How Does The P75 Neurotrophin Receptor Transmit Both Pro-survival And Pro-apoptotic Signals In Neurons?
Funder
National Health and Medical Research Council
Funding Amount
$265,500.00
Summary
Signaling by the two NGF receptors, TrkA and p75, determines the survival or death of sensory neurons and of certain brain neurons involved in memory and learning. The most baffling aspect of these receptors is that in most circumstances they cooperate with each other to maximise the survival of neurons when NGF is present, but in some situations they are opposed to each other. In the latter case, NGF treatment can lead to death, rather than rescue, of neurons. In the last three years we have de ....Signaling by the two NGF receptors, TrkA and p75, determines the survival or death of sensory neurons and of certain brain neurons involved in memory and learning. The most baffling aspect of these receptors is that in most circumstances they cooperate with each other to maximise the survival of neurons when NGF is present, but in some situations they are opposed to each other. In the latter case, NGF treatment can lead to death, rather than rescue, of neurons. In the last three years we have developed novel antisense oligonucleotides which can be used to switch off each receptor separately. These have been, and will continue to be, particularly valuable tools for our research. We have also uncovered a novel way in which the two receptors interact (via a signal transduction molecule known as SHC), which provides us with a competitive edge in this area. We have the expertise and equipment to identify and clone the missing factors that account for the paradoxical interactions between p75 and TrkA. A successful outcome from this project will have important benefits by improving our understanding of the factors controlling neuronal fate, and will help to develop treatments for neurodegenerative diseases.Read moreRead less
The Role Of Ryk/AF6/Eph Complexes In Neuronal Pathfinding/fasciculation
Funder
National Health and Medical Research Council
Funding Amount
$422,036.00
Summary
During embryonic development nerve cells in the central nervous system have to find the right connections to make with other nerve cells. The process by which nerve cells find the right partners to make connections with is called neuronal pathfinding. Once some nerve cells have made the right connections, other nerve cells attach to these cells and form bundles of nerve fibres. This process is called fasciculation or bundling. This whole process is vital to the normal development and function of ....During embryonic development nerve cells in the central nervous system have to find the right connections to make with other nerve cells. The process by which nerve cells find the right partners to make connections with is called neuronal pathfinding. Once some nerve cells have made the right connections, other nerve cells attach to these cells and form bundles of nerve fibres. This process is called fasciculation or bundling. This whole process is vital to the normal development and function of the central nervous system and the brain. Without the right connections between nerves, information could not be received, processed or sent to organs in the body. We are now starting to discover some of the molecules which control the process of nerve cell pathfinding during development. It has been known for some time that proteins called Eph receptors play an important role in neuronal pathfinding and development of the head region in mice. We have now discovered that two other proteins called Ryk and AF-6 are able to bind to Eph receptors. We have very recently created mice which lack the Ryk protein and these mice have defects in their head deveopment strikingly similarto the head defects seen in mice that lack Eph receptors. We now wish to see whether Ryk mice have defects in neuronal pathfinding and fasciculation as do mice lacking Eph receptors. We also think that Ryk, Af-6 and Eph receptors form a protein complex which can modify cell function. We now wish to explore how this protein complex can do this.Read moreRead less
Control Of Catecholamine Synthesis And Secretion By Angiotensin II.
Funder
National Health and Medical Research Council
Funding Amount
$271,650.00
Summary
In the stress response the catecholamines, including adrenaline, are secreted by the adrenal gland and the brain. This leads to the synthesis of new catecholamines in order to replace those that were lost. Synthesis of catecholamines is controlled by the activity and the amount of the enzyme tyrosine hydroxylase. Catecholamine synthesis and secretion is therefore a fundamental physiological process. This can be controlled by a number of mechanisms, including hormones such as angiotensin II. Angi ....In the stress response the catecholamines, including adrenaline, are secreted by the adrenal gland and the brain. This leads to the synthesis of new catecholamines in order to replace those that were lost. Synthesis of catecholamines is controlled by the activity and the amount of the enzyme tyrosine hydroxylase. Catecholamine synthesis and secretion is therefore a fundamental physiological process. This can be controlled by a number of mechanisms, including hormones such as angiotensin II. Angiotensin II has a number of functions including the control of blood pressure and body fluid homeostasis. Angiotensin II acts on the adrenal glands, the sympathetic nerves and the brain to produce these effects. It does so by increasing the secretion of catecholamines and these in turn modulate blood pressure and fluid homeostasis. The mechanism(s) whereby angiotensin II induces catecholamine secretion is not known, nor is it known how this leads to increased tyrosine hydroxylase activity and synthesis. The aim of this grant is therefore to determine how angiotensin II induces the activation of tyrosine hydroxylase, the secretion of catecholamines and the synthesis of new tyrosine hydroxylase. The significance of this work is that it will allow us to better understand how angiotensin II works and it will provide insights into the generation and control of hypertension and the mechanisms of the stress response. It is known that the pathways involved in angiotensin II stimulation of catecholamine secretion can be blocked by inhibitors of protein kinases and this leads to a reduction in blood pressure. It is therefore likely that this work will have therapeutic implications.Read moreRead less
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
How Does The LRP Receptor Megalin Promote Regenerative Neuronal Growth?
