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
The Role Of Cell Adhesion Molecules In Regulation Of Axon Advance
Funder
National Health and Medical Research Council
Funding Amount
$426,006.00
Summary
All cells contain on their surface a class of molecules, cell adhesion molecules, that enable them to adhere to other cells in tissues. Cell adhesion molecules have long been known to be involved in the guidance of axons to their targets during development. However the molecular mechanisms by which these molecules act are largely unknown. We propose to use the powerful genetic tools available in the fruitfly to dissect the mechanisms by which two cell adhesion molecules promote axon growth.
The Molecular Basis For Target Selection In The Central Nervous System By Sensory Axons
Funder
National Health and Medical Research Council
Funding Amount
$251,325.00
Summary
The normal function of the brain depends upon the specific connections that nerve cells make with each other. These connections are set up in the developing embryo when nerve cells send out long processes - axons - which grow towards their synaptic targets. How axons select their correct targets from amongst the millions of alternatives in the developing brain is unknown. A better understanding of this problem will help us develop therapies to assist regenerating axons re-establish correct conne ....The normal function of the brain depends upon the specific connections that nerve cells make with each other. These connections are set up in the developing embryo when nerve cells send out long processes - axons - which grow towards their synaptic targets. How axons select their correct targets from amongst the millions of alternatives in the developing brain is unknown. A better understanding of this problem will help us develop therapies to assist regenerating axons re-establish correct connections following injury to the brain or spinal cord. We propose to use a simple model system, the embryo of the fruitfly Drosophila, to find molecules that are involved in this process of neuron target recognition - ' axon targeting' molecules - and to study how they work. Drosophila can be genetically manipulated in ways not possible in higher animals. Furthermore the simplicity of its nervous system means that we can determine the connections of individual nerve cells with a high degree of precision. In the first part of our project, we will examine Drosophila embryos that carry mutations in genes suspected to code for targeting molecules. We will stain individual sensory nerve cells in these embryos with dyes to reveal the anatomy of their axons in the brain. If sensory axons terminate abnormally in the brain of a given mutant, the affected gene is likely to code for an axon targeting molecule. In the second part of the study, we will investigate the functions of candidate axon targeting molecules using two approaches. Firstly, we will seek to determine whether the molecule acts in the sensory axons or in their target cells. Secondly, we will use time-lapse microscopy to study how the homing behaviour of the sensory axons is affected in mutant embryos. The results of these studies will lead us closer to an answer to the question: How do axons recognise their specific target cells in the brain?Read moreRead less
Cellular Mechanisms Controlling Neural Crest Cell Migration Along The Developing Gut
Funder
National Health and Medical Research Council
Funding Amount
$368,895.00
Summary
Within the wall of the gut, there are a large number of neurons, probably more than are in the spinal cord. These enteric neurons play an essential role in controlling a number of gut functions including peristalsis (the propulsion of contents along the gut). Most of the neurons in the gut, including those in the large intestine, arise from precursors that emigrate from the hindbrain, and then migrate into and along the gastrointestinal tract during development. The colonization of the gut by ne ....Within the wall of the gut, there are a large number of neurons, probably more than are in the spinal cord. These enteric neurons play an essential role in controlling a number of gut functions including peristalsis (the propulsion of contents along the gut). Most of the neurons in the gut, including those in the large intestine, arise from precursors that emigrate from the hindbrain, and then migrate into and along the gastrointestinal tract during development. The colonization of the gut by neuron precursors takes 5 days in mice and 6 weeks in humans. Studies of the mechanisms controlling the migration of neuron precursors along the gut have provided fundamental information about cell migration in general. Genetic studies in humans and mice have identified some of the genes that are necessary for the migration of neuron precursors along the gastrointestinal tract, but for some of the key genes, their precise role is unknown. We have recently developed a method for imaging living neuron precursors migrating through explants of embryonic mouse gut. In the current proposal we will meld imaging and genetic studies to understand how mutations in particular genes lead to migration defects. In particular, how do particular mutations affect the migratory behaviour of enteric neural precursors? We have also previously shown that neuron precursors migrate along the gut in close association with axons. We will examine the nature of these interactions - in particular, who is following whom, and what happens when cell migration and axon growth are uncoupled? These studies, which will investigate a number of critical aspects of the migration of neural precursors into and along the developing gut, are central to understanding how the enteric nervous system is established along the gastrointestinal tract.Read moreRead less
Olfactory Ensheathing Cells: A Major Contributor To Axon Guidance?
