Le Téléthon est un format adapté avec succès à la télévision française par le binôme Groupe France Télévisions – Association française contre les myopathies depuis 1987, et à la télévision mexicaine depuis 1997 par le groupe de télévision Televisa, membre de la Fundación Teletón mexicaine. Le sujet de cette thèse porte sur la comparaison de l’adaptation de ce format qui est reproduit annuellement en différentes parties du monde, en se focalisant sur ces deux cas précis et leur contexte. Pour la réaliser, le corpus hétérogène est composé principalement d’une expérience sur le terrain, du matériel audiovisuel des émissions diffusées en 2006, et de deux publications officielles et commémoratives du Téléthon. Cette recherche se fonde sur le regard du chercheur comparatiste et démontre sa prise de conscience de sa subjectivité lors de l’interprétation. L’étude comparée s’installe alors dans un cadre conceptuel afin de comprendre l’Autre et ainsi de mieux définir le Téléthon dans sa complexité. Chacune des émissions est analysée séparément pour montrer ce que le format offre actuellement à la visibilité du handicap. S’inspirant de la Déclaration universelle de l’UNESCO sur la diversité culturelle, adoptée en 2001, le dialogue agit alors comme une condition majeure tout au long de l’étude, et, par conséquent, introduit un débat à partir des apports de la télévision sur la santé publique. Finalement, on verra que le Téléthon se retrouve corrélé avec la lutte contre la maladie parmi d’autres collectes et qu’il concerne l’éducation pour la santé / The Telethon is a program that has been successfully adapted to French television by the tandem of Groupe France Télévisions – Association française contre les myopathies (French Muscular Dystrophy Association) since 1987, and to Mexican television since 1997 by the Televisa television group, which is a member of the Mexican Fundación Teletón. This thesis compares the adaptation of this format that is repeated annually in various parts of the world, and focuses on these two specific cases and their contexts. To accomplish this, the heterogeneous support was mainly composed of experience in the field, audio-visual material from the programs broadcast in 2006, and two official publications to commemorate the Telethon. This research is based on the comparing researcher's views and highlights her awareness of her subjectivity in its interpretation. This comparative study is thus part of a conceptual framework in order to understand the Other and consequently to define the complexity of the Telethon more clearly. Each of the programs is individually dissected to show what the format currently offers for the visibility of the handicap. Inspired from the UNESCO universal declaration on cultural diversity that was adopted in 2001, the dialogue thus intervenes as a major condition throughout the study and as a result introduces into the debate the contribution of the television to public health. Finally, it can be seen that the Telethon is correlated with the combat against the illness among the other fundraising events and that it also concerns health education

La myopathie myotubulaire est une maladie musculaire congénitale très sévère. Le laboratoire d’accueil a démontré que les échantillons de muscle de patients atteints de cette maladie ainsi que le modèle murin présentent une surexpression de DNM2, alors que sa réduction par croisement génétique améliore les signes cliniques et histologiques de la maladie. Le but de ce travail consistait à développer, tester et valider des composés injectables qui ciblent DNM2 et diminuent son niveau. Deux approches thérapeutiques ont été développées l’une basée sur l’utilisation de virus adéno-associés (AAV) exprimant des shRNA, l’autre sur les oligonucleotides antisens (ASO). L’injection des vecteurs AAV-shDnm2 ou bien les ASO-Dnm2 pouvait corriger les défauts histologiques et fonctionnels des muscles des souris myopathes.Les résultats obtenus montrent le potentiel thérapeutique de la réduction de DNM2, et présente une nouvelle approche pour le traitement de la myopathie myotubulaire. / Myotubular myopathy is a severe muscle disease. We previously have shown that muscle specimens of both patients and the mouse model presented an overexpression of DNM2, while its genetic reduction prevents the development of the muscle phenotypes. The aim of this work was to develop, test and validate deliverable compounds. Two therapeutic approaches were used. Injection of antisense oligonucleotide or adeno-associated virus expressing shRNA restores a normal lifespan with improved muscle structure and function of the myopathic mice. These results demonstrate that therapeutic potential of reduction of DNM2 level and provides an attractive therapeutic strategy that could be applied to treat myotubular myopathy.

