The Functional Interplay Between Alpha Synuclein And Synaptophysin In Synaptic Vesicle Recycling
Funder
National Health and Medical Research Council
Funding Amount
$405,461.00
Summary
Parkinson’s Disease (PD) is the second most common neurodegenerative disorder, affecting 7 million people worldwide. ?-synuclein is a protein in that brain that is likely to contribute to the death of brain cells in PD, but the normal role of the protein remains unknown. This study will investigate the function of ?-synuclein in maintaining normal healthy brain activity. In addition, this work will help us understand the processes that go awry in neurodegenerative disease states such as PD.
PROBABILITY OF QUANTAL SECRETION AT NEUROMUSCULAR SYNAPSES
Funder
National Health and Medical Research Council
Funding Amount
$334,232.00
Summary
The classical preparation for the study of synaptic transmission is the amphibian neuromuscular junction, for which there is the largest body of experimental data. This synapse was instrumental in the discovery that transmitters are released in packets or quanta, that this occurs at specialized release sites in the nerve terminal, and that receptor molecules on the muscles cells are strategically placed to receive the transmitter. Our work on this synapse has shown that each of these release sit ....The classical preparation for the study of synaptic transmission is the amphibian neuromuscular junction, for which there is the largest body of experimental data. This synapse was instrumental in the discovery that transmitters are released in packets or quanta, that this occurs at specialized release sites in the nerve terminal, and that receptor molecules on the muscles cells are strategically placed to receive the transmitter. Our work on this synapse has shown that each of these release sites have different probabilities for the secretion of a quantum and that this probability is correlated with the width of the release site. More recently we have shown that, whilst the size of a quantum does not vary between adjacent release sites, the area over which the quantum is released does vary between sites. The probability of quantal secretion is proportional to this area, as is the number of vesicles present at the release site. In this project we intend to relate this probability of secretion to the proteins that regulate the release of a quantum and in particular how these proteins interact to determine the time course of increase in probability at a release site after the passage of an impulse. The affects of trains of impulses on this probability are also to be delineated, in particular how the calcium which enters the terminal during these trains determines a long-term enhancement in probability after the train has ceased. This research will provide a molecular description of secretion from motor-nerve terminals.Read moreRead less
Macrophages are white blood cells that provide front line defence against infection by initiating inflammatory responses by ingesting or phagocytosing microbes and by releasing soluble messengers (cytokines) to recruit other immune cells. These defensive functions require extensive trafficking of proteins within the macrophages. Protein trafficking is orchestrated in part by a family of membrane fusion proteins called SNAREs. By defining the relevant SNAREs, we have recently discovered a much ac ....Macrophages are white blood cells that provide front line defence against infection by initiating inflammatory responses by ingesting or phagocytosing microbes and by releasing soluble messengers (cytokines) to recruit other immune cells. These defensive functions require extensive trafficking of proteins within the macrophages. Protein trafficking is orchestrated in part by a family of membrane fusion proteins called SNAREs. By defining the relevant SNAREs, we have recently discovered a much acclaimed and novel pathway that allows efficient, combined cytokine secretion and phagocytosis in macrophages. Our studies proposed here will now expand on this discovery by comparing the phagocytic process, in terms of SNARE-mediated membrane and cytokine trafficking, for a wide range of microbes, highlighting differences that could provide new avenues for drug development. Moreover, since our strategy of using SNAREs to investigate and map trafficking pathways has proven so successful, we will now launch a major large-scale initiative to study ALL SNARE-mediated trafficking pathways in macrophages using a discovery pipeline of assays, including live cell imaging, we have developed. This will provide valuable information on many SNAREs including those associated with disease, and will elucidate trafficking pathways governing all macrophage actions in immunity, including cytokine secretion and antigen presentation. All of these pathways are highly relevant to current drug targets being used clinically or studied in inflammatory disease and for the development of vaccines.Read moreRead less
The Role Of Intersectin-1 In Endocytic Anomalies: Implications For Down Syndrome And Alzheimer's Disease
Funder
National Health and Medical Research Council
Funding Amount
$510,500.00
Summary
