A doença de Parkinson é a doença motora neurodegenerativa mais comum do mundo. Agregados proteicos contendo principalmente alfa-sinucleína é a principal marca da doença. Recentemente, tem sido demonstrado que defeitos na dinâmica mitocondrial e da autofagia são causados pelo acúmulo da proteína. No nosso estudo, foram utilizados neurônios derivados de SH-SY5Y ou de hiPSC de pacientes com a doença de Parkinson hereditária, além de leveduras para analisar a dinâmica mitocondrial e da autofagia e o envolvimento de proteínas desses processos na toxicidade da alfa- sinucleína. Foi observado a diminuição do tráfego mitocondrial em neurônios derivados das células SH-SY5Y que expressavam alfa-sinucleína A53T. Além disso a proteína mutante ainda levou ao aumento de espécies reativas de oxigênio, perturbação da autofagia e aumento da sinalização apoptótica. Os neurônios então foram tratados com NAP, um peptídeo neuroprotetor, que preveniu os efeitos tóxicos da alfa-sinucleína mutante. Leveduras contendo deleções nos genes Gem (Miro), Ypt53 (Rab5) e Atg8 (LC3) e expressando alfa-sinucleína dos tipos A30P e A53T, demonstraram que a toxicidade da alfa-sinucleína é dependente das disfunções na mitocôndria e na autofagia. A agregação da alfa-sinucleína A53T foi prevenida na ausência de Gem. Além disso, a toxicidade da proteína envolvendo a disfunção mitocondrial e sinalização apoptótica causada pelo estresse do ER foi dependente dos genes Gem e Atg8, respectivamente. Neurônios derivados de hiPSC de pacientes contendo a triplicação do gene da alfa-sinucleína, mostraram diminuição do transporte de mitocôndrias e do potencial de membrana da mitocôndria. Análises sobre a quantidade de vesículas lisossomais desses neurônios, demonstraram acúmulos dessas vesículas, sugerindo que a autofagia está alterada. Em um ensaio sobre a sensibilidade dos neurônios dopaminérgicos, foi observado que os neurônios contendo a alpha-sinucleína mutante são mais susceptíveis à rotenona, quando comparado com os neurônios dopaminérgicos do controle. A exposição à rotenona também causou mudanças na distribuição de mitocôndrias, sugerindo que o tráfego retrógrado da organela está alterado / Parkinson\'s disease (PD) is the most common motor neurodegenerative disease in the world. Protein aggregates containing mainly alpha-synuclein are a hallmark of disease. Mitochondria and autophagy defects have been suggested to be caused by alpha-synuclein toxicity. In this study, we investigated mitochondria and autophagy dynamics related to alpha-synuclein toxicity in neurons derived form SH-SY5Y cells, hiPSC from patients with familial PD or yeast. We found that SH-SY5Y neuroblastoma cells expressing A53T alfa- synuclein showed significantly inhibited mitochondrial trafficking. A53T alfa- synuclein also caused the highest increase in ROS production in the dysmobilized mitochondria in comparison to wild-type or A30P alfa- synuclein. Treatment with NAP, the 8 amino acid peptide identified as the active component of activity dependent neuroprotective protein (ADNP), completely annihilated the adverse effects of A53T on mitochondrial dynamics. During disruption of retrograde transport, we found disturbed autophagy and increased apoptosis signalization in neurons expressing A53T alpha-synuclein, suggest activation of the apoptosis pathway. Curiously, all groups expressing alpha-synuclein showed decreased levels of BCL-XL, revealing that mitochondria are susceptible to changes in the membrane potential in the presence of alphasynuclein. Nevertheless, treatment with NAP was effective in blocking the apoptosis pathway and restore autophagy. We created a model to study A30P and A53T alpha-synuclein toxicity related to Gem (Miro), Ypt53 (Rab5) and Atg8 (LC3) genes in Saccharomyces cerevisiae in which these genes were knocked down. We found that A30P alpha-synuclein toxicity was dependent on mitochondrial and autophagy dysfunction. A53T alpha-synuclein was more toxic than A30P alpha-synuclein, and its aggregation was dependent on Gem expression. A53T alpha-synuclein toxicity involving damaged mitochondrial and apoptotic signaling caused by ER stress was dependent on Gem and Atg8 genes, respectively. In a study involving dopaminergic neurons derived from hiPSCs from patients containing triplicated alpha-synuclein gene (SNCA3), we reported decreased mitochondrial trafficking and mitochondrial membrane potential, besides accumulation of lysosome vesicles. In a sensitivity assay, SNCA3 neurons demonstrated more susceptibility to rotenone toxicity, which alters intracellular mitochondrial distribution, impairing retrograde transport of the organelle

