Dynein is a motor protein complex that transports various types of intracellular cargos from the cell periphery towards the cell center. Dynein mutations are linked to several neurodegenerative diseases, including Charcot-Marie-Tooth disease (CMT). A mouse model of CMT was generated with a knock-in H304R dynein allele. This mutation at position 304 corresponds to the H306R mutation found in humans that can cause CMT. Here, a behavioral test was developed to study the onset and progression of CMT symptoms in these mice. In the tail suspension test, mice were suspended briefly by their tails and the posture of their hind limbs was scored. Wildtype mice spread their hind limbs outwards in a characteristic splayed posture, whereas heterozygous and homozygous mutants display abnormal phenotypes. In further investigation, the neuromuscular junctions of these mice were analyzed in order to understand the histological effects of the mutation and how the potential differences could result in the behavioral effects observed. The extent of neuromuscular junction innervation was examined along with the size and complexity of the neuromuscular junctions themselves through multiple criteria. This, when combined with the effects observed during the tail suspension behavioral test, seeks to establish the H304R mutant mouse as a successful model for CMT.

La myéline est une gaine formée par l’enroulement de la membrane plasmique de la cellule de Schwann autour de l’axone dans le nerf périphérique. Lorsque cette gaine est détruite, on parle de démyélinisation, cela provoque de nombreuses maladies, dont les maladies de Charcot Marie Tooth (CMT) de type 1. Les maladies CMT sont héréditaires et atteignent le système nerveux périphérique. Les symptômes communs incluent : une faiblesse musculaire, une démarche maladroite, des troubles de l’équilibre et des pieds très cambrés ou très plats. Le type le plus fréquent est la forme autosomique dominante CMT1A.Une duplication du bras court du chromosome 17 contenant le gène PMP22 (Peripheral Myelin Protein 22) induit la CMT1A. La PMP22, une petite protéine exprimée par les cellules de Schwann, est donc en excès et entraine une démyélinisation. Il existe un modèle de rats transgéniques PMP22 (ou rats CMT1A) mimant cette pathologie humaine. Les rats CMT1A surexpriment la pmp22 de souris de façon hétérozygote. Jusqu’à présent, aucun remède n’existe pour les maladies CMT. Un des traitements envisageables est la thérapie génique. Le but de mon projet de thèse était d’étudier la validité et l'efficacité de la thérapie génique chez les rats CMT1A. La stratégie consiste à réduire la surexpression de la protéine PMP22 chez le rat CMT1A à l’aide d’ARNsh anti-PMP22. Pour ne pas être détruits par l’organisme et maintenir une expression longue, ces ARN sh-PMP22 sont transférés chez le rat grâce à des vecteurs viraux dérivés de virus adéno-associés, ou AAV (pour adeno-associated virus). Nous avons donc injecté un des différents sérotypes d'AAV,l'AAV9 exprimant les ARN sh-PMP22 de souris ainsi que la GFP comme marqueur des cellules infectées dans les nerfs sciatiques de rats CMT1A à l’âge de 6 jours ou 7 jours.Nous avons d’abord confirmé que les virus thérapeutiques infectaient une très large proportion de cellules de Schwann dans le nerf sciatique de rat CMT1A et ensuite que l’infection de ces cellules par les virus exprimant les ARN sh-PMP22 induisait une diminution significative de l’expression de la protéine PMP22. L'analyse du phénotype moteur des rats CMT1A traités avec les AAV9 exprimant les ARN sh-PMP22 montre que les rats CMT1A traités ne développent pas la maladie observée dans les contrôles. Également, les rats CMT1A présentent une hypoalgésie, un phénotype qui n’apparait pas dans les CMT1A traités avec les vecteurs thérapeutiques. Le traitement par thérapie génique empêche la réduction de la vitesse de conduction nerveuse observé dans les rats malades. Concernant la biodistribution des virus, 2,5 mois après le traitement, en dehors des nerfs sciatiques ou les virus ont été injectés, le virus était présent dans les muscles qui entourent le nerf et aussi dans quelques ganglion dorsaux. Pour la réponse immunitaire,les rats injectés, à seulement 2 exceptions près, n’ont pas développé de facteurs neutralisants anti-AAV9. Cette thérapie génique pourrait être utilisée dans les essais cliniques.Avant de passer aux études cliniques pour le traitement de la maladie CMT1A à l’aide d’AAV9 exprimant des ARN sh-PMP22 humain, la dose d’expression de ce ARN sh-PMP22 doit être très soigneusement déterminée car si la PMP22 est trop réduite, une autre maladie peut se développer, la neuropathie héréditaire avec hypersensibilité à la pression. Il est aussi important d’avoir un outil bien adapté qui permet d’évaluer l’efficacité du traitement. Aucun existant n’est assez fiable pour mesurer la myéline du nerf périphérique. Pour remédier à ce manque, nous avons testé la technique d'imagerie Coherent Anti-stokes Raman Scattering (CARS) en