Dissertationen zum Thema „Usher syndrome type 3“

Malgré la forte prévalence de la déficience auditive, les mécanismes sous-jacents de la perte auditive progressive restent inconnus. Notre laboratoire a étudié le(s) rôle(s) de la clarine-1, responsable du syndrome d'Usher de type III, qui entraîne une perte auditive progressive, et de la clarine-2, responsable de la surdité non syndromique, dans le système auditif. En raison de la variabilité phénotypique chez les patients atteints du syndrome d'Usher de type III, même parmi les patients présentant les mêmes mutations génétiques, nous avons émis l'hypothèse qu'il pourrait y avoir une redondance fonctionnelle entre les deux clarines. Nous avons donc généré des souris knock-out totales et conditionnelles (Bhlhb5-cre et Myo15-cre) pour la clarine-1/clarine-2. En utilisant une approche multidisciplinaire, intégrant des études omiques et électrophysiologiques avec une imagerie à haute résolution dans le temps, j'ai identifié les voies moléculaires clés dérégulées en l'absence de clarine-1 et clarine-2 dans les cellules ciliées auditives et les neurones auditifs primaires. L'analyse phénotypique des souris Clrn1-/-Clrn2-/- a révélé une surdité profonde dès l'apparition de l'audition. Les enregistrements de courant de transduction mécano-électrique (MET) étaient absents chez les souris Clrn1-/-Clrn2-/-, mais seulement réduits chez les souris Clrn1-/- et Clrn2-/-. Ces résultats démontrent un rôle fonctionnel compensatoire de la clarine-1 et de la clarine-2 au niveau de la touffe ciliaire. J'ai également observé des anomalies de l'homéostasie ionique, nécessaires au fonctionnement normal de la MET et à la transmission synaptique, qui étaient plus graves chez les souris Clrn1-/-Clrn2-/- que chez les souris Clrn1-/- et Clrn2-/-. Ces changements ioniques s'accompagnent de troubles pré- et postérieurs à l'apparition de la maladie. Pour valider l'hypothèse selon laquelle le(s) rôle(s) principal(aux) de la clarine-1 et de la clarine-2 se situe(nt) dans les cellules ciliées, j'ai étudié des souris chez lesquelles la clarine-1 et la clarine-2 ont été inactivées de manière spécifique dans les cellules ciliées (Myo15-cre). Ces souris knock-out conditionnelles reproduisaient les changements ioniques et synaptiques observés chez les souris knock-out totales pour les clarines, entraînant une dégénérescence des neurones auditifs primaires. Pour renforcer cette hypothèse, j'ai étudié le phénotype auditif chez des souris ayant subi une délétion spécifique des neurones auditifs primaires (Bhlhb5-cre) de la clarine-1 et de la clarine-2. Ces souris avaient une audition normale jusqu'à l'âge de 6 mois, sans modification de l'épithélium sensoriel cochléaire ni de la dégénérescence des neurones auditifs primaires. Afin d'approfondir les fonctions moléculaires communes et uniques de clarine-1 et clarine-2, j'ai effectué une analyse séquentielle de l'ARN sur l'organe de Corti entier de souris Clrn1-/-, Clrn2-/- et Clrn1-/-Clrn2-/-. Conformément aux observations physiologiques, j'ai constaté une dysrégulation dans 8 catégories distinctes et physiologiquement pertinentes : le flux cationique, l’organisation et la fonction synaptique, l’endocytose et l’exocytose, la fonction neuronale et différenciation, la fonction métabolique, l’organisation de l'actine et du cytosquelette, l’homéostasie lipidique et l’inflammation. Nous concluons que la clarine-1 et la clarine-2 jouent des rôles communs et compensatoires dans l'activité de transduction mécano-électrique et dans l'intégrité pré- et post-synaptique. Les clarines sont également nécessaires à l'intégrité de la touffe ciliaire auditive, à l'homéostasie ionique dans les cellules ciliées auditives et à la survie des neurones auditifs primaires. Ces résultats permettront d'élucider de nouveaux mécanismes impliqués dans la perte progressive de l'audition
Despite high prevalence of debilitating hearing loss, underlying mechanisms of progressive hearing loss remain elusive. Our lab has been investigating the role(s) of clarin-1, responsible for Usher syndrome type III, causing progressive hearing loss, and clarin-2, responsible for non-syndromic hearing impairment, in the auditory system. Due to phenotypic variability in Usher Syndrome type III patients, even among patients with the same genetic mutations, we hypothesized that there may be a functional redundancy between the two clarins. Therefore, we generated clarin-1/clarin-2 total and conditional (Bhlhb5-cre and Myo15-cre) knockout mice. Using a multidisciplinary approach, integrating omics and electrophysiological studies with high resolution imaging over time, I pinpointed key molecular pathways dysregulated in the absence of clarin-1 and clarin-2 in auditory hair cells and primary auditory neurons. Phenotypic analysis of Clrn1-/-Clrn2-/- mice revealed profound deafness from hearing onset. Mechanoelectrical transduction (MET) current recordings were absent in Clrn1-/-Clrn2-/- mice, but only reduced in Clrn1-/- and Clrn2-/- mice. These results demonstrate a compensatory functional role of clarin-1 and clarin-2 at the hair bundle. I also observed abnormalities in ionic homeostasis, required for normal MET function and synaptic transmission, that were more severe in Clrn1-/-Clrn2-/- mice, relative to Clrn1-/- and Clrn2-/- mice. These ionic changes were accompanied by pre- and post-synaptic abnormalities, resulting in abnormal cytoplasmic vesicle accumulation and synaptic function in hair cells. Furthermore, I observed a progressive degeneration of the cochlear sensory epithelium and primary auditory neurons over time. To validate the hypothesis that the primary role(s) of clarin-1 and clarin-2 are in hair cells, I studied mice with hair cell-specific (Myo15-cre) deletion of clarin-1 and clarin-2. These conditional clarin knockout mice mimicked the ionic and synaptic changes found in total clarin knockout mice, resulting in primary auditory neuron degeneration. To reinforce this hypothesis, I studied the auditory phenotype in mice with primary auditory neuron-specific (Bhlhb5-cre) deletion of clarin-1 and clarin-2. These mice had normal audition up to 6 months of age, with no cochlear sensory epithelial changes or primary auditory neuron degeneration. To dig deeper into the common and unique molecular functions of clarin-1 and clarin-2, I performed RNA-seq on whole organ of Corti from Clrn1-/-, Clrn2-/-, and Clrn1-/-Clrn2-/- mice. In accordance with physiological observations, I found dysregulation in 8 distinct and physiologically relevant categories: cationic flux, synaptic organization and function, endocytosis and exocytosis, neuronal function and differentiation, metabolic function, actin and cytoskeletal organization, lipid homeostasis, and inflammation. We conclude that clarin-1 and clarin-2 play common and compensatory roles in mechanoelectrical transduction activity and pre- and post-synaptic integrity. The clarins are also required for auditory hair bundle integrity, ion homeostasis in auditory hair cells, and primary auditory neuronal survival. These findings will help elucidate novel mechanisms implicated in progressive hearing loss