Individuals with Down syndrome have three copies of human chromosome 21, rather than the normal two. We have discovered a gene called Intersectin-1, located on human chromosome 21, that is expressed at higher levels than normal in individuals with Down syndrome. Intersectin-1 has a role in endocytosis, a process whereby cells take up molecules from the outside. Endocytosis occurs in all cells but is highly specialised in the brain where chemical transmitters are released and then rapidly recover ....Individuals with Down syndrome have three copies of human chromosome 21, rather than the normal two. We have discovered a gene called Intersectin-1, located on human chromosome 21, that is expressed at higher levels than normal in individuals with Down syndrome. Intersectin-1 has a role in endocytosis, a process whereby cells take up molecules from the outside. Endocytosis occurs in all cells but is highly specialised in the brain where chemical transmitters are released and then rapidly recovered by endocytosis in a process enabling neurones to pass signals to one another. A disturbance in endocytosis has been reported as the earliest hallmark of Alzheimer's disease in both non-Down syndrome and Down syndrome individuals. This disturbance is characterised by the presence of enlarged endosomes (small packages in neuronal cells containing chemical neurotransmitters formed during endocytosis). These enlarged endosomes are present long before the characteristic plaques of Alzheimer's disease appear. Since all individuals with Down syndrome develop Alzheimer's-like neuropathology, there must be a common disease mechanism that can be traced to the extra gene dosage from chromosome 21. We propose that a malfunctioning of Intersectin-1 is this common mechanism and we aim to test our hypothesis by the generation and analysis of mouse models of disrupted endocytosis.Read moreRead less
Astrocyte-Neuron Communication: Unravelling The Role Of Astrocytes In The Modulation Of Neuronal Circuits
Funder
National Health and Medical Research Council
Funding Amount
$403,064.00
Summary
Astrocytes, a type of glial cell, are the most numerous cell type in the brain. They outnumber their neuronal counterparts by ten times and make up almost 90% of adult brain weight. They were originally thought to have only a supportive role in brain metabolism and the regulation of brain blood flow. It is now known that they also modulate neurons and their synapses through release of vesicles containing specific substances and have key roles in some neuropathic (e.g. pain and epilepsy) and neur ....Astrocytes, a type of glial cell, are the most numerous cell type in the brain. They outnumber their neuronal counterparts by ten times and make up almost 90% of adult brain weight. They were originally thought to have only a supportive role in brain metabolism and the regulation of brain blood flow. It is now known that they also modulate neurons and their synapses through release of vesicles containing specific substances and have key roles in some neuropathic (e.g. pain and epilepsy) and neurodegenerative states (e.g. Alzheimer's disease, Parkinson's disease, and multiple sclerosis). Many of these diseases are associated with a pathological astrocyte process known as 'reactivity'. This process remains enigmatic, resulting in so-called reactive gliosis, a reaction characterized by changes in gene expression, cell enlargement and changes in cell shape, and, in some cases, cell division. Most of the research on astrocyte reactivity has focused on the impairment of astrocyte metabolic activities. Comparatively little is known about the effect of reactive gliosis on so called 'newer' astrocyte roles such as their ability to interact with each other and nearby neurons using exocytosis of gliotransmitters (GTs: glutamate and ATP) and neurotrophic factors (NTFs: glial and brain derived neurotrophic factors). This project will both further investigate the normal mechanisms of astrocyte-neuron communication, and examine the effects of astrocyte reactivity on these mechanisms. The aim is to identify possible therapeutic targets to ameliorate the detrimental affects of neurodegeneration.Read moreRead less
Characterising The Role Of MID1 In X-linked Opitz Syndrome: Implications For CATCH22 And Related Disorders
Funder
National Health and Medical Research Council
Funding Amount
$211,527.00
Summary
Opitz syndrome is a debilitating genetic disorder which affects the normal development of many organs and tissues of the human embryo. Patients with Opitz syndrome commonly present with facial deformities (such as cleft lip and palate) as well as both genital and heart defects. Males are usually more severely affected than females although the severity of the disease can vary even amongst males of the same family. Patients can die suddenly in infancy or suffer further developmental impairment du ....Opitz syndrome is a debilitating genetic disorder which affects the normal development of many organs and tissues of the human embryo. Patients with Opitz syndrome commonly present with facial deformities (such as cleft lip and palate) as well as both genital and heart defects. Males are usually more severely affected than females although the severity of the disease can vary even amongst males of the same family. Patients can die suddenly in infancy or suffer further developmental impairment due to respiratory complications and swallowing difficulties that result from the significant facial deformities. A brighter outlook for patients is expected if early and often repeated surgical repair is undertaken to correct not only the facial deformities but also any heart and genital abnormalities. Our research laboratory has recently identified the gene that, when mutated, causes one form of Opitz syndrome. Defects in this gene account for around half the cases with the