Decoding Conserved Mechanisms That Control Neuronal Migration
Funder
National Health and Medical Research Council
Funding Amount
$526,950.00
Summary
During brain development, nerve cells interact with each other and their surrounding environment through a forest of molecules that are essential for precise cellular communication. Deficient signaling between these molecules causes defects in development and leads to disease. By employing genetic and biochemical approaches we propose to identify new mechanisms through which the brain develops, to better understand how brain diseases such as epilepsy and schizophrenia occur.
Neurons in the two hemispheres of the brain make connections with each other via a large fibre tract called the corpus callosum. In over fifty different human congenital syndromes the corpus callosum fails to form properly. Such syndromes, which include Aicardi syndrome, Andermann syndrome, Shapiro syndrome and Acrocallosal syndrome, can result in mental retardation, seizures, lack of motor coordination and ocular abnormalities in children. Our data on both mouse and human brain development show ....Neurons in the two hemispheres of the brain make connections with each other via a large fibre tract called the corpus callosum. In over fifty different human congenital syndromes the corpus callosum fails to form properly. Such syndromes, which include Aicardi syndrome, Andermann syndrome, Shapiro syndrome and Acrocallosal syndrome, can result in mental retardation, seizures, lack of motor coordination and ocular abnormalities in children. Our data on both mouse and human brain development show that the mouse is an excellent model system for understanding how the brain becomes wired up during development and what may go wrong in these disorders. Here we investigate the role of a family of genes called nuclear factor one (Nfi) genes in brain development. When mutated in mice, members of this gene family, principally Nfia and Nfib, cause severe malformations of the brain. The phenotype inlcudes a failure to form some midline glial populations, the expansion of the cingulate cortex and loss of the corpus callosum. The propoer formation of midline glial populations and the cingulate cortex are essential to callosal fomration and correct brain wiring. Defects in brain wiring in the cingulate cortex during development may underlie disorders such as schizophrenia, bipolar disorder and depression. In this project we will address the mechanism of function underlying the control of brain development by the Nfi genes. The expected outcomes of this research are to identify new mechanisms and genetic pathways critical to the formation of connections between the two sides of the brain and proper formation of the cingulate cortex. These results will improve our understanding of how the brain forms and what mechanisms may be disrupted during development that result in neurological and cognitive deficits in children and adults.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