Le somnambulisme est un trouble du sommeil fréquent qui appartient à la famille des parasomnies NREM. Malgré des décennies de recherche, sa pathophysiologie reste peu comprise. Les études de familles et les études de jumeaux démontrent qu’une forte composante héréditaire est en jeu. Toutefois, très peu d’études moléculaires ont été menées afin d’identifier des gènes impliqués et il n’y a toujours pas de consensus quant au mode de transmission dans les familles. Cet ouvrage contient deux études distinctes qui tenteront de répondre à ces deux problèmes. L’objectif de la première étude était de déterminer si des variants génétiques dans le gène Adénosine désaminase (ADA) étaient enrichis dans la population somnambule en comparaison avec les dormeurs sains. Le gène entier a été séquencé chez 251 patients somnambules provenant de Montréal et de Montpellier ainsi que chez 94 sujets contrôles sans histoire personnelle ni familiale de somnambulisme. Aucun variant génétique n’était enrichi chez les patients somnambules en comparaison avec les dormeurs sains et les bases de données génétiques publiques. Dans la deuxième étude, le premier objectif était de déterminer le mode de transmission du somnambulisme chez 20 familles canadiennes-françaises. Le deuxième objectif était de mesurer le risque récurrent ainsi que le risque relatif pour la fratrie et les enfants des patients index. Dans notre cohorte, le somnambulisme se transmettait principalement selon un mode autosomal dominant à pénétrance réduite. Les risques récurrents pour les apparentés de premier degré étaient : à vie 0,48 à 0,56, durant l’enfance 0,43 à 0,56 et à l’âge adulte 0,14 à 0,35. Les risques relatifs pour les apparentés de premier degré étaient : à vie 6,96 à 8,12, durant l’enfance 1,48 à 4,06 et à l’âge adulte 4,67 à 11,67 supérieurs à la population générale. D’autres études moléculaires comme le séquençage de l’exome et les études de liaison génétique dans les familles seront nécessaires afin d’identifier de nouveaux gènes candidats qui pourront agir à titre de biomarqueurs. Cela permettrait de faciliter le diagnostic et ultimement développer des approches thérapeutiques ciblées. / Sleepwalking is a common sleep disorder and it belongs to the family of NREM parasomnias. Despite decades of research, its pathophysiology remains poorly understood. Family and twin studies show that a strong hereditary component is involved. However, very few molecular studies have been conducted to identify the genes involved and there is still no consensus on the mode of transmission in families. This Master’s thesis contains two separate studies which will attempt to address these two problems. The aim of the first study was to determine whether genetic variants in the Adenosine Deaminase (ADA) gene were enriched in the sleepwalking population compared to healthy sleepers. The entire gene was sequenced in 251 sleepwalking patients from Montreal and Montpellier as well as in 94 control subjects with no personal or family history of sleepwalking. No genetic variants were enriched in sleepwalking patients compared to healthy sleepers and public genetic databases. In the second study, the first objective was to determine the mode of transmission of sleepwalking in 20 French-Canadian families. The second objective was to measure the recurrence risk as well as the relative risk for siblings and children of index patients. In our cohort, sleepwalking was transmitted mainly in an autosomal dominant mode with reduced penetrance. The recurrence risks for first-degree relatives were: lifetime 0.48 to 0.56, in childhood 0.43 to 0.56, and in adulthood 0.14 to 0.35. The relative risks for first-degree relatives were: lifetime 6.96 to 8.12, in childhood 1.48 to 4.06 and in adulthood 4.67 to 11.67 higher than the general population. Further molecular studies, such as exome sequencing, and genetic linkage studies in families will be needed in order to identify new candidate genes that can act as biomarkers. This would allow the development of an independent test for the diagnosis and ultimately have implications for targeted therapeutic approaches.

This study has determined the cellular site of adenosine deaminase (ADA) expression in the mouse during development from Days 5 through 13 (day vaginal plug was found = Day 0) of gestation. Developmental expression of ADA progressed in two overlapping phases defined genetically (maternal vs. embryonal) and according to region (decidual vs. placental). In the first phase, ADA enzyme activity increased almost 200-fold in the antimesometrial region (decidua capsularis + giant trophoblast cells) from Days 6 through 9 of gestation but remained low in the mesometrial region. Immunohistochemical staining revealed a major localization of ADA to the secondary decidua. In the second phase, ADA activity increased several-fold in the placenta (labyrinth + basal zones) from Days 9 through 13 of gestation but remained low in the embryo proper. Immunohistochemical staining revealed a major localization of ADA to secondary giant cells, spongiotrophoblast, and labyrinthine trophoblast. Regression of decidua capsularis and growth of the spongiotrophoblast population accounted for an antimesometrial to placental shift in both ADA enzyme activity and a 40-kDa immunoreactive protein band. To verify a shift from maternal to fetal expression, studies were performed with two strains of mice (ICR, Eday) homozygous for a different ADA isozyme (ADA-A, ADA-B). Blastocysts homozygous for Adab were transferred to the uterus of pseudopregnant female recipients homozygous for Adaa. The isozymic pattern in chimeric embryo-decidual units analyzed at Days 7, 9, 11, and 13 revealed a predominance of maternal-encoded enzyme at Days 7 through 11 of gestation and a shift to fetal-encoded enzyme by Day 13. Thus, maternal expression of ADA in the antimesometrial decidua may play a role during establishment of the embryo in the uterine environment, whereas fetal expression of ADA in the trophoblast might be important to placentation.

