The Role Of Heterochromatin In Regulating Cellular Proliferation And Development
Funder
National Health and Medical Research Council
Funding Amount
$504,000.00
Summary
Fundamental to the development of a multicellular organism is that for each cell type performing a specialised function, a different set of genes are turned on with the remainder being shut off. One of the most significant unanswered questions in biology is how a cell-type specific gene expression profile is established during early development. The answer to this question has important implications in understanding normal and abnormal cellular processes. Gene expression in a cell occurs in the ....Fundamental to the development of a multicellular organism is that for each cell type performing a specialised function, a different set of genes are turned on with the remainder being shut off. One of the most significant unanswered questions in biology is how a cell-type specific gene expression profile is established during early development. The answer to this question has important implications in understanding normal and abnormal cellular processes. Gene expression in a cell occurs in the nucleus where genes are stored. In the nucleus, DNA is not in a free form but is covered with an equivalent weight of protein (histones) to form a structure known as chromatin. It has become clear that the chromatin structure encompassing a gene is the critical factor that determines whether a gene is expressed or silenced. We propose that developmental and cell-type specific mechanisms operate in a cell to assemble genes into highly specialised chromatin structures that permit (euchromatin) or restrict (heterochromatin) gene expression. In other words, the genome of each different cell type is organised into a unique and dynamic chromatin pattern and this pattern determines the gene expression profile. This investigation will show that the critical cellular mechanism that determines the chromatin pattern for a particular cell type is the regulation of the quantity and quality of heterochromatin. Specifically, we will demonstrate that this is achieved, in a developmental and tissue specific manner, by changing the make-up of chromosomal domains through the replacement of histone proteins with specialised forms of histones called variants . In addition, we will expose a new mechanism of how heterochromatin formation controls the rate of cellular proliferation. This information will provide new insights into how gene expression profiles are established at precise times in early development, and offer a new strategy to inhibit the proliferation of cancer cells.Read moreRead less
REGULATION OF MICROTUBULE DYNAMICS BY LIM KINASE1 (LIMK1)
Funder
National Health and Medical Research Council
Funding Amount
$386,020.00
Summary
Disseminated cancer, unlike the localized disease, can rarely be cured by drug therapy. We have found that LIM kinase (LIMK1), a protein that was discovered in our laboratory, plays an important role in controlling the ability of tumour cells to spread, a process called metastasis. Thus, this protein becomes an important target for the development of new drug therapies to prevent the spread of cancer. We have found that LIMK1 is very important in controlling the polymerisation of one of the most ....Disseminated cancer, unlike the localized disease, can rarely be cured by drug therapy. We have found that LIM kinase (LIMK1), a protein that was discovered in our laboratory, plays an important role in controlling the ability of tumour cells to spread, a process called metastasis. Thus, this protein becomes an important target for the development of new drug therapies to prevent the spread of cancer. We have found that LIMK1 is very important in controlling the polymerisation of one of the most abundant molecules in the cell, actin. We have now preliminary data to show that LIMK1 also controls another important cellular protein, tubulin. Changes in tubulin polymerisation are of extreme importance for cell division and drugs affecting the state of tubulin are very potent as anti-cancer drugs. The goals of this research are: (1) To confirm that LIMK1 regulates the polymerisation of tubulin and (2) To demonstrate that LIMK1 regulates tubulin polymerisation by controlling the activity of p25, a protein involved in tubulin polymerisation that is modified by LIMK1. The results from this research will be highly significant because LIMK1 is a novel drug development target. Drugs that inhibit this protein may block the ability of tumours to invade and metastasise. Therefore, we have to identify the other functions of LIMK1 to eliminate the possibility that drugs that inhibit LIMK1 and metastasis don't affect other organs and cells in the body. New molecules regulated by LIMK1 may also be suitable targets for drug development because through their inhibition we may also regulate other LIMK1 activities and possibly metastasis.Read moreRead less
Structural Characterisation Of A Natural Inhibitor Of Sporulation Bound To Its Histidine Kinase Target
Funder
National Health and Medical Research Council
Funding Amount
$261,000.00
Summary