Le muscle squelettique a la capacité de se régénérer suite à une lésion grâce aux cellules satellites qui sont les cellules souches du muscle. Après dommage musculaire, les cellules satellites s’activent, prolifèrent, se différencient et fusionnent afin de reformer le muscle lésé. Cependant les cellules myogéniques ne sont pas les seules cellules impliquées dans la régénération musculaire. Des études précédentes réalisées au laboratoire ont montré chez la souris que les macrophages sont des cellules essentielles à la régénération musculaire. En effet, peu de temps après un dommage musculaire, les monocytes infiltrent le tissu lésé et se différencient en macrophages pro-inflammatoires Ly6Cpos (M1). Ces macrophages stimulent la prolifération des myoblastes et inhibent leur fusion. Puis les macrophages pro-inflammatoires changent de phénotype et deviennent des macrophages anti-inflammatoires Ly6Cneg (M2) qui stimulent la différenciation des myoblastes et les protègent de l’apoptose. Ainsi, en fonction de leur phénotype, les macrophages exercent des rôles trophiques séquentiels sur les myoblastes tout au long du processus de régénération musculaire. Dans la première partie de notre étude, nous montrons in vitro que les macrophages humains soutiennent les différentes étapes de la myogenèse. Les macrophages M1 sont fortement attirés par les myoblastes. De plus ils stimulent la prolifération des myoblastes et inhibent leur fusion. Les macrophages M2 attirent les myoblastes et stimulent leur différenciation permettant ainsi la formation de larges myotubes. En utilisant des anticorps bloquants spécifiques, nous avons identifié plusieurs molécules sécrétées par les macrophages régulant la myogenèse chez l’homme. Nos analyses in vivo chez l'homme confirment nos résultats obtenus in vitro. En effet, les macrophages M1 sont préférentiellement associés aux aires de régénération contenant des myoblastes non différenciés alors que les macrophages M2 sont associés aux aires de régénération contenant des myoblastes en différenciation. Dans un contexte de myopathie dégénérative, nous avons montré que les macrophages adoptent des phénotypes et des fonctions totalement différents des macrophages présents au cours de la régénération musculaire. Nous avons observé chez la souris et chez l’homme, que les macrophages exprimant des marqueurs M1 sont associés à la fibrose et qu’un traitement anti-inflammatoire réduit leur nombre dans le muscle dystrophique murin. Par isolement spécifique et cocultures ex vivo, nous avons montré qu'au cours de la régénération musculaire, les macrophages Ly6Cneg stimulent la production de collagène par les fibroblastes. A l'inverse au cours des myopathies dégénératives, ce sont les macrophages Ly6Cpos qui stimulent fortement l’établissement de la fibrose en agissant directement sur les fibroblastes. De plus, ces macrophages Ly6Cpos, qui régulent négativement les fibroblastes au cours de la régénération musculaire, stimulent la différenciation des fibroblastes et myofibroblastes dans les myopathies. De plus, ils les protègent de l'apoptose, participant ainsi à la persistance de ces cellules fibrosantes. Ainsi, nous avons confirmé chez l’homme in vitro et in vivo, le rôle de support séquentiel des macrophages au cours de la régénération musculaire. De plus, nous avons identifié différents effecteurs sécrétés par les macrophages M1 et M2 impliqués dans la régulation du processus myogénique chez l'adulte. Nous avons également montré que lors des myopathies dégénératives et au cours de la régénération musculaire, les macrophages adoptent un phénotype et des fonctions totalement différents, avec notamment un rôle profibrotique des macrophages pro-inflammatoires. / Skeletal muscle has the ability to regenerate after a chemical or physical injury thanks to satellite cells, the muscle stem cells. After damage, satellite cells proliferate, differentiate and fused to reform muscle. Myogenic cells are not the only on cells involved. Previous studies in the laboratory showed that, in mice, macrophages are crucial for skeletal muscle regeneration. Soon after an injury, macrophages infiltrate damaged muscle and differentiate into Ly6Cpos pro-inflammatory (M1) macrophages. They stimulate proliferation of myoblasts and