Le récepteur 5-HT6 de la sérotonine, un des derniers récepteurs de la sérotonine à avoir été découvert, est une des cibles les plus prometteuses pour traiter les déficits cognitifs de la schizophrénie et de la maladie d’Alzheimer. Les antagonistes 5-HT6 exercent des effets pro-cognitifs dans de nombreux paradigmes expérimentaux de cognition chez les rongeurs et plusieurs d’entre eux sont en développement clinique (phase III) dans la schizophrénie et la maladie d’Alzheimer. Exclusivement exprimé dans le système nerveux central, le récepteur 5-HT6 est présent dès les phases précoces du développement neural et est impliqué dans différents processus neuro-développementaux. Plusieurs études ont ainsi démontré que le récepteur jouait un rôle clé dans la migration des neurones (interneurones et neurones pyramidaux) du cortex cérébral (Riccio et al. Mol Psychiatry 14(3):280-90, 2009 ; Transl Psychiatry 11;1:e47, 2011 ; Jacobshagen et al. Development in revision). Grâce à un crible interactomique, notre équipe a récemment identifié un réseau de protéines recrutées par le domaine carboxy-terminal du récepteur, comprenant la cyclin-dependent kinase (Cdk)5 et certains de ses substrats et connues pour leur implication dans la migration neuronale, la pousse neuritique et la synaptogénèse. Nous avons également démontré que le récepteur stimulait la pousse neuritique de façon agoniste-indépendante par un mécanisme impliquant la phosphorylation du récepteur par Cdk5 et l’activation de la Rho GTPase Cdc42 (Duhr et al. Nature Chem. Biol., en révision). Cette étude a mis pour la première fois en évidence une activation constitutive d’un récepteur couplé aux protéines G dépendant de sa phosphorylation par une kinase associée. Des études préliminaires réalisées par l’équipe indiquent également que l’activation du récepteur 5-HT6 induit une diminution du nombre d’épines dendritiques et une modification de leur morphologie dans des cultures primaires de neurones d’hippocampe. Le projet de thèse aura pour objectif la caractérisation des mécanismes moléculaires impliqués dans cet effet. Une attention particulière sera portée sur le rôle de Cdk5 et de son substrat WAVE1, une protéine induisant la formation des épines dendritiques grâce à sa capacité à activer le complexe Arp2/3 (également identifié dans l’interactome du récepteur 5-HT6) et à promouvoir la polymérisation de l’actine. La phosphorylation de WAVE1 par Cdk5 inhibant son activité et la formation des épines, ce mécanisme pourrait être à l’origine de la diminution du nombre d’épines induite par le récepteur 5-HT6. Ces études seront réalisées in vitro, sur des cultures primaires de neurones d’hippocampe et in vivo, en utilisant un modèle (en cours de génération) de souris knock-in exprimant le récepteur 5-HT6 fusionné à une étiquette GFP. Grâce à ce modèle, un crible interactomique sera également réalisé afin d’identifier de nouveaux partenaires du récepteur potentiellement impliqués dans la différentiation neuronale dans un contexte tissulaire authentique. Ce projet sera réalisé à l’Institut de Génomique Fonctionnelle (IGF) au sein de l’équipe « Neuroprotéomique et signalisation des maladies neurologiques et psychiatriques » sous la co-direction de Philippe Marin et Séverine Chaumont-Dubel. Il permettra de caractériser de nouveaux substrats cellulaires potentiellement impliqués dans les déficits cognitifs de la schizophrénie de plus en plus considérée comme une pathologie du développement et d’identifier de nouvelles cibles pour le traitement précoce de ces déficits particulièrement invalidants et insuffisamment pris en en charge par l’arsenal antipsychotique existant. / The serotonin 5-HT6 receptor, one of the most recently cloned serotonin receptors, is a promising target for the treatment of cognitive deficits of both schizophrenia and Alzheimer’s disease. 5-HT6 receptor blockade by antagonists exerts pro-cognitive effects in a wide range of models of cognitive impairment in rodents and some of them are in phase III of clinical trials in schizophrenia and Alzheimer’s disease. The 5-HT6 receptor is exclusively expressed in the central nervous system, where it is detected at early phases of brain development. Studies have shown that 5-HT6 receptors have a key influence upon migration of both pyramidal neurons and interneurons of the cerebral cortex (Riccio et al. Mol Psychiatry 14(3):280-90, 2009 ; Transl Psychiatry 11;1:e47, 2011; Jacobshagen et al. Development, in revision). Using a proteomic strategy, our team recently identified a network of proteins interacting with the carboxy-terminal domain of the receptor. These include Cyclin-dependent kinase (Cdk)5 and some of its substrates, which are known to control neuro-developmental processes such as neuronal migration, neurite growth and dendritic spine morphogenesis. We have also demonstrated that the expression of the 5-HT6 receptor elicits neurite growth in an agonist-independent manner through a mechanism involving receptor phosphorylation