Usher syndrome type 1C is an autosomal recessive condition in which profound, congenital sensorineural deafness is found in association with vestibular hypofunction and childhood onset retinitis pigmentosa. The gene responsible for Usher type 1C, USH1C, codes for a PDZ domain-containing protein, harmonin, of unknown function. In addition, the locus for a form of non- syndromic autosomal recessive deafness, DFNB18, overlaps with the USH1C gene. In this thesis the USH1C gene is studied in more detail, both at the molecular level and at the protein level. Two cohorts of patients, individuals diagnosed with Usher type 1, and a group of sibs with recessive non-syndromic deafness concordant for markers flanking the DFNB18 locus, were screened for mutations in USH1C. One Usher type 1 patient was homozygous for a recurrent mutation, and the possibility of a founder effect was investigated by analysing intragenic SNPs. Another Usher type 1 patient had two novel coding mutations that were studied in more detail to establish whether they were likely to be disease-causing or represent rare polymorphisms. USH1C is an alternatively spliced gene with evidence for tissue-specific isoforms of the protein. The repertoire of alternative isoforms and their tissue distributions were studied in human foetal tissues using non-quantitative RT- PCR. Particular attention was paid to a putative isoform thought to utilize an alternative start site in the centre of the gene. This isoform may have importance in other tissues when a mutation at the 5' end of USH1C results in a non-functional protein from the usual start site. The sub-cellular localization of harmonin was investigated in individual human epithelial cells using fluorescent immunocytochemistry, and fluorescent immunohistochemistry was used to study the localization in mouse inner ear sections. Finally, to understand more about the possible role of harmonin in the ear and the eye, an in vitro GST pull-down assay was set up to investigate the interaction of harmonin with another Usher type 1 protein, protocadherin 15.

The present thesis belongs to the research area disability research and deal with specific aspects of cognition in individuals with Usher syndrome type 1 and 2. The subject has been investigated and is discussed within an interdisciplinary framework, though the theories applied and described are derived from the area of cognitive psychology. Usher syndrome is a rare genetic condition causing a combination of visual and hearing impairment: deafblindness. There is a congenital hearing loss that is profound in type 1 and moderate to severe in type 2. During mid-childhood symptoms of visual impairment, e.g. light sensitivity, emerge and a progressive loss of visual field follows as a result of the genetically caused eye disease Retinitis Pigmentosa. The syndrome has previously been well described with respect to the genetical and medical aspects, but there has been very little research with a cognitive perspective on the population. Studies 1 and 2 in the present thesis focused on children with Usher syndrome type 1 with cochlear implants and investigated phonological skills, lexical access, working memory and reading skill in the group. Studies 3 & 4 investigated the same cognitive abilities and theory of mind in adults with Usher syndrome type 2. In study 4 the performance on theory of mind in the adults with Usher syndrome type 2 was also compared to that of another group with genetically caused deafblindness: individuals with Alström syndrome. The results were that both the children and adults with Usher syndrome had significantly poorer phonological processing than the control groups with normal hearing. There was a large variation on performance on lexical access, especially in the group of children, however several individuals performed at the same level as the control group. Reading skill was found to be at level with the control groups’. There was also great variation in performance on ToM, however the majority of individuals performed similar to the control group with normal hearing and vision. The present project has resulted in some new knowledge on cognitive performance in  individuals with Usher syndrome type 1 and type 2. Performance in the participants with Usher syndrome can to a large extent can be understood by application of the models developed in previous research on populations with hearing impairment or deafness for understanding the impact of hearing with a hearing aid or cochlear implant. However, individuals with Usher syndrome experience additional difficulties in accessing information due to the progressive visual loss and the impact this has on performance is still largely unknown. Hence, the present project would recommend that interventions and support would be designed specifically to each individuals’ needs, with consideration of both the visual impairment and the hearing impairment.
Föreliggande avhandling tillhör ämnet handikappvetenskap och beskriver specifika kognitiva förmågor hos personer med Ushers syndrom typ 1 och 2. Avhandlingens ämne har undersökts utifrån ett tvärvetenskapligt perspektiv, även om de teorier som tillämpas och beskrivs huvudsakligen härrör inom området kognitiv psykologi. Ushers syndrom är en ovanlig genetisk åkomma som leder till kombinationen av syn- och hörselnedsättning: dövblindhet. Individer med typ 1 av syndromet har medfödd dövhet medan individer med typ 2 har en medfödd måttlig till grav hörselnedsättning. Någon gång i åldrarna 6-10 år börjar de första symptomen, till exempel nedsatt mörkerseende, på den genetiskt betingade progressiva synnedsättningen Retinitis Pigmentosa att framträda. Syndromet är väl beskrivet i forskningen med avseende på genetiska och medicinska aspekter, men det finns extremt lite tidigare forskning med kognitivt perspektiv om populationen. Studierna 1 och 2 i föreliggande avhandling fokuserade på barn med Ushers syndrom typ 1 och cochleaimplantat. Dessa studier undersökte fonologisk förmåga, lexikal access, arbetsminne och läsning i gruppen. Studie 3 undersökte samma kognitiva förmågor hos vuxna med typ 2 av syndromet. I studie 4 undersöktes även den sammansatta förmågan Theory of Mind hos de vuxna med typ 2 och deras prestation jämfördes både mot en kontroll grupp med normal hörsel och syn och en kontrollgrupp med annan typ av dövblindhet; Alström syndrom. Resultaten visade att både barnen och de vuxna med Ushers syndrom hade signifikant sämre fonologisk förmåga än kontrollgruppen med normal hörsel. Nivån på prestation varierade stort inom grupperna, särskilt mellan barnen med typ 1, och flera av individerna (barn och vuxna) presterade trots hörselnedsättningen på samma nivå som de normalhörande. Läsfärdigheten befanns vara i nivå med kontrollgrupperna. I den vuxna gruppen var det stor variation i prestation även på Theory of Mind, men de flesta av individerna presterade liknande som kontrollgruppen med normal hörsel och syn. Föreliggande projekt har resulterat i lite mer kunskap om kognitiva färdigheter hos individer med Ushers syndrom typ 1 och 2. De resultat som individerna med Ushers syndrome presterade kan till stor del förstås och tolkas genom tillämpning av teorier och modeller utvecklade för att den inverkan på kognitiva förmågor det har att ha nedsatt hörsel och höra med hjälp av hörselapparat eller cochleaimplantat. Dock tyder fynden i detta projekt även på att individer med Ushers syndrom på grund av den allvarliga synnedsättningen har ytterligare svårigheter att få tillgodogöra sig information, men i vilken utsträckning och på vilket sätt är ännu inte beskrivet. Utifrån fynden i föreliggande studie blev rekommendation att interventioner och stöd till personer med Ushers syndrom utformas specifikt till varje individ, med hänsyn taget både till hens grad av synnedsättning och hörselnedsättning.