inhibit their fusion. Then, pro-inflammatory macrophages skew towards a Ly6Cneg anti-inflammatory phenotype (M2). Anti-inflammatory macrophages stimulate differentiation of myoblasts and protect them from apoptosis. Thus, depending on their phenotype, macrophages exert sequential trophic roles on myoblasts throughout muscle regeneration. Here, we showed in vitro that human macrophages also support different steps of myogenesis. M1 macrophages are strongly attracted by mpcs. Moreover, they secrete molecules, which stimulate proliferation of mpcs and inhibit their fusion. M2 macrophages attract mpcs and stimulate differentiation of mpcs in order to form large myotubes. Using specific blocking antibodies, we identified molecules involved in the regulation of myogenesis by M1 and M2 macrophages in a human in vitro system. In vivo analysis of regenerating human muscle sections confirmed our results obtained in vitro. M1 macrophages are preferentially associated with proliferating myogenic cells while M2 macrophages are associated with differentiating myogenic cells. In degenerative myopathies, we showed that macrophages are completely different from those present during skeletal muscle regeneration. We observed in mouse and human that M1 marker-expressing macrophages are associated with fibrosis while anti-inflammatory treatment reduced this population, in association with an improvement of the dystrophic muscle. Isolated Ly6Cneg macrophages exhibit a mixed M1/M2 phenotype. In ex-vivo coculture experiments, we showed that Ly6Cpos macrophages strongly favor establishment of fibrosis by directly acting on fibroblasts while in regenerating muscle, these Ly6Cpos macrophages negatively regulate fibrosis. To resume, we confirm in human the supportive sequential roles of macrophages during skeletal muscle regeneration in vitro and in vivo. Moreover, we identified effectors secreted by M1 and M2 macrophages involved in the regulation of the myogenic process. We also highlight that during muscle regeneration and in degenerative myopathies, macrophages exhibit different phenotype associated with opposite functions, with a pro-fibrotic role for pro-inflammatory macrophages.

Myofibrillogenesis is a complex process, which involves assembly of hundreds of structural proteins in a highly ordered manner to form the contractile structural unit of muscle, the sarcomere. Several myopathic conditions reported in humans are caused due to abnormal myofibrillogenesis owing to mutations in the genes coding for many of these structural proteins. These myopathies have highly variable clinical features and time of onset. Since their aetiology is poorly understood, it becomes imperative to have a model system to study the muscle defects. Present study proposes to employ the Indirect Flight Muscle (IFM) system in Drosophila melanogaster as a model to analyse the development/onset of some of these myopathies and resulting pathophysiology. We have carried out a systematic study on mutations in two major proteins of the sarcomere, actin and myosin, to understand the pathophysiology associated with the disease conditions and in turn gain insights into the process of myofibrillogenesis. To verify whether the human muscle phenotypes are observed in flies, we analysed the IFM for functional and structural defects categorised by the presence of aberrant sarcomeric structures. An important question that we have addressed is whether mutants of the Drosophila IFM recapitulate human conditions and whether it can serve as a good genetic model to study the developmental mechanisms of the human skeletal myopathies in vivo. Mutations of the human ACTA1 skeletal actin gene produce seven congenital myopathies – actin myopathy, nemaline rod myopathy, intranuclear rod myopathy, congenital fibre type disproportion, congenital myopathy with core-like areas, cap disease and zebra body myopathy. Four known mutations in Act88F—a Drosophila homologue of ACTA1—occur at the same actin residues mutated in ten ACTA1 nemaline mutations, A138D/P, R256H/L, G268C/D/R/S and R372C/S. These Act88F mutants were examined for muscle phenotypes with nemaline structures. Mutant homozygotes show phenotypes ranging from lack of myofibrils to almost normal sarcomeres at eclosion. Whereas, heterozygotes