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
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.
Knowledge, Identification And Exploitation Of Dopaminergic Axon Guidance Cues Will Improve Cell Replacement Therapy For ParkinsonÍs Disease.
Funder
National Health and Medical Research Council
Funding Amount
$481,797.00
Summary
Many obstacles exist for cell transplantation in ParkinsonÍs Disease; namely poor graft survival, restoration of appropriate circuitry and adequate nerve fiber growth from new cells. Using knowledge of how neural circuits are established during fetal development, we will attempt to recapitulate these events following transplantation. Further, we will identify new and novel cues in regulating the connectivity and growth of these nerve fibers.
Restoration Of The Nigrostriatal Pathway In The Parkinsonian Brain
Funder
National Health and Medical Research Council
Funding Amount
$299,431.00
Summary
Many obstacles exist for cell transplantation in Parkinson's disease; namely poor restoration of the host brain circuitry due to incorrect graft placement. This results in incomplete motor function and unwanted side effects. Through iterative studies we endeavor to restore this circuitry by placing grafts in the appropriate location and promoting their survival and growth-integrations. This will require: optimizing the donor tissue and exposure of the graft to growth stimulating factors.
Wnt Signaling In Dopaminergic Neuronal Connectivity
Funder
National Health and Medical Research Council
Funding Amount
$564,721.00
Summary
A major obstacle in repairing the injured or diseased brain is inducing axons (nerve cell processes) to make the appropriate connections. This is especially true following cell replacement therapy (CRT) in Parkinson's disease (PD). We will examine the processes inducing axons in the dopamine pathways to grow. We hypothesize that Wnt signaling plays and important role and that therapeutic introduction of Wnt is required to repair the dopamine pathways following CRT in PD.
Promoting Regrowth Of Nerve Fibres Into The Epidermis During Diabetic Neuropathy By LRP Agonists
Funder
National Health and Medical Research Council
Funding Amount
$427,102.00
Summary
Nerve damage can develop post injury or disease and is often very debilitating, slow to heal and can cause increased pain. Our work aims to examine a new class of molecules that we show can activate selected fat-receptors on nerve cells to guide the growth of regenerating nerves. We will determine how these receptors function with the aim of developing a novel class of therapeutics directed at healing nerve damage.
Many infants and children suffer from bowel motility disorders, for example, chronic constipation affects up to 1 in 10 children. However, the cause of many of these paediatric motility disorders remains unknown. In this project, we will examine the development of wiring of the nervous system that controls bowel motility. This is the first study to investigate the development of cell-cell communication during early stages of nervous system development.