caractérisant avec succès les défauts de la myéline. Par conséquent, le CARS est une technique prometteuse permettant d’évaluer l’avancement des maladies de la myéline et l’efficacité de nouvelles thérapies pour les neuropathies périphériques démyélinisantes. / Myelin, a tissue synthesized by Schwann cells, covers and protects nerves. If damaged, it causes many demyelinating diseases such as the inherited peripheral nervous system disorder Charcot Marie Tooth or CMT type 1. CMT neuropathies display a large variability from one patient to another. Nevertheless, the most common symptoms include muscle weakness, an awkward way of walking (gait), equilibrium problem and highly arched or very flat feet. The most common subtype of CMT is an autosomal dominant disorder known as CMT1A. CMT1A is caused by the duplication of the peripheral myelin protein 22 (PMP22) gene on the short arm of chromosome 17 (17p11.2) resulting in an excess of PMP22. This leads to demyelination. PMP22 is a small protein expressed by Schwann cells. There is still no cure for CMT diseases. One approach for a treatment is gene therapy. The aim of my thesis project was to deliver proof of principle for a gene therapy approach on a CMT1A rat model characterized by extra copies of mouse pmp22 gene (CMT1A rat). The treatment strategy consisted in reducing PMP22 overexpression in CMT1A rats with shRNA against PMP22. Viral vectors like adeno-associated virus (AAV having serotypes from1-10) are used to deliver shRNA in vivo so that they won’t be destroyed by the organism and for them to be long-lasting. Thus, we injected sciatic nerves of 6-7-day-old CMT1A rats with AAV9 expressing shRNA PMP22 with a GFP marker. We first confirmed that the virus highly transduced Schwann cells and that AAV9 shRNA PMP22 decreased PMP22 protein expression in CMT1A rats’ sciatic nerves. CMT1A rats treated with AAV9 shRNA PMP22 showed that they didn’t develop the motor phenotype seen in controls. Moreover, hypoalgesia observed in CMT1A rats was alleviated by treatment. In addition, gene therapy increased the reduced nerve conduction velocity found in CMT1A rats. Concerning safety, no viral off-targets were detected except in muscles close to the injection site (sciatic nerve) and in the dorsal root ganglions. Except for 2 rats, there was no immune response against AAV; no anti-AAV9 neutralizing factors. Consequently, this gene therapy could be used in clinical trials. Before moving to clinical studies, the minimal effective dosage should be very carefully defined because if PMP22 is completely deleted, another disease is caused: Hereditary Neuropathy with Pressure Palsies. It is also crucial to have a strong readout to evaluate the outcome of a treatment. However, no tool consistent enough exists for examining the peripheral nerve. Thus, we tested the label-free imaging technique Coherent Anti-stokes Raman Scattering (CARS) and successfully characterized myelination defects. Consequently, CARS could be used as a consistent outcome measure for developing new therapies for demyelinating peripheral neuropathies.

Entre as neuropatias periféricas hereditárias, a Doença de Charcot Marie Tooth (CMT) é a mais prevalente, sendo o Charcot Marie Tooth Lidado ao X tipo 1 (CMTX1) o segundo subtipo mais comum, causado por mutações no gene GJB1 e de herança ligada ao X. A sintomatologia de fraqueza, atrofia e alteração de sensibilidade progressiva, de padrão simétrico e distal é característica da CMT e, no CMTX1, o acometimento do sistema nervoso central pode estar associado ao quadro típico. Com relação à eletroneurofisiologia, há redução dos parâmetros de velocidade de condução nervosa, com prolongamento da latência de onda F. Não há terapias modificadoras do curso da doença, sendo importante acompanhamento multidiciplinar a fim de assistir as possíveis deformidades, dando mais conforto e otimização das atividades de vida diária dos pacientes. O objetivo do presente estudo é relatar casos diagnosticados como CMTX1 atendidos pelo ambulatório de Neurogenética do Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo (HCFMRP-USP) e comparar aos dados da literatura pertinente. Os critérios de inclusão foram idade no atendimento abaixo de 17 anos e 11 meses e confirmação do CMTX1 por exame genético molecular, com mutação em GJB1. Assim, foram encontradas quatro crianças, três do sexo feminino e uma do masculino, com idade variando de 3 a 17 anos, sendo que em dois deles foi observado atraso na marcha independente. Os sinais clínicos e eletroneuromiográficos observados foram concordantes com a literatura, exceto por não apresentarem sinais de acometimento do sistema norvoso central (SNC) associados. A presença de atraso na marcha e surgimento de casos precoces suscita a necessidade de protocolo adequado para crianças no primeiro e segundo anos de vida; 1. Anotar época de aparecimento e duração do movimento de levantar-se e postura ereta ou não do tronco ao se manter sentado. 2. Tipo do engatinhar. 