Many bacteria, including some which are virulent pathogens such as anthrax (Bacillus anthracis), are able to enter a dormant state by forming spores (sporulation). These spores are extremely robust and may persist in the environment buried in the soil for example for hundreds of years. The initiation of sporulation occurs in response to changes in the cellular and environmental conditions which threaten the free replicating existence of the bacterium. The process of sporulation is controlled at ....Many bacteria, including some which are virulent pathogens such as anthrax (Bacillus anthracis), are able to enter a dormant state by forming spores (sporulation). These spores are extremely robust and may persist in the environment buried in the soil for example for hundreds of years. The initiation of sporulation occurs in response to changes in the cellular and environmental conditions which threaten the free replicating existence of the bacterium. The process of sporulation is controlled at the molecular level by a complex signaling relay. It is of course vital for the existence of the organism that control of sporulation is tightly regulated - preventing the onset of spore-formation in any but the desired circumstances. We aim to determine the three-dimensional structures of the molecules involved in this regulated process and how, by interacting with each other, they can pass on the signal to the bacterium to either start or stop the spore forming process. Ultimately, the results of this work might lead to antibacterial agents which could be used to control particularly dangerous strains of bacteria.Read moreRead less
Structural And Drug Discovery Studies Of Oxidative Stress Regulator, Thioredoxin-interacting Protein
Funder
National Health and Medical Research Council
Funding Amount
$288,210.00
Summary
Toxic oxygen molecules known as Reactive Oxygen Species (ROS) are by-product of normal metabolism. The excess of ROS is damaging and is well known to contribute to ageing process and age-related diseases such as cancer, diabetic complications, immune-system decline, and cardiovascular conditions to name a few. The human body possesses several defense systems that protect us from the excess of ROS maintaining a healthy level of ROS. A down-regulator of one of this systems, a protein called TXNIP, ....Toxic oxygen molecules known as Reactive Oxygen Species (ROS) are by-product of normal metabolism. The excess of ROS is damaging and is well known to contribute to ageing process and age-related diseases such as cancer, diabetic complications, immune-system decline, and cardiovascular conditions to name a few. The human body possesses several defense systems that protect us from the excess of ROS maintaining a healthy level of ROS. A down-regulator of one of this systems, a protein called TXNIP, has been recently discovered. The amount of TXNIP is increased in such conditions as high glucose, a first sign of diabetes, and under ischemia, a shortage of blood supply occurring during heart attack. This weakens the anti-oxidant defense systems and makes the organism more vulnerable to ROS exposure. Our team of researchers embarked on structural and functional studies of TXNIP with the purpose to identify small molecules that can interfere with the undesirable action of TXNIP. These molecules might become useful therapeutic agents to counteract weakening organism's ROS defense system caused by TXNIP in many disease conditions such as, cancer, diabetes and cardiac failure.Read moreRead less
MRNA Surveillance In Human Disease: Molecular Determinants Of Nonsense-mediated MRNA Decay
Funder
National Health and Medical Research Council
Funding Amount
$474,517.00
Summary
Inherited diseases are a common cause of human disability, illness and suffering. It has been estimated that 5-10% of the population will be affected by disorders with a genetic component. Thus studies on mechanisms of inherited diseases, especially those relating to genetic mechanisms with relevance across a wide range of individual disorders and gene mutations, are of great significance in diagnosis, molecular pathology and the eventual development of therapeutics. While there are many types o ....Inherited diseases are a common cause of human disability, illness and suffering. It has been estimated that 5-10% of the population will be affected by disorders with a genetic component. Thus studies on mechanisms of inherited diseases, especially those relating to genetic mechanisms with relevance across a wide range of individual disorders and gene mutations, are of great significance in diagnosis, molecular pathology and the eventual development of therapeutics. While there are many types of mutations, one relatively common type is called a premature termination mutation. Premature termination mutations introduce an inappropriate genetic signal that tells the cells to stop the formation of proteins before they are complete. This would result in the production of a protein that is shorter than normal, and these short proteins could be quite abnormal and drastically affect the normal function of cells. To overcome this, cells have developed elegant strategies that involve the deployment of quality control, or surveillance, mechanisms to remove the mutant gene product before it can be converted into an abnormal protein. This process is called nonsense mediated decay. Nonsense mediated decay is a complex process and some of the key components have been identified by studies on a small number of genes. However, our studies have identified several previously unknown aspects of the process that suggest that the currently held view of how nonsense mediated decay works is only the beginning of the story and further important complexity exists. The proposed research will explore the basic mechanisms of the surveillance process and determine the signals that initiate nonsense mediated decay. Since premature termination mutations cause one-third of all inherited genetic disorders, our studies will provide new insights into the surveillance mechanisms and will have wide applicability to our understanding of the basis of inherited disease.Read moreRead less