do allow myofibrillar assembly to certain extent; however, atypical structures are seen adjacent to normal sarcomeres. Aberrant Z disc-like structures and serial Z disc arrays, ‘zebra bodies’, are observed in homozygotes and heterozygotes of all the four Act88F mutants. The electron-dense structures observed in electron micrographs show homologies to human nemaline bodies/rods, but are much smaller than those typically found in the human myopathy. A possible mechanism for the ‘zebra bodies’ is proposed based on this study. Analysis of IFM at early developmental stages shows that in three of the mutants, there is an abnormal myofibril assembly leading to malformed sarcomeres mirrored in the adult stages. In one of the Act88F mutants, normal myofibrils are seen post-eclosion but the IFM show activity dependant progression of muscle degeneration. All the Act88F mutants produce dominant disruption of muscle structure and function which cannot be rescued even by three copies of the wild type Act88F gene implying that the mutants are strong antimorphs. Myosin myopathies are a group of human muscle diseases with heterogeneous clinical features and are caused by mutations in the skeletal muscle myosin heavy chain. We identified two chemical mutagen generated flightless mutants, Ifm(2)RU1 and ifm(2)RU2 that map closely to myosin heavy chain gene (Mhc) region. Since there are no structural proteins predicted in the mapped region, it was likely that these two are Mhc mutations. We show that Ifm(2)RU1 and ifm(2)RU2 are indeed Mhc mutations and the molecular aberrations affect amino acid residues present in the myosin rod region. Human muscle myosin heavy chain (MyHC) mutations that cause Laing early onset distal myopathy and myosin storage myopathy occur in this domain of the protein. Even though mutations lie in the same region of myosin rod, Ifm(2)RU1 is semidominant, whereas ifm(2)RU2 is recessive. Both the mutants show IFM defects and the presence of abnormal myofibrils. Mutant myofibrillar structures can be rescued with an additional wild type Mhc gene copy. However, the restored myofibrillar structure is incapable of rescuing the flight ability of mutants. The muscle phenotypes are due to defects in thick filament assembly which manifest from the early stages of sarcomere development. The MHC protein rod region is an α-helix that forms coiled-coils which further self assemble to form thick filaments or aggregates as observed in in vitro conditions. Biophysical and biochemical analyses reveal that the coiled-coil structure of mutant rods is not affected, however the thermodynamic stability is altered in ifm(2)RU2 mutation. Interestingly, rod aggregate size and stability are not affected in mutant rods. The Drosophila MHC mutant rods were studied along with four MHC mutant rods that harbour human rod mutations to compare the molecular consequences. The Drosophila mutations do not hamper the rod structure and assembly. Therefore, the defects may arise due to altered interactions with myosin rod binding proteins. Flightin is an extensively studied myosin rod binding protein. The amount and phosphorylation status of flightin are an extremely sensitive measure of thick filament assembly. Flightin phosphorylation is affected in the mutants suggesting a functional dependence on MHC and it also indicates MHC instability. In the light of the work done, we have assessed the mutations with respect to their structure-functional implications. The acto-myosin interactions responsible for the defects are also discussed. Formation of unusual myofibrillar structures are analysed with regards to the process of myofibrillogenesis. An understanding of this entire process with the information available from IFM is reviewed in detail. The work so far has helped in understanding the manifestation of myopathies at tissue/cellular levels with insights into the plausible mechanisms of origin of the disease phenotypes. Myopathic condition may arise due to developmental or functional defects. For therapeutic considerations, the fly provides a simple test to inspect the effects of adding extra copies of the wild type gene. We conclude that the Drosophila IFM provide a good model system for the study of human ACTA1 and MyHC myopathies.