3. Idade em meses no início de sentar e andar com e sem apoio. 4. Análise da funcionalidade manual, motricidade fina com auxílio de testes da especialidade em terapia ocupacional, desde os primeiros meses. 5. Tipo de marcha e época de início da marcha. 6. Reflexos fásicos - evolução - com atenção especial aos aquilianos, que são os mais precocemente acometidos. 7. Verificação de clônus de tornozelo, no sentido de detecção de sinais de espasticidade. Para crianças maiores de 3 anos de idade: 1. Início do uso de chinelo (capacidade de reter o chinelo nos pés - desenvolvimento da propriocepção). 2. Verificação do equilíbrio estático e dinâmico de acordo com Lefèvre (1972), nas faixas etárias de 3 a 7 anos. / Among the hereditary peripheral neuropathies, Charcot-Marie-Tooth disease (CMT) is the most prevalent, being the second most common the subtype CMTX1, caused by mutations in the GJB1 gene and producing a X-linked inheritance. The symptoms of symmetrical and distal weakness, atrophy and progressive sensory changes, are characteristics of the CMT and in the CMTX1 central nervous system involvement is often associated with the typical picture. With respect to eletroneurophysiology, there is reduction of nerve conduction velocity parameters, with extension of F wave latency. There is no modifier therapies of the course of the disease, being important, multidisciplinary monitoring to assist the possible deformities, giving more comfort and optimization of daily life activities of patients. The main objective of this study is to report cases diagnosed as CMTX1 by Neurogenetics Clinic of the Hospital of Clinics of the School of Medicine at Ribeirão Preto, São Paulo University (HCFMRPUSP) and to compare the data from the relevant literature. Inclusion criteria were age in attendance below 17 years and 11 months and CMTX1 confirmation by genetic testing, mutation GJB1. Four children were included, three female and a male, with age ranging from 3 to 17 years. Two of them presented late onset of independent walking. Clinical and eletroneuromiographics finds resulted similar to that observed in the literature, except for the absence of clinical signs of CNS involvement. The presence of delay for independent walking raises the need for proper protocol for children in the first and second years of life: 1. Time of onset (age) and duration of motion to lift from a horizontal position and upright posture of trunk to keep sitting. 2. Type of crawl. 3. Age in months earlier to sit and walk with and without support. 4. Analysis of manual functionality, fine motricity with specialty tests in occupational therapy, since the first few months age. 5. Type of gear when he or she begins to walk with support, and then, without support, the use of the heels. 6. Stretch Reflex - evolution - with special attention to the aquileus, that are the most affected early. 7. Ankle clonus checking, aimed to detecting signs of spasticity. For children after 3 years of age: 1. Initiation of the use of slippers (ability to retain the slippers on the feet - proprioception development). 2. Verification of static and dynamic balance according to Lefèvre (1972), in the age groups from 3 to 7 years.

Entre as neuropatias periféricas hereditárias, a Doença de Charcot Marie Tooth (CMT) é a mais prevalente, sendo o Charcot Marie Tooth Lidado ao X tipo 1 (CMTX1) o segundo subtipo mais comum, causado por mutações no gene GJB1 e de herança ligada ao X. A sintomatologia de fraqueza, atrofia e alteração de sensibilidade progressiva, de padrão simétrico e distal é característica da CMT e, no CMTX1, o acometimento do sistema nervoso central pode estar associado ao quadro típico. Com relação à eletroneurofisiologia, há redução dos parâmetros de velocidade de condução nervosa, com prolongamento da latência de onda F. Não há terapias modificadoras do curso da doença, sendo importante acompanhamento multidiciplinar a fim de assistir as possíveis deformidades, dando mais conforto e otimização das atividades de vida diária dos pacientes. O objetivo do presente estudo é relatar casos diagnosticados como CMTX1 atendidos pelo ambulatório de Neurogenética do Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo (HCFMRP-USP) e comparar aos dados da literatura pertinente. Os critérios de inclusão foram idade no atendimento abaixo de 17 anos e 11 meses e confirmação do CMTX1 por exame genético molecular, com mutação em GJB1. Assim, foram encontradas quatro crianças, três do sexo feminino e uma do masculino, com idade variando de 3 a 17 anos, sendo que em dois deles foi observado atraso na marcha independente. Os sinais clínicos e eletroneuromiográficos observados foram concordantes com a literatura, exceto por não apresentarem sinais de acometimento do sistema norvoso central (SNC) associados. A presença de atraso na marcha e surgimento de casos precoces suscita a necessidade de protocolo adequado para crianças no primeiro e segundo anos de vida; 1. Anotar época de aparecimento e duração do movimento de levantar-se e postura ereta ou não do tronco ao se manter sentado. 