Submitted by isabela.moljf@hotmail.com (isabela.moljf@hotmail.com) on 2017-04-20T12:04:36Z No. of bitstreams: 1 williantassiogomesnovato.pdf: 21495870 bytes, checksum: 315183cde6b8aeeb62723ff350f4bc9e (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-04-20T13:10:32Z (GMT) No. of bitstreams: 1 williantassiogomesnovato.pdf: 21495870 bytes, checksum: 315183cde6b8aeeb62723ff350f4bc9e (MD5) / Made available in DSpace on 2017-04-20T13:10:32Z (GMT). No. of bitstreams: 1 williantassiogomesnovato.pdf: 21495870 bytes, checksum: 315183cde6b8aeeb62723ff350f4bc9e (MD5) Previous issue date: 2017-01-27 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A presente tese propõe um estudo de alvos específicos recorrentes a quimioterapia da Doença de Alzheimer. Estudos apontam que complexos de platina(II) podem ser utilizados como compostos anti-aglomeração de peptídeos β-amilóide que se compactam entre as fendas sinápticas, impedindo a efetivação do estímulo do potencial de ação, e com isso, inativação da região cerebral. Estas espécies são portadoras de sítios com potencial probabilidade de coordenação metálica, onde a ordem de reatividade de cada aminoácido foi investigada. Para tanto, foram elaborados experimentos para validação de resultados de barreira de energia livre de ativação utilizando Teoria do Funcional de Densidade (DFT) para a hidrólise do complexo pt01, Pt(ofen)Cl2 ( ΔG# 1,EXP=26,94; ΔG#1,TEO=25,54 kcal mol-1) e também para substituição nucleofílica de segunda ordem de cloreto por histidinas (HIS) ( ΔG# 1,EXP=20,73; G# 1,TEO=20,74 kcal mol-1). Após ajuste metodológico, o mesmo protocolo foi utilizado para comparar a reatividade para todos os aminoácidos (AA) que constituem a espécie β-amilóide dada por MET > LYS > HIS > GLU > ASP, e termodinamicamente é pronunciado com a comparação LYS > HIS > GLU > ASP > MET. Para verificar o perfil estrutural para agregados peptídicos e consequentemente, atribuição de um valor energético em cada evento recorrente entre os ligantes derivados de fenantrolina, batofenantrolina, curcumina e pt01, a metodologia de Docking Molecular e cálculos de Dinâmica Molecular (DM) seguidos de cálculos MM-PBSA foram necessários, dos quais foram indicativos de desestruturação da agregação inicial. Após análise estrutural dada por resultados de DM, foi possível observar a alta flexibilidade dos resíduos na região central do peptídeo quando é inserido o ligante curcumina, na forma enoláto (CUR-1). O modelo de simulação mais destacável foi 9PEP@pt01, onde é observado o completo colapso do agregado, obtendo valor mais negativo de GGBTOT = -39±7 kcal mol-1, valor este que porta 19 kcal mol-1 mais negativo comparado aos outros ligantes, e portanto, evidenciando o papel da platina como potencial fator utilizado em estágios de aglomeração inicial, mesmo sem a coordenação metálica com os sítios de MET, LYS ou HIS. / The present thesis proposes a study of specific targets recurrent to Alzheimer's disease chemotherapy. Studies show that platinum (II) complexes can be used as anti-agglomeration compounds of -amyloid peptides that are compacted between the synaptic clefts, preventing the activation of the action potential stimulus, and thus, inactivation of the brain region. These species are carriers of sites with potential probability of metallic coordination, where the order of reactivity of each amino acid was investigated. For this, experiments were developed to validate the results of activation free energy barrier using Density Functional Theory (DFT) for the hydrolysis of the pt01 complex, Pt(ofen)Cl2 ( ΔG# 1,EXP=26,94; ΔG# 1,TEO=25,54 kcal mol-1) and also for second order nucleophilic substitution of histidines (HYS) (ΔG# 1,EXP=20,73; ΔG# 1,THEO=20,74 kcal mol-1). After methodological adjustment, the protocol was used to compare the reactivity for all aminoacids (AA) which constitute the -amyloid species given by MET > LYS > HIS > GLU > ASP, and is thermodynamically pronounced with the comparison LYS > HIS > GLU > ASP > MET. To verify the structural profile for peptide aggregates and, consequently, assign an energetic value in each recurrent event among the ligands derived from phenanthroline, batofenanthroline, curcumin and pt01, the Molecular Docking methodology and Molecular Dynamics (DM) calculations followed by MM-PBSA approximation with indicative of the destructuring of the initial aggregation. After structural analysis given by DM results, it was possible to observe the high flexibility of the residues in the central region of the peptide when the ligand curcumin is inserted, in the enolate form (CUR-1). The most detachable simulation model was 9PEP @ pt01, where the complete collapse of the aggregate is observed, obtaining a more negative value of GGBTOT = -39±7 kcal mol-1. This value carries 19 kcal mol-1 plus negative compared to other ligands, and therefore, evidencing the role of platinum as a potential factor used in initial agglomeration stages, even without metallic coordination with the MET, LYS and HYS sites.

