Investigation Of Delta3 Function And Notch Signalling During Cell Fate Specification In Mouse And Human
Funder
National Health and Medical Research Council
Funding Amount
$221,717.00
Summary
This project seeks to understand how cells within the developing embryo are produced and how they are given a specific identity. These processes often require the cell to make a decision about what type of cell it will become. We are using the Delta3 gene, which is present in humans and in the mouse, as a tool for our investigations. Delta3 is expressed at the surface of the cell and Notch (its receptor) is present on the surface of neighbouring cells. Delta3 on one cell will bind to Notch on th ....This project seeks to understand how cells within the developing embryo are produced and how they are given a specific identity. These processes often require the cell to make a decision about what type of cell it will become. We are using the Delta3 gene, which is present in humans and in the mouse, as a tool for our investigations. Delta3 is expressed at the surface of the cell and Notch (its receptor) is present on the surface of neighbouring cells. Delta3 on one cell will bind to Notch on the neighbouring cell and activates Notch. When Notch is activated in a cell it pushes the cell to make its decision. This project aims to determine what exactly is the function of Delta3 in mammals and how at the level of the individual cell this protein exerts its effects. We have generated a mouse in which the Delta3 gene is no longer active and have observed that embryos do not develop normally. We will explore these defects (which affect the skeleton and the brain) in detail in order to define their origins. We will also use these abnormal mice to identify genes, which require the function of Delta3 for their normal activity. It is not only important to define the function of Delta3 in mammals but also to determine this protein functions. We wish to know how exactly Delta3 interacts with Notch. That is, which part of the Delta3 protein binds to which part of the Notch protein. We can address this by modifying the Delta3 protein in small (but revealing ways) and see if it can still bind the Notch receptor in a cell culture assay. Our studies have relevance to humans because recently it has been shown that Delta and Notch are associated with a human syndrome (spondylocostal dysostosis) in which individuals suffer from abnormal skeletons.Read moreRead less
The Role Of The Transcriptional Co-activator, Qkf, In Adult Neural Stem Cell Self-renewal And Multi-potency.
Funder
National Health and Medical Research Council
Funding Amount
$403,709.00
Summary
In recent years there has been considerable interest in stem cells because they have the potential to provide new therapeutic approaches to disease. Indeed, haematopoietic stem cells are already used in treatments for leukaemia. Many organs in adult humans contain stem cells, including the brain. In order to develop safe, and effective, stem cell-based treatments for human diseases it is necessary to determine how proliferation and differentiation are regulated in adult stem cells.
Pathogenesis Of Rett Syndrome: Molecular Genetics And Animal Models
Funder
National Health and Medical Research Council
Funding Amount
$437,310.00
Summary
Rett syndrome (RS) is a devastating progressive genetic disorder affecting motor and intellectual development, and occurs almost exclusively in females. It is characterised by normal development for the first 6-12 months of life, followed by developmental regression with the loss of learned purposeful hand function, loss of acquired speech and communicative abilities, sometimes leading to the incorrect diagnosis of autism. It may be the most common cause of progressive mental retardation in girl ....Rett syndrome (RS) is a devastating progressive genetic disorder affecting motor and intellectual development, and occurs almost exclusively in females. It is characterised by normal development for the first 6-12 months of life, followed by developmental regression with the loss of learned purposeful hand function, loss of acquired speech and communicative abilities, sometimes leading to the incorrect diagnosis of autism. It may be the most common cause of progressive mental retardation in girls, with an estimated prevalence in Australia of 1 per 10,000 females under the age of twelve years. Mutations in a gene called MECP2 appears to be the cause of RS in up to 80% of affected girls and women. Now that the gene responsible for many cases of RS has been found, there are many new questions. Do all girls with RS have mutations in the MECP2 gene? Will knowing the exact mutation in the MECP2 gene be of help in predicting how severe the disorder will be in individual patients? Why is it that the brain appears to be primarily affected? Which other genes might play a role in the symptoms seen in RS? Could it be possible to develop specific treatments for RS? This research will address a number of important issues. Firstly, our genetic studies of RS subjects will result in early diagnosis, which is often delayed until after a child turns 5 years of age. Secondly, we are developing mouse models of the human disease, which will put us in a much better position in beginning to understand the biological basis of RS. Early diagnosis may enable the initiation of early treatment strategies in the short term, with the long-term goal of developing specific therapies that may potentially cure the disorder. Finally it will enable accurate genetic counselling for both the immediate and extended family members.Read moreRead less