Afin de se répliquer et de se propager efficacement, les virus ont développé de multiples stratégies leur permettant d’échapper au système de défense innée : le système IFN de type I. Ce travail de thèse a alors consisté à étudier les interactions entre protéines virales et protéines de ce système de défense afin de mieux comprendre les mécanismes de subversion virale et d’identifier d’éventuelles cibles cellulaires thérapeutiques. La reconstruction d’un réseau d’interactions entre ces protéines nous a permis d’identifier des stratégies différentielles de subversion pour 4 familles virales et de montrer un ciblage massif et significatif des protéines du système IFN de type I par les virus. Les protéines en interaction directe avec ces protéines sont également fortement touchées par les virus et sont de potentiels modulateurs du système IFN de type I. Parmi ces modulateurs, le processus biologique sur-représenté est le transport nucléocytoplasmique et la protéine KPNA1 impliquée dans ce processus a retenu notre attention. L’étude fonctionnelle de l’interaction entre la protéine KPNA1 et la protéine NS3 du VHC a montré que la protéine NS3 associée à son cofacteur NS4A inhibe partiellement la réponse IFN de type I en empêchant l’import nucléaire de STAT1. Ce phénotype pourrait résulter de la dégradation de KPNA1 par NS3/4A. Par ailleurs, l’identification de nouveaux inter-acteurs de la protéine NS1 du virus influenza par criblage double-hybride levure a révélé la protéine induite par les IFN de type I, ADAR1, comme partenaire de la protéine NS1 de multiples souches virales et nous avons montré qu'ADAR1 est un facteur pro-viral dont la fonction editing est activée par NS1 / To replicate and propagate efficiently, viruses have developed multiple strategies allowing them to escape the innatedefense system: the type I IFN system, This work of thesis then consisted in studying the interactions between viralproteins and proteins of this defence system in order to understand better the mechanisms of viral subversion andidentifY possible therapeutic cellular tatgets. The reconstruction of a network of interacting proteins involved in the typeI IFN system allowed us to identifY differentiai subversion strategies for 4 viral families and to show a massive andsignificant targeting of proteins of the type I IFN system by viruses. Proteins directly interacting with the type Iinterferon system network are also strongly targeted by viruses and are potential modulators of the type I IFN system.Among these modulators, the most tatgeted function conesponds to the transport of NLS-bearing substrates to thenucleus and the KPNAI protein involved in this process held our attention. The functional study of the interactionbetween KPNA1 and NS3 protein of the HCV showed that NS3 protein associated with its cofactor NS4A inhibitsprutially the type I IFN response by preventing the nuclear translocation of ST A Tl. This phenotype could result fromthe degradation of KPNAI by NS3/4A. Besides, the identification of new cellular prutners ofNS 1 prote in of influenzavirus by yeast two-hybrid screens revealed ADARI, an interferon-stimulated prote in, as partner of NS 1 of ali testedvirus strains and we showed that ADARI is an essential host factor for viral replication and its editing function isactivated by NS 1 protein

Indiana University-Purdue University Indianapolis (IUPUI) / Multiple sclerosis (MS) is a disabling disease that afflicts an estimated two million people worldwide. The disease is characterized by degradation of the myelin sheath that insulates neurons of the central nervous system manifesting as a heterogeneous collection of symptoms. Two enzymes, protein arginine deaminases type 2 and 4 (PAD2 and PAD4) have been implicated to play an etiologic role in demyelination and neurodegeneration by catalyzing a post-translational modification of arginine peptide residues to citrulline. The pathogenesis of MS is poorly understood, though vitamin D deficiency is a well-associated risk factor for developing the disorder. Using the experimental autoimmune encephalomyelitis (EAE) model of MS we demonstrate vitamin D treatment to attenuate over-expression of PAD 2 and 4 in the brain and spine during EAE. In addition, we identify two molecules produced by peripheral immune cells, IFNɣ and IL-6, as candidate signaling molecules that induce PAD expression in the brain. We demonstrate vitamin D treatment to inhibit IFNɣ mediated up regulation of PAD2 and PAD4 both directly within the brain and by modulating PAD-inducing cytokine production by infiltrating immune cells. These results provide neuroprotective rational for the supplementation of vitamin D in MS patients. More importantly, these results imply an epigenetic link between vitamin D deficiency and the pathogenesis of MS that merits further investigation.