Computational Study Of Selectivity, Gating And Mutation In The Acetylcholine Receptor And Potassium Channels
Funder
National Health and Medical Research Council
Funding Amount
$301,393.00
Summary
One way cells in living organisms communicate with each other is via the passage of charged particles across the cell membrane. This takes place through ion channels, large protein molecules that span the membrane and allow small molecules or ions to pass through a central pore. Malfunction of ion channels is known to underlie a variety of disorders including epilepsy, hypertension, kidney disease, heart attack, deafness. Channels also provide promising targets for making new broad spectrum anti ....One way cells in living organisms communicate with each other is via the passage of charged particles across the cell membrane. This takes place through ion channels, large protein molecules that span the membrane and allow small molecules or ions to pass through a central pore. Malfunction of ion channels is known to underlie a variety of disorders including epilepsy, hypertension, kidney disease, heart attack, deafness. Channels also provide promising targets for making new broad spectrum antibiotics and antivirals. This project aims to study two important types of ion channel: acetylcholine receptors that convey signals between nerve and muscle cells, and potassium channels that regulate the nerve impulses themselves. The binding of the neurotransmitter acetylcholine released from a nerve cell to acetylcholine receptors in the muscle cell prompts the opening of a cation conductive pore. The resulting influx of ions initiates a cascade of events ending in the contraction of the muscle fibre. However, the way in which this channel opening is initiated and how ions move into the muscle cell remain to be determined. Potassium channels are primarily used to rapidly 'switch off' nerve impulses so that subsequent messages can be passed through the nerve cell. To do this they have to be highly discriminatory, allowing only potassium to pass across the cell membrane and not sodium that would initiate another impulse. Although we now know what these tiny proteins look like, it is not clear how they differentiate between types of ions while still allowing many millions to pass each second. We will use computer simulations to study how these two type of channel open and close, and how they discriminate between different ion types. Using sophisticated computational techniques on Australia's most powerful supercomputers we aim to elucidate this fundamental area of human biology in the hope of deriving treatments for some debilitating neuromuscular diseases.Read moreRead less
Characterisation Of A Novel Human Neuromuscular Disease Associated With Deficiency Of The Syntrophins And Dystrobrevin.
Funder
National Health and Medical Research Council
Funding Amount
$284,069.00
Summary
The muscular dystrophies are a group of hereditary muscle diseases which can result in severe and progressive muscle weakness. Children with muscular dystrophy have significant and worsening disabilities; many are unable to walk and, in severe cases, the weakness impairs the muscles of breathing resulting in death at an early age. The more common muscular dystrophies present in early childhood; however some forms of muscular dystrophy are so severe that muscle weakness is obvious at birth, affec ....The muscular dystrophies are a group of hereditary muscle diseases which can result in severe and progressive muscle weakness. Children with muscular dystrophy have significant and worsening disabilities; many are unable to walk and, in severe cases, the weakness impairs the muscles of breathing resulting in death at an early age. The more common muscular dystrophies present in early childhood; however some forms of muscular dystrophy are so severe that muscle weakness is obvious at birth, affected babies are never able to breathe adequately, and die during the first weeks of life. No specific treatment is currently available. Until recently the underlying gene and protein abnormalities resulting in the majority of cases of muscular dystrophy were unknown and hence definitive diagnosis and prenatal diagnosis was not possible. We have recently identified deficiency of a group of muscle proteins, the syntrophins and dystrobrevin, in 15 children with severe weakness, in whom the cause was previously unknown. This group of patients represent the first examples of a novel neuromuscular disorder. We will now identify the disease-causing genetic mutations in these patients and determine how abnormalities in these muscle proteins lead to muscle weakness and degeneration. This research will have immediate application to clinical practice as we will be able to give the childrens' families accurate information about the risk to future offspring and offer prenatal diagnosis. In addition, it will provide new and important information concerning the normal function of human skeletal muscle, which can be used to develop therapies for affected patients.Read moreRead less
The Role Of Connexin40 In The Pathogenesis Of Atrial Fibrillation Probed By Targeted In Vivo Gene Transfer
Funder
National Health and Medical Research Council
Funding Amount
$529,015.00
Summary
Atrial fibrillation (AF) is a fast and irregular heart rhythm that can predispose sufferers to heart failure and stroke. AF occurs as the result of abnormal electrical conduction in the upper heart chambers. We have found that a protein called Cx40 causes abnormal conduction in heart cells when grown in culture. The aim of this research is to see if AF occurs when Cx40 is increased and prevented when Cx40 is decreased in an AF animal model, potentially defining Cx40 as new therapeutic target.