Novas abordagens terapêuticas vêm sendo introduzidas para doenças musculares genéticas como distrofias musculares e miopatias congênitas, distúrbios que permanecem sem cura até o momento. Estes recentes avanços motivaram um interesse renovado e crescente por métodos não invasivos para a caracterização e monitoramento do músculo afetado, particularmente durante e após intervenções terapêuticas. Neste contexto, modelos animais são essenciais para uma melhor compreensão dos mecanismos das doenças e para testar novas terapias. Recentemente, avanços significativos na avaliação não invasiva de modelos murinos para doenças musculares genéticas foram alcançados. Entretanto, diversas linhagens de camundongos ainda não foram caracterizadas de maneira não invasiva, e ainda é necessário o desenvolvimento de métodos sensíveis para a identificação precoce de alterações sutis no músculo de camundongos afetados. A proposta desta tese é aplicar técnicas não invasivas inovadoras no estudo do músculo de modelos murinos para doenças musculares genéticas com fenótipos variados. Três modelos murinos para distrofias musculares (mdx, Largemyd, mdx/ Largemyd) e um modelo murino para miopatia congênita (KI-Dnm2R465W) foram estudados com métodos de Ressonância Magnética Nuclear (RMN). Duas linhagens distróficas (Largemyd, mdx/ Largemyd) e camundongos normais após injúria foram estudados através de micro-Tomografia Computadorizada (micro-CT). Em RMN, todas as linhagens de camundongos afetados apresentaram aumento de T2 muscular, o que foi relacionado a diversas anomalias na análise histológica, como necrose e inflamação, mas também a conjuntos de fibras em regeneração ou a fibras com citoarquitetura alterada. A combinação de RMN com análise de textura permitiu a identificação não ambígua de todas as linhagens distróficas, sendo que apenas a comparação dos valores de T2 muscular não permitiu esta diferenciação. Camundongos mdx mostraram alterações funcionais e morfológicas na rede vascular do músculo. Estudo piloto em camundongos KI-Dnm2R465W revelou tendências de comprometimento da função muscular. Por fim, imagens de micro-CT não permitiram a detecção de diferenças na composição muscular em camundongos distróficos. Este conjunto de resultados não apenas enriquece o painel de modelos murinos para doenças musculares genéticas caracterizados de maneira não invasiva, mas também demonstra um certo grau de especificidade nas anomalias observadas nas imagens, como revelado pela análise de textura. Estes resultados também mostraram que métodos não invasivos de RMN podem ser suficientemente sensíveis para identificar alterações sutis no fenótipo muscular murino, mesmo em estágios precoces. Esta tese foi desenvolvida sob acordo de co-tutela internacional entre a França e o Brasil, e compreendeu uma importante transferência de conhecimento, com os primeiros estudos não invasivos de músculo murino realizados no Brasil. / Novel therapeutic approaches are being introduced for genetic muscle diseases such as muscle dystrophies and congenital myopathies, all of them having remained without cure so far. These recent developments have motivated a renewed and augmented interest in non-invasive methods for muscle characterization and monitoring, particularly during and after therapeutic intervention. In this context, animal models are essential to better understand the disease mechanisms and to test new therapies. Recently, significant advances in the non-invasive evaluation of mouse models for genetic muscle diseases have been achieved. Nevertheless, there were still several mouse strains not characterized non-invasively, and it was necessary to develop sensitive methods to identify subtle alterations in the murine affected muscle. The purpose of this thesis was to apply non-invasive techniques in the study of murine models for genetic muscle diseases with variable phenotypes. Three mouse models for muscle dystrophy (mdx, Largemyd, mdx/ Largemyd) and one mouse model for congenital myopathy (KI-Dnm2R465W) were studied with Nuclear Magnetic Resonance (NMR) methods. Two dystrophic strains (Largemyd, mdx/ Largemyd) and normal mice after injury were studied through micro-Computed Tomography (micro-CT). On NMR, all affected mouse strains presented increased muscle T2, which could be related to variable features in the histological evaluation, including necrosis and inflammation, but also to clusters of fibers under regeneration or with altered cytoarchitecture. The combination of NMR and texture analyses allowed the unambiguous differential identification of all the dystrophic strains, although it was not feasible when comparing the muscle T2 measurements only. Mdx mice showed functional and morphological alterations of vascular network. In the KI-Dnm2R465W mice, a pilot study revealed tendencies of functional impairment. Finally, micro-CT images were unable to detect differences in muscle´s content in dystrophic mice. Altogether, these results not only increased the number of murine models for genetic muscle diseases non-invasively characterized, it also demonstrated some degree of specificity of the imaging anomalies, as revealed by texture analysis. It also showed that non-invasive NMR methods can be sensitive enough to identify subtle alterations in murine muscle phenotype, even in early stages. This thesis was developed under an international joint supervision between France and Brazil, and comprised an important transfer of technology, with the first non-invasive studies of murine muscles performed in Brazil.