Le syndrome d’Usher (USH) associe une surdité neurosensorielle congénitale et une perte progressive de la vision par rétinite pigmentaire. Pendant ma thèse, l’essentiel de mon travail a porté sur un gène responsable du syndrome d’Usher de type 2, USH2A. Ce gène code pour l’usherine, une protéine associée aux liens fibreux interstéréociliaires situés à la base de la touffe ciliaire des cellules ciliées de la cochlée. Ces liens transitoires disparaissent autour du 9e jour post-natal (P9), chez la souris et le complexe moléculaire associé à ces liens inclut l’usherine, adgrv1 (un récepteur membranaire couplé aux protéines G), la whirline, et pdzd7 (deux protéines sous-membranaires d’échafaudage contenant des domaines PDZ). Des travaux précédents ont montré que l’interaction de ces quatre protéines était nécessaire à un développement correct de la touffe ciliaire, qui lui-même conditionne la transduction mécano-électrique opérée par les cellules ciliées. Pendant ma thèse, j’ai étudié les effets, à court terme et à long terme, de l’absence de la plus longue des 2 isoformes connues de l’usherine, l’isoforme-b transmembranaire, sur des souris mutantes pour le gène Ush2a (Ush2aΔTM/ΔTM). Chez ces souris, j’ai effectué des mesures de courants de transduction mécano-électrique, des enregistrements des potentiels évoqués auditifs (PEA), des tests de masquage auditif, et une analyse morphologique des cellules ciliées par imagerie au microscope électronique à balayage. Ainsi, j’ai pu montrer que les liens interstéréociliaires basaux étaient présents à P4 et que les courants de transduction mécano-électrique étaient normaux à P7. L’absence de l’isoforme-b de l’usherine n’a, en fait, que très peu de conséquences morphologiques et fonctionnelles sur la touffe ciliaire des cellules ciliées de la cochlée durant les 3 ou 4 premiers mois de vie chez la souris. A partir de l’âge de 4 mois cependant, les souris Ush2aΔTM/ΔTM souffrent d’une perte progressive de l’audition et d’anomalies de la sélectivité dans l’analyse des fréquences du son, dues surtout à un dysfonctionnement des cellules ciliées externes. Ces résultats viennent alimenter le débat sur le caractère progressif de la surdité du syndrome d’Usher de type 2A. La surdité des patients USH2A est considérée comme étant le plus souvent non progressive, mais plusieurs études ont révélé que certains patients souffrent en fait d’une surdité progressive. Mon travail a permis de montrer que chez la souris, la surdité en rapport avec des mutations d’Ush2a peut également être progressive. L’existence potentielle d’une fenêtre temporelle chez les patients USH2A dont la surdité moins sévère à la naissance, va ensuite s’aggraver, pourrait permettre d’envisager dans le futur un traitement curatif précoce du déficit auditif de ces patients, par thérapie génique
Usher syndrome (USH) is characterised by a sensorineural congenital deafness and a progressive loss of vision by retinitis pigmentosa. During my PhD, my main focus of study was a gene responsible for Usher syndrome type 2, USH2A. This gene codes for usherin, a protein associated with the fibrous links located at the base of the hair bundle of cochlear, and vestibular hair cells. In mice, these transitory links start to disappear as of postnatal day 9 (P9), and the molecular complex with which they are associated is composed of usherin, adgrv1 (an adhesion G protein coupled receptor), whirlin, and pdzd7 (two submembranous PDZ domain-containing scaffold proteins). Previous work has shown that the interaction in between these 4 proteins is essential for the development of the hair bundle, the structure responsible for the initiation of the mechano-electrical transduction (MET) process in the hair cells. During my thesis, I studied the short term and long term effects of the absence of the longest of the 2 usherin isoforms, the transmembrane b-isoform, in mice carrying a mutation in the Ush2a gene (Ush2aΔTM/ΔTM). In these mice, I measured mechano-electrical currents, auditory brainstem responses, undertook auditory masking tests, and analysed scanning electron micrographs of cochlear hair bundles. Through this work, I showed that basal lateral links similar to ankle links could be observed on P4, and that MET currents were normal on P7. The absence of the long b-isoform of usherin actually has very little effect on the morphology or the function of the cochlear hair bundle in mice, until 3 or 4 months of age. As of 4 months old however, Ush2aΔTM/ΔTM mice suffer from a progressive hearing loss, and frequency selectivity defects, mainly cause by a dysfunction of outer hair cells. These results will further add to the debate on whether the hearing loss in Usher syndrome type 2A is progressive or not. Hearing loss in USH2A patients is generally considered non progressive, but several studies have given indication to the contrary. My work has shown that in mice, deafness caused by mutations to the Ush2a gene can also follow a progressive pattern. The potential existence of this temporal window in USH2A patients whose hearing impairment is less severe at birth, but gets worse over time, could allow clinicians to use gene therapy as curative treatment for patients who fall into this category

