A Distrofia Muscular de Duchenne (DMD) é uma doença neuromuscular, de origem genética ligada ao cromossomo X, lócus Xp21, causada por uma mutação do gene que codifica a proteína distrofina, responsável pela estabilidade do sarcolema. Na ausência / deficiência de distrofina, as células musculares são susceptíveis a danos pelos ciclos contínuos de degeneração e regeneração limitada. Inflamação, necrose e fibrose são características fisiopatológicas que levam à principal consequência da DMD, a perda de função muscular. Ocorre uma vez em cada 3000 - 3500 nascidos do sexo masculino. O camundongo mdx é um modelo distrófico amplamente utilizado na pesquisa devido à sua uniformidade genética, fácil manuseio e reprodução. Ainda não há cura da DMD, no entanto, os avanços na terapia de drogas usando glicocorticoides diminuem a progressão da doença. Posteriormente, foram estudadas terapias alternativas, dentre elas a terapia com ácido ursólico (AU). O AU é um composto natural da família triterpenóide que atua como um inibidor da atrofia muscular, aumentando a massa muscular e a força muscular. Com o objetivo de usar a AU como uma terapia alternativa, foi analisado seu efeito na suplementação diária em 20 mdx avaliados por 4 semanas. Após o tratamento foram realizadas medidas sérica de creatinofosfoquinase (CPK), teste de Kondziela para medir a força muscular, análise das citocinas fibrogênicas TNF-α e TGF-β e a histopatologia dos músculos extensor longo dos dedos (ELD), tibial cranial (TA) e diafragma (DIA). Como resultado, o grupo tratado com AU mostrou diminuição dos níveis de CPK e aumento significativo da força muscular, diminuição da expressão das citocinas TNF-α e TGF-β, maior regeneração muscular, estabilidade das fibras, indicando que o AU oferece uma proteção para as fibras musculares. / Duchenne muscular dystrophy (DMD) is a severe genetic neuromuscular disease, linked to the X chromosome, Xp21 locus, caused by a mutation of the gene that encodes the protein dystrophin, is responsible for the stabilization of sarcolemma. In the absence / dystrophin deficiency, muscle cells are susceptible to damage by the continuous cycles of degeneration and limited regeneration. Inflammation, necrosis and fibrosis are pathophysiological characteristics that lead to the main consequence of DMD, the loss of muscle function. It occurs once in every 3000 - 3500 live male births. The mdx mouse is a dystrophic model widely used in research due to its genetic uniformity, easy handling and reproduction. However, there is no DMD cure, however, advances in drug therapy using glucocorticoids decrease the progression of the disease. Subsequently, alternative therapies were studied, i.e. therapy with ursolic acid (UA). UA is a natural compound of the triterpenoid family that acts as an inhibitor of muscle atrophy, increasing muscle mass and strength. With the objective of using UA as an alternative therapy, the effect of daily supplementation at 20 mdx was evaluated for 4 weeks. After treatment were conducted measurements of serum creatine phosphokinase (CPK), Kondziela test to measure muscle strength, fibrogenic cytokine and histopathological analysis of the long extensor muscle (ELD), cranial tibialis (TA) and the diaphragm (DIA) muscles. As a result, the UA treated group showed decreased CPK levels, and increased muscle strength, decreased expression of TNF-α, TGF-β cytokines, greater muscle regeneration, fiber stability, indicating protection of muscle fibers to injury.