[Truncated abstract] Mutations in the skeletal muscle -actin gene (ACTA1) have been shown to be one cause of a broad group of muscle disorders all termed the congenital myopathies. Over 170 different mutations have now been identified across all 6 coding exons of ACTA1 in patients presenting with muscle weakness and any one or more of the following histopathological features: nemaline rods, intranuclear rods, fibre-type disproportion, excess of thin filaments and central cores. While the identification of the causative gene has been of great comfort for affected patients and their families, with pre-natal genetic testing becoming available, the ultimate aim is to develop a therapy for these disorders. Of the therapies currently being explored for the muscular dystrophies, up-regulation of an alternative gene seemed to be one of the most promising avenues for treatment of the ACTA1 diseases. Up-regulation of utrophin, the foetal homologue of dystrophin, has been shown to be a promising therapy for the treatment of Duchenne muscular dystrophy. The main aim of my research was to determine whether up-regulation of cardiac -actin, the predominant -actin expressed in foetal skeletal muscle and in the adult heart, could be used as a therapy for the ACTA1 diseases. A proof-of-concept experiment was performed whereby skeletal muscle -actin knock-out (KO) mice (all of which die by postnatal day 9) were crossed with transgenic mice over-expressing cardiac -actin (known as Coco mice) in postnatal skeletal muscle. ... While patients that are ACTA1 nulls have been identified in a number of mainly consanguineous populations, the majority of ACTA1 mutations result in dominant disease in which the mutant protein interferes with the function of the wild-type skeletal muscle -actin. Research described in this thesis also focuses on characterizing two transgenic mouse models of dominant ACTA1 disease at the ultra-structural, cellular and functional level; this is the first step towards a proof-of-concept experiment to determine whether cardiac -actin up-regulation can dilute out the pathogenesis of dominant ACTA1 disease. It has long been noted that patients with ACTA1 disease do not have ophthalmoplegia, even in the most-severely affected individuals. Protein analysis performed on extraocular muscle (EOM) biopsies obtained from humans, sheep and pigs showed that the EOMs co-express cardiac and skeletal muscle -actin, with cardiac -actin comprising 70 % of the striated -actin pool. Thus we propose that sparing of the EOMs in ACTA1 disease is at least in part due to cardiac -actin diluting out the pathogenesis associated with expression of the mutant skeletal muscle -actin. This finding provides further support for the hypothesis that dilution of mutant skeletal muscle -actin in dominant ACTA1 disease by up-regulation of cardiac -actin may be a viable therapy for this group of devastating muscle diseases. The research contained herein has advanced the understanding of the pathobiology of skeletal muscle -actin diseases and provides strong evidence in support of cardiac -actin up-regulation as a promising therapy for these diseases.

Introduction: Recent findings and better understanding to the pathogenesis of rheumatic diseases contributed to the development of biological therapies targeting cytokines and immune cells. Several S100 proteins exert cytokine-like effects and participate in the regulation of the inflammatory process. The aim of this work was to study the role of selected S100 proteins in the activity and in the pathogenesis of the rheumatic diseases. Results: Our data show for the first time an association of S100A4 proteinwith RA disease activity and decrease of the bioactive form, but not the total amount of S100A4, after aplication of tumour necrosis factor (TNF) blocking biologic therapy in patients with RA. We demonstrated that in vitro S100A4 acts as a potent pro-inflammatory mediator inducing production of TNFα, interleukin (IL)-1β and IL-6 in PBMCs via Toll-like receptor 4 (TLR-4), transcription factor NFκB and tyrosine kinases erk1/2 and p38. Moreover, S100A4 can play an important role in the pathogenesis of inflammatory myopathies. S100A4 is present in the inflammatory infiltrate of the affected muscles and in the regenerating muscles and may act as a cytokine-like factor indirectly promoting muscle fiber damage by stimulating mononuclear cells to increase the synthesis of pro-inflammatory cytokines. We...

