Novel Features And Mechanisms Of Congenital Myopathies
Funder
National Health and Medical Research Council
Funding Amount
$464,500.00
Summary
Congenital myopathies are inherited diseases of skeletal muscle that typically present at birth or in early childhood and are characterised by poor muscle tone and muscle weakness. This group of disorders includes nemaline myopathy, central core disease, congenital fiber type disproportion, and myotubular myopathy. All of these disorders are characterised by disorganisation of the sarcomere, the major structure within skeletal muscle cells that is involved in contraction. In addition, the congen ....Congenital myopathies are inherited diseases of skeletal muscle that typically present at birth or in early childhood and are characterised by poor muscle tone and muscle weakness. This group of disorders includes nemaline myopathy, central core disease, congenital fiber type disproportion, and myotubular myopathy. All of these disorders are characterised by disorganisation of the sarcomere, the major structure within skeletal muscle cells that is involved in contraction. In addition, the congenital myopathies have features in common with virtually all muscle diseases such as slow fibre predominance and alterations in contractile force. We are using nemaline myopathy as a representative congenital myopathy to examine features in common amongst the myopathies, characteristic of the congenital myopathies and specific to nemaline myopathy. In nemaline myopathy patients, mutations have been found in five genes that encode proteins of the filamentous systems of the sarcomere. A feature specific to nemaline myopathy is the presence of abnormal structures of the sarcomere called nemaline rods. We have analysed a large number of nemaline myopathy patients that have mutations in the genes that encode the filament proteins alpha-skeletal actin and tropomyosin. In addition, we have generated mouse models for nemaline myopathy and propose to generate an additional one with novel features. Our mouse model has revealed that a feature previously thought exclusive to dystrophies, is also present in nemaline myopathy. The combined analysis of well-characterised patient samples and mouse models will allow us to address longstanding questions about this particular congenital myopathy and myopathies in general. We will determine how rods form and their protein composition. Our mouse models in particular will allow us to address the molecular mechanisms that underpin the increase in slow twitch fibres and the effects that a particular mutation has on muscle function.Read moreRead less
THE ROLES OF CYTOSKELETAL PROTEINS IN SKELETAL MUSCLE FUNCTION AND DISEASE
Funder
National Health and Medical Research Council
Funding Amount
$466,650.00
Summary
Congenital myopathies are inherited diseases of skeletal muscle that typically present at birth or in early chilhood and are characterised by poor muscle tone and muscle weakness. This group of disorders includes nemaline myopathy, central core disease, congenital fiber type disproportion, and myotubular myopathy. All of these disorders are characterised by disorganisation of the sarcomere, the major structure within skeletal muscle cells that is involved in contraction. In nemaline myopathy pat ....Congenital myopathies are inherited diseases of skeletal muscle that typically present at birth or in early chilhood and are characterised by poor muscle tone and muscle weakness. This group of disorders includes nemaline myopathy, central core disease, congenital fiber type disproportion, and myotubular myopathy. All of these disorders are characterised by disorganisation of the sarcomere, the major structure within skeletal muscle cells that is involved in contraction. In nemaline myopathy patients, mutations have been found in five genes that encode proteins of the filamentous systems of the sarcomere. Therefore, the genes for other thin filament, thick filament and Z-line proteins are excellent candidates for these disorders. Research from our lab has identified a novel region of the sarcomere and the genes encoding the proteins present in this region provide additional candidates for the congenital myopathies. We will further characterise the proteins in this novel structure to determine its function and the role that it plays in muscle disease pathologies. In order to study the relationship between disease pathology and muscle weakness in nemaline myopathy, we generated a mouse model by expressing a mutant protein, a-tropomyosin slow, found in human patients in mice. All features of the disease found in humans are present in the mice. A key feature of this disease in mice is the ability for muscle cells to grow in diameter or hypertrophy to offset the muscle weakness. We will use these mice to trial therapies including hypertropy-inducing agents, to prevent and reverse muscle weakness. In addition, we will generate an additional mouse model for this disease with a mutation in a gene encoding another filamentous protein. A comparison of the two models using microarray analysis will help us identify additional genes that are being affected in this disease and to generate a molecular expression profile that will aid in the diagnosis of this disease.Read moreRead less
Characterisation Of A Novel Family Of Skeletal Muscle Gene Regulators
Funder
National Health and Medical Research Council
Funding Amount
$443,250.00
Summary
Muscle cells may be broadly divided into two classes, slow- or fast-twitch, with different physiological and biochemical properties. These properties are largely determined by the protein products of several multi-gene families that encode the contractile apparatus characteristic of muscle cells. The pattern of expression of these muscle-specific genes defines a muscle cell as either a slow-twitch or fast-twitch myofibre. Skeletal muscle is inherently plastic in its ability to express different ....Muscle cells may be broadly divided into two classes, slow- or fast-twitch, with different physiological and biochemical properties. These properties are largely determined by the protein products of several multi-gene families that encode the contractile apparatus characteristic of muscle cells. The pattern of expression of these muscle-specific genes defines a muscle cell as either a slow-twitch or fast-twitch myofibre. Skeletal muscle is inherently plastic in its ability to express different genes in response to altered functional demand, and under certain circumstances, fibres can convert from one type to another. Conditions known to cause myofibre conversion in humans include congenital myopathies, spinal injury, and exercise. We have identified a novel family of proteins that regulate the genes that confer fibre type. In this proposal, we will further characterise the function of each of these proteins in skeletal muscle development and fibre determination. In addition, the gene that encodes these proteins is one of many deleted in the human condition Williams-Beuren Syndrome (WBS). WBS is characterised by supravalvular aortic stenosis (SVAS), neurological and cognitive defects, infantile hypercalcemia, dental malformations, musculoskeletal anomalies and growth retardation with short stature. The musculoskeletal anomalies, including joint contractures, muscular pain and kyphoscoliosis, cause WS patients to lack stamina and fatigue easily. An underlying myopathy has been reported and may account for the physical limitations, however the disease causing gene-genes have not been identified. We predict that a lack of the MusTRD proteins contributes to these conditions. In general, the findings from our study will yield insights that will lead to improved treatments of patients who suffer from muscle disease or have sustained a nerve injury and improved approaches to excercise training.Read moreRead less
Long-term Surgical And Socioeconomic Outcomes Following Aortopulmonary Septal Defect Repair In Children
Funder
National Health and Medical Research Council
Funding Amount
$89,197.00
Summary
About 2% of heart defects are due to communication between the 2 main arteries exiting the heart (truncus arteriosus and aortopulmonary window). If untreated, up to 30% of children die in the first year of life. With surgery many patients are now surviving into adulthood. The long-term outcomes are unknown. This study will review all patients with this defect across Australian and New Zealand. Results from this study will allow us to best manage these patients in the short and long-term.
Understanding The Cause Of Muscle Weakness In Nemaline Myopathy (NM) – Moving Towards The Development Of Targeted Treatments
Funder
National Health and Medical Research Council
Funding Amount
$408,768.00
Summary
Congenital myopathy patients have unremitting, life-long muscle weakness that severely affects their quality of life and ability to perform normal daily activities. Currently no effective therapies exist for these conditions, largely due to our limited understanding of the mechanisms leading to muscle weakness. This ECF aims to determine the cause of weakness and test two therapies which have shown promise for other conditions and can be translated into clinical use for myopathies if effective.