Molecular Mechanisms Of Dynamin-mediated Endocytosis In Nerve Terminals
Funder
National Health and Medical Research Council
Funding Amount
$1,033,626.00
Summary
Neurons communicate by neurotransmitter release from synaptic vesicles stored in nerve endings. There is a finite vesicle number, so they are recycled (endocytosis) by the protein dynamin. Our aim is to reveal how new vesicles are produced when the brain is under very high activity, to better understand diseases of the synapse like epilepsy. We propose that two forms of the dynamin gene mediate this process, only under conditions of high neuronal firing, such as occurs during a seizure.
Inhibitory Signalling Switches Define The Machinery Of Synaptic Vesicle Endocytosis
Funder
National Health and Medical Research Council
Funding Amount
$387,489.00
Summary
The nerve cells in our brains are in constant communication to sustain life. Communication involves one nerve cell responding to electrical stimulation by releasing chemical messengers, from vesicles, onto the next cell. Our research focuses on the mechanism of recycling of vesicles. Targeting this mechanism is a way to gain fundamental knowledge of how to intervene medically when communication fails, or when communication needs to be dampened, in neurological diseases.
Phosphorylation Of Synaptic Vesicle Glycoprotein 2 (SV2) Regulates Endocytosis Of Synaptotagmin For Synaptic Transmission
Funder
National Health and Medical Research Council
Funding Amount
$613,311.00
Summary
Antiepileptic drugs typically target ion transporters or neurotransmitter receptors. Synaptic vesicle glycoprotein 2 (SV2) is a rare example of a synaptic vesicle recycling protein that is the target of an antiepileptic drug. It also binds botulinum and tetanus neurotoxins. We discovered SV2 contains activity-dependent signalling molecules. Charactersation of these molecules and will allow a deeper understanding of the molecular basis for its role in epilepsy and toxin action.
Differential Regulation Of Two Modes Of Exocytosis By Protein Phosphatases
Funder
National Health and Medical Research Council
Funding Amount
$399,750.00
Summary
The release of signals from nerve endings (exocytosis) is of fundamental importance to nervous system function. The recent recognition that nerve cells can release transmitter by at least two distinct modes of exocytosis has led to the need for a deeper understanding of the mechanisms that regulate exocytosis. Our identification of the key role played by two enzymes, PP2A and PP2B, represents a major insight into the molecular mechansisms regulating this process. The experiments will lead to the ....The release of signals from nerve endings (exocytosis) is of fundamental importance to nervous system function. The recent recognition that nerve cells can release transmitter by at least two distinct modes of exocytosis has led to the need for a deeper understanding of the mechanisms that regulate exocytosis. Our identification of the key role played by two enzymes, PP2A and PP2B, represents a major insight into the molecular mechansisms regulating this process. The experiments will lead to the identification of how PP2A and PP2B are regulated at the molecular level and the targets that are important in the control of exocytosis. The project will also develop new tools to specifically manipulate the two modes of exocytosis in order to understand their contribution to normal and pathological neurotransmission. Strong stimulation of exocytosis is associated with learning and memory in normal brain and neuronal damage under certain pathological conditions. Since switching from 1 mode of exocytosis to another is also induced by strong stimulation, an understanding of the molecular mechanisms that control the different modes of exocytosis may eventually lead to clinical applications.Read moreRead less
Mechanisms Of Synaptic Vesicle Endocytosis Revealed By Its Regulatory Phosphoproteome
Funder
National Health and Medical Research Council
Funding Amount
$545,216.00
Summary
The nerve cells in our brains are in constant communication to sustain life. Communication involves electrical stimulation of one nerve cell which then responds by releasing chemical messengers, from vesicles, onto the next cell. Our research focuses on the mechanism of recycling of vesicles. Targeting this mechanism is a way to gain fundamental knowledge of how to intervene medically when communication fails, or when communication needs to be dampened, such as in some neurological diseases.