O objetivo do presente estudo foi avaliar a aptidão reprodutiva de cães da raça Golden Retriever afetados pela distrofia muscular. Realizou-se avaliações andrológicas em 11 cães com idades entre 10 meses e 4 anos. Destes, 7 eram afetados pela distrofia muscular e 4 sadios, utilizados como controle. Todos foram submetidos a exame clinico, análise seminal e ultra-sonografia dos órgãos reprodutores. Analisou-se também a morfologia dos testículos e seus respectivos funículos espermáticos dos cães que foram a óbito. Detectou-se as seguintes alterações nos cães afetados pela distrofia: atrofia muscular, andar rígido, pneumonia por aspiração, fragilidade do diafragma com projeção do estomago para a cavidade torácica, megaesôfago e cardiomiopatia dilatada. Em relação aos órgãos genitais dois dos cães apresentaram criptorquidismo bilateral. Os resultados das análises seminais mostraram que os cães afetados pela distrofia possuem maior quantidade de defeitos espermáticos maiores e totais. Nas avaliações ultra-sonográficas não foram identificadas diferenças entre os cães afetados pela distrofia quando comparados com cães sadios. As análises histopatológicas evidenciaram alterações morfológicas nos testículos e músculos cremáster de cães afetados pela doença. Os testículos apresentaram degeneração testicular e o músculo cremáster retração de fibras musculares com hialinizacao dos miócitos. Conclui-se então que a distrofia muscular em cães da raça Golden Retriever pode comprometer sua aptidão reprodutiva. / The aim of the present research was to evaluate the reproductive condition of Golden Retriever dogs affected by muscular dystrophy. Breeding soundness examination was performed in 11 male dogs aged between 10 months and 4 years. Seven of this total were affected by muscular dystrophy and 4 healthy dogs that served as control. All dogs were submitted to a through physical exam, seminal evaluation and ultrasound of the reproductive tract. Testicle and spermatic cord morphology of post-mortem dogs were also examined. The following alterations were observed for the affected dogs: muscular atrophy, stiff walk, aspiration pneumonia, diaphragmatic fragility with stomach projection to the torax, megaesophagus e dilated cardiomyopathy. In relation to the genital tract, two dogs presented with bilateral cryptorchidism. Semen evaluation revealed high percentage of major and total sperm defects in affected dogs. Ultrasonographic exams were similar among healthy and affected dogs. Histophatology of the testicle and cremaster muscle revealed morphologic alterations in affected dogs represented by degeneration and muscular retraction with miocyte hyalinization, respectively. In conclusion, affected Golden Retriever dogs have their reproductive performance compromised by the muscular dystrophy.

A Distrofia Muscular dos cães Golden Retriever (GRMD), é uma miopatia degenerativa causada pela ausência de uma proteína, a distrofina, geneticamente homóloga à distrofia muscular de Duchenne que acomete humanos, portanto, estes cães são considerados modelos experimentais para estudos que buscam tratamentos para esta doença progressiva e sem cura. Neste trabalho, foram selecionadas sete diferentes medicamentos, entre eles: Sildenafil; Ácido ursodesoxicólico; Acetilcisteína; Losartana Potássica; Micofenolato de Mofetila; Talidomida e Diltiazen, formando um coquetel de medicamentos com a finalidade de tratar os efeitos deletérios causados pela distrofia muscular, proporcionando dessa forma, uma melhor qualidade e sobrevida para os pacientes distróficos. Cada medicamento foi escolhido pela sua ação: sildenafil, aumento do óxido nítrico; ácido ursodesoxicólico, antiinflamatório; Acetilcisteína, antioxidante; Losartana Potássica, antifibrótico e cardioprotetor; Micofenolato de Mofetila, imunossupressor; Talidomida, antiTNF; diltiazen, bloqueador dos canais de cálcio. Para o experimento, foram utilizados 6 cães machos GRMD, sendo 2 controle e 4 experimentais, com o tratamento iniciado aos 80 dias até 10 meses de idade. Os animais foram avaliados em diferentes momentos, com exames séricos, histologia básica, imuno-histoquímica e PCR.Após avaliações, podemos concluir que o coquetel de medicamentos, não causou melhora clínica nos cães do grupo experimental. A dosagem de leucócitos, TGP, CK e a expressão de NFkβ e TGFβ1 foi menor no grupo experimental comparado com o grupo controle, sugerindo uma melhora do processo inflamatório e tardia progressão da distrofia muscular no grupo experimental. / The Golden Retriever Muscular Dystrophy (GRMD), is a degenerative myopathy caused by the absence of a protein, dystrophin, genetically homologous to the Duchenne Muscular Dystrophy that affects humans, so these dogs are considered experimental models for studies that seek treatments for this progressive disease with no cure. In this work, we selected seven different medications, including: Sildenafil, Ursodeoxycholic Acid, Acetylcysteine, Losartan Potassium, Mycophenolate mofetil, Thalidomide and Diltiazem concomitantly forming a cocktail of drugs in order to treat the deleterious effects of muscular dystrophy, thereby providing a better quality and survival for patients dystrophic. Each drug was chosen for its action: sildenafil, increasing nitric oxide; ursodeoxycholic acid, anti-inflammatory; acetylcysteine, an antioxidant; losartan, antifibrotic and cardioprotective; mycophenolate mofetil, an immunosuppressant; thalidomide, antiTNF; Diltiazem, calcium channel blocker. For the experiment, 6 male dogs were utilized GRMD, and two control and four experimental. Treatment started with 80 days to 10 months of age. The animals were evaluated at different times with serum levels, basic histology, immunohistochemistry and PCR. After the evaluations, we conclude that the cocktail of drugs, no clinical improvement in the experimental group. The dosage of leukocytes, ALT, CK and NFkβ and TGFβ1 expression was lower in the experimental group compared with the control group, suggesting an improvement in the inflammatory process and delayed progression of muscular dystrophy in the experimental group.