Funder
National Health and Medical Research Council
Funding Amount
$408,739.00
Summary
Promoting the regenerative growth of neurons to allow recovery from traumatic brain injury or Alzheimer's disease is a major goal of neuroscientists. This project continues the Chief Investigators' work in which they have discovered the regenerative potential of a protein and focuses on how this protein interacts with a key neuronal receptor, megalin, which appears to drive the regenerative process. This work will identify new targets for therapies for a range of nervous system disorders.
Factors Affecting The Conductance Of GABA(A) Channels
Funder
National Health and Medical Research Council
Funding Amount
$406,650.00
Summary
GABA(A) receptors provide most of the inhibition in the brain. If they are blocked, animals suffer from seizures and die. They are the target for a wide variety of medically useful drugs such as anaesthetics, tranquillisers such as valium and anti-epleptic drugs. All these drugs boost their effectiveness and increase inhibition in the brain. Most of them were discovered by chance. In this project, we will find out more about these receptors. This will give us more information about how the brain ....GABA(A) receptors provide most of the inhibition in the brain. If they are blocked, animals suffer from seizures and die. They are the target for a wide variety of medically useful drugs such as anaesthetics, tranquillisers such as valium and anti-epleptic drugs. All these drugs boost their effectiveness and increase inhibition in the brain. Most of them were discovered by chance. In this project, we will find out more about these receptors. This will give us more information about how the brain works and also help in the search for better, more selective drugs.Read moreRead less
Proteolytic Cleavage Of The P75 Neurotrophin Receptor Mediates Cell Death
Funder
National Health and Medical Research Council
Funding Amount
$238,500.00
Summary
The p75 neutrotophin receptor (p75NTR) is a major inducer of nerve cell death, and is active in a wide range of neurodegenerative conditions, including Alzheimer's disease, motor neuron disease, multiple sclerosis, stroke and nerve trauma. This study aims to understand and to characterise the events that regulate this receptor. In particular, we will investigate the role that cleavage or controlled breakdown of the receptor plays in mediating its cell death activity. A fundamental aspect of this ....The p75 neutrotophin receptor (p75NTR) is a major inducer of nerve cell death, and is active in a wide range of neurodegenerative conditions, including Alzheimer's disease, motor neuron disease, multiple sclerosis, stroke and nerve trauma. This study aims to understand and to characterise the events that regulate this receptor. In particular, we will investigate the role that cleavage or controlled breakdown of the receptor plays in mediating its cell death activity. A fundamental aspect of this proposal is determining whether cleavage is due to presenilin-dependent activity, given that presenilin mutations have been demonstrated in most familial Alzheimer s disease cases. While this will increase our understanding of one of factors contributing to Alzheimer's disease, it also has much broader implications. A wide range of pharmaceuticals which regulate presenilin cleavage are already being developed and clinically tested for their efficacy in the treatment of Alzheimer s disease. Should our research demonstrate that p75NTR cleavage is the key process that regulates neuronal degeneration it will have major ramifications for approaches to the treatment of other p75NTR-associated neurodegenerative conditions.Read moreRead less
Regulation Of P75 Death Signalling: How Neurotransmitter- And Neurotrophic- Signals Determine Cell Survival
Funder
National Health and Medical Research Council
Funding Amount
$292,216.00
Summary
Nerve cell survival is dependent on trophic support in the form of growth factors and synaptic input, both of which promote recovery after nerve injury. The survival pathways activated by growth factors are generally well characterised, whereas survival signals activated by synaptic activity are largely unexplored. This proposal aims to discover how synaptic activity prevents nerve cell death by looking at how synaptic activity inhibits the processes active in dying nerve cells.
Molecular Determinants Of Inhibitory Synaptic Function Studied Using Mutant And Transgenic Mice
Funder
National Health and Medical Research Council
Funding Amount
$496,500.00
Summary
Communication between nerve cells is the key to effective brain function and when disturbed, pathological states such as epilepsy, schizophrenia, fear and anxiety, spasticity and motor disorders ensue. This project is based on new data which suggests that the site of this communication, called the synapse, is a much more dynamic structure than previously thought. Based on our work to date, where we have demonstrated the recruitment of selected classes of neurotransmitter receptors into synapses, ....Communication between nerve cells is the key to effective brain function and when disturbed, pathological states such as epilepsy, schizophrenia, fear and anxiety, spasticity and motor disorders ensue. This project is based on new data which suggests that the site of this communication, called the synapse, is a much more dynamic structure than previously thought. Based on our work to date, where we have demonstrated the recruitment of selected classes of neurotransmitter receptors into synapses, our aim is to use a range of naturally occuring mice mutants, as well as transgenic mice to modulate the receptor levels and so to examine the role of synaptic function and synaptic dynamics. The outcomes of this project will provide fundamental new knnowledge aimed at understanding how communication in the nervous system works and may suggest ways in which modulation of this information flow could be used to treat disorders of brain function.Read moreRead less