Determining The Pathobiology Of Human Sarcomeric Myopathies Using Zebrafish
Funder
National Health and Medical Research Council
Funding Amount
$509,541.00
Summary
Laing muscular dystrophy and ACTA1 congenital muscular dystrophy are severe muscle diseases with high morbidity. We will create zebrafish strains that carry these diseases and use these to understand the causes of muscle failure and investigate possible areas of treatment for these conditions.
Molecular And Cellular Basis For Muscle Regeneration In Zebrafish.
Funder
National Health and Medical Research Council
Funding Amount
$541,104.00
Summary
Muscle repair occurs via the use of muscle stem cells, which provide skeletal muscle with its regenerative capacity. Muscle stem cells are particularly important in muscle diseases such as muscular dystrophies where muscle regeneration is an important factor in disease progression. We will identify the processes controlling muscle regeneration utilising zebrafish as a model organism. We hope this research will lead to an understanding of how muscle stem cells are generated.
The Role Of Scube Genes In Hedgehog Signal Transduction
Funder
National Health and Medical Research Council
Funding Amount
$496,446.00
Summary
Cancer often results form the miss-regulation and-or mutation of genes that control tissue formation in the developing embryo. Particular sets of genes combine to form a signal transduction pathway that coordinates the cell's response to its environment during the course of normal fetal growth. One such pathway is called the Hedgehog signal transduction pathway which has been shown to coordinated cell division and patterning within malignant and normal tissues. Genes encoding components of this ....Cancer often results form the miss-regulation and-or mutation of genes that control tissue formation in the developing embryo. Particular sets of genes combine to form a signal transduction pathway that coordinates the cell's response to its environment during the course of normal fetal growth. One such pathway is called the Hedgehog signal transduction pathway which has been shown to coordinated cell division and patterning within malignant and normal tissues. Genes encoding components of this pathway are mutated in the most common forms of human cancers. Understanding how this pathway is regulated is critical to designing strategies to treat the onset and progression of these cancers. The studies outlined in this grant plan to study a new component of this pathway that we have identified in our laboratory, in an easy to study vertebrate model, the zebrafish embryo. We plan to study how this class of proteins, termed scube proteins, acts to control activation of the pathway. We hope this will lead to a fuller understanding of this process, and at the same time help understand the nature of the end result of the patterning process within the muscle cells that we are studyingRead moreRead less
The Regulation And Function Of Cadherin-mediated Adhesion Within The Zebrafish Myotome.
Funder
National Health and Medical Research Council
Funding Amount
$436,773.00
Summary
Co-ordinating how cells interact with their neighbours and where different cells are positioned within an organ is the role of proteins termed cell adhesion molecules. They delineate and sort cells into different groups depending on which cell adhesion molecules are expressed on their surface. Cell adhesion molecules are also important during the onset of disease, in particular cancer, where the levels and type of cell adhesion molecules expressed on the surface of a cancer cell can determine ho ....Co-ordinating how cells interact with their neighbours and where different cells are positioned within an organ is the role of proteins termed cell adhesion molecules. They delineate and sort cells into different groups depending on which cell adhesion molecules are expressed on their surface. Cell adhesion molecules are also important during the onset of disease, in particular cancer, where the levels and type of cell adhesion molecules expressed on the surface of a cancer cell can determine how invasive or aggressive the cancer cell will become. However, despite the fundamental importance that cell adhesion plays in sorting out cells in every tissue, the exact basis of cell migratory behaviours that occur within the intact organism remain poorly defined. We have examined the ability of specific members of a particular class of cell adhesion molecules, the classical Cadherins, to control formation of muscle. To do this we have examined muscle formation within embryos of the zebrafish, a small embryologically accessible fresh water fish. We have determined how different cadherin molecules co-ordinate the final pattern of the myotome, the structure that gives rise to the majority of muscle in the early embryo. We have determined that differential cell adhesion drives cell sorting of specific muscle cell types via differential use of members of the classical cadherin family of proteins. This study aims to look further at the way that these proteins are regulated in different muscle cells of the forming body. By understanding how these molecules regulate cell sorting and adhesion within the zebrafish myotome we hope to be able to apply this knowledge to how these molecules control the formation of more complex tissues. Furthermore, we believe the implication of specific signalling pathways in the control of cadherin gene expression has particular implications for the role these proteins play in the progression of metastatic cancer.Read moreRead less
Characterisation Of The Regenerative Response In A Zebrafish Model Of Duchenne Muscular Dystrophy