The main goal of diploma thesis Subjective and objective view on the importance of rehabilitation or individuals whit pgysical disabilities is to analyze rehabilitation meaning for the person with physical disabilities, specifically for a lady with muscular dystropgy from subjective and objective point of view. First chapters describe theoretical background of terminology, physical disability definition and characteristics, description of rehabilitation as whole and its elements. Following chapter focuses on research and case study. For the elaboration of the diploma thesis, were used analysis of professional literature, a qualitative research survey based on direct observation, interviews, anamnestic questionnaires and medical dokumentation analysis. The research revealed the importance of rehabilitation from a both objective and subjective point of view. Objective findings after intensive physioterapy during the rehabilitation stay were entirely consistent with the subjective feelings of the person who was the subject of the research. Key words: physical disabilities, muscular dystrophy, comprehensive rehabilitation

Many congenital skeletal muscle disorders including muscular dystrophies are caused by genetic mutations that lead to a dysfunction in myocytes effectively binding to the extracellular matrix. This leads to a chronic and continuous cycle of breakdown and regeneration of muscle tissue, ultimately resulting in loss of muscle function and patient mortality. Such disorders lack effective clinical treatments and challenge researchers to develop new therapeutics. The current drug development process often yields ineffective therapeutics due to the lack of genetic homology between pre-clinical animal models and humans. In addition current engineered tissue models using human cells fail to properly emulate native muscle morphology and function due to necrotic tissue cores and an abundance undigested ECM protein. Thus, a more precise benchtop model of 3D engineered human muscle tissue could serve as a better platform for translation to a disease model and could better predict candidate drug efficacy during pre- clinical development. This work presents the methodology for generating a high-content system of contiguous skeletal muscle tissue constructs produced entirely from human cells by using a non-adhesive hydrogel micro-molding technique. Subsequent culture and mold modifications confirmed by morphological and contractile protein analysis improve tissue longevity and myocyte maturation. Finally, mechanical strength and contractile force measurements confirmed that such modulations resulted in skeletal muscle microtissues that were more mimetic of human muscle tissue. This cell self-assembly technique yielded tissues approximately 150um in diameter with cell densities approaching that of native muscle. Modifications including seeding pre-differentiated myoblasts and the addition of ECM producing fibroblasts improved both tissue formation efficiency and cell alignment. Further culture modifications including supplementation of the culture medium with 50ug/ml ascorbic acid and 100ng/ml Insulin-like growth factor-1 coupled with a mold redesign that allowed tissue to passively contract during maturation while still remaining anchored under tension further improved ECM production, myogenic differentiation, and long-term longevity in culture. Further confirmation of the culture improvements were demonstrated by increases in mechanical strength and contractile force production. In conclusion, this approach overcomes cell density limitations with exogenous ECM-based methods and provides a platform for producing 3D models of human skeletal muscle by making tissue entirely using cells. Future work will attempt to translate the methodology used for tissue generation and long-term culture to create benchtop models of disease models of skeletal muscle, streamlining pre- clinical benchtop testing to better predict candidate drug efficacy for skeletal muscle diseases and disorders along with elucidating side effects of non-target drugs.