Le syndrome d’Usher (USH) associe une surdité neurosensorielle congénitale et une perte progressive de la vision par rétinite pigmentaire. Pendant ma thèse, l’essentiel de mon travail a porté sur un gène responsable du syndrome d’Usher de type 2, USH2A. Ce gène code pour l’usherine, une protéine associée aux liens fibreux interstéréociliaires situés à la base de la touffe ciliaire des cellules ciliées de la cochlée. Ces liens transitoires disparaissent autour du 9e jour post-natal (P9), chez la souris et le complexe moléculaire associé à ces liens inclut l’usherine, adgrv1 (un récepteur membranaire couplé aux protéines G), la whirline, et pdzd7 (deux protéines sous-membranaires d’échafaudage contenant des domaines PDZ). Des travaux précédents ont montré que l’interaction de ces quatre protéines était nécessaire à un développement correct de la touffe ciliaire, qui lui-même conditionne la transduction mécano-électrique opérée par les cellules ciliées. Pendant ma thèse, j’ai étudié les effets, à court terme et à long terme, de l’absence de la plus longue des 2 isoformes connues de l’usherine, l’isoforme-b transmembranaire, sur des souris mutantes pour le gène Ush2a (Ush2aΔTM/ΔTM). Chez ces souris, j’ai effectué des mesures de courants de transduction mécano-électrique, des enregistrements des potentiels évoqués auditifs (PEA), des tests de masquage auditif, et une analyse morphologique des cellules ciliées par imagerie au microscope électronique à balayage. Ainsi, j’ai pu montrer que les liens interstéréociliaires basaux étaient présents à P4 et que les courants de transduction mécano-électrique étaient normaux à P7. L’absence de l’isoforme-b de l’usherine n’a, en fait, que très peu de conséquences morphologiques et fonctionnelles sur la touffe ciliaire des cellules ciliées de la cochlée durant les 3 ou 4 premiers mois de vie chez la souris. A partir de l’âge de 4 mois cependant, les souris Ush2aΔTM/ΔTM souffrent d’une perte progressive de l’audition et d’anomalies de la sélectivité dans l’analyse des fréquences du son, dues surtout à un dysfonctionnement des cellules ciliées externes. Ces résultats viennent alimenter le débat sur le caractère progressif de la surdité du syndrome d’Usher de type 2A. La surdité des patients USH2A est considérée comme étant le plus souvent non progressive, mais plusieurs études ont révélé que certains patients souffrent en fait d’une surdité progressive. Mon travail a permis de montrer que chez la souris, la surdité en rapport avec des mutations d’Ush2a peut également être progressive. L’existence potentielle d’une fenêtre temporelle chez les patients USH2A dont la surdité moins sévère à la naissance, va ensuite s’aggraver, pourrait permettre d’envisager dans le futur un traitement curatif précoce du déficit auditif de ces patients, par thérapie génique
Usher syndrome (USH) is characterised by a sensorineural congenital deafness and a progressive loss of vision by retinitis pigmentosa. During my PhD, my main focus of study was a gene responsible for Usher syndrome type 2, USH2A. This gene codes for usherin, a protein associated with the fibrous links located at the base of the hair bundle of cochlear, and vestibular hair cells. In mice, these transitory links start to disappear as of postnatal day 9 (P9), and the molecular complex with which they are associated is composed of usherin, adgrv1 (an adhesion G protein coupled receptor), whirlin, and pdzd7 (two submembranous PDZ domain-containing scaffold proteins). Previous work has shown that the interaction in between these 4 proteins is essential for the development of the hair bundle, the structure responsible for the initiation of the mechano-electrical transduction (MET) process in the hair cells. During my thesis, I studied the short term and long term effects of the absence of the longest of the 2 usherin isoforms, the transmembrane b-isoform, in mice carrying a mutation in the Ush2a gene (Ush2aΔTM/ΔTM). In these mice, I measured mechano-electrical currents, auditory brainstem responses, undertook auditory masking tests, and analysed scanning electron micrographs of cochlear hair bundles. Through this work, I showed that basal lateral links similar to ankle links could be observed on P4, and that MET currents were normal on P7. The absence of the long b-isoform of usherin actually has very little effect on the morphology or the function of the cochlear hair bundle in mice, until 3 or 4 months of age. As of 4 months old however, Ush2aΔTM/ΔTM mice suffer from a progressive hearing loss, and frequency selectivity defects, mainly cause by a dysfunction of outer hair cells. These results will further add to the debate on whether the hearing loss in Usher syndrome type 2A is progressive or not. Hearing loss in USH2A patients is generally considered non progressive, but several studies have given indication to the contrary. My work has shown that in mice, deafness caused by mutations to the Ush2a gene can also follow a progressive pattern. The potential existence of this temporal window in USH2A patients whose hearing impairment is less severe at birth, but gets worse over time, could allow clinicians to use gene therapy as curative treatment for patients who fall into this category

Inherited Retinal Diseases (IRDs) represent a major cause of blindness worldwide. Adeno-associated viral (AAV) vector-based gene therapies represent the most promising treatments. We aimed to develop gene therapies for gyrate atrophy of the choroid and retina (GA) and Usher syndrome type 1B (USH1B) retinitis pigmentosa. GA is characterized by ornithine aminotransferase [OAT, coding sequence (CDS) ∽1.3 Kb] deficiency. We demonstrated in vitro expression and activity of 3XFlag-tagged human OAT (hOAT-3XFlag). AAV vector carrying the hOAT-3XFlag expression cassette improved the structural retinal defects in the Oat-/- mouse model of GA. Bi-allelic mutations in the Myosin7A gene (MYO7A) (CDS ∽6.7 Kb) cause USH1B, the most common combination of inherited congenital deafness and blindness. We demonstrated effective delivery and expression of MYO7A in mice and pigs using dual AAV vectors. During AAV manufacturing, we found a contaminant vector resulting from recombination between two homologous sequences in the AAV vector containing the 5’ half of hMYO7A. This was removed by changing one of the two sequences while maintaining the same MYO7A expression levels in vivo. We selected three therapeutic doses of dual AAV-hMYO7A that rescue retinal defects in shaker-1 mice, a mouse model of USH1B. These doses will be translated in patients with USH1B. In the same mouse model, we confirmed biological potency of dual AAV-hMYO7A that will be used in the clinical trial. Overall, these studies offer promising results, paving the way for a gene therapy of GA and for the clinical translation of dual AAV vectors in USH1B subjects.

Approximately 7000 rare disorders exist, affecting 2 percent of Canadians and millions of people worldwide. Given that for many rare diseases only one allele is mutated, we hypothesize inducing expression of the remaining wild-type allele may have a therapeutic effect. SMAD3 heterozygosity results in Aneurysms-Osteoarthritis Syndrome (AOS) – an aortic aneurysm disorder also known as Loeys-Dietz Syndrome Type 3. We conducted a screen of FDA-approved compounds and found that 13-cis-retinoic acid (13-CRA) induces SMAD3 in normal human fibroblast cultures. Treatment with therapeutic concentrations of 13-CRA increased SMAD3 mRNA in normal human fibroblasts, patient fibroblasts, wild-type murine vascular smooth muscle cells and Smad3+/- murine vascular smooth muscle cells. Increases in SMAD3 protein were also observed in normal human fibroblasts, patient fibroblasts, and wild-type murine vascular smooth muscle cells. Immunofluorescent imaging revealed the primary site of protein induction to be nuclear. We report here the in vitro induction of SMAD3 mRNA and protein by therapeutic levels of 13-CRA and suggest further investigation of this modality for the treatment of AOS.

