Senataxin, A Novel Protein Involved In The DNA Damage Response
Funder
National Health and Medical Research Council
Funding Amount
$500,460.00
Summary
The human genome is constantly exposed to agents-chemicals that cause DNA damage. Some of these are generated during normal metabolism and are referred to as reactive oxygen species while others comprise damaging sunlight, radiation and a variety of chemical agents. These agents can lead to cancer and a range of pathologies to different tissues including deterioration of brain function. This project is designed to investigate these processes using a specific genetic disorder as a model system. T ....The human genome is constantly exposed to agents-chemicals that cause DNA damage. Some of these are generated during normal metabolism and are referred to as reactive oxygen species while others comprise damaging sunlight, radiation and a variety of chemical agents. These agents can lead to cancer and a range of pathologies to different tissues including deterioration of brain function. This project is designed to investigate these processes using a specific genetic disorder as a model system. This disorder is called ataxia with oculomotor apraxia type 2 or AOA2. This condition develops in the teenage to early twenties and as the name suggests is characterised by loss of control of gait together with difficulties of eye movement. It is due to reduced function of a particular region of the brain called the cerebellum responsible for controlling movement. We have initial data suggesting that cells from these patients are very sensitive to environmental chemicals and their capacity to carry out repair of damage to DNA is compromised. We will investigate the nature of the defect at the molecular level and establish the function of the protein defective in this syndrome. This information will be important to determining specific therapies for AOA2 patients and may also have relevance to other neurodegenerative disorders.Read moreRead less
Noncoding RNAs As Prognostic Markers And Therapeutic Targets In Breast Cancer
Funder
National Health and Medical Research Council
Funding Amount
$550,283.00
Summary
Normal human development involves a symphony of genetic changes that control the growth and differentiation of different types of cells during embryogenesis. For many years it has been assumed that most genetic information is transacted by proteins, and that the remaining 98% of the human genome that does not encode proteins was (apart from a limited amount of associated regulatory elements) largely non-functional evolutionary junk. However, this may not be the case. Recent results from our labo ....Normal human development involves a symphony of genetic changes that control the growth and differentiation of different types of cells during embryogenesis. For many years it has been assumed that most genetic information is transacted by proteins, and that the remaining 98% of the human genome that does not encode proteins was (apart from a limited amount of associated regulatory elements) largely non-functional evolutionary junk. However, this may not be the case. Recent results from our laboratory and others have shown that most of our genome and that of other mammals is actually expressed as noncoding RNA, which appears to be developmentally regulated. These RNAs (of which there appear to be tens of thousands, well outnumbering the protein-coding mRNAs) have been referred to as the hidden layer or dark matter of our genome, as they have barely been studied, but appear to play a central role in both normal and abnormal development in humans. There is now increasing evidence that many noncoding RNAs, including small regulatory RNAs called microRNAs, are perturbed in cancer and that these perturbations may be directly involved in, and be an accurate indicator of, cancer state and the direction of cancer progression. If this is true we need to understand the expression and functions of these RNAs in order to develop better diagnostics and perhaps powerful new therapeutics for cancer, based on RNA technology and generic delivery systems. This project will explore the patterns of noncoding RNA expression in normal breast development and in breast cancer, to identify those RNAs that direct or accompany the differentiation of these tissues, and to test the effects of interfering with their expression on these processes. These foundation studies lie at the leading edge of a new understanding of human genetics and cancer, and will provide a platform for future applications in medicine that utilize this information and understanding.Read moreRead less
Functions Of A Novel Conserved DNA Damage Response Protein Family In Telomere Stability
Funder
National Health and Medical Research Council
Funding Amount
$282,825.00
Summary
The free DNA ends of chromosomes, termed telomeres, generally resemble broken DNA. Because broken DNA is a major contributing factor to the onset of cancer, cells try to fix broken ends. However, in case of telomeres, such repair processes have to be prevented because otherwise different chromosomes would fuse with each other. Fused chromosomes are very fragile and cannot be evenly distributed between dividing cells, and are therefore another important trigger of cancer development. Therefore, c ....The free DNA ends of chromosomes, termed telomeres, generally resemble broken DNA. Because broken DNA is a major contributing factor to the onset of cancer, cells try to fix broken ends. However, in case of telomeres, such repair processes have to be prevented because otherwise different chromosomes would fuse with each other. Fused chromosomes are very fragile and cannot be evenly distributed between dividing cells, and are therefore another important trigger of cancer development. Therefore, chromosome ends are covered by a cap, which hides them from the DNA damage response machinery. From these considerations it is clear that there are close connections between the cellular DNA damage response and chromosome ends. Moreover, recently it has become clear that DNA damage proteins are also required to stop normal cells from growing, a process termed senescence. Senescence is a consequence of shortened chromosome ends, and does not occur in cancer cells. Altogether, it is clear that DNA breaks and senescence are two of the major questions for our understanding of cancer development. We have identified a novel conserved protein family that is involved in the response to DNA damage in yeast and humans. In addition, the yeast Mdt1 protein is a very sensitive indicator of changes in the telomere cap. Absence of proteins that organise the cap leads to the addition of several phosphate groups to the Mdt1 protein. We propose that phosphate-coupled Mdt1 prevents chromosome ends from fusion with each other, or from fusing with broken DNA ends after widespread damage. As a consequence, cells that have mild cap defects die at an >1000-fold increased rate in response to DNA damage when they also lack Mdt1. As part of this application we want to find out the precise mechanism by which Mdt1 stabilises chromosome ends, and test our hypothesis that the corresponding human protein termed ASCIZ also has similar functions in protecting chromosome ends.Read moreRead less