Orientador: Humberto Santo Neto / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-10T05:09:51Z (GMT). No. of bitstreams: 1 Ferretti_Renato_M.pdf: 2564906 bytes, checksum: ad6eec170e1a021892d4ba5f418fe910 (MD5) Previous issue date: 2007 / Resumo: A Distrofia Muscular de Duchenne (DMD) e o camundongo mdx, modelo experimental da doença, caracterizam-se pela ausência de distrofina e pela necrose das fibras musculares. Alguns músculos são protegidos da mionecrose e admite-se que nestes a expressão das proteínas reguladoras de cálcio está aumentada. Os músculos intrínsecos da laringe (ILMs) apresentam características anatômicas e fisiológicas semelhantes aos músculos extra-oculares (EOMs), que são protegidos da mionecrose em pacientes portadores de DMD e camundongos mdx. Assim levantamos a hipótese de que os ILMs são protegidos da necrose de suas fibras e apresentam expressão diferenciada de proteínas reguladoras do cálcio. Foram avaliados os ILMs e músculos apendiculares de camundongos C57Bl/10 (controles) e mdx, adultos e idosos. Foi analisado a porcentagem de núcleos centrais, como um sinal de fibras lesionadas e em reparação e foi utilizado o azul de Evans, como marcador de lesão miofibrilar. Após a caracterização desses músculos, foi estudado por imunohistoquímica e imunobloting, o nível da expressão de proteínas reguladoras do cálcio, calsequestrina e Ca2+-ATPase do retículo sarcoplasmático (SERCA1). Observou-se que, exceto o músculo cricotireóideo (CT), nenhum ILMs dos camundongos mdx adultos ou idosos apresentaram sinais de miopatia, entretanto núcleos centrais foram visíveis no músculo tibial anterior do mesmo animal. Houve aumento significativo da porcentagem de núcleos centrais no músculo CT comparado com outros ILMs, o qual piorou com envelhecimento. A expressão de SERCA1 e calsequestrina está aumentada nos ILMs distróficos em relação aos controles, distintamente do que ocorre nos músculos apendiculares. Assim, conclui-se que os ILMs dos camundongos mdx são protegidos da mionecrose e mostram níveis elevados de SERCA1 e calsequestrina, sugerindo que a manutenção da homeostase do cálcio pode estar envolvida na proteção desses músculos / Abstract: Duchenne muscular dystrophy (DMD) and mdx mice, a model for DMD, is characterized by the lack of dystrophin expression and muscle fiber necrosis. Some muscle are enigmatically protected and admitted that an elevated expression of calcium-binding proteins. The intrinsic laryngeal muscles (ILMs) share many anatomical and physiological properties with extra-ocular muscles, which are unaffected in both Duchenne muscular dystrophy and mdx mice. We hypothesized that ILMs are spared from myonecrosis in the mdx and investigated whether this possible protection is related to an increased expression of calcium-binding proteins, SERCA1 and calsequestrin, which may be protective against the elevated calcium levels seen in dystrophic fibers. ILMs and limb muscles of adult and aged control C57Bl/10 and mdx mice were used. The percentage of central nucleated fibers, as a sign of muscle fibers that had experienced injury and regeneration, and myofibers labeling with Evans blue dye, as a marker of myofiber damage, were studied. After this characterization, the expression of Sarco-endoplasmic-reticulum Ca2+-ATPase (SERCA1) and calsequestrin was examined using immunofluorescence and immunoblotting. Except for the cricothyroid muscle (CT), none of the ILMs from adult and old mdx mice showed signs of myofiber damage. Central nucleation was readily visible in tibialis anterior of the same mdx mice. A significant increase in the percentage of central nucleated fibers was observed in adult CT compared to the other ILMs, which was worsened by age. Dystrophic ILMs presented a significant increase in the proteins studied, in comparison to controls. These proteins were reduced in the non-spared mdx muscles. Thus we show that the ILMs are spared from the lack of dystrophin and the increase of SERCA1 and calsequestrin may permit a better maintenance of calcium homeostasis with the consequent absence of myonecrosis / Mestrado / Anatomia / Mestre em Biologia Celular e Estrutural

Myotonic Dystrophy Type I (DM1) is a multi-systemic genetic neuromuscular degenerative disease, has a prevalence in most populations of about 1:8000 and is caused by the nuclear retention of pathogenically expanded DMPK mRNA. A previous DM1 RNAi-kinome screen in our lab has identified kinases that reduced both count and area of DMPK mRNA foci in vitro. One such discovered kinase is PACT, which has showed to decrease foci count and area in DM1 fibroblasts by 30-50%. This study explored PACT as well as binding partner DICER involved in cellular RNA processing machinery, to highlight potential therapeutic targets in DM1. DM1 fibroblasts treated with PACT siRNA showed a non-significant trend of upregulation in MBNL1 mRNA and protein expression. PACT knockdown also showed trend of missplicing normalization in SERCA-1, more prominently seen in DM1-2000 human fibroblasts, whereas IR (insulin receptor) splicing remained unaffected. On the other hand, DICER knockdown did not have profound affect on foci integrity as well as MBNL1 RNA and protein xpressions in DM1 fibroblasts. SERCA-1 splicing in DICER siRNA treated samples also remained unchanged. We report here our findings in pursuit of potential therapeutic targets for the treatment of DM1.