Porcine circovirus type 2 (PCV2) is the causative agent of porcine circovirus-associated disease (PCVAD). Porcine reproductive and respiratory syndrome (PRRS) is caused by PRRS virus (PRRSV). Both PCV2 and PRRSV have caused devastating diseases in the swine industry worldwide, resulting in immense economic losses. One of the most common co-infections in the swine industry is PCV2 and PRRSV. The aim of this dissertation research is to explore different experimental approaches to develop novel vaccines against the two major pathogens affecting swine production and study the basic mechanisms that may be involved in viral pathogenesis. Two types of porcine circovirus (PCV), PCV1 and PCV2, have been identified thus far. PCV1, first identified as a contaminant of the PK-15 cell line, is non-pathogenic and has a low prevalence in swine herds. PCV2 is highly prevalent in most swine-producing countries and is associated with clinical PCVAD. The non-pathogenic PCV1 shares similar genomic organization with PCV2. Previously, it has been demonstrated that a genetically modified infectious chimeric PCV1-2a virus can tolerate up to a 27 aa insertion in the C-terminus of the ORF2 without affecting infectivity and produce a dual immune response against PCV2cap and the inserted epitope tag. Therefore, we evaluated the use of the non-pathogenic PCV1 wild-type (wt) virus and chimeric PCV1-2a vaccine virus (vs) to express four known B-cell epitopes of PRRSV. Peptide epitopes of PRRSV-VR2385, including GP2II (aa 40–51, ASPSHVGWWSFA), GP3I (aa 61–72, QAAAEAYEPGRS), GP5I (aa 35–46, SSSNLQLIYNLT), and GP5IV (aa 187–200, TPVTRVSAEQWGRP) were inserted in frame into the C-terminus of the ORF2 of PCV1wt as well as the PCV1-2avs. Four PCV1-PRRSVEPI chimeric viruses and four PCV1-2a-PRRSVEPI chimeric viruses were successfully rescued and shown to be infectious in vitro and co-expressed PCV1cap or PCV2cap with each specific PRRSV epitope. Two independent animal studies were conducted to evaluate whether the non-pathogenic PCV1 can serve as a vaccine delivery vector and whether the PCV1-2a vaccine virus can be used to develop a bivalent vaccine against both PCV2 and PRRSV. We demonstrated that three PCV1-PRRSVEPI chimeric viruses and two PCV1-2a-PRRSVEPI chimeric viruses were infectious in pigs. Importantly, we demonstrated that the PCV1-PRRSVEPI and PCV1-2a-PRRSVEPI chimeric viruses not only induced specific PCV1 or PCV2 IgG antibody but also specific anti-PRRSV epitope antibody responses as well. Regardless of the PCV backbone used, we showed that the PCV-PRRSV chimeric viruses elicited neutralizing antibodies against PRRSV-VR2385. These results provided a proof of concept for the potential use of the non-pathogenic PCV1 as a vaccine delivery system for PRRSV or other swine pathogens and the use of PCV1-2a vaccine virus to generate a bivalent vaccine against both PCV2 and PRRSV. PRRSV causes a persistent infection and immunosuppression. Immunomodulation of the host immune system is caused by modulation of numerous interleukins, such as type I interferons, tumor necrosis factor alpha (TNF-α), interleukin-1 (IL-1), interleukin-6 (IL-6), and interleukin-12 (IL-12) in infected pigs. Antigen-presenting cells (APCs) are the first line of defense, and their infection plays an important role in innate-mediated immune regulation during early immune responses. Among the APCs, pulmonary alveolar macrophages (PAMs), pulmonary interstitial macrophages (PIMs), and dendritic cells (DCs) are the main targets for PRRSV replication. The role of PRRSV-DCs interaction is not fully understood, and current research focuses on the production and regulation of interferons through DC-SIGN receptors. In this study, we evaluated the immunomodulation of MoDCs by PRRSV through interactions with the pDC-SIGN receptor, by blocking pDC-SIGN with recombinant hICAM-3-Fc or anti-pDC-SIGN mAb. Our results indicate that recombinant hICAM-3-Fc enhances mRNA expression of proinflammatory cytokines and that anti-pDC-SIGN mAb inhibits mRNA expression of TNF-α and IL-1α and enhances the expression of IL-12 induced by PRRSV in MoDCs. The results will help understand the molecular mechanisms of PRRSV pathogenesis.
Ph. D.

Les maladies cardio-vasculaires et métaboliques représentent une proportion de plus en plus importante des facteurs réduisant la qualité et l’espérance de vie et entrainant une hausse vertigineuse des dépenses publiques dans le domaine de la santé. Cette augmentation est une des conséquences du vieillissement de la population dans nos sociétés occidentales ainsi que d’un changement marqué du mode de vie. Ce même phénomène touche également de plus en plus les pays en voie de développement. Devant cette urgence à remédier aux conséquences d’une telle explosion, la recherche des bases moléculaires de ces pathologies ainsi que de bio-marqueurs permettant d’augmenter leur prédictibilité représente une priorité. L’approche génétique, dans ce contexte, est une des voies les plus prometteuses. Cette approche présente de nombreuses variantes. Une des plus populaires dans la dernière décennie est l’approche des études d’association génome entier. La stratégie développée repose sur l’hypothèse d’un rôle important joué par variants génétiques fréquents pour des pathologies fréquentes. Ce paradigme a été nommé l’hypothèse de « Maladie fréquente, polymorphisme génétique fréquent » (« Common Variant / Common Disease »). Dans le cadre de ma thèse, j’explore l’effet de variants fréquents sur trois pathologies, le Diabète de Type 2, la Prolapsus Valvulaire Mitral, pathologies fréquentes et le Syndrome de Brugada, qui est rare dans la population. Ces trois pathologies présentent un poids important dans l’explosion des besoins sanitaires des populations, soit par la gravité des complications pour le Diabète de Type 2, soit par les besoins d’intervention chirurgicale lourde pour le Prolapsus Valvulaire Mitral ou enfin par le risque de Mort Subite inexpliquée pour le Syndrome de Brugada. J’ai appliqué différentes techniques génétiques que sont l’imputation, la méta-analyse et la correction de stratification afin de contribuer à mettre en évidence leurs bases génétiques. Dans le diabète de Type 2, la mise en évidence de l’architecture génétique était déjà bien avancée et j’ai participé à l’approfondissement de ces connaissances. Ces travaux ont permis de mettre en évidence jusqu’à 40 gènes associés après correction pour le nombre de tests. De façon important, nous avons montré qu’il existe une composante polygénique importante et que la plupart des gènes impliqués pointent vers un dysfonctionnement des cellules bêta. Les études sur le Prolapsus Valvulaire Mitral sont à un stade moins avancé. J’ai sélectionné des variants génétiques montrant une association possible et ces variants sont en cours de réplication. Les résultats préliminaires sur l’étude Framingham montrent la possible implication de gènes de la matrice extracellulaire. Enfin, pour le Syndrome de Brugada, j’ai clairement identifié trois loci qui montrent une association très significative et ne laissant pas de place au doute. Ces loci ont été répliqués aussi bien dans une population Européenne que dans une population Japonaise. Si l’implication de gènes codant pour des canaux ionique est confirmée, une autre voie liée au développement cardiaque est également mise en évidence. Enfin, au cours de ma thèse, j’ai également contribué à faire apparaître la notion de variant fréquent pour pathologie rare, dans l’étude d’association portant sur le Syndrome de Brugada
The escalating prevalence of cardio-vascular and metabolic disorders, and the limitations of currently available preventive and therapeutic options are increasingly important factors reducing the quality and life expectancy resulting in a dramatic increase in public spending in the health field. This emergency highlights the need for a more complete understanding of the pathogenesis of these diseases as well as the need for bio-markers to increase their predictability is a priority. The genetic approach, in this context, is among the most promising strategies. This approach has many variants. One of the most popular in the last decade is the approach of genome-wide association studies. The strategy is based on the assumption of an important role played by common genetic variants for common diseases. This paradigm has been called the assumption of "common variant, common disease". As part of my thesis, I explored the effect of common variants in three diseases, Diabetes Type 2, Mitral Valvular Prolapse, both being common pathologies and the Brugada syndrome, which is rare in the population. These three diseases strongly contribute to the explosion of population health needs, either by the severity of complications for Type 2 Diabetes, through the need of major surgery for Mitral Valvular Prolapse and through the increased risk of Sudden Death for Brugada Syndrome. I applied various techniques such as genetic imputation, meta-analysis and correction of stratification to help highlight their genetic bases. In Type 2 diabetes, highlighting of the genetic architecture was already well advanced and I participated in the deepening of knowledge. This work helped identify up to 40 genes. We have also shown that there is a substantial polygenic component underlying the genetic architecture of this disease and that most of the identified genes point to a dysfunction of beta cells. Studies on Mitral Valvular Prolapse are less advanced. I selected genetic variants showing a possible association and these variants are being replicated. Preliminary results on the Framingham study showed the possible involvement of genes of the extracellular matrix. Finally, for Brugada Syndrome, I clearly identified three loci that show a highly significant association with the disease. These loci were replicated as well in a European population in Japanese population. If the involvement of genes coding for ion channel proteins (SCN5A and SCN10A) seems to be confirmed, strengthening the definition of Brugada Syndrome as a channelopathy, another pathway possibly related to cardiac development was also identified (through the gene HEY2). Finally, during my PhD, I also contributed to create the concept of common variant for rare disease (CV/CR)