Doublecortin (Dcx): A MAP For Migration In The Developing Brain
Funder
National Health and Medical Research Council
Funding Amount
$366,100.00
Summary
When a child is born with mental retardation or epilepsy, every parent wants to know why. There are many treatable causes, including poor nutrition, damage at birth and exposure to viruses or drugs. Other triggers for mental retardation and epilepsy are neither preventable nor treatable. Of the latter group, genetic diseases are one of the most important causes and are still not fully understood. At the Children's Medical Research Institute, we are involved in finding out how the brain develops ....When a child is born with mental retardation or epilepsy, every parent wants to know why. There are many treatable causes, including poor nutrition, damage at birth and exposure to viruses or drugs. Other triggers for mental retardation and epilepsy are neither preventable nor treatable. Of the latter group, genetic diseases are one of the most important causes and are still not fully understood. At the Children's Medical Research Institute, we are involved in finding out how the brain develops normally so that we can come to understand how our genes can cause conditions such as mental retardation and epilepsy. In understanding the normal development of the brain, we have focused on a gene known as doublecortin (Dcx). Mutations in doublecortin result in both mental retardation and epilepsy in a condition known as lissencephaly (smooth brain). Children with lissencephaly have fewer nerve cells (neurons) within their brains when compared to others of the same age, a problem thought to arise before their birth. At this time, the neurons are formed deep within the brain and migrate from this starting point to a final resting place nearer to its surface. This migration fails in lissencephaly and suggests a very important role for doublecortin in normal migration and brain development. We intend to undertake biochemical approaches which will tell us Dcx function in neuronal cells and in animals which have had Dcx expression altered. Dcx is reported to interact with the cells scaffolding system (microtubules). We will investigate interactions of normal and modified Dcx with microtubules. Following on the neuronal cell studies, transgenic mice will be developed expressing normal and mutated Dcx which will allow in depth analysis of gene function in an in vivo system. Ultimately our studies will lead to an understanding of Dcx role in microtubule dynamics and its involvement in neuronal migration and lissencephaly.Read moreRead less
Identifying The Pathological Mechanism Of Polyalanine Expansion Mutations In The X-linked Hypopituitarism Gene SOX3
Funder
National Health and Medical Research Council
Funding Amount
$402,846.00
Summary
Mental retardation (MR) is a debilitating disorder which affects 1-3% of the population. In many cases, MR results from changes (mutations) in genes which regulate the development of the brain before birth. We are studying families with an inherited form of MR termed X-linked Hypopituitarism (XH) in which only boys are affected. In addition to intellectual disability, boys with XH also have poor pituitary function resulting in short stature and slow metabolism. In severe cases, where the pituita ....Mental retardation (MR) is a debilitating disorder which affects 1-3% of the population. In many cases, MR results from changes (mutations) in genes which regulate the development of the brain before birth. We are studying families with an inherited form of MR termed X-linked Hypopituitarism (XH) in which only boys are affected. In addition to intellectual disability, boys with XH also have poor pituitary function resulting in short stature and slow metabolism. In severe cases, where the pituitary has failed to form completely, these babies are extremely ill and in some instances do not survive. We have previously shown that XH is due to an unusual change in the SOX3 gene in which the number of consecutive alanine residues is increased above a critical threshold (polyalanine expansion mutations). Similar mutations have recently been identified in several other genes that also cause severe birth defects. However, little is currently known about how polyalanine expansion mutations cause these disorders. The overall aim of this proposal is generate a mouse model for this disorder. Analysis of these mice will help us to answer many unresolved questions about this disorder including: How does the mutant protein cause this disorder? Which parts of the brain and pituitary are affected and how is their function altered? How does the mutant protein affect other genes and proteins in the cell? Ultimately, we hope that this mouse model will help us to develop new and improved therapies for XH and other disorders that are caused by alanine expansion mutations.Read moreRead less