L'amyotrophie spinale infantile (SMA) est une maladie génétique autosomique récessive de l'enfant pour laquelle aucun traitement efficace n'existe. La SMA est caractérisée par la perte spécifique des motoneurones spinaux conduisant à une faiblesse musculaire sévère. Le décès des patients survient lorsque les muscles vitaux sont touchés. Cette maladie est causée par la mutation du gène Survival of Motor Neuron 1 (Smn1) conduisant à une diminution importante de l’expression de la protéine Survival of Motor Neuron (SMN). Tous les patients possèdent un ou plusieurs gènes copie de Smn1, le gène Smn2. Ces copies modulent la sévérité de la maladie en produisant une faible quantité de transcrits SMN complets, en particulier possédant l’exon 7, un exon alternatif qui code pour un domaine important pour que la protéine SMN soit fonctionnelle et stable. Des résultats récents, obtenus au laboratoire, indiquent que l'exercice physique retarde la mort des motoneurones, conduit à une augmentation du taux de maturation postnatale des unités motrices et déclenche l’expression du gène Smn2 chez des souris mimant la SMA de type II. Les premières données moléculaires suggèrent que les effets de l'exercice physique pourraient être relayés par la signalisation dépendante 1) des récepteurs au NMDA (Biondi et coll., J Neurosci, 2008) et/ou 2) du récepteur à IGF-1. Dans notre étude, nous avons d’abord testé les effets de l’activation directe des récepteurs au NMDA (NMDAR) dans un contexte de SMA. Nous montrons qu’une activation adéquate de ces récepteurs dans plusieurs modèles souris mimant les SMA sévères accélère la maturation postnatale des unités motrices, limite l'apoptose dans la moelle épinière et active l’expression du gène Smn2 favorisant l'expression de la protéine SMN. Ces effets bénéfiques sont dépendants du niveau d’activation des NMDARs et suggèrent que l'accélération de la maturation postnatale des unités motrices, induite par le NMDA, est indépendante du niveau d’expression de la protéine SMN. De manière importante, l’activation pharmacologique des NMDARs augmente fortement la durée de vie de deux modèles différents de souris mimant la SMA de type sévère. L'analyse des cascades de signalisation intracellulaire a révélé une altération inattendue des profils d’activation des voies de signalisation ERK et AKT/CREB, qui se rééquilibrent quand les NMDARs sont activés (Branchu et coll., J Neurosci, 2010).Comme la kinase ERK est constitutivement suractivée dans la moelle épinière des souris mimant la SMA, nous avons ensuite examiné son rôle potentiel dans la régulation de l'expression des gènes Smn2. Nous avons démontré que l'inhibition pharmacologique de la voie de signalisation MEK/ERK/Elk-1, notamment avec un médicament anti-cancéreux actuellement en essai clinique de phase 2, est bénéfique pour les souris mimant la SMA de type I. Nous avons identifié une relation croisée entre les voies de signalisation ERK et AKT impliquant la modulation, calcium-dépendante, de l'activité CaMKII. Ainsi, l'inhibition pharmacologique de ERK durant la phase symptomatique de la maladie chez ces souris, entraîne l'activation de la voie CaMKII/AKT/CREB et conduit à une augmentation significative de l’expression de la protéine SMN dans les motoneurones suite à une augmentation de la transcription du gène Smn2. Ces modifications sont corrélées avec une augmentation remarquable de la durée de vie et de la mobilité des souris et une neuroprotection des motoneurones spinaux. De plus, l’inhibition de ERK dans des cellules musculaires différenciées provenant de patients atteints de SMA de type II induit également une augmentation de l’activité de la voie AKT/CREB et de l’expression de SMN (Branchu et coll., J Neurosci, en révision positive). Enfin, nous avons montré que l'exercice physique est capable de diminuer l'expression du récepteur à l'IGF-1 (IGF-1R), qui est surexprimé dans la moelle épinière des souris mimant la SMA sévère... / Spinal muscular atrophy (SMA) is a severe autosomal recessive disease in childhood for which no efficient therapy is currently available. SMA is characterized by the specific loss of spinal motor neurons leading to a severe muscular weakness and death when vital muscles are affected. This disease is caused by mutation of the survival of motor neuron 1 (Smn1) gene leading to a deficiency of the Survival of Motor Neuron (SMN) protein expression. All patients retain one or more copies of the Smn2 gene, which modulates the disease severity by allowing a small amount of full-length SMN transcripts and stable SMN protein to be produced. Recent results in our laboratory indicate that physical exercise delays motor neuron death, leads to an increase in the motor-units postnatal maturation rate and trigger Smn2 gene expression in motor neurons. Furthermore, on the one hand, exercise is capable of specifically enhancing the expression of the gene encoding NR2A, the major activating subunit of the NMDA receptor in motor neurons. This subunit is known to be dramatically down-regulated in the spinal cord of severe SMA-like mice. Accordingly, inhibiting NMDA-receptor activity abolishes the exercise-induced effects on muscle development, motor neuron protection and life span gain (Biondi et al., J Neurosci, 2008). Thus, we tried to restore NMDA-receptor function as a therapeutic approach to SMA treatment. We demonstrated that an adequate NMDA receptor activation in severe SMA-like mouse model significantly accelerated motor-unit postnatal maturation, counteracted apoptosis in the spinal cord, and induced a marked increase in SMN expression resulting from a modification of Smn2 gene transcription pattern. These beneficial effects are dependent on the level of NMDA receptor activation since a treatment with high doses of NMDA led to an acceleration of the motor unit maturation but favored the apoptotic process and decreased SMN expression. Thus, these results suggest that the NMDA-induced acceleration of motor-unit postnatal maturation occurred independently of SMN. The NMDA receptor activating treatment strongly extended the life span in two different severe SMA-like mouse models. The analysis of the intracellular signaling cascades that lay downstream the activated NMDA receptor revealed an unexpected competition between the MEK/ERK/Elk-1 and the AKT/CREB signaling pathways for Smn2 gene regulation. Actually, the reactivation of the AKT/CREB pathway, thought calcium influx and the phosphorylation of CaMKII, opposed to MEK/ERK/Elk-1 inhibition, induces an enhanced SMN expression (Branchu et al., J