Spinal muscular atrophy is an autosomal recessive genetic disease that results from the loss and/or degeneration of alpha motor neurons in the lower part of the spinal cord. With ~ 1 in 6000 live births per year being affected, this disease is the second leading cause of infant death and is caused by the loss or decrease of the Survival of Motor Neuron protein (SMN). While a lot is known about the role that SMN plays in the cytoplasmic assembly of spliceosomal small nuclear ribonucleoproteins (snRNPs), it remains a crucial question in the field to gain a better understanding of what specific/distinct function(s) SMN might have in motor neurons. We have identified novel interactions between SMN and two RNA-binding proteins (RBPs) known to be components of axonal RNA granules. More specifically, we demonstrated that SMN interacts with HuD and SERBP1 in a direct fashion in foci-like structures along neurites of motor neuron-derived cells. We have also demonstrated that the SMN/HuD interaction is required for the localization of HuD into RNA granules in neurites of motor neuron-derived cells. Furthermore, I have shown that SERBP1 is down-regulated in the absence of normal levels of SMN and, most importantly, that over-expression of SERBP1 can rescue SMA-like neuronal defects using a cell culture model of the disease. These findings may help shed light on the non-canonical molecular pathway(s) involving SMN and RBPs in motor neurons and underscores the possible therapeutic benefits of targeting these RBPs in the treatment of SMA.

Trichostatin A (TSA) is a histone deacetylase inhibitor with beneficial effects in spinal muscular atrophy mouse models that carry the human SMN2 transgene. Whether TSA specifically targets the upregulation of the SMN2 gene or whether other genes respond to TSA and in turn provide neuroprotection in SMA mice is unclear. We have taken advantage of the Smn2B/- mouse model that does not harbor the human SMN2 transgene, to test the hypothesis that TSA has its beneficial effects through a non-Smn mediated pathway. Daily intraperitoneal injection of TSA from postnatal day 12 to 25 was performed in the Smn2B/- mice and littermate controls. Previous work from our laboratory demonstrated that treatment with TSA increased the median lifespan of Smn2B/- mice from twenty days to eight weeks. As well, there was a significant attenuation of weight loss and improved motor behavior. Pen test and righting reflex both showed significant improvement, and motor neurons in the spinal cord of Smn2B/-mice were protected from degeneration. Both the size and maturity of neuromuscular junctions were significantly improved in TSA treated Smn2B/- mice. Here, we have shown that TSA treatment does not increase the levels of Smn protein in mouse embryonic fibroblasts or myoblasts obtained from the Smn2B/- mice. Further, qPCR analysis revealed no changes in the level of Smn transcripts in the brain or spinal cord of TSA-treated SMA mice. Similarly, western blot analysis revealed no significant increase in Smn protein levels in the brain, spinal cord, hind limb muscle, heart muscle, or the liver of TSA treated Smn2B/- mice. However, TSA has beneficial effects in the muscles of Smn2B/- mice and improves motor behavior and myofiber size. TSA improves muscle development by enhancing the activity of myogenic regulatory factors independent of the Smn gene. The beneficial effect of TSA is therefore likely through an Smn-independent manner. Identification of these protective pathways will be of therapeutic value for the treatment of SMA.

Diss. (sammanfattning) Stockholm : Karol. inst., 2002. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2005. / Härtill 6 uppsatser.

Thesis (Ph. D.)--University of Missouri-Columbia, 2008. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Vita. "May 2008" Includes bibliographical references.

Thesis--Copenhagen. / Summary in Danish. Includes bibliographical references (p. 127-130).

Thesis (Ph. D.)--Case Western Reserve University, 2005. / [School of Medicine] Department of Genetics. Includes bibliographical references. Available online via OhioLINK's ETD Center.

Thesis (Ph.D.)--McMaster University, 2004. / Includes bibliographical references (p. 106-123). Also available via World Wide Web.

