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.
Mechanisms Controlling The Excitability Of Corneal Nociceptor Nerve Terminals
Funder
National Health and Medical Research Council
Funding Amount
$364,759.00
Summary
The project uses a new approach that allows, for the first time, electrical activity to be recorded and analysed from the very fine nerve endings of nerves whose activation results in painful sensations. Using this technique the mechanisms by which substances released in damaged and inflamed tissues lead to discharge of action potentials and the sensation of pain will be investigated. In particular the project investigates the role of a population of sodium ion selective pores (channels) that ar ....The project uses a new approach that allows, for the first time, electrical activity to be recorded and analysed from the very fine nerve endings of nerves whose activation results in painful sensations. Using this technique the mechanisms by which substances released in damaged and inflamed tissues lead to discharge of action potentials and the sensation of pain will be investigated. In particular the project investigates the role of a population of sodium ion selective pores (channels) that are uniquely expressed in pain sensing nerves. These channels have been hypothesised to play an important role in determining the behaviour of these nerves. In addition, the project investigates how some substances released in inflamed tissues sensitize pain sensing nerves, causing them to more readily discharge action potentials. This change is the major cause of pain associated with inflammatory diseases such as arthritis. In summary, the proposed project will provide new insight into how pain sensing nerves function. This knowledge is essential for the development of more effective strategies for treating pain resulting from inflamed and damaged tissue.Read moreRead less
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
Synaptic Transmission In The Mammalian Central Nervous System
Funder
National Health and Medical Research Council
Funding Amount
$460,500.00
Summary
In order to properly understand the complex functions of the brain and the abnormalities underlying neurological disorders, we must understand how individual neurons communicate with each other. Communication occurs at specialized contacts, or synapses. An individual neuron may receive tens of thousands of synaptic contacts from hundreds or thousands of other neurons. Despite intensive investigation, the processes which regulate synaptic strength between central neurons are poorly understood. Th ....In order to properly understand the complex functions of the brain and the abnormalities underlying neurological disorders, we must understand how individual neurons communicate with each other. Communication occurs at specialized contacts, or synapses. An individual neuron may receive tens of thousands of synaptic contacts from hundreds or thousands of other neurons. Despite intensive investigation, the processes which regulate synaptic strength between central neurons are poorly understood. The overall aim of this proposal is to understand the basic mechanisms underlying synaptic transmission at excitatory and inhibitory synaptic connections in the mammalian brain. We will investigate specific synaptic connections in the central pathways of the auditory system, because our previous studies have demonstrated a number of key technical advantages in studying these synapses. We will use electrophysiological recording from synaptic terminals and neurons in isolated living slices of the brainstem of mice. We will use imaging techniques and electron-microscopy to examine the structural details of synaptic connections, as structure is thought to play a major role in determining the strength of synaptic transmission. We will also study the structural and functional properties of auditory synaptic connections in congenitally deaf animals. Our recent study comparing normal and congenitally deaf mice has already revealed significant differences. Our results will provide important insights in the regulation of synaptic strength in the central nervous system, and into the regulation of synaptic transmission at central synapses which have developed under conditions of abnormal sensory activation.Read moreRead less
Sulfonadyn-based Dynamin I-specific Inhibitors And Epilepsy
Funder
National Health and Medical Research Council
Funding Amount
$835,291.00
Summary
Epilepsy affects 1% of people, yet 30% do not respond to anti-epileptic drugs (AEDs). Traditional drug discovery fails to improve this situation. Our team discovered dynamin as a new target for better AED design and our lead sulphonadyns reduces seizures in animals. We will design better sulfonadyns that can ultimately be used for clinical trials by designing the drugs away from its actions outside of neurons. If successful, this will accelerate new AED development with less side-effects.
Development Of Pthaladyn-based Dynamin I-selective Inhibitors For Treatment Of Epilepsy
Funder
National Health and Medical Research Council
Funding Amount
$564,310.00
Summary
About 1% of the World�s population suffers from epilepsy; 30% fail to respond to anti-epileptic drugs (AED). Current AED development pathways have changed little in the past 20 years with the majority of current AEDs dampening the release of crucial chemical signals 24/7. Our new drugs, which inhibit a protein called dynamin, are only recruited at the onset of a seizure. Our approach will significantly enhance the day to day lives of those afflicted by epilepsy.