Mechanisms Of Nedd4/Nedd4-2-mediated Regulation Of The Epithelial Sodium Channel
Funder
National Health and Medical Research Council
Funding Amount
$471,000.00
Summary
The epithelial sodium channel (ENaC) is a highly specific ion channel expressed in the apical membrane of some tissues. In the kidney, ENaC activity is responsible for maintaining sodium balance, blood volume and blood pressure. In the lung ENaC function is required for fluid clearance. Abnormal regulation of ENaC is associated with conditions such as hypertension, cystic fibrosis and pulmonary oedema. Delineating the molecular basis of the regulation of ENaC is vital in understanding disease me ....The epithelial sodium channel (ENaC) is a highly specific ion channel expressed in the apical membrane of some tissues. In the kidney, ENaC activity is responsible for maintaining sodium balance, blood volume and blood pressure. In the lung ENaC function is required for fluid clearance. Abnormal regulation of ENaC is associated with conditions such as hypertension, cystic fibrosis and pulmonary oedema. Delineating the molecular basis of the regulation of ENaC is vital in understanding disease mechanisms and in defining targets for novel therapeutics for the treatment of disorders that arise due to sodium imbalance. Furthermore, ENaC and the molecules involved in the channel regulatory cascade are potential candidate genes in defining the genetic causes of human hypertension and salt wasting disorders. Previous studies from our laboratories and by other groups have shown that Nedd4 and Nedd4-2 proteins are key players in regulating ENaC activity. Our recent NHMRC supported work has identified another important protein, Grk2, as a regulator of ENaC. The work proposed in this application is an extension of our recent findings and will enable us to fully define how Nedd4-Nedd4-2 and Grk2 regulate the activity of ENaC.Read moreRead less
Assembly Of Mitochondrial Respiratory Chain Complexes And Defects Associated With Disease
Funder
National Health and Medical Research Council
Funding Amount
$464,610.00
Summary
A group of protein assemblies termed respiratory complexes are found in the inner membrane of mitochondria in our cells and are responsible for producing most of our energy. These complexes consist of many different protein subunits and are built by the help of numerous known and unknown assembly factors. For example, assembly of Complex I of the respiratory chain requires 39 different proteins that are made outside mitochondria and are then transported inside to be somehow joined together with ....A group of protein assemblies termed respiratory complexes are found in the inner membrane of mitochondria in our cells and are responsible for producing most of our energy. These complexes consist of many different protein subunits and are built by the help of numerous known and unknown assembly factors. For example, assembly of Complex I of the respiratory chain requires 39 different proteins that are made outside mitochondria and are then transported inside to be somehow joined together with the 7 other subunits that are made by mitochondria. This is clearly a complicated procedure and we have little information on how its assembly is achieved. We do know however that mistakes in the assembly of these complexes (particularly Complex I) do happen. In Australia, about 50 children born each year have inherited disorders of mitochondrial energy generation. The most severe disorders cause infant death, while others present later causing a range of degenerative diseases, particularly affecting brain, muscle and heart. Defects in the respiratory chain have also been implicated in Parkinson's disease, Alzheimer's disease, type-2 diabetes and in cell death. In order to understand how respiratory complex defects cause disease, we need to understand more about how these complexes are built. The aim of this proposal is to investigate how Complex I is assembled, how it interacts with other respiratory complexes, and to identify and characterise proteins that aid in its assembly. We will also analyse assembly defects in cells from patients with suspected respiratory complex deficiencies. This work will aid in our understanding of not only how protein complexes are built, but how defects in their assembly can cause disease. This will be informative to families of affected individuals and may aid in future diagnosis and prevention of diseases where defects in mitochondria are implicated.Read moreRead less
Ligand Interactions Of Platelet Glycoprotein Ib-IX-V In Thrombosis
Funder
National Health and Medical Research Council
Funding Amount
$363,098.00
Summary
The transition of circulating blood platelets from a fluid-phase, non-adherent state to an adherent, activated and aggregated state (thrombus formation) is critical in the normal haemostatic response to blood vessel injury and in thrombotic diseases such as heart attack and stroke. One unique platelet receptor, the glycoprotein Ib-IX-V complex, is of particular interest, because it initiates platelet aggregate or thrombus formation at high fluid shear stress in flowing blood, including the patho ....The transition of circulating blood platelets from a fluid-phase, non-adherent state to an adherent, activated and aggregated state (thrombus formation) is critical in the normal haemostatic response to blood vessel injury and in thrombotic diseases such as heart attack and stroke. One unique platelet receptor, the glycoprotein Ib-IX-V complex, is of particular interest, because it initiates platelet aggregate or thrombus formation at high fluid shear stress in