A síndrome da dor patelofemoral (SDPF) é o diagnóstico mais comum em populações fisicamente ativas. A SDPF está relacionada com o mau alinhamento dos membros inferiores durante tarefas de descarga de peso, causando maior estresse e dor na articulação patelofemoral. Esse mau alinhamento está relacionado com um aumento da inclinação ipsilateral do tronco, adução do quadril, abdução do joelho e maior grau de rotação interna da tíbia durante atividades dinâmicas, como agachamento unipodal, corrida, salto e subir e descer escadas. Fatores anatômicos e biomecânicos estão relacionados a alterações ao redor da articulação femoropatelar, como menor força de extensão do joelho, atraso na ativação do vasto medial em relação ao vasto lateral e atrofia do músculo quadríceps. Recentemente, alterações do quadril (fatores proximais), tornozelo e pé (fatores distais) têm sido propostas como fatores contribuintes da SDPF. No entanto, as evidências sobre ativação e alteração da morfologia muscular dos membros inferiores, principalmente nos fatores proximais e distais, são escassas. Esta tese teve como objetivo verificar as alterações neuromusculares dos membros inferiores e determinar se algum parâmetro neuromuscular explicava a cinemática durante tarefas unipodais. Após a apresentação dos motivos para realização deste estudo (Capítulo I), no Capítulo II objetivamos verificar as alterações neuromusculares (ativação muscular e morfologia muscular) relacionadas aos fatores proximais e distais na SDPF por meio de uma revisão sistemática. As buscas foram realizadas nas bases de dados Medline (via PubMed), Scielo, Scopus, PEDro, Cochrane Central, Embase e ScienceDirect databases até abril de 2018 para estudos avaliando ativação muscular ou parâmetros de morfologia muscular das articulações do tronco, quadril e tornozelo/pé. Dois revisores independentes avaliaram cada trabalho para inclusão e qualidade. Dezenove estudos foram identificados (SDPF, n = 319; GC, n = 329). Três estudos investigaram os músculos ao redor das articulações do tronco e tornozelo/pé. Quinze estudos investigaram os músculos ao redor da articulação do quadril. As evidências foram inconclusivas sobre a ativação do transverso do abdome/oblíquo interno (TrA/OI) na SDPF durante atividades de alta velocidade. Os níveis de ativação, duração e atraso na ativação de Glúteo Médio (GMed), glúteo máximo (GMax), biceps femoral (BF) and semitendinoso (ST) foram inconclusivos nos estudos incluídos. Não foram observadas diferenças na ativação de gastrocnêmio lateral (GL), gastrocnêmio medial (GM), sóleo (SOL), tibial anterior (TA) e fibular longo (FIB). Apenas um estudo incluído avaliou parâmetros da morfologia muscular, sem alterações na espessura muscular e na intensidade do eco GMed e GMax. Com base na falta de evidências sobre alterações na ativação muscular em torno das articulações do quadril, tornozelo e pé durante tarefas dinâmicas, e no fato de que um único estudo avaliou os resultados da morfologia muscular (GMed e GMax) na SDPF, propusemos um artigo original (Capítulo III) que teve como objetivo comparar os parâmetros neuromusculares dos membros inferiores e a cinemática no plano frontal durante tarefas unipodais de descarga de peso em mulheres com SDPF e determinar se algum resultado neuromuscular explicava o índice dinâmico de valgo (IVD) durante as tarefas. As buscas foram realizadas nas bases de dados Medline (via PubMed), Scielo, Scopus, PEDro, Cochrane Central, Embase e ScienceDirect databases até abril de 2018 para estudos avaliando ativação muscular ou parâmetros de morfologia muscular das articulações do tronco, quadril e tornozelo/pé. Dois revisores independentes avaliaram cada trabalho para inclusão e qualidade. Dezenove estudos foram identificados (SDPF, n = 319; GC, n = 329). Três estudos investigaram os músculos ao redor das articulações do tronco e tornozelo/pé. Quinze estudos investigaram os músculos ao redor da articulação do quadril. As evidências foram inconclusivas sobre a ativação do transverso do abdome/oblíquo interno (TrA/OI) na SDPF durante atividades de alta velocidade. Os níveis de ativação, duração e atraso na ativação de Glúteo Médio (GMed), glúteo máximo (GMax), biceps femoral (BF) and semitendinoso (ST) foram inconclusivos nos estudos incluídos. Não foram observadas diferenças na ativação de gastrocnêmio lateral (GL), gastrocnêmio medial (GM), sóleo (SOL), tibial anterior (TA) e fibular longo (FIB). Apenas um estudo incluído avaliou parâmetros da morfologia muscular, sem alterações na espessura muscular e na intensidade do eco GMed e GMax. Com base na falta de evidências sobre alterações na ativação muscular em torno das articulações do quadril, tornozelo e pé durante tarefas dinâmicas, e no fato de que um único estudo avaliou os resultados da morfologia muscular (GMed e GMax) na SDPF, propusemos um artigo original (Capítulo III) que teve como objetivo comparar os parâmetros neuromusculares dos membros inferiores e a cinemática no plano frontal durante tarefas unipodais de descarga de peso em mulheres com SDPF e determinar se algum resultado neuromuscular explicava o índice dinâmico de valgo (IVD) durante as tarefas. Quinze mulheres com SDPF e quinze mulheres saudáveis pareadas por 5 idade (grupo controle - GC) foram comparadas com os seguintes testes: (1) questionário funcional; (2) espessura muscular ao redor do quadril (GMed e tensor da fáscia lata - TFL), joelho (VL e VM) e tornozelo/pé (TA e FIB); (3) IVD e ativação muscular durante agachamento e salto vertical unipodais; (4) torque isométrico máximo para abdução do quadril, extensão do joelho e eversão/ inversão do pé; e (5) ativação muscular durante testes isométricos