Neurosci, 2010). On the other hand, exercise is capable of strongly decreasing the expression of IGF-1 receptor (IGF-1R); which is over-expressed in the spinal cord of severe SMA-like mice. We report that this reduction is also correlated with a reactivation of the AKT/CREB pathway and a MEK/ERK/Elk-1 inhibition. Therefore we generated an IGF-1R+/- SMA-like mouse model to investigate the functional link between IGF-1R expression level and the intracellular signaling pathway triggered in SMA spinal cord. We provided the first evidence that reducing the IGF-1R expression level is neuroprotective for SMA motor neurons, accelerates motor-unit postnatal maturation and leads to a remarkable increase in SMN expression and lifespan. The analysis of the intracellular signaling cascades revealed the same competition for Smn2 gene regulation. However, the activation of AKT/CREB is calcium-independent. In addition, we showed a drastic reduction of STAT3 phosphorylation and SOCS-1 and -3 expressions, which are over-expressed in SMA spinal cord and known to positively modulate ERK phosphorylation and negatively AKT (Data not published). Taken together all these data suggest new perspectives to therapeutic strategy, based on specific pharmacological correction, for SMA...

Ces travaux de recherche s’inscrivent dans le cadre du développement de nouvelles surfaces biocompatibles capables de contrôler l’adhésion d’agents pathogènes responsables de maladies neurodégénératives telles que les maladies de Creutzfeld Jacob, Alzheimer, Parkinson et Lewis. Deux axes de recherche ont été privilégiés. Notre approche se focalise en amont des dosages sur l’amélioration des procédures de stockage des prélèvements biologiques réalisés dans des tubes de type Eppendorf. Ces tubes en polypropylène induisent une perte du matériel génétique de plus de 70% accentuant la faible concentration en agent pathogène pour la détection immunoenzymatique. Dans le but de réduire les phénomènes indésirables d’adhésion des agents pathogènes à la surface des supports de stockage, deux voies de traitement ont été envisagées dans ce travail de thèse. La première consiste à modifier la surface du tube Eppendorf en une étape par décharge plasma fluoré, la seconde à créer de nouvelles surfaces hydrophiles en deux étapes couplant la technique des plasmas froids au greffage de polymères, les agents pathogènes pouvant être hydrophiles ou hydrophobes. Avec cette dernière technique, une voie originale a été abordée de part l’utilisation de solutions de greffage complexes composées à la fois de polymères et de molécules tensioactives. Les surfaces ainsi obtenues présentent une nano-structuration. Toutes les étapes de modification de la surface interne des tubes de stockage ont été caractérisées. Ces surfaces sont alors décrites selon leur caractère hydrophile ou hydrophobe grâce à la détermination des énergies de surface polaire et apolaire, selon leur charge de surface obtenue par mesure du potentiel d’écoulement, selon leur composition chimique déterminée par spectroscopie à photoélectrons X (XPS) et enfin selon leur topographie et leur rugosité relevées par microscopie à force atomique (AFM). Les interactions entre les groupements fonctionnels ainsi obtenus à la surface des tubes de stockage après les divers traitements et les protéines antigéniques considérées ont été interprétées en se référant aux différents modèles de l’adhésion pour des gammes de pH proches des protocoles biologiques usuels. Afin de s’assurer que ces nouvelles surfaces permettent bien une diminution de l’adhésion des agents infectieux sur la paroi interne des tubes de polypropylène, des analyses immunoenzymatiques ont été réalisées au sein des centres hospitaliers participant au projet STREP NEUROSCREEN n° LSHB-CT 2006-03 7719 (CRPP de Liège et CHU de Lyon). Ces analyses ont permis de montrer que la modification des surfaces entraîne une diminution de l’absorption des agents pathogènes jusqu'à 100% permettant ainsi une meilleure détection. / The research work presented in this thesis considers the development of newµbiocompatible surfaces that are able to control the adhesion of specific proteins responsible for the development of neurodegenerative diseases such as Creutzfeldt–Jakob, Alzheimer, Parkinson and Lewis body disease. Our approach was focused on problems prior to the detection step, which were never considered before, particularly on the improvement of Eppendorf tubes that are used for the storage of body fluids like cerebrospinal fluid and blood. Namely these tubes made of polypropylene induce the depletion of biological material, in some cases even over 70%, resulting in a low concentration of these proteins for the further immunoenzymatic detection. With the purpose to reduce the adhesion of specific proteins on the surface of supports, two courses of treatments were anticipated. The first one consists of surface modification by highly reactive fluorine plasma treatment and the second one incorporates development of new hydrophilic surfaces by coupling two techniques, plasma activation and subsequent grafting of polymer materials. With the latter approach, an original way of surface modification has been attained by using complex solutions of polymers and surfactants that permits controlled configuration of nanostructured surfaces. All steps of surface modifications were well characterized by different physicochemical methods. The surface hydrophilic/hydrophobic character was determined by measurements of polar and apolar surface energy, surface charge by magnitude of zeta potential, surface chemistry was evaluated by x-ray photoelectron spectroscopy (XPS), while the surface roughness and topography were monitored by atomic force microscopy (AFM). The interactions between functional groups of treated supports and proteins were interpreted referring to different models of adhesion established for a range of pH values close to the classical biological protocols. Finally, in order to validate that the new surfaces are able to prevent or decrease the adhesion of neurodegenerative agents on the surfaces of Eppendorf tubes, the immunoenzymatic analyses were carried out in hospital centres of partners that were participating to the project STREP NEUROSREEN n° LSHB-CT-2006-03 7719 (Centre de Recherche sur les Protéines Prion; Liege (ULG), Hospices Civils de Lyon (CHUL) and Lancaster University (L-UNI)). These analyses showed that the treatments led to a decrease of antigen adsorption up to 100%, enabling (allowing) better detection of pathogenic agents.