Funder
National Health and Medical Research Council
Funding Amount
$575,749.00
Summary
The olfactory (smell) system is a unique part of the nervous system because nerve cells are generated throughout life. Understanding how the olfactory system grows and regenerates may lead to therapeutic approaches to repair other regions of the nervous system. This project will use high resolution digital time-lapse imaging of living nerve cells and the specialised cells called olfactory ensheathing cells to determine how the behaviour of these cells can be manipulated to improve regeneration.
The Dynamics Of Gradient Sensing By Growth Cones: Timelapse Imaging And Mathematical Modelling
Funder
National Health and Medical Research Council
Funding Amount
$493,305.00
Summary
Problems in the wiring up of the brain underlie several nervous system disorders. The goal of this project is to understand better how this wiring normally forms. This will ultimately lead to a better understanding of what can go wrong with brain wiring, and how to fix such problems. It will also lead to a better understanding of how to make axons regenerate after injury. Our approach is to use a combination of timelapse imaging of neurons in culture, and mathematical modelling, to understand ho ....Problems in the wiring up of the brain underlie several nervous system disorders. The goal of this project is to understand better how this wiring normally forms. This will ultimately lead to a better understanding of what can go wrong with brain wiring, and how to fix such problems. It will also lead to a better understanding of how to make axons regenerate after injury. Our approach is to use a combination of timelapse imaging of neurons in culture, and mathematical modelling, to understand how the tips of the wires growing between neurons sense their environment. By comparing our experimental measurements with our theoretical results we will arrive at a detailed and accurate model of this sensing process. This will allow us to make predictions about how these developmental events normally occur in vivo, and what can go wrong.Read moreRead less
Wnt-Ryk Signaling In The Establishment Of Major Axon Tracts In The Embryonic Mouse Brain
Funder
National Health and Medical Research Council
Funding Amount
$513,946.00
Summary
The corpus callosum is the major interhemispheric commissure in the human brain, comprising approximately 3 million myelinated fibers which connect homologous regions in the neocortex. To date more than 50 different human congenital syndromes have been described in which the corpus callosum does not form leading to epilepsy and mental retardation. We have identified a new guidance molecule (Ryk) which is crucial for corpus callosum formation. This project aims to dissect that molecular mechanism ....The corpus callosum is the major interhemispheric commissure in the human brain, comprising approximately 3 million myelinated fibers which connect homologous regions in the neocortex. To date more than 50 different human congenital syndromes have been described in which the corpus callosum does not form leading to epilepsy and mental retardation. We have identified a new guidance molecule (Ryk) which is crucial for corpus callosum formation. This project aims to dissect that molecular mechanisms controlling Ryk signaling during corpus callosum development. Our analysis of Ryk function will advance our understanding of the molecular mechanisms underlying the formation of this important commissure.Read moreRead less
Wnt Signaling In Dopaminergic Neuronal Connectivity
Funder
National Health and Medical Research Council
Funding Amount
$387,489.00
Summary
During development, the brain establishes intricate and precise connections. In several brain pathways, little is known about the processes regulating this connectivity. Furthermore, it is likely that the same processes will be required to repair the injured- diseased brain. This project builds on our preliminary data, that Wnt proteins are important regulators of developing dopamine pathways, and has implications for dopamine disorders including Parkinson’s disease and addiction.
Molecular And Cellular Mechanisms Of Axon Growth And Guidance In The Vertebrate Nervous System
Funder
National Health and Medical Research Council
Funding Amount
$467,545.00
Summary
There are millions of nerve cells in the vertebrate brain, each forming very precise and specific connections within neural circuits. During development of the embryo most of these cells are wired together. A Telstra technician will use the different colours of telephone cables to correctly connect them. Likewise, the growing processes of nerve cells in the brain use specific markers or labels as cues to establish the correct wiring. The aim of the present project is to characterize the specific ....There are millions of nerve cells in the vertebrate brain, each forming very precise and specific connections within neural circuits. During development of the embryo most of these cells are wired together. A Telstra technician will use the different colours of telephone cables to correctly connect them. Likewise, the growing processes of nerve cells in the brain use specific markers or labels as cues to establish the correct wiring. The aim of the present project is to characterize the specific role of some of these labels on nerve cells during development. This project will provide new fundamental knowledge about how brain cells are wired together during development of the embryo. This knowledge is essential for establishing strategies to enhance repair of brain cells following ischemic, excitotoxic or mechanical injury.Read moreRead less