Dominant Repeat Expansion Diseases - A Common RNA Mediated Pathogenic Pathway?
Funder
National Health and Medical Research Council
Funding Amount
$281,118.00
Summary
There are fourteen human genetic diseases that are caused by a similar mutation mechanism and have similar clinical outcomes - the loss of function, degeneration and eventual death of nerve cells. This group of diseases includes Huntington's Disease. They are transmitted from parent to offspring such that each child of an affected parent has 50% risk of inheriting the affected gene and therefore developing the disease. The symptoms of these diseases typically develop later in life - between the ....There are fourteen human genetic diseases that are caused by a similar mutation mechanism and have similar clinical outcomes - the loss of function, degeneration and eventual death of nerve cells. This group of diseases includes Huntington's Disease. They are transmitted from parent to offspring such that each child of an affected parent has 50% risk of inheriting the affected gene and therefore developing the disease. The symptoms of these diseases typically develop later in life - between the ages of 35 and 50 years. While the different genes for these diseases have been identified the pathways that lead from their similar form of mutation to their similar clinical outcomes are not yet understood. Some evidence suggests that certain of these diseases have a common toxic component but this component is not shared by all of the disease genes and so an additional agent that they have in common is being sought. This research will use a genetic model organism - the vinegar fly, Drosophila melanogaster, to test the identity of a good candidate (RNA) for a common toxic agent and to provide information about the pathway by which RNA leads to nerve cell degeneration and death. Accurate and complete knowledge of the identity and composition of the pathways that lead from the mutation to the disease are crucial for correct target identification in the development of drug leads.Read moreRead less
The Molecular Basis For Target Selection In The Central Nervous System By Sensory Axons
Funder
National Health and Medical Research Council
Funding Amount
$251,325.00
Summary
The normal function of the brain depends upon the specific connections that nerve cells make with each other. These connections are set up in the developing embryo when nerve cells send out long processes - axons - which grow towards their synaptic targets. How axons select their correct targets from amongst the millions of alternatives in the developing brain is unknown. A better understanding of this problem will help us develop therapies to assist regenerating axons re-establish correct conne ....The normal function of the brain depends upon the specific connections that nerve cells make with each other. These connections are set up in the developing embryo when nerve cells send out long processes - axons - which grow towards their synaptic targets. How axons select their correct targets from amongst the millions of alternatives in the developing brain is unknown. A better understanding of this problem will help us develop therapies to assist regenerating axons re-establish correct connections following injury to the brain or spinal cord. We propose to use a simple model system, the embryo of the fruitfly Drosophila, to find molecules that are involved in this process of neuron target recognition - ' axon targeting' molecules - and to study how they work. Drosophila can be genetically manipulated in ways not possible in higher animals. Furthermore the simplicity of its nervous system means that we can determine the connections of individual nerve cells with a high degree of precision. In the first part of our project, we will examine Drosophila embryos that carry mutations in genes suspected to code for targeting molecules. We will stain individual sensory nerve cells in these embryos with dyes to reveal the anatomy of their axons in the brain. If sensory axons terminate abnormally in the brain of a given mutant, the affected gene is likely to code for an axon targeting molecule. In the second part of the study, we will investigate the functions of candidate axon targeting molecules using two approaches. Firstly, we will seek to determine whether the molecule acts in the sensory axons or in their target cells. Secondly, we will use time-lapse microscopy to study how the homing behaviour of the sensory axons is affected in mutant embryos. The results of these studies will lead us closer to an answer to the question: How do axons recognise their specific target cells in the brain?Read moreRead less
Copper Homeostasis And APP-induced Neurodegeneration In Drosophila
Funder
National Health and Medical Research Council
Funding Amount
$381,223.00
Summary
Alzheimer s disease, a debilitating neurodegenerative disorder suffered by many of our elderly, is characterised by the presence of abnormal protein accumulations called plaques in the brains of affected patients. Plaques contain amyloid protein and also have high levels of the essential metals copper and zinc. Copper is needed for the formation of these protein aggregations and increases the toxic effects of amyloid, leading to the idea that copper-binding chemicals could be used to treat Alzhe ....Alzheimer s disease, a debilitating neurodegenerative disorder suffered by many of our elderly, is characterised by the presence of abnormal protein accumulations called plaques in the brains of affected patients. Plaques contain amyloid protein and also have high levels of the essential metals copper and zinc. Copper is needed for the formation of these protein aggregations and increases the toxic effects of amyloid, leading to the idea that copper-binding chemicals could be used to treat Alzheimer s disease. However experiments in animal models have produced conflicting results, some suggesting that increased copper levels protect against neuronal damage while others claim the opposite effect. Comparison of these studies is hampered by the different experimental systems used. We will clarify the role of copper in the progression of Alzheimer s disease using a simple insect model, the fly Drosophila melanogaster. Production of amyloid in Drosophila neuronal tissues produces a neurodegenerative effect similar to that seen in human brains, but in a matter of weeks rather than the years required in humans. We will combine production of amyloid with production of copper uptake and export proteins to investigate the effect of changing copper levels. We will also test the effect of increasing copper and other metals in the diet to see whether dietary levels are an important factor in disease progression. Finally, we will use the Drosophila model to test large numbers of metal binding compounds and drugs for ones that slow or halt the neuronal damage caused by amyloid production, identifying potential therapeutics for the treatment of Alzheimer s disease. This work will provide a vital and definitive clarification of the role of copper in the progression of Alzheimer s disease and potentially lead to the development of novel treatments for this disease that is rapidly becoming a major social and economic problem in the developed world.Read moreRead less
The Role Of Cell Adhesion Molecules In Regulation Of Axon Advance
Funder
National Health and Medical Research Council
Funding Amount
$426,006.00
Summary
All cells contain on their surface a class of molecules, cell adhesion molecules, that enable them to adhere to other cells in tissues. Cell adhesion molecules have long been known to be involved in the guidance of axons to their targets during development. However the molecular mechanisms by which these molecules act are largely unknown. We propose to use the powerful genetic tools available in the fruitfly to dissect the mechanisms by which two cell adhesion molecules promote axon growth.