Typically, a Parkinson’s disease (PD) patient would display instances of tremor and bradykinesia (slowness of movement) at an early stage of the disease and later develop gait disturbances and postural instability. So, it is important to measure the tremor occurrences in subjects to detect the onset of PD. Also, it is equally essential to monitor the gait impairments that the patient displays, as the order at which the PD symptoms appear in subjects vary from one to another. The primary goal of this thesis is to develop a monitoring system for PD patients using wearable sensors. To achieve that objective, our work focused first on identifying the most significant features that would best distinguish between PD and normal healthy subjects. Here, the various gait and tremor features were extracted from the raw data collected from the wearable sensors and further analyzed using statistical analysis and pattern classification techniques to pick the most significant features. In statistical analysis, the analysis of variance (ANOVA) test was conducted to differentiate the subjects based on the values of the mean. Further, pattern classification was carried out using the Linear Discriminant Analysis (LDA) algorithm. The analysis of our results shows that the features of heel force, step distance, stance and swing phases contributed more significantly to achieving a better classification between a PD and a normal subject, in comparison with other features. Moreover, the tremor analysis based on the frequency-domain characteristics of the signal including amplitude, power distribution, frequency dispersion, and median frequency was carried out to identify PD tremor from different types of artifacts.

Les maladies neurodégénaratives (MNDs) sont les troubles neurologiques les plus fréquents chez l’homme et touchent des millions de personnes à travers le monde. Elles affectent le fonctionnement du système nerveux de façon chronique et progressive et conduisent souvent au décès du malade. L’évolution de ces maladies est très variable et les traitements disponibles actuellement ne permettent pas de modifier leur progression mais seulement d’atténuer les manifestations symptomatiques.Les récepteurs σ1 correspondent à une classe unique de récepteurs transmembranaires du réticulum endoplasmique. Exprimés au niveau du SNC et en particulier dans les neurones, les lymphocytes et les oligodendrocytes, ces récepteurs sont connus pour être impliqués dans la régulation de nombreux neurotransmetteurs. Même si les mécanismes de transduction après leur activation ne sont pas complètement élucidés, de plus en plus d’études mettent en évidence le potentiel thérapeutique de ces récepteurs. En effet, depuis leur découverte, les récepteurs σ1 ont été impliqués dans de nombreuses pathologies dont des MNDs.Ces travaux de thèse s’inscrivent donc dans ce contexte. Le projet consistait à concevoir, synthétiser et évaluer de nouveaux ligands σ1 pour une utilisation en neuroprotection. Les dérivés tétrahydroquinolin-hydantoïnes préalablement conçus au laboratoire, ont montré des affinités nanomolaires envers la protéine σ1, une bonne sélectivité, une faible cytotoxicité et des propriétés ADME compatibles avec un développement thérapeutique. Evalués dans différents modèles, ces composés ont montrés des propriétés anti-inflammatoires associées à une action neuroprotective. Cependant, bien que les Tic-hydantoïnes soient des composés chimiquement stables, ils ont montré une faible stabilité métabolique. Trois nouvelles familles de composés ont donc été conçues et synthétisées afin de pallier à ces problèmes. Leurs affinités, sélectivités, cytotoxicités et propriétés ADME ont été évaluées. Des tests comportementaux ont également été réalisés sur les composés les plus intéressants afin de déterminer leur profil agoniste ou antagoniste. Finalement, le meilleur candidat, évalué dans un modèle in vivo de sclérose en plaques, a montré des propriétés neuroprotectrices intéréssantes. / Neurodegenerative diseases are the most common neurological disorders in humans, affecting millions of people worldwide. They affect the nervous systems in chronic and progressive way and often lead to the death of the patient. The evolution of these diseases is highly variable and currently available treatments do not alter their growth but only moderate symptomatic manifestations.Sigma-1 receptors represent a structurally unique class of transmembrane receptors of the endoplasmic reticulum. Expressed in the central nervous system and especially in neurons, lymphocytes and oligodendrocytes, these receptors are known to be involved in the regulation of numerous neurotransmitters. Even if the signal transduction pathway after activation of σ1 receptors is not completely understood, more and more evidences suggest that they represent a potential therapeutic target in many diseases. Indeed, since their discovery, the σ1 receptors have been implicated in various pathologies including neurodegenerative disorders. Thus, it is in this context that our interest is focused on the conception and synthesis of novel σ1 receptors ligands for the treatment of neurodegenerative diseases. Fused and optimized tetrahydroquinoline-hydantoin derivatives designed in our laboratory showed nanomolar σ1 affinity, σ2 /σ1 selectivity, very low cytotoxicity and ADME properties compatible with therapeutic development. Evaluated in different models, these compounds showed an anti-inflammatory activity associated with a neuroprotective action. However, while the Tic-Hydantoin derivatives are chemically stable, they showed a low metabolic stability. Thus, three novel families of compounds were synthesized in order to compensate for these problems. Their affinities, selectivities, cytotoxicities and their ADME properties were evaluated. Behavioural testing was carried out on the most interesting compounds to determine the agonist or antagonist profil. Finally, evaluated in in vivo model of multiple sclerosis, the best compound showed interesting neuroprotective properties.