Study of Gordon (PHAII) and Gitelman (GS) syndromes revealed the importance of the WNK pathway and thiazide-sensitive Na-Cl Cotransporter (NCC) in the renal control of blood pressure. PHAII mutations lead to WNK accumulation resulting in the hyperphosphorylation of the downstream effector, SPAK, which overactivates NCC causing salt retention and hypertension. Mutations causing deletion of exon-9 in Cullin-3, which normally ubiquitylates WNKs for degradation, were recently discovered to cause the severest subtype of PHAII (PHA2E) with early onset salt-sensitive hypertension and hyperkalaemia. The reasons for this severity have remained elusive, however clues came from SPAK knock-out mice which recapitulate GS, the phenotypic mirror image of PHAII, typically caused by activation-inhibiting NCC phosphorylation site mutations resulting in salt-wasting and hypotension. As these mice were also discovered to have reduced vascular tone, it suggests the WNK pathway may have extra-renal roles in vascular smooth muscle function and highlights inhibition of SPAK function as a promising anti-hypertensive strategy with multiple sites of action. To address these possibilities the work aimed to phenotype: (1) heterozygous CUL3$^{WT/\Delta403-459}$ mice to investigate a possible vascular contribution to PHAII pathophysiology, (2) homozygous knock-out mice of MO25, a master regulator known to increase SPAK activity up to 100-fold independent of WNKs, and (3) homozygous SPAK$^{L502A/L502A}$ knock-ins, predicted to have disrupted SPAK binding to WNK/NCC, in order to validate SPAK signalling inhibition as a viable anti-hypertensive strategy. In mice, the CUL3$^{\Delta403-459}$ proteins are hyperflexible, hypermodified and ultimately have reduced WNK ubiquitylation. This lead to hypertension, hyperkalaemia, hyperchloraemia with compensated metabolic acidosis and growth retardation, which closely recapitulates human PHA2E. The discovery of increased vascular tone suggests an explanation for the severity of CUL3$^{\Delta}$$^{ex9}$PHAII. In mice, homozygous MO25$\alpha$ knock-out proved embryonically lethal, while homozygous MO25$\beta$ knock-out did not meaningfully alter blood pressure or electrolyte homeostasis. However, the SPAK$^{L502A}$ protein had a decreased ability to bind WNKs and cation-chloride cotransporters NCC and NKCC1/2, serving to reduce their activation. SPAK$^{L502A/L502A}$ mice showed typical features of GS with mild hypokalaemia, hypomagnesaemia, hypocalciuria and salt-wasting hypotension. The mice also presented with decreased markers of vascular tone potentially due to effects on cardiovascular and neuronal NKCC1. These results show that SPAK binding is crucial for blood pressure control and pharmacological inhibition of this binding is an attractive anti-hypertensive strategy.

碩士
國立台北護理學院
聽語障礙科學研究所
98
Usher syndrome type II (USH2), an autosomal recessive disorder, is the most common type of User syndrome and characterized by congenital moderate to severe sensorineural hearing loss and progressive retinitis pigmentosa. Up to date, there are 4 loci associated with USH2. Defects in the USH2A gene have been responsible for most cases of USH2, but the locations and frequency of mutation sites are different between ethnicities. In this report, we screened the entire coding region of USH2A isoform B for a Taiwan family with 2 USH2 patients and 9 relatives by direct sequencing, and uncovered 17 different sequence variations, including 15 polymorphism sites and 2 novel mutations. Thirteen of 15 polymorphism sites have been reported in previous publications related to Eastern Asian populations and 2, c.997T>C and c.7448T>G, are novel. The 2 novel mutations, c.2187C>A (p.C729X) and c.13852delG (p.A4618fs), are compound heterozygotes in this family. Our results indicate that the mutation spectrum of USH2A gene among Taiwan population may differ from non-Eastern Asian populations. The finding of the report provides information not only for clinical diagnoses and follow up patients of this family in the future but also for the development of novel clinical diagnoses tools and therapies.