at a serine residue by associated Cdk5 and engagement of the Rho GTPase Cdc42 (Duhr et al. Nature Chem. Biol., in revision). These studies show for the first time a constitutive activation of a G protein-coupled receptor mediated by its phosphorylation by an associated protein kinase. Preliminary experiments performed by the team also revealed that 5-HT6 receptors activation decreases the number of dendritic spines and modify spine morphology in hippocampal neurons in primary culture. This thesis project aims at characterizing the signalling mechanisms underlying the control of dendritic spine morphogenesis by the 5-HT6 receptors. Particular attention will be paid to Cdk5 and its substrate WAVE1, a protein known to induce neurite growth via the activation of the Arp2/3 complex (also identified in the 5-HT6 receptor interactome), which promotes actin polymerization. As phosphorylation of WAVE1 by Cdk5 inhibits its activity, we hypothesize that Cdk5-elicited phosphorylation of WAVE1 in the receptor-associated complex might underlies its control of spine morphogenesis. This project will combine in vitro studies performed on primary cultured hippocampal neurons and in vivo studies using transgenic mice expressing GFP tagged 5-HT6 receptors (this mouse line is currently being generated). We will also take advantage of this model to perform a novel interactomics screen to identify in an authentic tissue context novel receptor partners potentially involved in dendritic spine formation. This project should reveal novel cellular targets for the alleviation of the currently untreated and strongly debilitating cognitive deficits of schizophrenia, which are thought to result from abnormalities of brain development. It will be realized at the Institute of Functional Genomics in the “Neuroproteomics and signaling of neurodegenerative and psychiatric disorders” team under the supervision of Philippe Marin and Séverine Chaumont-Dubel.

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A presente pesquisa tem como objetivo investigar o percurso histórico da classificação psiquiátrica Transtorno do Espectro Autista (TEA). Os deslizamentos taxonômicos desde sua primeira forma, o Autismo Precoce, nas cinco versões de um dos principais sistemas de classificação psiquiátricas utilizados no Brasil, o Manual Diagnóstico e Estatístico de Transtornos Mentais (DSM), trouxeram impactos socioeconômicos, éticos e políticos que merecem ser observados com cautela. Essa nova forma de diagnosticar o autismo não se mostrou nada sutil, uma vez que se trata de uma categoria nosográfica muito abrangente e que trouxe consigo uma epidemia de diagnósticos de TEA. Para alcançar esse objetivo, foram utilizadas as pesquisas bibliográfica e documental. Na discussão final, propomos, com base na investigação realizada, um olhar crítico para a comodificação da psicopatologia denominada TEA / The purpose of this research is to investigate the historical path of the Autism Spectrum Disorder (ASD) psychiatric classification. The nomenclature changes since its initial form, Autism Infantile, contained in the five versions of one of the main psychiatric classification systems used in Brazil, the Diagnostic and Statistical Manual of Mental Disorders (DSM) have generated socio-economic, ethical and political impacts that need be carefully analyzed. This new method of diagnosing autism has proven to be not subtle at all, since it pertains to a very comprehensive nosographic category and which gave rise to an epidemic of ASD diagnoses. In order to meet such purpose, we used bibliographic and documentary researches. In the final discussion we propose, from the investigation conducted, a critical analysis on the commodification of the psychopathology referred to as ASD

O Transtorno do Espectro Autista (TEA) é um transtorno neuropsiquiátrico grave caracterizado por comprometimento da capacidade de interação social e comunicação e pela presença de interesses, atividades e comportamentos repetitivos e restritos. O TEA apresenta alta heterogeneidade genética e pode ser enquadrado em diferentes modelos de herança, o que torna difícil apontar os fatores genéticos associados ao transtorno e compreender de que forma eles interagem e ocasionam, em última instância, sua manifestação clínica. Ainda, fenômenos como penetrância incompleta e discordância entre gêmeos monozigóticos são frequentemente observados em famílias com indivíduos afetados, tornando ainda mais complexo o entendimento do envolvimento de cada um dos fatores genéticos na etiologia do TEA. Uma forma de contornar esses problemas é a utilização de abordagens transcriptômicas no estudo desse transtorno. Nesse contexto, a busca por variantes patogênicas deixa de ser o principal foco do estudo e a atenção volta-se para a investigação de vias de sinalização e processos biológicos que estejam desregulados durante o processo de diferenciação neuronal e que sejam compartilhados pelos indivíduos afetados. Usando como principal ferramenta