Alzheimer’s disease is a debilitating, progressive neurodegenerative disorder in the elderly, characterized by severe loss of memory and higher cognitive functions. In the hundred years since its discovery, Alzheimer’s disease (AD) has traversed from the status of a ‘rare neurological oddity’ to one of the greatest challenges faced by healthcare and medicine in this millennium. A reported 44 million people currently suffer from AD but only 1 in 4 people have been diagnosed. Although AD has been an area of intense research for almost 50 years now, most studies have focused on the end stage disease. Years of study on the pathological cause underlying AD; have conclusively shown that the accumulation of the sticky peptide, Aβ, is one of the major triggers of AD pathogenesis. However, after the initial Aβ trigger, multiple processes contribute to disease progression, so that by the time a patient is diagnosed on the basis of overt behavioral phenotypes, it is difficult to understand and differentiate between the causative mechanisms and the consequential effects of the disease. It is, perhaps, because of this, that we are still struggling to find therapies for AD which will stop or at the very least slow the course of the disease. In the 2015 report on AD, issued by the Alzheimer’s association, much emphasis has been placed on the early diagnosis of AD and the revision of the diagnostic criteria for AD. According to the new guidelines proposed in 2011, AD has been divided into three stages where the first stage occurs before the appearance of overt behavioral symptoms such as memory loss, whereas by the 1984 guidelines, cognitive disabilities must have already occurred for diagnoses of AD. This proposed preclinical stage of AD has been defined, reflecting the current belief that AD pathogenesis begins almost 20 years before the occurrence of behavioral dysfunction. However, no diagnostic criteria are currently available to establish this stage. Hence, there is a need to understand the early pathogenic mechanisms of AD, which will yield early therapeutic targets as well as early diagnostic markers of AD. One of the earliest documented events in AD pathogenesis is synaptic dysfunction, which is later manifested as loss of dendritic spines. Deficits in long term potentiation (LTP) has been demonstrated in Aβ exposed hippocampal slices as well as in mouse models of AD, much before the appearance of pathological hallmarks such as plaques and tangles as well as overt behavioral phenotypes. While these and other studies indicate clearly that elevated levels of soluble Aβ peptide leads to impairment of synaptic function, the underlying molecular mechanisms are yet to be elucidated. One of the purported mediators of Aβ induced dysfunction is oxidative stress. The Aβ peptide, especially the Aβ42, is a self aggregating peptide with a propensity to form peptidyl radicals. Interaction of the peptidyl radicals with biomolecules leads to the generation of more free radical species via cascading chain reactions. Additionally, Aβ peptide has also been demonstrated to have synaptotoxic effects via its effect on NMDA receptors and calcium influx leading to deregulated reactive oxygen species (ROS) production as well as excitotoxicity. Hence, with a view to understanding Aβ mediated early synaptic dysfunction in AD, we studied early signaling changes in the synaptosomes derived from the cortex of APP/PS1 mice model of AD at various ages. The APP/PS1 model contains a mouse/human chimeric APP gene bearing the KM670/671NL Swedish mutation and the human PS1 gene with an exon 9 deletion. These mice exhibit behavioral deficits from 7 months of age while plaque deposition and gliosis become apparent by 9 months of age. We chose to study both pre-symptomatic ages (1 and 3 months old) as well as post symptomatic (9 months old) mice. Post nuclear supernatant (PNS) as well as synaptosomes were isolated from the cortex of APP/PS1 and age matched control mice. We assayed the levels of reactive oxygen species (ROS) in the PNS and the synaptosomes of post symptomatic 9 months old APP/PS1 mice and age matched controls. In contrast to reports of enhanced oxidative stress markers in the brains of AD patients, we did not find any increase in the levels of ROS in the PNS of post symptomatic APP/PS1 mice compared to age matched controls. However, synaptosomes from the cortex of these animals exhibited a significant increase in ROS levels in APP/PS1 mice compared to controls. We further found that there was significant increase in the ROS levels in synaptosomes, but not PNS, of very young asymptomatic 1 and 3 months old APP/PS1 mice. This is a first demonstration of synapse specific increase in oxidative stress in AD mice, as young as 1 month of age, indicating that disease specific mechanisms operate at the synapse much before the appearance of any overt cellular or behavioral symptoms. The increase in synaptic ROS levels correlated with a small but significant increase in the levels of Aβ42 in the brains of APP/PS1 mice compared to controls. We also found a concurrent change in the redox status of the cytoskeletal protein, actin, at the