Trabalho de revisão do 6º ano médico com vista à atribuição do grau de mestre (área científica de genética) no âmbito do ciclo de estudos de Mestrado Integrado em Medicina.
Introdução: O Síndrome de Usher (USH) é uma doença autossómica recessiva caracterizada por um quadro de défice auditivo neurosensorial e retinite pigmentar, associado ou não a disfunção vestibular. USH é dividido em três tipos, sendo o USH tipo I o mais grave, caraterizado por surdez grave a profunda bilateral congénita, disfunção vestibular e retinite pigmentar diagnosticada durante a infância. Nas famílias com USH tipo I, MYO7A é o gene mais frequentemente mutado (50%). Este gene codifica para a proteína Miosina VIIa, previamente descrita como uma proteína motor de transporte e participando na formação da adesão célula a célula. Num estudo anterior foi encontrada uma nova alteração (c.4489G>C) no gene MYO7A num doente português com USH tipo I. Este trabalho propôs-se a avaliar a possibilidade de esta alteração ser responsável pelo fenótipo. Métodos: Uma avaliação clínica completa foi feita de forma a confirmar o fenótipo do doente. As análises por Sequenciação do exão 34 do gene MYO7A da amostra do doente e por PCR-RFLP das amostras do doente e de 250 indivíduos normais sem USH foram efetuadas para avaliar a presença da alteração c.4489G>C. Adicionalmente, foram realizados estudos in silico, usando software disponíveis online e a conservação evolutiva num grupo de primatas e não primatas. Finalmente, para determinar a expressão da alteração c.4489G>C nos transcritos do gene MYO7A, foram estudadas amostras de epitélio nasal do doente e de dois indivíduos normais. Resultados/Discussão: Foi confirmada a presença da variante c.4489G>C no doente com USH do tipo I e a sua ausência em 250 indivíduos normais. Os softwares online usados demostraram que a variante era lesiva, provavelmente deletéria ou causadora da doença. O estudo da conservação evolutiva demonstrou uma região altamente conservada no genoma e na proteína, em todas as espécies estudadas. Foi ainda possível identificar a expressão da variante c.4489G>C nos transcritos da amostra do doente e a sua ausência nas amostras dos indivíduos normais. Conclusão: Assim, foi possível concluir que a nova alteração c.4489G>C do gene MYO7A é uma mutação missense homozigótica, provavelmente responsável pelo USH do tipo I no doente português e que a sua expressão foi encontrada nos transcritos do epitélio nasal do doente. Usher syndrome (USH) is an autosomal recessive disorder characterized by the association of a sensorineural hearing impairment and retinitis pigmentosa, with or without vestibular dysfunction. USH is divided in three types, being USH type I the most severe form, characterized by severe to profound congenital and bilateral sensorineural hearing loss, congenital vestibular dysfunction and retinitis pigmentosa diagnostic during childhood. In USH type I families, MYO7A is the most commonly mutated gene (50%). This gene codes for Myosin VIIa protein, previously described as a motor transport protein and participating in the establishment of cell-cell adhesions. In a previous study, it was found a novel homozygous variant (c.4489G>C) in MYO7A gene in an USH type I Portuguese patient. This work purposed to appraise the possibility of this variant be responsible for the phenotype. A complete evaluation was performed to ascertain the clinical phenotype of the patient. Patient’s sample Sequencing analysis of MYO7A gene exon 34 and PCR-RFLP analysis of patient and 250 DNA samples from normal individuals without USH was accomplished to assess the c.4489G>C variant presence. Additionally, in silico studies using available internet software and evolutionary conservation in a group of primates and non-primates was performed. Finally, in order to determine if the c.4489G>C variant allele was expressed in MYO7A gene transcripts, nasal epithelium samples from the patient and two normal individuals were studied. The presence of c.4489G>C variant in an USH type I patient and its absence in 250 normal individuals was confirmed. Internet software used determined that this variant was probably damaging, deleterious or disease causing. Evolutionary conservation study showed a highly conserved region both in nucleotide and amino acid sequences from Homo sapiens to Molecular studies of a novel mutation in MYO7A gene in Usher Syndrome type I 13 Caenorhabditis elegans. Expression of c.4489G>C variant in patient’s cDNA sample was identified as well as its absence in the two normal individuals cDNA samples. In conclusion, this study revealed that the novel c.4489G>C MYO7A gene variant is a homozygous missense mutation, probably responsible for USH type 1 in a Portuguese patient and its expression found in patient’s nasal epithelium transcripts.

The role of omega-3 long chain polyunsaturated fatty acids (n-3 LCPUFA), in particular docosahexaenoic acid (DHA) in decreasing fat deposition, fat cell formation and improving insulin sensitivity in vitro and in adult animals had led to suggestions that increasing the supply of these fatty acids before birth could improve later metabolic health outcomes in the child. However, few studies had explored the role of DHA in programming of obesity and type 2 diabetes, and the results had been inconsistent. Furthermore, the mechanisms through which exposure to an increased supply of DHA during development impacted on later health outcomes in the infant were also unclear. While studies in animal models had highlighted the importance of epigenetics in the link between intrauterine nutrition and the subsequent risk of obesity and insulin resistance in the offspring, the role of whether epigenetics in the prenatal programming of obesity in humans was unknown. In addition, while there was evidence that placental alterations played a critical role in developmental programming, few studies had explored the effect of DHA on placental gene expression/function. The central aim of this thesis was to determine the effect of a specific nutritional intervention (maternal DHA supplementation) on (1) markers of metabolic health (BMI, percent body fat, insulin sensitivity) in the children at 5 years of age and (2) global and gene-specific DNA methylation profiles in children at birth and at 5 years of age. I also aimed to determine the effect of DHA on placental proliferation and gene expression in vitro. This thesis studied children born to women who participated in a large randomised controlled trial of n-3 LCPUFA supplementation in pregnancy, the DOMInO trial, at birth and 5 years of age. Insulin sensitivity in these children was estimated from the HOMA-IR index at 5 years of age. DNA was obtained from blood samples of the DOMInO children collected at birth (n=1012) and at 5 years of age (n=715) for the assessment of global and genome-wide methylation. A human placenta first trimester cell line (HTR8/SVneo) was treated with a DHA-rich emulsion in order to determine effects of DHA on placental proliferation and gene expression. Maternal DHA supplementation was associated with a reduced insulin sensitivity (increased HOMA-IR index) and increased fasting insulin concentrations in the children at 5 years of age, particularly in males. There were also small but significant differences in methylation of 44 genomic regions at birth and 30 at 5 years of age, and more differentially methylated regions (DMRs) in males compared to females at both time points. DHA treatment increased proliferation rate of HTR8/SVneo cells, and 96 genes were differentially expressed between DHA and no treatment groups. Overall, the results of this thesis provide evidence that maternal DHA supplementation may reduce insulin sensitivity in the children, although whether this translates into differences in the incidence of type 2 diabetes later in life remains to be determined. I also demonstrated that DHA has small but significant effects on DNA methylation of specific genomic regions, and significantly altered proliferation and gene expression of a placental cell line in vitro, which suggests that both epigenetic and placental modifications may be involved in mediating the effects of increased DHA exposure before birth on health outcomes in the child.
Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2015.