o sequenciamento do transcriptoma de células progenitoras neurais (NPC) e neurônios derivados de células-tronco pluripotentes induzidas (iPSC), identificamos uma série de alterações transcricionais importantes entre pacientes e controles, sugerindo que, a despeito da grande heterogeneidade genética associada ao transtorno, essas alterações se refletem em processos biológicos comuns. Nossos resultados são consistentes com os obtidos em trabalhos anteriores realizados com outros modelos de estudo e as linhagens celulares geradas a partir de nosso protocolo parecem refletir de forma fidedigna o perfil de expressão do cérebro fetal. Ainda, em um caso particular incluído neste estudo, investigamos as consequências transcricionais e funcionais de uma duplicação na região 17p13.3 - alteração previamente implicada em outros casos de autismo - nas células neuronais deste paciente, contribuindo para a compreensão do papel desta duplicação na patofisiologia do TEA. Dessa forma, nosso trabalho reforça a validade do uso de células neurais derivadas de iPSC e de abordagens transcricionais para o estudo de transtornos do neurodesenvolvimento / Autism Spectrum Disorder (ASD) is a severe neuropsychiatry disorder characterized by impaired social interaction and communication, restricted interests and repetitive behaviors. ASD is highly genetically heterogeneous and can be caused by different inheritance models, which hampers the identification of the genetic factors associated to the disorder. Incomplete penetrance and discordance between monozygotic twins are often observed in families of affected individuals, making it even more complex to understand the involvement of genetic factors in ASD. Applying transcriptomic approaches to study this disorder is an interesting way to overcome these problems. In this context, searching for pathogenic variants is no longer the study\'s main focus. Instead, one aims to investigate signaling pathways and biological process that are deregulated during neuronal differentiation and shared by affected individuals. Based on the transcriptome sequencing of neural progenitor cells (NPC) and neurons derived from induced pluripotent stem cells (iPSC), we were able to identify a series of important transcriptional alterations between patients and controls, which suggest that despite the great genetic heterogeneity associated to ASD, those alterations are reflected in common biological processes. Our results are consistent with those obtained in previous studies performed with other models and the lineages generated by our protocol seem to reliably reflect fetal brain expression profile. Moreover, in a particular case included in this study, we investigated transcriptional and functional consequences of a duplication located at 17p13.3 - an alteration previously found in other autism cases - in the neuronal cells of this patient, contributing towards a better comprehension of the role of this duplication in ASD pathophysiology. Hence, our work reinforces the validity of the use of neural cell derived from iPSC and transcriptional approaches in the studies of neurodevelopmental disorders

This study focuses on the situation and social conditions in school for primary and secondary school students with ASD in mainstream schools in Mainland China. Based on the current situation in China, although compulsory education has been popularized at an early stage, under the system of examination-oriented education, the distribution of educational resources is very uneven. Searches for published journals and articles with relevant program for children with ASD have been carried through several databases, and six articles are included as results. Few relevant studies concerning the current situation in mainland China exist. The social condition and school situation of children with ASD is complex and vary between environments. Thus it is hard to determine what education mode that is the most appropriate for children with ASD as well as the support they need. Limitation of the study and future research is also discussed in the thesis

Autism spectrum disorders (ASDs) are a biologically-based and behaviorally-defined spectrum of conditions which impact development. These conditions affect and are diagnosed based on features in three psychological and behavioral domains: social interaction, communication, and repetitive behaviors. Developing better ways to identify early signs of autism, whether through behavioral or other types of measures, is important because it will allow children to gain access to interventions and treatments earlier, which has demonstrated positive outcomes. Over the past 10 years, the prevalence of reported autism cases has increased. As a result, much research has focused on the etiology and phenotype of autism. Investigations seeking early signs of autism have generally studied vulnerable populations, particularly infants with an older sibling diagnosed with autism. Aside from observable behavioral