Dynamin Inhibitors As Tools For Dissecting The Endocytic Pathway In Neurons
Funder
National Health and Medical Research Council
Funding Amount
$470,250.00
Summary
Nerve cells communicate by the release of neurotransmitters which are packaged in synaptic vesicles inside nerve endings. There is a finite number of vesicles, so they are recycled (endocytosis) for reuse. Some human neural diseases hijack the endocytic pathway for entry of pathological peptides, proteins or viruses to paralyse, kill or infect neurons. Our overall aim is to control nerve communication to ultimately allow us to treat disorders of nerve communication like epilepsy. At its most ext ....Nerve cells communicate by the release of neurotransmitters which are packaged in synaptic vesicles inside nerve endings. There is a finite number of vesicles, so they are recycled (endocytosis) for reuse. Some human neural diseases hijack the endocytic pathway for entry of pathological peptides, proteins or viruses to paralyse, kill or infect neurons. Our overall aim is to control nerve communication to ultimately allow us to treat disorders of nerve communication like epilepsy. At its most extreme, completely blocking endocytosis quickly results in a complete block in nerve communication. Therefore slowing it down (rather than blocking) might be a means to control some neural diseases. For example, a seizure is the uncontrolled firing of neurons. The main mechanisms controlling endocytosis converge on the protein dynamin. Dynamin can assemble into a tiny, tightly wound helix or spring. When energy (GTP hydrolysis) is applied to the nanospring it rapidly releases to cleave off empty recycling synaptic vesicles from the cell wall back into the neuron. Our premise is that blocking the nanospring may lead to a new generation of antiepileptic drugs. To achieve this we have already discovered the first chemical inhibitors of dynamin. In this project we will determine how they work, by showing that they target distinct sites in dynamin. We have embarked on an ambitious chemical synthesis program to greatly improve the potency and specificity of the inhibitors. We will expand this with an iterative approach using combinatorial chemistry. When applied to neurons, the drugs appear to be the first endocytosis inhibitors. Will test our proposal that they will reveal multiple points of action of dynamin in various stages of endocytosis. This project will prove the principle that the development of anti-dynamin drugs could lead to the first anti-endocytic drugs. This has the potential to lead to future development of targeted antiepileptic and anticancer drugs.Read moreRead less
The Function Of Dynamin Phosphorylation Sites In Synaptic Vesicle Endocytosis
Funder
National Health and Medical Research Council
Funding Amount
$794,565.00
Summary
Neurons communicate with each other via the release of neurotransmitters which are packaged in synaptic vesicles inside nerve endings. There are a finite number of vesicles, so they are recycled (endocytosis) for reuse. Synaptic vesicle exocytosis is very fast and normally endocytosis is a little slower, mopping up the used vesicles. Recently we showed that endocytosis can control synaptic transmission, hence it's an integral part of an overall cycle of synaptic transmission. We found that when ....Neurons communicate with each other via the release of neurotransmitters which are packaged in synaptic vesicles inside nerve endings. There are a finite number of vesicles, so they are recycled (endocytosis) for reuse. Synaptic vesicle exocytosis is very fast and normally endocytosis is a little slower, mopping up the used vesicles. Recently we showed that endocytosis can control synaptic transmission, hence it's an integral part of an overall cycle of synaptic transmission. We found that when endocytosis cannot keep up then exocytosis slows, greatly reducing the function of neurons. A complete block would result in paralysis of brain and muscles. Our team has been revealing the underlying molecular mechanisms of endocytosis in order to better understand diseases of the synapse like schizophrenia, epilepsy and Alzheimer's disease. We discovered that endocytosis is a regulated process at the heart of which is a pair of phosphorylation sites (points of phosphate attachment) in the key protein dynamin I. Our hypothesis is that endocytosis occurs in two forms, fast and slow. We propose to test the idea that proteins that associate with dynamin via the phosphorylation sites determine whether the fast or slow mode is used. Additionally, we propose that the first phosphorylation site is the trigger for endocytosis, while the second serves to recruit reserve supplies of dynamin to support the slow mode when it's required. A better understanding of Dyn and endocytosis is crucial to understanding brain disorders of synaptic transmission and ultimately for developing therapies. For example, a seizure is the uncontrolled firing of neurons. Our overall aim is to understand the control mechanisms of nerve communication to ultimately allow us to treat disorders of nerve communication like epilepsy.Read moreRead less
How Amyloid Causes Neurodegeneration: The Role Of Transthyretin In Familial Amyloidotic Polyneuropathy
Funder
National Health and Medical Research Council
Funding Amount
$618,950.00
Summary
This project seeks to understand the biochemical basis of nerve degeneration in a disease known as familial amyloidotic polyneuropathy. This disease is caused by a protein known as transthyretin, which is abnormally deposited around nerves and causes nerve damage. The project is highly likely to provide clues which help us understand some related dementia causing diseases like Alzheimer's disease and prion diseases such as scrapie and mad cow disease.
Targetting Nogo A As A Means To Promote CNS Axonal Regrowth
Funder
National Health and Medical Research Council
Funding Amount
$325,911.00
Summary
Unlike the peripheral nervous system, regenerative nerve fiber growth and structural plasticity are limited in the adult mammalian central nervous system (CNS), following injury. Although lesioned axons can sprout spontaneously, this regeneration attempt is transitory and no significant re-growth occurs over long distances. Consequently, injury to the CNS often leads to permanent disability. In many cases, it has been shown that it is not the absence of growth-promoting molecules in the CNS but ....Unlike the peripheral nervous system, regenerative nerve fiber growth and structural plasticity are limited in the adult mammalian central nervous system (CNS), following injury. Although lesioned axons can sprout spontaneously, this regeneration attempt is transitory and no significant re-growth occurs over long distances. Consequently, injury to the CNS often leads to permanent disability. In many cases, it has been shown that it is not the absence of growth-promoting molecules in the CNS but rather the presence of axon outgrowth inhibitors, including components of both CNS myelin and astroglial scars that limit regeneration. Given that axonal injury is an important pathological determinant of permanent disability in multiple sclerosis (MS), we have recently investigated the role of the CNS neurite outgrowth inhibitor, Nogo A in the development of a chronic form of murine MS-like disease. We showed that targeting Nogo A by active and passive immunization blunts clinical signs, demyelination and axonal damage associated with this model of MS. These results identify Nogo A as an important determinant of the development of autoimmune-mediated demyelination and suggest that its blockage may help to maintain and-or to restore the neuronal integrity of the CNS after autoimmune insult in disease such as MS. The principal goal of this application is to study the mechanism by which blockade of Nogo A improves clinical outcome in disease like MS and to determine whether neurite sprouting accounts for such an improvement. Targeting Nogo A and-or its receptor, has the potential to not only regulate-modulate the process of autoimmune mediated demyelination but could lead to the first therapy ever offered to patients that helps damaged nerves regenerate after axonal injury following neurodegeneration due to insult or disease.Read moreRead less