The mechanical contraction of the heart is tightly coupled to rapid and concerted electrical excitation of the cardiac muscle. This electrical activity is facilitated by a highly synchronized conduction system consisting of channels, pumps, and transporters that facilitate the flow of charged ions between cellular compartments, the cytoplasm, and the interstitial fluid between cells. The biophysical properties of these membrane proteins have been studied for many years, but their role in the generation of potentially lethal cardiac arrhythmias and their interactions with drugs remains an important field of research. The cardiac isoform of the voltage-gated Na+-channel, Nav1.5, has garnered widespread interest because of its role in the generation of electrical impulses in the cardiac myocyte, its association with congenital conduction disorders and acquired cardiac arrhythmias, and its unique pharmacological properties. The Congenital Long QT Syndrome Type 3 (LQT3) arises from heritable mutations in SCN5A - the gene encoding Nav1.5 - that disrupt the inactivation process responsible for imparting a refractory period and that often cause a sustained depolarizing late current (INaL). The gain of function depolarizing currents arising from LQT3 mutant channels cause a prolongation of the ventricular action potential and leave patients susceptible to asynchronous electrical activity, ventricular arrhythmias, and sudden cardiac death. The disruption of channel inactivation can arise through a wide range of modalities, including changes in inactivation voltage-dependence and kinetics, and has been shown to occur with varying degrees of severity. Because of this range of phenotypes there is heterogeneity in the risk factors for arrhythmia and sudden cardiac death and in the utility of Na+-channel blocking antiarrhythmic drugs. Moreover, INaL has been implicated as a proarrhythmic and potentiating factor in several acquired cardiac ailments including heart failure, ischemia, and hypertrophy. There is therefore a large unmet need for improved understanding of INaL and mechanisms of its selective inhibition, and LQT3 mutant channels provide a reliable experimental model for this class of cardiac arrhythmias. This study will employ a combination of electrophysiological and computational methods to unravel mechanisms by which mutant Nav1.5 produces pro-arrhythmic currents and the interactions of different disease-causing mutant channels with a set of clinically relevant antiarrhythmic drugs. Chapter 1 of this study presents a functional characterization of one LQT3 mutation, F1473C, that was discovered in a patient with severe QT prolongation, frequent ventricular arrhythmias, and a poor response to pharmacological intervention. This mutation gives rise to INaL by a mechanism that is functionally distinct from the mechanism discovered previously in the canonical LQT3 mutation, ΔKPQ (1505-1507del), and causes a unique response to channel inhibitors. In order to better understand the mechanisms of this divergent pharmacology, Chapter 2 presents the development of a series of computational models which explore the gating dysfunctions that cause INaL and how these pathological changes can influence the predicted safety and efficacy of pharmacological intervention. These models predict that the majority of mutation- specific drug effects can be attributed to differential mutant channel gating, but raise the possibility that mutations may directly alter the physical chemical interaction between drugs and channels. Finally, Chapter 3 presents an attempt to explore this possibility using an innovative chemical biology technique - the site-specific incorporation of unnatural amino acids - that allows for the measurement of precise chemical interactions hypothesized to vary in a mutation-dependent manner. The findings presented in this work promote the need for patient-specific screening of antiarrhythmic agents and lay the groundwork for the use of in silico systems analysis of cardiovascular pharmacology.

Calcium is a cation which plays a pivotal role as second messenger, thus its concentration in cells needs to be finely regulated. Many systems work for that purpose, including Ca2+ sensor proteins, which undergo conformational changes upon Ca2+ coordination via EF-hands. Ca2+ sensors can be ubiquitous or tissue specific. Examples in this sense are represented by Guanylate Cyclase Activating Protein 1 (GCAP1) and Calcium- and Integrin-Binding Protein 2 (CIB2), involved in sight and hearing respectively. Missense point mutations in GCAP1 and CIB2 were found to be associated with genetic diseases characterized by retinal dystrophies and/or deafness. During my PhD, I focused my attention on the characterization of two point mutations namely p.Glu111Val (E111V) in GCAP1, leading to Cone/Rod dystrophy in an Italian family, and p.Glu64Asp (E64D) in CIB2, linked to Usher syndrome type 1J (USH1J), a rare disease characterized by the copresence of blindness and deafness. In particular, I spent the first part of the PhD investigating the role of CIB2 which is still under debate, finding that it is per se uncapable to work as a Ca2+ sensor under physiological conditions and that the conservative mutation linked to USH1J perturbs an allosteric communication between pseudo-EF1 and EF3, thus blocking the protein in an unfunctional conformation. Then, I characterized E111V GCAP1, finding that it is incapable of regulating its molecular target (Guanylate Cyclase), leading to a constitutive active enzyme and thus a progressively high concentrations of Ca2+ and cGMP in cells, which may explain the pathological phenotype. Looking for a potential therapeutic approach for Cone-Rod dystrophies, we found that the well-established Ca2+-relay model, explaining the gradual activation of Guanylate Cyclase by multiple GCAP molecules following gradual changes in intracellular Ca2+ concentrations, seems to be species-specific, since it apparently does not work in the same way in humans as in mouse and bovine photoreceptors. Finally, we identified a general method for the characterization of the interaction between a ubiquitous Ca2+ sensor protein (calmodulin) and inorganic CaF2 nanoparticles, suggesting their suitability as devices for nanomedicine applications.

This thesis focuses on the effects of n-3 polyunsaturated fatty acids (n-3 PUFA) on development of non-alcoholic fatty liver disease (NAFLD) in experiment, on prevalence of this condition in patients with type 2 diabetes mellitus and metabolic syndrome and also on non-invasive diagnostics. The aim was to study the effect of n-3 PUFA on NAFLD development in an experimental model and based on analysis of a group of patients with type 2 diabetes and metabolic syndrome to assess the prevalence of this condition. Lastly we aimed to evaluate non-invasive diagnostic methods of liver fibrosis and NASH. We demonstrated beneficial effects of n-3 PUFA administration on NAFLD development in a C57/Bl6 mice high fat methionin-cholin defficient dietary model of NAFLD. n-3 PUFA administration led to biochemical improvement, decrease of lipid accumulation in the liver as well as improvement of histology. These effects are determined by complex modulation of lipid metabolism, mainly due to decrease in availability of fatty acids for triglyceride synthesis in the liver, changes of adipokine levels and amelioration of proinflammatory status in the liver. In a group of type 2 diabetics we found NAFLD prevalence of almost 80%, 14% of these patients had also signs of liver fibrosis or cirrhosis. Non-invasive methods...