differences, biological abnormalities, often within the gastrointestinal and immune systems as well as endocrine, autonomic and other systems, have been observed in a significant number of children diagnosed with autism. These features raise the possibility that cellular and tissue change in body and brain may be altering brain function such that behaviors emerge later and downstream of these cellular and tissue problems. However, research on the pathophysiology underlying these medical features, and particularly regarding how they develop in infancy, has received almost no attention. Such investigation would require measuring pathophysiological and medical features alongside current standard measures of behavioral and phenotypical presentations of autism. This thesis describes a study, funded by the Department of Defense Autism Research Program and carried out at the Massachusetts General Hospital Lurie Center, that proposed to look for early markers of autism in the pathophysiological domains in high risk infants and place them into developmental context by correlating these observations (some of which might potentially become early markers) with well-established neurocognitive measures. The goal of the study is to find biomarkers of clinical importance that reflect the pathophysiologial development of autism which might substantially precede behavioral changes that are currently used as a standard of diagnosis, but are not developmentally apparent or reliably measurable until well into the second or third year of life. While the overall scope of the study encompassed a range of systemic and nervous system measures as well as neurocognitive assessments, the focus of this thesis is mainly on a subset of the behavioral and neurocognitive measures collected through the study, specifically the Autism Diagnostic Observation Scale (ADOS), Autism Observational Scale for Infants (AOSI), Mullen Scales of Early Learning (MSEL) and Vineland Adaptive Behavior Scales (VABS). Subject development was tracked and assessed through developmental quotients (DQs) and then correlated to measures designed to identify autistic-like features. Results demonstrate that verbal development was the most significant indicator for autism. Additionally, delay in communication preceded problems with socialization. The analysis and information used for this thesis will contribute to the infrastructure utilized by the investigators for assessing further behavioral data. In addition, this behavioral data and the metrics generated in these analyses will be analyzed in relation to physiological data (e.g. brain, autonomic, metabolic, immune, and microbiome data). Tracking early biomedical development, especially alongside the current standard of observing behavioral development, has the potential of offering more comprehensive understanding of the brain-behavior-body relationship in children diagnosed with ASD, which can hopefully contribute to a non-invasive, more accurate, and earlier method of diagnosis and to the development of more treatment options.

There is increasing interest in the role of peers in facilitating the social interaction of pupils with ASD through Peer-mediated Interventions (PMI). A systematic literature review was conducted to provide an overview of methods used to evaluate the impact of PMI and provide examples of innovative practice. Four databases were searched. Following application of inclusion and exclusion criteria and coding of studies, 10 were included in the final review. The review found that measuring the outcome of PMI at the level of target pupils has been a focus, with less attention given to exploring experiences of participants; impact on peers and implementation of PMI within an educational context. An innovative PMI was implemented within a mainstream primary school to promote the social inclusion of a Year 3 male pupil with ASD, with his class and five peers. Key elements of the PMI included development of the programme with school staff, whole class awareness raising and a small group peer network. The intervention was evaluated through structured playground observations of pupil-peer interaction, interviews with the target pupil and school staff and a peer focus group. Findings indicated that this small-scale PMI had a positive impact at the level of the target pupil and peers. Key factors facilitating the implementation of this intervention within a school context were also identified. A structured dissemination strategy that involved consultation activities with key stakeholders explored the refinement of an ecologically valid and feasible model for delivery in mainstream schools. Future considerations in developing the intervention framework include; refining elements of the programme based on feedback from key stakeholders and trialling the delivery of the intervention by school staff trained in the programme. Implications for Educational Psychologists (EPs) in the development and delivery of the intervention are discussed.

