Oxygen Toxicity As A Factor In Retinal Degenerations: Genetic And Environmental Mechanisms
Funder
National Health and Medical Research Council
Funding Amount
$269,250.00
Summary
This project will explore the mechanisms underlying a group of blinding diseases called Retinitis Pigmentosa (RP). They are caused by the death or degneration of the light-receptive cells of the retina of the eye (photoreceptors). It is well established that many forms of RP are caused by genetic mutations but many cases (40-50%) occur 'sporadically', i.e. without a family history. Further there is growing evidence that the rate at which genetic forms of the disease progress is strongly influenc ....This project will explore the mechanisms underlying a group of blinding diseases called Retinitis Pigmentosa (RP). They are caused by the death or degneration of the light-receptive cells of the retina of the eye (photoreceptors). It is well established that many forms of RP are caused by genetic mutations but many cases (40-50%) occur 'sporadically', i.e. without a family history. Further there is growing evidence that the rate at which genetic forms of the disease progress is strongly influenced by environmental factors, particularly light and oxygen. To analyse how these environmental factors affect the stability of the retina, we will use a range of techniques (including gene array technology) to study the molecular events which link light or oxygen stress to photoreceptor death. The work will be done in mouse 'models' of the disease. It is increasingly well established that the rodent (rat and mouse) retina and human retina share a basic structure and functional detail. These models allow intensive investigation, with results which are directly applicable to human disease. Our principal emphasis will be on three aspects of these models: (1) the molecular mechanisms induced in the retina by light stress or oxygen stress; (2) the role of mitochondria (cellular organelles essential for both cell metabolism and cell stability; and (3) genes which regulate the vulnerability of photoreceptors to oxygen stress. RP has been recognised for nearly 100 years as a leading cause of blindness in young adults. It is usually diagnosed in the young adult as a failure of night vision, but the prognosis is grim (relentlessly progressive loss of vision), and there is still no effective treatment. The work proposed will contribute to our understanding of the basic mechanisms involved, and will explore some approaches to therapy for, or at least to mitigation of the blindness of RP.Read moreRead less
Post Transcriptional Regulation Of Plasminogen Activator Inhibitor Type 2 Gene Expression
Funder
National Health and Medical Research Council
Funding Amount
$318,000.00
Summary
The process of wound healing, cell migration and the spread of cancers requires the recruitment of specialised proteases to the cell surface . These proteases act to degrade other proteins, mainly in the extracellular space, which in turn allows cells to move around, wounds to close, and blood clots to disappear. The plasminogen activating system is one of the enzyme systems involved in these events. One of the proteases that cleaves plasminogen to its active form, plasmin, is urokinase (u-PA) a ....The process of wound healing, cell migration and the spread of cancers requires the recruitment of specialised proteases to the cell surface . These proteases act to degrade other proteins, mainly in the extracellular space, which in turn allows cells to move around, wounds to close, and blood clots to disappear. The plasminogen activating system is one of the enzyme systems involved in these events. One of the proteases that cleaves plasminogen to its active form, plasmin, is urokinase (u-PA) and the activity of u-PA is regulated by its natural inhibitor called plasminogen activator inhibitor type 2 (PAI-2). u-PA is strongly implicated in the progression of metastatic cancer and high levels of PAI-2 relative to u-PA is regularly seen as a positive prognostic indicator for metastatic cancer. In this situation, PAI-2 acts to limit the activity of u-PA thereby restricting the migration potential of the cancer. PAI-2 is unusual because it exists both inside and outside the cell. Outside the cell, PAI-2 acts to inhibit u-PA activity, while inside the cell, PAI-2 also plays a role in the inhibition of cell growth and differentiation. It is therefore important to understand how the production of PAI-2 is regulated in cells. A significant component of PAI-2 regulation occurs post-transcriptionally, particularly at the level of mRNA stability. We have identified some of the proteins that bind to PAI-2 mRNA and influence its longevity in the cell. This project aims to further undertand how these as well as other PAI-2 mRNA binding proteins influence the expression of the PAI-2 gene.Read moreRead less
Post Transcriptional Regulation Of The Plasminogen Activator Inhibitor Type 2 Gene
Funder
National Health and Medical Research Council
Funding Amount
$241,527.00
Summary