La maladie de Steinert ou dystrophie myotonique de type 1 (DM1), dystrophie musculaire la plus commune chez l’adulte, est causée par l’expansion instable de triplets CTG dans la région 3’ non traduite du gène DMPK (Dystrophia Myotonica Protein Kinase). Cette maladie multisystémique, affectant principalement les muscles squelettiques et le cœur, est liée à l’épissage. En effet, les CUG exp forment des structures secondaires dans le noyau capables de séquestrer la protéine MBNL1, facteur d’épissage alternatif. En parallèle, un autre facteur d’épissage alternatif, CELF1 est stabilisé. La dérégulation de la balance entre ces deux protéines cause des défauts d’épissage, responsables de certains symptômes de la maladie, comme la myotonie, des défauts de conduction cardiaque et une résistance à l’insuline, causés respectivement par l’épissage aberrant du canal chlorure Clcn1, du canal sodique SCN5A et du récepteur à l’insuline IR. De plus, des dérégulations indépendantes de l’épissage sont aussi mises en jeu dans la DM1 mais leur responsabilité dans l’apparition des symptômes de la maladie reste à identifier. Pour identifier des dérégulations transcriptionnelles indépendantes de l’épissage mais liées à la progression et à la sévérité des symptômes, nous avons généré de nouveaux modèles drosophile de la DM1 avec un nombre croissant de répétitions CTG. Ces modèles étudiées au stade larvaire récapitulent les caractéristiques majeures de la DM1 : la formation de foci et une hypercontractilité musculaire. De plus, nous avons identifié dans ce modèle des dérégulations géniques indépendantes de l’épissage mais dépendantes du nombre de répétitions CTG. Notamment, une atténuation de Gbe1, codant pour une enzyme de branchement du glycogène pourrait participer aux phénotypes musculaires. Afin d’étudier les symptômes cardiaques de la maladie qui touchent 80% des patients et représentent la deuxième cause de mortalité, nous avons utilisé le modèle DM1 de drosophile développé dans notre équipe, et réalisé des analyses physiologiques cardiaques sur des mouches adultes qui expriment 960 CTG dans le cœur (Hand>DM1 960 ), un ARNi pour Mbl, l’orthologue de MBNL1, ou qui surexpriment l’orthologue de CELF1, Bru-3. Ces trois modèles DM1 reproduisent les symptômes cardiaques majeurs observés chez les patients comme des défauts de conduction, de l’arythmie (fibrillation) ou encore une cardiomyopathie dilatée. Afin d’identifier des dérégulations géniques susceptibles d’être responsables de ces défauts, nous avons réalisé une analyse transcriptomique par séquençage ARN après collection de l’ARN spécifique du cœur par la technique du TU-tagging. Les gènes dérégulés identifiés dans ces contextes ont été classés en fonction de leur conservation et du niveau de dérégulation. Parmi eux, la surexpression dans le cœur adulte de Straightjacket (Stj), l’orthologue de CACNA2D4 qui code pour une sous-unité d’un canal calcique voltage- dépendant, cause des défauts de conduction et de la fibrillation, mimant ce qui a été observé en contexte DM1 960 et gain de fonction pour Bru-3. Dans l’avenir, nous aimerions confirmer son implication dans la physiologie cardiaque et en particulier dans la DM1 en analysant son expression chez les patients présentant des défauts cardiaques similaires. / The most common muscular dystrophy found in adults, Steinert disease or Myotonic Dystrophy Type 1 (DM1) is caused by an unstable CTG repeat expansion in the 3’ untranslated region of the Dystrophia Myotonica Protein Kinase (DMPK) gene. This multisystemic disease, affecting particularly skeletal muscles and the heart, is called a spliceopathy because it involves the sequestration of the MBNL1 splicing factor by the expanded CUG-carrying transcripts and the stabilization of the CELF1 splicing factor. The misbalance of these two factors is responsible for splicing defects that cause most of the disease symptoms, like myotonia, conduction defects and arrhythmia but also insulin resistance, respectively associated to missplicing of Clcn1, SCN5A and IR. Moreover, DM1 toxicity is also associated to splice-independent deregulations but their link to disease symptoms remain poorly understood. To identify transcriptional deregulations independent of splicing and associated to disease progression and severity, we generated new DM1 Drosophila models with increasing number of CTG repeats. These larval models recapitulated the main DM1 muscular symptoms such as hypercontractility and foci formation and allowed us identifying gene deregulations independent