e funcionais. Uma regressão linear múltipla (modelo Stepwise) foi usada para verificar se alguma variável neuromuscular explicava o IVD durante as tarefas unipodais. O tamanho de efeito (ES) foi usado para determiner a magnitude da diferença entre os grupos. Comparado ao GC, o grupo SDPF apresentou: (1) menor espessura do GMed (-10.02%; ES = -0.82) e maior espessura do TFL (+18.44%; ES = +0.92) e do FIB (+14.23%; ES = +0.87); (2) menor ativação do TA durante o agachamento unipodal (-59,38%; ES = -1.29); (3) menor ativação do GMed durante o salto vertical unipodal (-28.70%; ES = -1.35) e (4) maior ativação do GMed durante o teste isométrico de abdução de quadril (+34.40%; ES = +0.77). IVD durante o agachamento unipodal foi explicado pela ativação do VL durante a tarefa somente no GC, enquanto a espessura do TA no GC e o torque de eversores do pé no SDPF explicou o IVD durante o salto vertical unipodal. Com base em nossos resultados, as mulheres com SDPF apresentaram alterações neuromusculares significativas nas articulações do quadril e tornozelo/pé. No entanto, apenas fatores distais explicaram o IVD no grupo SDPF. / Patellofemoral pain syndrome (PFPS) is the most common diagnoses in physically active populations. PFPS is related with lower limbs poor alignment during weight-bearing tasks, causing higher patellofemoral joint stress and pain. This poor alignment is related with an increase of ipsilateral trunk lean, hip adduction, knee abduction and greater tibial internal rotation during dynamic activities such as single-leg squat, running, jumping, and stepping tasks. Anatomical and biomechanical factors are related with unwanted changes around the patellofemoral joint, such as lower knee extension strength, delayed onset of vastus medialis activation relative to vastus lateralis and quadriceps muscle atrophy (knee joint muscles intrinsic changes). Recently, hip (proximal), ankle and foot (distal) changes have been proposed as PFPS contributing factors. However, the evidences about lower limb muscle activation and morphology changes, mainly in proximal and distal factors, are scarce. This thesis aimed to create clinical subgroups based in lower limb neuromuscular changes and determine if some neuromuscular outcome explained kinematics during single-leg tasks. After displaying the reasons to perform this study (Chapter I), in Chapter II we aimed to verify neuromuscular changes (muscle activation and muscle morphology) related to proximal and distal factors in PFPS through a systematic review. Medline (via PubMed), Scielo, Scopus, PEDro, Cochrane Central, Embase and ScienceDirect databases were searched until April 2018 only for retrospective studies evaluating muscle activation or muscle morphology parameters of trunk, hip and ankle/foot joints. Two independent reviewers assessed each paper for inclusion and quality. Twenty retrospective studies were identified (PFPS, n=319; CG, n=329). Three studies investigated muscles around trunk and ankle/foot joints. Fifteen studies investigated muscles around the hip joint. Evidences were inconclusive about transversus abdominis/internal oblique (TrA/IO) activation in PFPS during high-speed activities. Gluteus medius (GMed), gluteus maximus (GMax), bíceps femoris (BF) and semitendinous (ST) activation level, activation duration and activation onset were inconclusive in the included studies. No differences were observed in gastrocnemius lateralis (GL), gastrocnemius medialis (GM), soleus (SOL), tibialis anterior (TA) and fibularis (FIB) muscle activation. Only one included study evaluated muscle morphology parameters, without changes in the GMed and GMax muscle thickness and echo intensity. Based in the lack of evidences about muscle activation changes in PFPS patients’ muscles around hip, ankle and foot joints during dynamic tasks, and in the fact that a single study evaluated muscle morphology outcomes (GMed), we proposed an original article (Chapter III) that aimed to compare lower limb neuromuscular parameters and frontal plane kinematics during single-leg tasks in women with PFPS, and determine if some neuromuscular outcome explained dynamic valgus index (DVI) during tasks. Fifteen PFPS women and fifteen healthy age-matched women (control group - CG) were compared with the following tests: (1) functional questionnaire; (2) hip (GMed and tensor fasciae latae - TFL), knee (VL and VM) and ankle/foot (TA and FIB) muscle thickness; (3) DVI and muscle activation during single-leg squat and vertical jump; (4) maximal isometric torque for hip abduction, knee extension and foot eversion/inversion; and (5) muscle activation during isometric and functional tests. A multiple- 7 stepwise regression analysis was used to test if neuromuscular outcomes explained DVI during single-leg tasks. Effect sizes (ES) were used to determine the magnitude of between-groups differences. Compared to the CG, PFPS showed: (1) smaller GMed (-10.02%; ES = -0.82) and greater TFL (+18.44%; ES = +0.92) and FIB muscle thickness (+14.23%; ES = +0.87); (2) lower TA muscle activation during single-leg squat (-59,38%; ES = -1.29); (3) lower GMed muscle activation during single-leg jump (-28.70%; ES = -1.35) and (4) greater GMed muscle activation during hip abduction isometric test (+34.40%; ES = +0.77). DVI during single-leg squat was explained by VL activation during this task only in CG, whereas lower TA muscle thickness in the CG and higher foot eversion torque in PFPS explained DVI during single-leg vertical jump. Based in our results, females with PFPS showed significant neuromuscular changes at the hip and ankle/foot joints. However, only distal factors explained DVI in the PFPS group.