disorder. Evidence suggests that there may be a number of other genes involved in causing the remaining cases of the disease. The proposed research is aimed at investigating the molecular and developmental mechanisms that go awry as a result of the gene mutation. It is anticipated that these studies will provide valuable scientific knowledge about why some patients are more severely affected than others as well as offering clues to the identity of the genes that cause the remaining cases of Opitz syndrome. The results also have potentially important implications for the understanding of other diseases that show similar deformities. The knowledge gained from this research is expected to provide a valuable aid for effective genetic counselling (as well as the option of prenatal diagnosis) for families at risk of further affected pregnancies. This will also ultimately lead to more effective disease management and correction in the affected child.Read moreRead less
Molecular And Clinico-pathological Investigation Of Congenital Myopathies
Funder
National Health and Medical Research Council
Funding Amount
$743,290.00
Summary
Congenital myopathies are inherited disorders causing muscle weakness from birth. Some types lead to early death of the affected child, while others are compatible with life to adulthood. Like any disease of childhood, the congenital myopathies cause considerable trauma to the families concerned. Couples at risk of having another affected child frequently wait for prenatal diagnosis to become available for their particular disease before attempting to have further children. However, prenatal dia ....Congenital myopathies are inherited disorders causing muscle weakness from birth. Some types lead to early death of the affected child, while others are compatible with life to adulthood. Like any disease of childhood, the congenital myopathies cause considerable trauma to the families concerned. Couples at risk of having another affected child frequently wait for prenatal diagnosis to become available for their particular disease before attempting to have further children. However, prenatal diagnosis is only possible once the gene causing a disorder and the mutation in an individual family are identified. In the past, the Laboratories collaborating in this project, the Molecular Neurogenetics Laboratory, Australian Neuromuscular Research Institute, Perth, and the Neurogenetics Research Unit, New Children s Hospital, Sydney, have identified disease genes for congenital myopathies. Prenatal diagnosis is now possible for families whose disease-causing mutation is identified. However the genetic cause of many of the congenital myopathies remains unknown. DNA and other samples have been sent to the Laboratories from around the world, making us reference centres for congenital myopathy research. Part one of the project is to study these and Australasian samples, to identify other congenital myopathy genes. This will help families who currently cannot have prenatal diagnosis. Finding the genes also increases understanding of the diseases by clarifying which proteins are involved. In part two of the project we shall study the mutated proteins, to try to unravel how the gene mutations cause the diseases. The third part of the project is to reevaluate the highly variable muscle pathology in congenital myopathies in cases where the disease gene is now known, in order to investigate genotype-phenotype correlations. Understanding the pathologic basis of the congenital myopathies will ultimately allow us to begin to think rationally about possible treatments.Read moreRead less
Deficiency of the protein dysferlin causes muscular dystrophy, an inherited degenerative disorder of skeletal muscle. Interestingly, muscle disease due to deficiency of dysferlin does not occur until early adulthood. Affected individuals are very active with normal strength until this age and then there is rapid progression of weakness. Many patients lose the ability to walk within a few years of onset. Little is known about the functional role of dysferlin in muscle, how dysferlin deficiency re ....Deficiency of the protein dysferlin causes muscular dystrophy, an inherited degenerative disorder of skeletal muscle. Interestingly, muscle disease due to deficiency of dysferlin does not occur until early adulthood. Affected individuals are very active with normal strength until this age and then there is rapid progression of weakness. Many patients lose the ability to walk within a few years of onset. Little is known about the functional role of dysferlin in muscle, how dysferlin deficiency results in muscular dystrophy, or why dysferlin-deficient muscle is functionally normal prior to the rapid onset of symptoms. Therefore, the goal of this study is to characterize the role of dysferlin in normal and diseased skeletal muscle. We will examine the consequence of dysferlin-deficiency in patient muscle biopsy samples and patient muscle cells in culture. We will assess the role of dysferlin in the fusion and formation of new muscle cells, examine the effect of dysferlin-deficiency on muscle membrane repair, and establish how normal and mutant dysferlin is made, trafficked and degraded within muscle cells. This research will have immediate applications to the diagnosis and counselling of patients with dysferlin-related disease. In addition it will provide valuable information concerning the mechanisms of disease, essential to the development of specific and successful therapies.Read moreRead less