2. Tipo do engatinhar. 3. Idade em meses no início de sentar e andar com e sem apoio. 4. Análise da funcionalidade manual, motricidade fina com auxílio de testes da especialidade em terapia ocupacional, desde os primeiros meses. 5. Tipo de marcha e época de início da marcha. 6. Reflexos fásicos - evolução - com atenção especial aos aquilianos, que são os mais precocemente acometidos. 7. Verificação de clônus de tornozelo, no sentido de detecção de sinais de espasticidade. Para crianças maiores de 3 anos de idade: 1. Início do uso de chinelo (capacidade de reter o chinelo nos pés - desenvolvimento da propriocepção). 2. Verificação do equilíbrio estático e dinâmico de acordo com Lefèvre (1972), nas faixas etárias de 3 a 7 anos. / Among the hereditary peripheral neuropathies, Charcot-Marie-Tooth disease (CMT) is the most prevalent, being the second most common the subtype CMTX1, caused by mutations in the GJB1 gene and producing a X-linked inheritance. The symptoms of symmetrical and distal weakness, atrophy and progressive sensory changes, are characteristics of the CMT and in the CMTX1 central nervous system involvement is often associated with the typical picture. With respect to eletroneurophysiology, there is reduction of nerve conduction velocity parameters, with extension of F wave latency. There is no modifier therapies of the course of the disease, being important, multidisciplinary monitoring to assist the possible deformities, giving more comfort and optimization of daily life activities of patients. The main objective of this study is to report cases diagnosed as CMTX1 by Neurogenetics Clinic of the Hospital of Clinics of the School of Medicine at Ribeirão Preto, São Paulo University (HCFMRPUSP) and to compare the data from the relevant literature. Inclusion criteria were age in attendance below 17 years and 11 months and CMTX1 confirmation by genetic testing, mutation GJB1. Four children were included, three female and a male, with age ranging from 3 to 17 years. Two of them presented late onset of independent walking. Clinical and eletroneuromiographics finds resulted similar to that observed in the literature, except for the absence of clinical signs of CNS involvement. The presence of delay for independent walking raises the need for proper protocol for children in the first and second years of life: 1. Time of onset (age) and duration of motion to lift from a horizontal position and upright posture of trunk to keep sitting. 2. Type of crawl. 3. Age in months earlier to sit and walk with and without support. 4. Analysis of manual functionality, fine motricity with specialty tests in occupational therapy, since the first few months age. 5. Type of gear when he or she begins to walk with support, and then, without support, the use of the heels. 6. Stretch Reflex - evolution - with special attention to the aquileus, that are the most affected early. 7. Ankle clonus checking, aimed to detecting signs of spasticity. For children after 3 years of age: 1. Initiation of the use of slippers (ability to retain the slippers on the feet - proprioception development). 2. Verification of static and dynamic balance according to Lefèvre (1972), in the age groups from 3 to 7 years.

Spinal muscular atrophy (SMA) and Charcot-Marie-Tooth disease type 2D (CMT2D)/distal SMA type V (dSMAV) are two incurable neuromuscular disorders that predominantly manifest during childhood and adolescence. Both conditions are caused by mutations in widely and constitutively expressed genes that encode proteins with essential housekeeping functions, yet display specific lower motor neuron pathology. SMA results from recessive inactivating mutations in the survival motor neuron 1 (SMN1) gene, while CMT2D/dSMAV manifests due to dominant point mutations in the glycyl-tRNA synthetase (GlyRS) gene, GARS. Using a number of different model systems, ranging from Caenorhabditis elegans to the mouse, this thesis aimed to identify potential novel therapeutic compounds for SMA, and to increase our understanding of the mechanisms underlying both diseases. I characterised a novel C. elegans allele, which possesses a point mutation in the worm SMN1 orthologue, smn-1, and showed its potential for large-scale screening by highlighting 4-aminopyridine in a screen for compounds able to improve the mutant motility defect. Previously, the gene encoding three isoforms of chondrolectin (Chodl) was shown to be alternatively spliced in the spinal cord of SMA mice before disease onset. I performed functional analyses of the three isoforms in neuronal cells with experimentally reduced Smn levels, and determined that the dysregulation of Chodl likely reflects a combination of compensatory mechanism and contributor to pathology, rather than mis-splicing. Finally, working with two Gars mutant mice and a new Drosophila model, I have implicated semaphorin-plexin pathways and axonal guidance in the GlyRS toxic gain-of-function disease mechanism of CMT2D/dSMAV.