Novas abordagens terapêuticas vêm sendo introduzidas para doenças musculares genéticas como distrofias musculares e miopatias congênitas, distúrbios que permanecem sem cura até o momento. Estes recentes avanços motivaram um interesse renovado e crescente por métodos não invasivos para a caracterização e monitoramento do músculo afetado, particularmente durante e após intervenções terapêuticas. Neste contexto, modelos animais são essenciais para uma melhor compreensão dos mecanismos das doenças e para testar novas terapias. Recentemente, avanços significativos na avaliação não invasiva de modelos murinos para doenças musculares genéticas foram alcançados. Entretanto, diversas linhagens de camundongos ainda não foram caracterizadas de maneira não invasiva, e ainda é necessário o desenvolvimento de métodos sensíveis para a identificação precoce de alterações sutis no músculo de camundongos afetados. A proposta desta tese é aplicar técnicas não invasivas inovadoras no estudo do músculo de modelos murinos para doenças musculares genéticas com fenótipos variados. Três modelos murinos para distrofias musculares (mdx, Largemyd, mdx/ Largemyd) e um modelo murino para miopatia congênita (KI-Dnm2R465W) foram estudados com métodos de Ressonância Magnética Nuclear (RMN). Duas linhagens distróficas (Largemyd, mdx/ Largemyd) e camundongos normais após injúria foram estudados através de micro-Tomografia Computadorizada (micro-CT). Em RMN, todas as linhagens de camundongos afetados apresentaram aumento de T2 muscular, o que foi relacionado a diversas anomalias na análise histológica, como necrose e inflamação, mas também a conjuntos de fibras em regeneração ou a fibras com citoarquitetura alterada. A combinação de RMN com análise de textura permitiu a identificação não ambígua de todas as linhagens distróficas, sendo que apenas a comparação dos valores de T2 muscular não permitiu esta diferenciação. Camundongos mdx mostraram alterações funcionais e morfológicas na rede vascular do músculo. Estudo piloto em camundongos KI-Dnm2R465W revelou tendências de comprometimento da função muscular. Por fim, imagens de micro-CT não permitiram a detecção de diferenças na composição muscular em camundongos distróficos. Este conjunto de resultados não apenas enriquece o painel de modelos murinos para doenças musculares genéticas caracterizados de maneira não invasiva, mas também demonstra um certo grau de especificidade nas anomalias observadas nas imagens, como revelado pela análise de textura. Estes resultados também mostraram que métodos não invasivos de RMN podem ser suficientemente sensíveis para identificar alterações sutis no fenótipo muscular murino, mesmo em estágios precoces. Esta tese foi desenvolvida sob acordo de co-tutela internacional entre a França e o Brasil, e compreendeu uma importante transferência de conhecimento, com os primeiros estudos não invasivos de músculo murino realizados no Brasil. / Novel therapeutic approaches are being introduced for genetic muscle diseases such as muscle dystrophies and congenital myopathies, all of them having remained without cure so far. These recent developments have motivated a renewed and augmented interest in non-invasive methods for muscle characterization and monitoring, particularly during and after therapeutic intervention. In this context, animal models are essential to better understand the disease mechanisms and to test new therapies. Recently, significant advances in the non-invasive evaluation of mouse models for genetic muscle diseases have been achieved. Nevertheless, there were still several mouse strains not characterized non-invasively, and it was necessary to develop sensitive methods to identify subtle alterations in the murine affected muscle. The purpose of this thesis was to apply non-invasive techniques in the study of murine models for genetic muscle diseases with variable phenotypes. Three mouse models for muscle dystrophy (mdx, Largemyd, mdx/ Largemyd) and one mouse model for congenital myopathy (KI-Dnm2R465W) were studied with Nuclear Magnetic Resonance (NMR) methods. Two dystrophic