synapse. As early as 1 month of age, there was a significant decrease in the protein level of reduced actin indicating that there is an increase in the level of oxidized actin at the synapse. This loss of reduced actin was specific to the fibrillar pool of actin while no significant change was observed in the redox status of the monomeric globular pool of actin. Oxidation of actin has been demonstrated to lead to its depolymerization. Concurrently, we found a significant loss of fibrillar actin in the synaptosomes of APP/PS1 mice. Actin is the major cytoskeletal protein at the synapse. Changes in the globular to fibrillar actin ratio at the synapse at early pre-symptomatic ages in APP/PS1 mice will likely lead to structural and consequent functional changes at the synapse. This could potentially be one of the triggers of synaptic dysfunction in AD. Furthermore, changes in the Akt-mTOR signaling pathway was also observed in the synaptosomes of 1 month old APP/PS1 mice, which is sustained at 9 months. There was a significant loss of the mTOR-pS6K-4EBP1 axis in the synaptosomes, but not PNS, of APP/PS1 mice. We found that loss of Akt signaling, as evinced by loss of Akt phosphorylation, Akt kinase activity as well as loss of phosphorylation of downstream effector GSK3β, potentially underlies the loss of mTOR signaling. Further, the loss of Akt signaling is mediated by synapse specific redox modification of Akt and consequent interaction with the protein phosphatase PP2a. Loss of the Akt-mTOR signaling at the synapse is indicative of deficits in local protein translation. Loss of this essential synaptic function, which plays critical roles in synapse maintenance as well as synaptic plasticity during learning and memory, at an early age, will have long ranging impact on synaptic function such as long term potentiation (LTP) in APP/PS1 mice. Our study is the first demonstration of oxidative stress and consequent signaling changes which occur specifically at the synapse of very young 1 month old APP/PS1 mice. These changes occur much before the appearance of overt phenotype such as plaque deposition and behavioral dysfunction but sustain till the appearance of classical pathological hallmarks. Hence, the study demonstrates that disease progression starts much before previously thought and provides us a critical time window during which therapeutic strategies designed to delay or stop these changes might change the course of AD.

Les protéoformes désignent toutes les formes sous lesquelles une protéine peut être présente. Cela inclut les formes portant des modifications post-traductionnelles, les isoformes et les formes résultant d’épissages alternatifs. Ces modifications peuvent influer sur la fonction d’une protéine, d’où l’intérêt de développer des méthodes sensibles, spécifiques et robustes de quantification de protéoformes pour une meilleure compréhension de mécanismes pathologiques ou la recherche de biomarqueurs. L’objectif de ce travail a été d’exploiter les avantages de la spectrométrie de masse à haute résolution pour la caractérisation et la quantification de protéoformes de protéines associées à des maladies neurodégénératives. Nous nous sommes principalement intéressés à deux protéines, la C9ORF72 et l’alpha-synucléine. Dans un premier temps, une méthode de quantification des deux isoformes de la C9ORF72 a été développée et appliquée à une cohorte de 43 cerveaux humains comprenant des cas de démences fronto-temporale (DFT) avec ou sans mutation C9ORF72. Les résultats obtenus montrent pour la première fois par spectrométrie de masse une diminution d’environ 50% de l’isoforme longue de la C9ORF72 en présence de la mutation. Dans une seconde étape, nous avons élargi l’analyse à la quantification multiplexe de 49 protéines cérébrales potentiellement impliquées dans les DFT. En parallèle, nous nous sommes intéressés aux formes tronquées de l’alpha-synucléine. Leur quantification a été réalisée par une approche top-down dans des tissus cérébraux et une approche par bottom-up dans le liquide céphalorachidien (LCR). Enfin, l’analyse a été étendue à la quantification multiplexe de l’alpha-synucléine et de la protéine tau du LCR. / Proteoforms describe the complexity of protein forms. This includes forms with post-translational modifications, isoforms and forms resulting from alternative splicing. These modifications can influence the function of a protein, hence the interest in developing sensitive, specific and robust methods for the quantification of proteoforms for a better understanding of pathological mechanisms or biomarkers discovery. The objective of this work was to take advantage of high-resolution mass spectrometry for the characterization and quantification of proteoforms associated with neurodegenerative diseases. We mainly focused on two proteins, C9ORF72 and alpha-synuclein. First, a method for quantifying the two C9ORF72 isoforms was developed and applied to a cohort of 43 human brains including cases of frontotemporal dementia (FTD) with or without C9ORF72 mutation. The results obtained show for the first time by mass spectrometry a decrease of about 50% of the long isoform of C9ORF72 in the presence of the mutation. Then, we extended the analysis to the multiplex quantification of 49 brain proteins potentially involved in FTD. In parallel, we focused on the truncated forms of alpha-synuclein. Their quantification was performed by a top-down approach in brain tissue and a bottom-up approach in cerebrospinal fluid (CSF). Finally, the analysis was extended to the multiplex quantification of alpha-synuclein and tau protein in CSF.