The process of wound healing, removal of blood clots, cell migration and the metastatic spread of cancers requires the recruitment of specialised proteases. These proteases act primarily to degrade other proteins, mainly in the extracellular space, which in turn allow cells to move around, wounds to close, and blood clots to disappear. The plasminogen activating system is one of the most important enzyme systems involved in these events. One of the proteases that cleaves plasminogen to its activ ....The process of wound healing, removal of blood clots, cell migration and the metastatic spread of cancers requires the recruitment of specialised proteases. These proteases act primarily to degrade other proteins, mainly in the extracellular space, which in turn allow cells to move around, wounds to close, and blood clots to disappear. The plasminogen activating system is one of the most important enzyme systems involved in these events. One of the proteases that cleaves plasminogen to its active form, plasmin, is urokinase (u-PA). Plasminogen activator inhibitor type 2 (PAI-2) is a serine protease inhibitor that inhibits u-PA activity. The degree of u-PA activity therefore depends on the relative levels of u-PA and PAI-2. In addition to controlling u-PA activity, PAI-2 also influences intracellular events including cell proliferation, differentiation and apoptosis. PAI-2 protein and mRNA levels are substantially modulated by many cytokines and growth factors. This project addresses the molecular mechanisms underlying the regulation of PAI-2 gene expression. We have recently shown that a significant degree of PAI-2 regulation occurs at the level of PAI-2 mRNA stability, and we have identified two regions within the PAI-2 mRNA that play a role in this process. Both regions provide binding sites for cellular proteins. We have identified one of these binding proteins to be HuR, a protein that has recently been shown to control the stability of other mRNAs. The specific aims of this project are firstly, to determine the role of HuR in the control of PAI-2 mRNA stability, and secondly, to clone a characterise the other PAI-2 mRNA binding proteins we have identifed. An understanding of how cells modulate levels of PAI-2 mRNA will significantly add to the broader field of gene regulation and may also provide new clues to influence PAI-2 levels in the body.Read moreRead less
The Molecular Basis For The Increased Incidence Of Thrombosis Associated With The Prothrombin G20210A Gene Polymorphism
Funder
National Health and Medical Research Council
Funding Amount
$213,838.00
Summary
Prothrombin is an important enzyme involved in the formation of blood clots. Recently, a mutation was discovered in the prothrombin gene. This mutation occurs at a frequency of 2% in the normal population but occurs at an increased frequency (6%) in patients with thrombosis and is associated with an increase in the levels of prothombin in the blood. The position of this mutation in the prothrombin gene corresponds to the last residue of the prothrombin mRNA. We have preliminary data to suggest t ....Prothrombin is an important enzyme involved in the formation of blood clots. Recently, a mutation was discovered in the prothrombin gene. This mutation occurs at a frequency of 2% in the normal population but occurs at an increased frequency (6%) in patients with thrombosis and is associated with an increase in the levels of prothombin in the blood. The position of this mutation in the prothrombin gene corresponds to the last residue of the prothrombin mRNA. We have preliminary data to suggest that this mutation results in the prothrombin mRNA being more stable, which in turn allows for the production of more prothrombin protein, leading to an increased risk of developing a blood clot. The aim of this project is to explore the mechanisms leading to the elevated levels of prothrombin observed patients with this mutation.Read moreRead less
Post-transcriptional Regulation Of Plasminogen Activator Inhibitor 2 Gene Expression
Funder
National Health and Medical Research Council
Funding Amount
$508,838.00
Summary
Plasminogen activator inhibitor type 2 (PAI-2) is a protease inhibitor that has intracellular and extracellular functions. The PAI-2 gene is highly regulated at the level of PAI-2 mRNA stability. We have identified regions within the PAI-2 transcript essential for this regulation and a number of novel proteins that engage these regions. This project is aimed at understanding how these and other proteins control PAI-2 expression at the mRNA level.
Molecular Mechanisms For The Cell-type Specific Regulation Of The Tissue-type Plasminogen Activator Gene
Funder
National Health and Medical Research Council
Funding Amount
$490,500.00
Summary
Tissue-type plasminogen activator (t-PA) is an important enzyme that is widely known for its ability to remove blood clots. More recently, t-PA has been shown to influence memory development and under pathological conditions can promote neuronal cell death. t-PA is produced by many cells including the endothelial cells that line the blood vessels, fibroblasts, as well as cells within the central nervous system. The t-PA gene is regulated very differently in these cell types and this project will ....Tissue-type plasminogen activator (t-PA) is an important enzyme that is widely known for its ability to remove blood clots. More recently, t-PA has been shown to influence memory development and under pathological conditions can promote neuronal cell death. t-PA is produced by many cells including the endothelial cells that line the blood vessels, fibroblasts, as well as cells within the central nervous system. The t-PA gene is regulated very differently in these cell types and this project will address the mechanisms underlying the cell-type specific regulation of the t-PA gene. Endothelial cells, fibroblasts and neuronal cell cultures will be used to study the regulation of t-PA expression. Information gained will not only add to the understanding of the broader field of gene regulation, but may also provide clues to manipulate the expression of the t-PA gene in different cells.Read moreRead less