Spinal Muscular Atrophy (SMA) is caused by mutation or deletion of the Survival Motor Neuron 1 (SMN1), which encodes cell-ubiquitous SMN protein. Although classified as a neuromuscular disease, a range of systemic pathologies is reported in SMA patients. Despite a clear understanding of the genetics, the role of SMN protein in SMA pathogenesis is somewhat unclear, especially in tissues outside the CNS. Here, we describe failed liver development in response to reduced SMN levels, in a Taiwanese mouse model of severe SMA. Molecular analysis revealed significant changes in proteins involved in cell cycling and blood homeostasis including coagulation prior to motor neuron pathology. With SMN being directly associated with some of these proteins, this indicates primary liver pathology in SMA. Study of livers obtained from two other mouse models of SMA; severe SMNΔ7 and intermediate 2B, which have slightly higher SMN levels than Taiwanese SMA mice, also revealed significant overlapping pathologies, suggestive of high intrinsic susceptibility of the liver to SMN decrease. Proteomic study of pre-symptomatic 2B/- liver revealed significant perturbations in mitochondrial bioenergetics, which could account for metabolic defects in SMA patients. Vascular changes can be observed in mouse models of SMA and even skeletal muscle of severe SMA patients. Although Taiwanese SMA liver showed no morphological changes to its vasculature, it does have impairments in several key vascular signaling molecules, including VEGF and Tie-2. Furthermore, we report for the first time significant vascular changes in a zebrafish model of SMA, that could be associated with defective neuronal-vascular signaling and is supported by preliminary findings in the Taiwanese SMA retina. This thesis uncovers perturbations in several clinically relevant signalling pathways directly linked to SMN decrease, independent of the motor neurone pathology. Taken together this work emphasises the importance of a systemic therapy in SMA.