The purpose of this study is to examine depictions of individuals diagnosed with autism spectrum disorder (ASD) to reach an understanding of how they perceive their diagnosis. Furthermore the purpose of this study is to reach an understanding of how sense of stigmatisation can be related to the diagnosis and how depictions of ASD can affect the individual’s sense of stigmatisation. The study is based on narrative analysis of autobiographies by individuals diagnosed with ASD. The study is also based on document analysis of material containing facts about ASD. The theoretical approach used in the study is stigma theory. The study shows that individuals diagnosed with ASD perceive their diagnosis as part of their personality. Furthermore the study shows that receiving the diagnosis contributes to sense of stigma, but also contributes to self perception. The analysis discusses how knowledge of perceptions of stigma related to the diagnosis can be useful to professionals working with individuals with ASD.

Engrailed (En) est un facteur de transcription important pour la mise en place de la segmentation de l’embryon et du plan d’organisation antéro-postérieur. Comme d’autres membres de la famille des homéoprotéines, Engrailed peut aussi agir comme une molécule de signalisation extracellulaire, internalisable grâce à son domaine « pénétratine » et stimulant dans la cellule cible la transcription ou la traduction des ARNm. De cette façon, Engrailed guide les axones en modifiant la traduction dans le cône de croissance axonal et l’infusion cérébrale d’Engrailed protège les neurones dopaminergiques dans un modèle de la maladie de Parkinson en augmentant la traduction de protéines mitochondriales. Des troubles cognitifs et un déficit des interactions sociales ont été observés chez les souris En1+/- et les souris En2-/-. Une augmentation de l’expression d’En2 a aussi été observée chez des patients atteints de troubles du spectre autistique. Néanmoins, le lien entre les modifications de l’expression d’Engrailed et l’autisme ne sont pas compris. L’objectif de cette thèse a été d’étendre notre connaissance des fonctions d’Engrailed dans une région télencéphalique où elle est a priori peu exprimée (l’hippocampe). Nos résultats confirment l’expression d’En1 et En2 dans l’hippocampe mature et décrivent les variations de l’expression de ces gènes au cours du développement de cette structure. En1 et En2 présentent des patrons d’expression différents pendant la première semaine postnatale et chez l’adulte suggérant que des variations du dosage génique d’Engrailed sont liées à certaines phases du développement, en particulier au début de la synaptogenèse. Nous avons également découvert que dans les cultures de cellules d’hippocampe Engrailed est exprimé dans les neurones et que son expression est plus forte dans les neurones GABA-ergiques, notamment dans leurs prolongements dendritiques et axonaux. Nous avons constaté qu’un excès d’Engrailed (décrit dans certains cas de TSA) augmente la complexité dendritique ainsi que la densité des épines dendritiques plastiques mais sans augmenter parallèlement la formation de synapses matures excitatrices. Nous avons observé des variations de densité des épines dendritiques chez les souris En2-/- et les souris En1+/-, ce qui confirme l’implication d’Engrailed dans leur formation ou leur stabilisation. Si dans nos conditions expérimentales l’excès d’Engrailed ne modifie pas la densité des synapses, un mutant d’Engrailed qui présente une interaction réduite avec eIF4E est moins efficace qu’Engrailed pour augmenter la densité des épines et diminue la densité des boutons présynaptiques et le synaptic matching. Ces résultats indiquent que l’interaction avec eIF4E régule au moins en partie les effets d’Engrailed sur la spinogenèse et suggèrent également une implication d’Engrailed dans la formation ou la stabilisation des boutons présynaptiques. Le rôle clef d’eIF4E dans la traduction permet de postuler que certains effets d’Engrailed observés dans notre étude pourraient dépendre de la synthèse protéique. Nos résultats montrent à cet égard qu’Engrailed augmente la synthèse protéique dans les neurones d’hippocampe. Cette traduction est différente de celle induite par la LTP chimique (LTPc) car insensible à l’action des oligomères synthétiques d’AβO, responsables sous leur forme naturelle de synaptopathies dans le contexte de la maladie d’Alzheimer. Engrailed permet également de restaurer la traduction défaillante de neurones issus de souris TG2576, modèles de la maladie d’Alzheimer. Dans leur ensemble, nos résultats identifient Engrailed comme un nouvel acteur de la plasticité dendritique. Ils révèlent qu’un excès d’Engrailed au cours de la synaptogenèse modifie les caractéristiques des dendrites, une situation susceptible d’altérer les caractéristiques fonctionnelles du réseau dendritique dans une situation de surexpression pathologique de la protéine. (...) / Engrailed (En) is an important transcription factor in embryo’s segmentation and anterior-posterior axis establishment during early embryogenesis. As several homeoproteins, Engrailed