of splicing. Among them, Gbe1 coding for a glycan branching enzyme is attenuated in the DM1 context in a CTG-repeat dependant manner and could participate in the severity of muscle phenotypes. To better understand the causes of cardiac symptoms that represent the second cause of death and affecting 80% of DM1 patients, we took advantage of our DM1 inducible Drosophila model and performed phenotypic analyses on the heart of adult flies expressing: 960 CTG specifically in the heart (Hand>DM1 960 ), a RNAi for the Drosophila MBNL1 orthologue (Muscleblind, Mbl) or overexpressing the CELF1 orthologue (Bruno-3, Bru3). These DM1 adult models display conduction abnormalities, arrhythmicity (fibrillation) and dilated cardiomyopathy (DCM). Thus, these three pathogenic contexts recapitulated collectively the main DM1 cardiac symptoms and prompted us to perform transcriptional profiling to identify symptom’s-associated gene deregulations. To identify new molecular actors responsible for the DM1 associated heart defects, we performed cardiac cell-specific transcriptional analyses by RNA-sequencing, using TU-tagging technique. Then, we selected deregulated candidate genes that could be linked to the particular observed phenotypes and ranked depending on their conservation and deregulation level. Among them, increased expression of Straightjacket (Stj), the CACNA2D4 orthologue, encoding a subunit of voltage- dependent calcium channel results in fibrillation and conduction defects, thus mimicking cardiac symptoms found in DM1 960 and Bru-3 gain of function contexts in which it was up- regulated. Whether identified candidates are deregulated in DM1 patients displaying cardiac abnormalities remains to be tested.

La Dystrophie Myotonique de type 1 (DM1) est cause par l’expansion anormale d’un triplet CTG dans la partie 3’UTR du gène DMPK, entrainant l’agrégation du transcrit mutant dans des inclusions ribonucléoprotéiques appelées foci. D’après plusieurs études structurales sur des courtes répétitions CUG, il a été proposé que les expansions CUG se replient en une structure en tige-boucle qui interfère avec l’activité de plusieurs facteurs lié au métabolisme de l’ARN et altère leur fonction cellulaire. Le facteur d’épissage muscleblind-like 1 (MBNL1) a été identifié par sa capacité à interagir avec les répétitions CUG. In vivo, ces répétitions entrainent la séquestration de cette protéine aboutissant en une déplétion nucléaire. Un autre facteur d’épissage, la CUG Binding protein (CUGBP1), est également impliqué dans la pathologie. Au lieu d’être séquestré par les répétitions, la stabilité protéique de CUGBP1 est augmentée dans les tissus DM1 entrainant un gain d’activité pour ce facteur. La séquestration de MBNL1 et la stabilisation de CUGBP1 résultent en la dérégulation de l’épissage alternatif de plusieurs transcrits musculaires et du cerveau et la réexpression d’isoformes protéiques fœtales dans les tissus adultes. Cependant, de récentes études suggèrent que d’autres facteurs ou voies de signalisation que celles faisant intervenir MBNL1 et CUGBP1 pourraient être impliquées dans la pathologie DM1.Le but de mon travail de thèse a été d’identifier de nouveaux facteurs ayant la capacité d’interagir avec les répétitions CUG. A l’aide d’une purification sur chromatographie d’affinité utilisant un ARN contenant 95 répétitions CUG comme appât, nous avons identifié l’ARN hélicase p68/DDX5. p68 fait partie de la famille des protéines DEAD-box, caractérisée par un core protéique conservé constitué de neufs domaines hautement conservés, dont le motif DEAD, à l’origine du nom de ces protéines. p68 est impliquée dans de nombreux aspects du métabolisme de l’ARN, dont la transcription, l’épissage, l’export, la traduction et la dégradation des ARN. Nous avons montré, que p68 colocalise avec les foci CUG dans un modèle cellulaire exprimant la partie 3’UTR du gène DMPK contenant de longues répétitions CTG. Nous avons identifié que p68 augmente l’interaction de MBNL1 sur les répétitions CUG et une structure secondaire particulière d’un élément régulateur de l’ARN pré-messager cardiac Troponin T (TNNT2), dont l’épissage est dérégulé dans la pathologie. L’insertion de mutations dans le core de l’hélicase de p68 abolit l’effet de p68 sur la fixation de MBNL1 ainsi que la colocalisation de p68 avec les expansions CUG in vivo, suggérant que le remodelage des structures secondaires ARN de manière ATP-dépendante par p68 facilite l’interaction de MBNL1. Nous trouvons également que la compétence de p68 pour réguler l’inclusion