⁺-Oszillationen in einzelnen Zellen (keine Wellen). Bei höheren Histamin-Konzentrationen war eine anhaltende Ca²⁺-Erhöhung oder ein synchrones <quote>Ca²⁺-beating</quote> in der gesamten Drüse zu beobachten. <p> Des Weiteren wurde die Frage untersucht, ob eine Erhöhung der intrazellulären cAMP-Konzentration den IP<SUB>3</SUB> Ca²⁺-Signalweg in den Epithelzellen der Speicheldrüse beeinflussen kann. Es zeigte sich, dass cAMP den durch schwellennahe 5-HT-Konzentrationen induzierten Ca²⁺-Anstieg verstärkte. Diese Verstärkung wurde durch eine PKA-vermittelte Sensitivierung des IP<SUB>3</SUB>-Rezeptor/Ca²⁺-Kanals für IP<SUB>3</SUB> verursacht. Immunzytochemische Untersuchungen deuten dar-auf hin, dass die Proteinkinase A eng mit dem IP<SUB>3</SUB>-Rezeptor/Ca²⁺-Kanal assoziiert ist. Diese Messungen zeigen erstmals, dass auch bei Invertebraten der Botenstoff cAMP, PKA-vermittelt, den IP<SUB>3</SUB>-Rezeptor/Ca²⁺-Kanal des ER für IP<SUB>3</SUB> sensitiviert. / Fluid- and protein-secretion in the salivary glands of insects are controlled by hormones or neurotransmitters. These agonists activate two signalling cascades: the cAMP-pathway and the IP>sub>3</sub>/Ca-pathway. The functional crosstalk between these two signalling pathways is poorly understood. <p> Functional crosstalk between cAMP-pathway and IP₃/Ca²⁺-pathway was investigated in the salivary glands of the blowfly, <I>Calliphora vicina</I>. Histamine and 5-alpha-methyltryptamine were used in an attempt to activate the cAMP-pathway selectively, as suggested previously. By using transepithelial potential-measurements and microfluorometric Ca²⁺-imaging it was demonstrated that both substances activate the cAMP- and the IP₃/Ca²⁺-pathway. The physiological effects of histamine were investigated in detail. These experiments show that histamine causes an intracellular Ca²⁺-elevation that, in some preparations exhibits oscillations with concentration-dependent frequencies. In contrast to 5-HT induced intracellular Ca²⁺-oscillations and propagating intercellular Ca²⁺-waves histamine produces local Ca²⁺-oscillations in single cells or synchronous <quote>Ca²⁺-beating</quote> in the whole gland.<p> In addition the effects of increasing cAMP on the IP₃/Ca²⁺-pathway in the salivary glands of the blowfly were studied. It could be demonstrated that cAMP augments the 5-HT-induced Ca²⁺-increase in glands stimulated with low doses of 5-HT. This potentiation is the result of a PKA-mediated sensitisation of the IP₃-receptor/Ca²⁺-channel for IP₃. Results of immunocytochemical analyses show that the PKA is spatially associated with the ER.<p> These results show for the first time that in invertebrates as well as in vertebrates the second messenger cAMP sensitises the IP₃-receptor/Ca²⁺-channel for IP₃ by the action of a PKA.