flowing blood, including the pathological shear stress that occurs in a sclerotic coronary artery. Our published and preliminary results show how GPIb-dependent interaction of platelets with von Willebrand factor, the major adhesive ligand for GPIb-IX-V, is dependent on the level of shear stress. Using a cross-species (human to canine) homology-swap approach, where human sequence is replaced by the corresponding canine sequence within discrete structural domains, a sequence of GPIb has been identified which becomes increasingly important as hydrodynamic shear stress increases. It is proposed to further define the interactive surface of GPIb that recognizes von Willebrand factor at increasing shear, and to define the relationship between the shear-dependent alteration of GPIb conformation and its ability to interact with other pro-thrombotic or pro-inflammatory binding partners.Read moreRead less
Structure And Interactions Of The Malarial Vaccine Candidate AMA1
Funder
National Health and Medical Research Council
Funding Amount
$351,000.00
Summary
Malaria remains one the most lethal infectious diseases in the world today. It is directly responsible for 1-2 million deaths annually, many of these in children under 5 years of age. More than 300 million clinical cases are reported annually and over 40% of the global population (in excess of 2 billion people) are at risk. There is an urgent need for a vaccine against this disease, particularly because of the recent increase in forms of the parasite resistant to many of the best anti-malarial d ....Malaria remains one the most lethal infectious diseases in the world today. It is directly responsible for 1-2 million deaths annually, many of these in children under 5 years of age. More than 300 million clinical cases are reported annually and over 40% of the global population (in excess of 2 billion people) are at risk. There is an urgent need for a vaccine against this disease, particularly because of the recent increase in forms of the parasite resistant to many of the best anti-malarial drugs. AMA1 is an asexual stage antigen and a leading vaccine candidate. Little is known about the function of this protein, but it has been proposed to play a role in invasion of red blood cells. A clearer understanding of the structure of parasite antigens such as AMA1 that induce a protective response in infected individuals would provide a stimulus to research into recombinant antigens as vaccines and a deeper understanding of host-parasite interactions. The aims of this project are to determine the three-dimensional structures of the three major structural domains of AMA1 and of the complete AMA1 antigen. We shall also determine the structures, both in aqueous solution and bound to AMA1, of small peptides identified by phage display as being capable of binding to AMA1 and blocking parasite entry into red blood cells. The overall goal of this work is to determine the structure of AMA1 and define the structural basis for its interaction with small peptides capable of blocking its activity as well as the structural features necessary for AMA1 to react with protective antibodies. The structure of AMA1 will provide a molecular basis for the design of engineered antigens capable of eliciting a protective immune response against AMA1. The inhibitory peptide structures will likewise provide a molecular basis for the design of non-peptidic blockers of AMA1. Either or both of these may be useful therapeutics leads in the fight against malaria.Read moreRead less
Regulator Of G-protein Signalling-5: A Key Modulator Of Vascular Maturation And The
Funder
National Health and Medical Research Council
Funding Amount
$548,396.00
Summary
Tumours progressively grow in part because they escape destruction by the immune system. New blood vessels grow inside tumours by a process called angiogenesis, which in turn stops disease-fighting cells in their tracks. However, we have now discovered that it is possible to reverse angiogenesis by normalising the blood vessels. This effectively means the barriers are broken down and the tumour can be opened to the immune system or cancer fighting drugs. Furthermore, we have identified a protein ....Tumours progressively grow in part because they escape destruction by the immune system. New blood vessels grow inside tumours by a process called angiogenesis, which in turn stops disease-fighting cells in their tracks. However, we have now discovered that it is possible to reverse angiogenesis by normalising the blood vessels. This effectively means the barriers are broken down and the tumour can be opened to the immune system or cancer fighting drugs. Furthermore, we have identified a protein which appears to be very important for normalisation, a process which is currently not well understood. This proposal continues our pioneering work on vessel normalisation and will use models of highest clinical relevance to study the dynamics of vessel remodelling in tumours. Our approach is different to current angiogenesis research which simply tries to block or destroy the blood vessels that feed tumours. We expect our findings to lead to highly specific and effective anti-tumour therapies. Moreover, vessel growth in tumours has striking parallels to other vascular processes in the body, which have important implications for major and common human diseases such as high blood pressure and atherosclerosis. We now have the tools to study these processes and their abnormalities in our newly established disease model. By gaining insight into these disorders we will be able to develop novel approaches to stop disease progression.Read moreRead less