de l’exon alternatif 5 de TNNT2 dépend de l’intégrité des sites de fixation de MBNL1.Nous proposons que p68 agit comme un modificateur de l’activité de MBNL1 sur ces cibles d’épissage ainsi que sur les expansions CUG à l’origine de la pathologie. / Myotonic Dystrophy type I (DM1) is caused by an abnormal expansion of CTG triplets in the 3’ UTR of the DMPK gene, leading to the aggregation of the mutant transcript in nuclear RNA foci. Based on structural studies on short CUG repeats, it has been proposed that expanded CUG repeats fold into an imperfect hairpin structure that interferes with the activities of RNA binding proteins and alters their normal cellular function. The muscleblind-like 1 protein (MBNL1) was identified by its ability to bind to CUG repeats. It has been shown that the expanded mutant transcript promotes the sequestration of the MBNL1 splicing factor in nuclear RNA foci. CUGBP1 is another splicing factor that is involved in DM1. Instead of being sequestered by the repeats, the steady-state level of CUGBP1 is increased in DM1 tissues, leading to a gain of activity of the protein. The sequestration of MBNL1 and the up-regulation of CUGBP1 in DM1 results in the misregulation of alternative splicing of a subset of muscle and brain-specific transcripts, leading to the re-expression of fetal isoforms in adult tissues. However, several recent studies suggest that factors or signaling pathways other than MBNL1 and CUGBP1 could be involved in DM1 pathogenesis.The aim of this work was to isolate new factors that bind to CUG repeats. Using an affinity chromatography strategy with an RNA containing 95 pure CUG repeats, we identified the RNA helicase p68 (DDX5). p68 is a prototype of DEAD-box RNA helicase proteins. This family is characterized by a conserved core, consisting of nine conserved motifs including the DEAD signature, which gives rise to the name to these proteins. p68 is involved in many aspects of RNA metabolism including transcription, RNA processing, RNA export, translation and mRNA degradation. We showed that p68 colocalized with RNA foci in cells expressing the 3’UTR of the DMPK gene containing expanded CTG repeats. We found that p68 increased MBNL1 binding onto pathological repeats and the stem-loop structure regulatory element within the cardiac Troponin T (TNNT2) pre-mRNA, splicing of which is misregulated in DM1. Mutations in the helicase core of p68 prevented both the stimulatory effect of the protein on MBNL1 binding and the colocalization of p68 with CUG repeats, suggesting that remodeling of RNA secondary structure through a ATP-dependant manner by p68 facilitates MBNL1 binding. We also found that the competence of p68 for regulating TNNT2 exon 5 inclusion depended on the integrity of MBNL1 binding sites.We propose that p68 acts as a modifier of MBNL1 activity on splicing targets and pathogenic RNA.

La dystrophie musculaire facioscapulohumérale (FSHD) est la troisième myopathie la plus fréquente en Europe. La maladie atteint progressivement les muscles du visage, des bras et des jambes. Les symptômes apparaissent dans la majorité des cas avant 20 ans et la maladie, souvent douloureuse, provoque fréquemment un handicap majeur qui nécessite de se déplacer en fauteuil roulant. J'ai démontré que la protéine KLF15 est surexprimée dans les tissus des patients FSHD et dans les myoblastes cultivés in vitro et prélevés sur des patients FSHD. Des résultats préliminaires indiquent que la surexpression du facteur KLF15 pourrait être expliquée par le stress oxydant induit par DUX4 et la surexpression de certains facteurs de myogenèse induits par DUX4c. J'ai démontré que KLF15 interagit directement avec les répétitions D4Z4 et contrôle leur fonction d'activation de transcription. Ainsi KLF15 sert de médiateur entre les répétitions D4Z4 et deux gènes dans la région 4q35: FRG2 et DUX4c ce que explique la surexpression de ces deux gènes dans la FSHD. La surexpression du gène DUX4c, homologue du DUX4, perturbe le programme de différentiation musculaire en activant certains facteurs de myogenèse (myomiRs ou microRNAs myogéniques). En somme, la découverte du rôle du facteur KLF15 dans la FSHD met en évidence une boucle de rétrocontrôle positif qui relie la surexpression du facteur KLF15 avec la surexpression des gènes codés dans la région 4q35. Le rôle central du facteur KLF15 dans ce nouveau modèle de la maladie permet d'envisager une nouvelle piste thérapeutique pour la dystrophie FSHD basé sur l'inhibition du facteur KLF15. / Facioscapulohumeral muscular dystrophy (FSHD), a dominant hereditary disease with a prevalence of 7 per 100,000 individuals, is associated with a partial deletion in the subtelomeric D4Z4 repeat array on chromosome 4q. The D4Z4 repeat contains a strong transcriptional enhancer that activates promoters of several FSHD-related genes. We here report that the enhancer within the D4Z4 repeat binds the Krüppel-like factor KLF15. KLF15 was found to be upregulated during myogenic differentiation induced by serum starvation or by overexpression of the myogenic differentiation factor MYOD. When overexpressed, KLF15 activated the D4Z4 enhancer and led to overexpression of DUX4c (Double homeobox 4, centromeric) and FRG2 (FSHD region gene 2) genes, whereas its silencing caused inactivation of the D4Z4 enhancer. In immortalized human myoblasts the D4Z4 enhancer was activated by the myogenic factor MYOD, an effect that was abolished upon KLF15 silencing or when the KLF15 binding sites within the D4Z4 enhancer were mutated, indicating that the myogenesis-related activation of the D4Z4 enhancer was mediated by KLF15. KLF15 and several myogenesis-related factors were found to be expressed at higher levels in myoblasts, myotubes and muscle biopsies from FSHD patients than in healthy controls. We propose that KLF15 serves as a molecular link between myogenic factors and the activity of the D4Z4 enhancer, and thus contributes to the overexpression of the DUX4c and FRG2 genes during normal myogenic differentiation and in FSHD.

Esta pesquisa teve como objetivo estudar a aplicação de células-tronco do epitélio olfatório de coelhos com o uso da videolaparoscopia na face costal do músculo diafragma do modelo mdx. A cirurgia laparoscópica foi utilizada como recurso visualizador da cavidade abdominal, com finalidade de guiar precisamente a aplicação de células-tronco no tecido lesionado. Foram utilizados 10 animais controles, BALB/C57 (grupo A) para padronizar a intervenção cirúrgica; 03 mdx controles (grupo B) que não receberam terapia celular e 03 mdx que receberam terapia celular (grupo C). Padronizou-se a videolaparoscopia em decúbito dorsal com elevação de vinte graus dos membros torácicos e realizou-se 1 aplicação de células-tronco do epitélio olfatório de coelhos, 3x105. Após 8 dias estes animais foram eutanasiados com overdose anestésica e o músculo diafragma e intercostal foram coletados. Na análise estrutural do músculo diafragma no grupo A, observou as fibras musculares com mesmo diâmetro e núcleos das células periféricos. Os fascículos musculares encontravam-se organizados com presença de fibras reticulares em pequena quantidade. As mesmas características estruturais foram observadas no músculo intercostal. No grupo B, as fibras musculares apresentavamse com diferentes diâmetros, núcleos celulares centralizados, com presença de fibrose perimisial. O músculo intercostal apresentou os mesmos achados, entretanto de forma mais branda. Os fascículos musculares tanto do m. diafragma e intercostal estavam desorganizados e observou-se uma grande quantidade de fibras colágenas e reticulares. No grupo C, observou-se uma leve diminuição do infiltrado inflamatório, porém os núcleos das células ainda se apresentavam centrais. Diferentemente dos dois grupos descritos acima, no grupo C observou-se a presença de células de degranulação e de cordões de mioblastos, demonstrando uma moderada reorganização muscular. Em relação aos fascículos musculares e a quantidade de fibras colágenas e reticulares, estes se mantiveram com as mesmas características do grupo B. Na análise de migração das células-tronco, observamos a marcação positiva da Proteína verde fluorescente (GFP) no músculo diafragma a fresco e na análise imunoistoquímica confirmando os achados estruturais obtidos. Contudo não houve marcação positiva para os cordões de mioblastos. Sugerimos que a aplicação local de células-tronco do epitélio olfatório de coelhos utilizando a videolaparoscopia foi capaz de implantar células-tronco no músculo diafragma. Entretanto, não podemos atribuir os resultados estruturais obtidos nos animais que receberam terapia celular às células-tronco. Acredita-se que alguma sinalização até o momento desconhecida, possa ter estimulado tais alterações histológicas. Portanto, este experimento pode acrescentar novas perspectivas na utilização futura das célulastronco no modelo distrófico canino, por exemplo, o GRMD (Golden Retriever Muscular Dystrophy), além de estimular a pesquisa para maior esclarecimento sobre as células do epitélio olfatório de coelho. / This