Funder
National Health and Medical Research Council
Funding Amount
$435,750.00
Summary
Muscular Dystrophy is the most common lethal inherited disorder of children. Within dystrophic patients skeletal muscle fibres undergo cycles of muscle breakdown and regeneration until the regenerative response is exhausted, leading to a progressive muscle wasting. Regeneration of skeletal muscle is controlled by a specialised set of stem cells termed satellite cells that are activated to produce new muscle fibres in response to injury. As such satellite cells have been the targets of intense in ....Muscular Dystrophy is the most common lethal inherited disorder of children. Within dystrophic patients skeletal muscle fibres undergo cycles of muscle breakdown and regeneration until the regenerative response is exhausted, leading to a progressive muscle wasting. Regeneration of skeletal muscle is controlled by a specialised set of stem cells termed satellite cells that are activated to produce new muscle fibres in response to injury. As such satellite cells have been the targets of intense investigation for the development of cell based therapies for muscular dystrophies. We have developed a new vertebrate animal system in which to analyse muscular dystrophy and the control of satellite cell function, the zebrafish. We have shown that a mutation in a gene responsible for causing Duchenne Muscular Dystrophy in humans also causes a similar disease in Zebrafish. Zebrafish are an embryologically and genetically tractable model system in which to study muscle cell biology. The ability to visualise muscle growth within an optically transparent embryo and larvae, coupled with a large number of mutations affecting muscle patterning and growth suggest that it is a suitable model to explore muscle maintenance. The specific aims of this proposal are to determine in our new dystrophic zebrafish model, how regeneration controls the onset and pathology of muscle fibre loss. We wish to determine if muscle stems cells analogous to those known to function in mammalian muscle can be detected in zebrafish in normal and dystrophic muscle. We then plan to identify novel genes controlling muscle growth and regeneration through the genetic and embryological advantages that zebrafish as a model organism provide. We hope this will lead to a better understanding of how muscle stem cells are generated and are activated in muscular dystrophy and we hope this will open new avenues for muscle stem cell based therapies of the disease.Read moreRead less
Skeletal muscle responds to exercise or mechanical load, in a process known as hypertrophy. Hypertrophy is initiated by a population of immature muscle cells known as myoblasts which fuse to form myotubes, and then mature to form muscle fibers (differentiation). Many proteins involved in a cascade of activation and-or deactivation are important for regulating hypertrophy (hypertrophic signaling). Failure of skeletal muscle to induce hypertrophy can lead to muscle degeneration. The FHL proteins a ....Skeletal muscle responds to exercise or mechanical load, in a process known as hypertrophy. Hypertrophy is initiated by a population of immature muscle cells known as myoblasts which fuse to form myotubes, and then mature to form muscle fibers (differentiation). Many proteins involved in a cascade of activation and-or deactivation are important for regulating hypertrophy (hypertrophic signaling). Failure of skeletal muscle to induce hypertrophy can lead to muscle degeneration. The FHL proteins are highly expressed in skeletal muscle. FHL proteins are molecular scaffolds which direct assembly of protein complexes to form the muscle contraction machinery (sarcomere). We propose FHL proteins will initiate-regulate skeletal muscle hypertrophy. Increased levels of FHL1 correlate with skeletal muscle hypertrophy. However, it is unclear if increased FHL1 is alone sufficient to induce hypertrophy directly. We have genetically engineered mice to express elevated levels of FHL1 specifically in skeletal muscles (FHL1 transgenic mice) and these mice show muscle enlargement. FHL1 transgenic mice have larger muscle fibers and are >7-fold stronger than non-transgenic littermates. We are currently examining which cell signaling pathways are affected by elevated FHL1. We are also investigating the role of another family member FHL3 in the differentiation of immature myoblasts, a process essential for both embryonic and postnatal skeletal muscle (hypertrophy) development. In the cell nucleus, FHL2 regulates genes which control cell growth and death and increased nuclear levels of FHL2 been detected in prostate cancer biopsies. Recently we demonstrated that FHL2 binds and is sequestered from the nucleus, by a protein, filamin. We are investigating the FHL2-mediated regulation of genes in human melanoma cells, which due to gene mutation are devoid of filamin and will determine how this affects FHL2 function in muscle.Read moreRead less
Role Of Laminin-mediated Adhesion In Regulating Muscle Cell Attachment In Development And Disease.
Funder
National Health and Medical Research Council
Funding Amount
$490,202.00
Summary
Muscular dystrophies and myopathies are amongst the largest group of inherited disorders to afflict the human condition. It is our hope that the results of this research will lead to a better understanding of how treatments could be employed to correct such disorders. Our development of zebrafish models of common muscular dystrophies allows us to study these disorders utilising the advantages of the zebrafish system.