can act as an extracellular signalling molecule which can be internalized by target cells thanks to its penetratin domain and act through transcriptional and/or translation dependent mechanisms. Engrailed has for instance, translation-dependent effects on axonal guidance and cerebral infusion of Engrailed protects dopaminergic neurons in a Parkinson disease model by increasing mitochondrial protein translation. Also, cognitive defects were observed in En1+/+ and En2-/- and En2 expression is increased in ASD patients. This work consisted in extending the knowledge of Engrailed expression and functions. We explored the links with a telencephalic structure where it is a priori fewly expressed (hippocampus). Our results confirm En1 and En2 expression in the mature hippocampus and describe their respective expression along the development of this structure. En1 and En2 have different expression patterns during the first post-natal week as well as in the adulthood suggesting a genetic dosage of Engrailed during the development, specifically with the beginning of synaptogenesis. We also reveal that Engrailed, expressed in hippocampal neurons, is more expressed in GABA-ergic neurons, notably in their dendritic and axonal neurites. We observe that an excess of Engrailed (described in some ASD cases) increases dendritic complexity as well as plastic dendritic spine density, without affecting mature excitatory synapses. We show that En2-/- and heterozygote En1 mice have variations in dendritic spine density, which confirms that Engrailed is involved either in their formation or stabilization. Even though our experiments show no modification of synapse density with an excess of Engrailed, a mutant showing a decreased eIF4E interaction and less efficient than wild type Engrailed to increase dendritic spine density, decreases presynaptic button density and synaptic matching. Those results indicate that eIF4E interaction with Engrailed is, at least in part, responsible for its effects on spinogenesis and suggest a role of Engrailed in presynaptic button formation/stabilization. Key-role of eIF4E in translation allow to hypothesize that some of Engrailed effects we report could be translation dependent. In this sense, our results show that Engrailed is able to increase proteic synthesis in hippocampal neurons. This translation is different from the one induced by chemical LTP (LTPc): it is not altered by synthetic AβO, which are the main toxic agent when produced at abnormally high levels in Alzheimer disease. Engrailed is also able to restore defaulting translation in neurons from Alzheimer disease mice model (TG2576). As a whole, our results identify Engrailed as a novel actor in dendritic plasticity. They reveal that an excess of Engrailed during synaptogenesis can modify dendrite characteristics. This can lead to dendritic network dysfunction in a context of pathologic surexpression of Engrailed. Our observations open to new perspectives contributing to a better understanding of the relationship between Engrailed and ASD. Finally, this work lays the foundation to potentially fruitful links between Engrailed and AβOligomers signalling pathways, where modulation of protein synthesis could be a therapeutic lever in physiopathologic conditions.

The most common comorbid disorder for adolescents with autism spectrum disorder (ASD) is depression, with more severe symptoms demonstrated in those with high cognitive ability. Feelings of loneliness are associated with depression. There is a dearth of information regarding pertinent variables for loneliness of friendship quality, friendship motivation, and social skills in high ability adolescents with ASD. This study employs a multiple case study design with 10 twice-exceptional adolescent males with high cognitive ability and ASD (ages 13-9 to 18-11) to investigate these variables. Adolescent, parent, and teacher interviews were completed, transcribed, and analyzed using Consensual Qualitative Research (CQR). Results describe friendship quality for these youth, with particular contributions to current understanding of companionship, security, help, closeness and balance. Findings inform friendship motivation, as well, and etiologies of amotivation are documented. Results indicate positive and negative influences of high intelligence on interpersonal functioning, along with immaturity and symptoms of rigidity affecting friendships, as well. Pathway analyses reveal twice-exceptional youth with insecure friendships experience loneliness and introjected motivation for friendships, along with increases in peer dyadic relationships and decreases in loneliness. Those with insecure friendships and perseverative interest in peers also present with suicidal ideation and/or attempts. Future research should expand the use of individual therapies (i.e., cognitive behavioral therapy for depression) for these twice-exceptional teens, particularly in middle school, with modifications to accommodate difficulties with perseveration on negative emotions, as well as explore coping strategies of engaging with fictional characters when lonely.