research aimed to investigate the application of stem cells from the rabbit olfactory epithelium with the use of laparoscopy in the diaphragm costal face of the of the mdx model. Laparoscopic surgery was used as a visualizer resource of the abdominal cavity; with the purpose to precisely direct stem cells application in the injury tissue. Were used 10 control animals, BALB/C57 (group A) to standardize the surgical intervention, 03 mdx controls (group B) that did not receive cell therapy and 03 mdx that received cell therapy (group C). The laparoscopic technique was standardized in the supine position with twenty degrees elevation of the thoracic members, subsequently was held an application of stem cells from the olfactory epithelium of rabbits, 3x105. After 8 days the animals were euthanized by using anesthetic overdose and the diaphragm and intercostal muscles were collected. The structural analysis of the group A diaphragm presented muscles fibers with same diameter and the cells nuclei presented peripheral. The muscle fascicles were organized with the presence of reticular fibers in small quantities. The same structural characteristics were observed in the intercostal muscle. The group B, presented muscle fibers with different diameters, centralized nuclei cell, with perimisial fibrosis. The intercostal muscle showed similar findings, less severely though. The muscle fascicles of both diaphragm and intercostal muscles were disorganized and presented a large amount of collagen and reticular fibers. In group C, were found a slight decrease of the inflammatory infiltrates, but, at this point, the cells nuclei were central. Differently from the two groups described above, the group C presented cell degranulation and myoblasts cords, demonstrating moderate muscle reorganization. The muscle fascicles and the amount of collagen and reticular fibers remained with the same characteristics of the group B. When examining the stem cells migration, it could be observed, in the fresh diaphragm, a positive marking of green fluorescent protein (GFP). The immunoistochemical analysis confirmed the findings obtained. However, the myoblasts cords were not positive stained. It could be suggested that the rabbit olfactory epithelium stem cells application using the laparoscopic technique was able to conduct stem cells to the diaphragm. Meanwhile, this cannot attribute the structural results obtained from animals which received cell therapy. It is believed that some signaling until the moment unknown may have stimulated these histological changes. Therefore, this experiment can add new perspectives for cell therapy in dystrophic canine model, for example, GRMD (Golden Retriever Muscular Dystrophy).

A miostatina é um agente regulador negativo do crescimento muscular. Na terapia de suplementação com testosterona observou-se diminuição na expressão da miostatina. Este trabalho tem como objetivo determinar a influência do esteróides anabolizantes na expressão do gene da miostatina em camundongos normais, C57BL e no modelo distrófico Largemyd. Utilizamos a técnica de PCR em tempo real, para determinarmos a expressão relativa dos genes. Os animais tratados apenas com esteróide apresentaram aumento significativo em sua massa corpórea, com melhora de desempenho nas avaliações funcionais no Largemyd. Não foram observadas diferenças significativas na expressão do genes da miostatina no músculo normal e distrófico. Concluímos que o uso do esteróide anabolizante foi benéfico para o aumento na força do modelo Largemyd, mas o aumento de massa corpórea nestes animais, como no camundongo normal, não deveu-se a inibição da expressão da miostatina. / Myostatin is a negative regulator agent of muscle growth. In the testosterone supplementation therapy we observed decreased myostatin expression. The aim of this project is to determine the influence of anabolic steroids in the expression of myostatin gene in normal C57BL mice and in the dystrophic model Largemyd. We used the Real Time PCR assay to determine the relative expression of genes. Animals treated only with steroids presented significant increase in body mass and Largemyd showed improvement in the functional evaluations. There werent significant differences in the myostatin gene expression in the normal and dystrophic muscle. We concluded that the use of anabolic steroid was benefic to the increase of the strength in the Largemyd model, but the increase of body mass in these animals, as in the normal mice, is not related to the inhibition of myostatin expression.