strains (Largemyd, mdx/ Largemyd) and normal mice after injury were studied through micro-Computed Tomography (micro-CT). On NMR, all affected mouse strains presented increased muscle T2, which could be related to variable features in the histological evaluation, including necrosis and inflammation, but also to clusters of fibers under regeneration or with altered cytoarchitecture. The combination of NMR and texture analyses allowed the unambiguous differential identification of all the dystrophic strains, although it was not feasible when comparing the muscle T2 measurements only. Mdx mice showed functional and morphological alterations of vascular network. In the KI-Dnm2R465W mice, a pilot study revealed tendencies of functional impairment. Finally, micro-CT images were unable to detect differences in muscle´s content in dystrophic mice. Altogether, these results not only increased the number of murine models for genetic muscle diseases non-invasively characterized, it also demonstrated some degree of specificity of the imaging anomalies, as revealed by texture analysis. It also showed that non-invasive NMR methods can be sensitive enough to identify subtle alterations in murine muscle phenotype, even in early stages. This thesis was developed under an international joint supervision between France and Brazil, and comprised an important transfer of technology, with the first non-invasive studies of murine muscles performed in Brazil.

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Les myopathies centro-nucléaires (CNM) sont un groupe de maladies musculaires sévères caractérisées par une faiblesse musculaire générale. La forme la plus sévère est la CNM liée à l’X (XLCNM), causée par des mutations de la Myotubularine (MTM1). D’autres formes autosomales existent et sont causées par des mutations de l’Amphiphysine2 (BIN1) et de la Dynamine2 (DNM2). Les mécanismes pathologiques menant aux CNMs restent à éclaircir et à ce jour aucune thérapie n’est disponible pour traiter les patients. Nous avons modulé les niveaux de protéines de MTM1, BIN1 et DNM2 dans des modèles murins de CNMs. Nous avons découvert que la sous-régulation de DNM2 sauvait le modèle murin de XLCNM et que la sur-expression de la protéine BIN1 humaine sauvait le modèle murin XLCNM ainsi que la forme autosomale causée par les mutations DNM2. Nous avons montré que MTM1 contrôlait l’adhésion cellulaire et le recyclage de l’intégrine dans les cellules musculaires. Nous avons observé que la sur-expression de BIN1 sauvait la dérégulation du recyclage de l’intégrine dans le modèle murin de XLCNM, ce qui suggère un lien fonctionnel entre BIN1 et MTM1 nécessaire pour l’adhésion focale au niveaux musculaire. Notre étude montre que MTM1, BIN1 et DNM2 participe à une voie de signalisation commune et que BIN1 et DNM2 représentent de nouvelles cibles thérapeutiques pour le traitement des CNM. / Centronuclear myopathies (CNM) are a group of severe muscle disorder characterized by general muscle weakness. The most severe form is the X-linked CNM (XLCNM), caused by mutations in Myotubularin (MTM1). Others autosomal forms are caused by mutations in Amphiphysin 2 (BIN1) and Dynamin 2 (DNM2). The CNM pathomechanisms are still unclear and to date there are no therapies available to the disease. To investigate the pathways dysregulated in CNM and to identify new therapeutic strategies, we modulated MTM1, BIN1 and DNM2 protein levels in the CNM mouse models. We discovered that DNM2 downregulation rescued the XLCNM mouse model and that the overexpression of human BIN1 rescued the XLCNM and the autosomal dominant CNM form due to DNM2 mutations. We have also showed that MTM1 controls cell adhesion and integrin recycling in mammalian skeletal muscle and BIN1 overexpression rescued the integrin recycling alteration in XLCNM mouse model suggesting that MTM1 and BIN1 are functionally linked and necessary for focal adhesions in muscle. Therefore, our studies highlight that MTM1, BIN1 and DNM2 are in a common pathway and, BIN1 and DNM2 could be new therapeutic targets to treat the different CNM forms.