Microsatellites, or simple tandem repeat sequences, occur naturally in the human genome and have important roles in genome evolution and function. However, the expansion of microsatellites is associated with over two dozen neurological diseases. A common denominator among the majority of these disorders is the expression of expanded tandem repeat-containing RNA, referred to as xtrRNA, which can mediate molecular disease pathology in multiple ways. Frontotemporal Dementia (FTD) and Amyotrophic Lateral Sclerosis (ALS) are two fatal neurodegenerative diseases with significant clinical, neurological and genetic overlap thus referred to as C9FTD/ALS. Currently, gaps in the study of the underlying disease mechanisms persist, which can aid in the identification of promising therapeutic approaches. Access to simple models of neurological repeat expansion disease is critical for investigating biochemical mechanisms and for early therapeutic discovery. To better understand the molecular pathology of C9FTD/ALS repeat expansion disorder, we cloned GGGGCC repeats, which are the leading genetic cause of C9FTD/ALS. We employed a recursive directional ligation (RDL) technique to build multiple GGGGCC repeat-containing vectors and validated the cloning to facilitate step-by-step characterization of disease mechanisms at the cellular and molecular level using these vectors. In this study, we also differentiated C9FTD/ALS patient-derived induced pluripotent stem cells (iPSCs) to neural stem cells (NSCs) to be used as model systems. The use of iPSCs and NSCs to reveal important insights into the pathogenic mechanisms and to generate multiple neural cell types presents an excellent opportunity for researchers to model neurodegenerative diseases for cell therapy and drug discovery. We further investigated potential nuclear export mechanisms for C9FTD/ALS xtrRNA. The nuclear export mechanisms of xtrRNA in C9FTD/ALS are not well studied. ASOs and siRNAs were employed to knockdown genes of interest to study their involvement in the nuclear export of xtrRNA. We saw promising results on knockdown of TorsinA involved in nuclear export of xtrRNAs, corroborated by a substantial increase in the average number of xtrRNA foci in the nucleus. Our initial study provides evidence that TOR1A may be involved in the nuclear export of aberrant C9FTD/ALS repeat-containing RNAs. Due to the lack of reliable and robust assays to detect RAN translation products, the effect of the knockdown of TorsinA in these cell lines still remains to be explored. But the current study lays the groundwork for a deeper understanding of the less-studied nuclear export mechanisms in C9FTD/ALS and could reveal new therapeutic approaches to selectively block the nuclear export of xtrRNA through the use of RNAi and ASOs. The insights gained from this study will help us understand future events in the xtrRNA life cycle such as repeat translation mechanisms.

The neuronal ceroid lipofuscinoses (NCLs) are a family of neurodegenerative diseases predominantly affecting infants and children, which in some cases can present into adulthood. There are fourteen genes comprising the 13 known subtypes of NCLs (CLN1-CLN8, CLN10-CLN14; CLN9 has been reclassified as CLN4). The NCL diseases share common molecular and clinical features, including cellular accumulation of autofluorescent storage material, characteristic histological findings (curvilinear inclusions, fingerprint profiles, and granular osmophilic deposits), markedly low brain weight, seizures, blindness, motor dysfunction and behavioral disabilities. Though the functions of the CLN proteins are not fully understood, they are mainly localized to the lysosomal compartment and autophagic pathway. Previous works have focused on understanding the individual functions of the CLN proteins. However, there is little research examining the interactions between CLN proteins and their involvement in neurogenesis. The CLN proteins also show involvement in various other signaling pathways, notably the mTOR and p53 pathways, and may therefore have implication as important signaling molecules during development and aging. In this thesis, I outline a variety of interactions between CLN proteins, as well as their role in lysosome formation and autophagy. I further examine the involvement of these proteins in lysosomes of microglia, and potential functions of microglia during neurogenesis in childhood and adulthood. I hypothesize that the CLN proteins are likely involved in a common pathway which is highly regulated during neurogenesis through microglial release of pro-inflammatory molecules. Though these diseases are incurable, enzyme replacement shows promise as a treatment for NCL; cerliponase alpha (BioMarin Pharmaceuticals) is the first and only FDA-approved enzyme replacement treatment for CLN2 disease. Future in-depth investigation of protein-protein interactions as well as their involvement in signaling pathways during development is necessary in order to find a cure for these devastating diseases.