Protein Partners Of Rapsyn That Regulate Acetylcholine Receptor Clustering
Funder
National Health and Medical Research Council
Funding Amount
$411,000.00
Summary
Spinal nerves control our limb muscles by releasing chemical signals directly onto the surface of muscle fibres that they contact. These chemical signalling contacts are called synapses. They are like the synapses between nerve cells in our brains but easier to study, meaning that we can make more rapid progress in understanding how synapses work. The sensor receptors for chemical signals at the nerve-to-muscle synapse are held in place on the muscle fibre surface by a protein called rapsyn. In ....Spinal nerves control our limb muscles by releasing chemical signals directly onto the surface of muscle fibres that they contact. These chemical signalling contacts are called synapses. They are like the synapses between nerve cells in our brains but easier to study, meaning that we can make more rapid progress in understanding how synapses work. The sensor receptors for chemical signals at the nerve-to-muscle synapse are held in place on the muscle fibre surface by a protein called rapsyn. In turn, rapsyn must be organized by other chemical signals from the nerve, but we don't know exactly how this happens. When the receptors become disorganized at the synapse, in diseases such as Myasthenia Gravis, we lose control of our muscles. This project will employ newly developing techniques of proteomics and genomics to identify new proteins that bind to rapsyn and to test how they work to organize receptors at the synapse. By identifying the proteins that control rapsyn we may be able to develop new treatments for Myasthenia Gravis that restore the function of the synapse with less side effects than current therapies.Read moreRead less
Postsynaptic Signalling Systems That Sustain The Nerve-muscle Synapse
Funder
National Health and Medical Research Council
Funding Amount
$598,041.00
Summary
Neuromuscular junctions (NMJ) are the synapses through which motor nerves control our voluntary muscle cells. This project will investigate the molecular signalling system between nerve and muscle that helps maintain healthy NMJs. Normal ageing involves a progressive decline in muscle strength, often leading to loss of independence in the elderly. We will use a mouse model to test whether a breakdown of the NMJ signalling system contributes to the loss of strength in old age.
Role Of Synaptogenesis In Developmental Motoneuron Cell Death
Funder
National Health and Medical Research Council
Funding Amount
$361,650.00
Summary
Naturally occurring cell death is an important and necessary event that shapes the developing embryo. It occurs in all organs of the developing body. In the nervous system about 50% of all neurons die at a time when they are making contact with one another or with their target organs. The underlying mechanisms that drive programmed neuronal cell death are not known. One possibility is that the formation of neuronal contacts (synapses) with other neurons and target cells determines the fate of a ....Naturally occurring cell death is an important and necessary event that shapes the developing embryo. It occurs in all organs of the developing body. In the nervous system about 50% of all neurons die at a time when they are making contact with one another or with their target organs. The underlying mechanisms that drive programmed neuronal cell death are not known. One possibility is that the formation of neuronal contacts (synapses) with other neurons and target cells determines the fate of a neuron. The connections of motor neurons with muscle during this period of developmental neuronal cell death is the best model to examine this phenomenon. In this grant we are in an exciting position to be able to address what causes neuronal cell death, as we have a number of mice that lack key molecules needed for the formation of specializations that allow neuronal contacts to be made between motor neurons and their muscle, and with other neurons within the spinal cord. By examining the function of motor neurons, counting them and screening for molecular changes in these mice, we will be able to dissect out the mechanism of how a motor neurons' fate is determined during the period of programmed cell death. The outcomes of this research will enable us to understand how the nervous system is shaped during development and will increase our knowledge about the basis of adult neurodegenerative diseases. For example, the pathology of Alzheimer's is characterised by a breakdown in neuronal connections that ultimately result in neuronal death and a loss of thought processes (cognition).Read moreRead less
Gene Therapy To Cure Botulinum Toxin Intoxication And New Motoneuron Delivery System
Funder
National Health and Medical Research Council
Funding Amount
$390,321.00
Summary
The aim of the project is to establish two biotechnological strategies to help curing motoneuronal diseases. Botulinum neurotoxins (BoNTs) are the deadliest toxins known. They provoke profound flaccid neuromuscular paralysis that leads to death due to respiratory failure. There are no current therapies available and affected patients require respiratory assistance for up to 7 months with sophisticated respirators. BoNT is therefore an acquired motoneuronal disease and a well-known biological wea ....The aim of the project is to establish two biotechnological strategies to help curing motoneuronal diseases. Botulinum neurotoxins (BoNTs) are the deadliest toxins known. They provoke profound flaccid neuromuscular paralysis that leads to death due to respiratory failure. There are no current therapies available and affected patients require respiratory assistance for up to 7 months with sophisticated respirators. BoNT is therefore an acquired motoneuronal disease and a well-known biological weapon which is also easy to produce in large quantities. It is therefore important to provide a quick and efficient way of overriding BoNT-induced paralysis other than very costly mechanical respirators. Our first strategy aims at designing a gene therapy against botulism. BoNTs promote muscular paralysis by cleaving molecules implicated in the mechanism of neuronal communication (SNARE proteins). Our aim is to deliver genetically modified uncleavable forms of SNAREs to rescue neuronal communication and prevent botulism. BoNT are comprised of two chains: a toxic light chain and a non toxic heavy chain which is responsible for the extreme selectivity of BoNT for motoneurons and for delivering the light chain in the motoneuronal cytosol by a mechanism named translocation. Our second aim is to use the BoNTs atoxic heavy chain to engineer a selective motoneuronal delivery system. This could be useful in the future to deliver molecules of interest in diseased motoneurons.Read moreRead less
Molecular Mechanisms That Help Organise Effective Synaptic Transmission.
Funder
National Health and Medical Research Council
Funding Amount
$555,825.00
Summary
This study will test the idea that adhesion molecules alpha4- and beta2-laminin are needed for proper development and function of motor nerve - muscle connections. This study will provide insights into how such molecules control effective nerve-muscle communication, in both health and disease. We also believe that our results will provide the basic knowledge needed for identifying pharmacological targets that could improve such connections, and to promote reconnections between nerve and muscle.