Characterization Of The 72 KDa Inositol Polyphosphate 5-phosphatase
Funder
National Health and Medical Research Council
Funding Amount
$454,050.00
Summary
Cells respond to external signals and the enviroment to undergo cell growth, secretion and or other specialized functions including control of cell death and or cell size. We have identified a new enzyme (72 kDa 5-phosphatase) which resides inside the cell, which we have evidence plays a role in regulating both the movement of intracellular vesicles and also lipid signals stimulated by insulin. We have characterised the phospholipids that the enzyme cleaves and demonstrated the generation of new ....Cells respond to external signals and the enviroment to undergo cell growth, secretion and or other specialized functions including control of cell death and or cell size. We have identified a new enzyme (72 kDa 5-phosphatase) which resides inside the cell, which we have evidence plays a role in regulating both the movement of intracellular vesicles and also lipid signals stimulated by insulin. We have characterised the phospholipids that the enzyme cleaves and demonstrated the generation of new cell signals at specific subcellular localizations on intracellular membranes. We predict the generation of these specific lipid signals may play a significant role in controlling the transport of intracellular cargo to specific sites in the cell. In this grant proposal we aim to examine the regulation of specialised cargo called the glucose transporter, which is found in fat and muscle cells, and also the mannose 6-phosphate receptor, which regulates the trafficking of specific enzymes which mediate digestion of proteins. These studies include the clarification of which phospholipid signals the enzyme terminates and where in the cell this occurs. Secondly, we will examine the movement of the glucose transporter GLUT-4 in unstimulated cells and in response to insulin and furthermore how expression of the novel enzyme regulates its movement. We will also examine the movement of the mannose 6-phosphate receptor and the specific phospholipid signals which control the route the receptor traffics, using inhibitors of lipid signals and expression of lipid phosphatases and kinases. We will also examine how our novel enzyme forms complexes with other molecules in the cell and characterise these novel molecules using basic biochemical assessment of enzyme activity and function. Finally we will examine the regulation of intracellular messages by our novel enzyme following insulin stimulation, which facilitates glucose uptake into the cell.Read moreRead less
The West Nile Viral Protease, NS3: A Target For Antiviral Drug And Vaccine Design
Funder
National Health and Medical Research Council
Funding Amount
$230,500.00
Summary
The West Nile Virus (WNV) was first isolated from a woman in the West Nile region of Uganda in 1937. It is one of ~70 known flaviviruses (e.g. Dengue fever, Yellow fever, West Nile, Kunjun, Japanese encephalitis, St. Louis encephalitis, tick-borne encephalitis, Australian encephalitis and the related hepatitis C virus) which annually infect hundreds of millions of people worldwide, particularly in tropical and sub-tropical areas, and cause major public health problems. WNV is endemic in the Midd ....The West Nile Virus (WNV) was first isolated from a woman in the West Nile region of Uganda in 1937. It is one of ~70 known flaviviruses (e.g. Dengue fever, Yellow fever, West Nile, Kunjun, Japanese encephalitis, St. Louis encephalitis, tick-borne encephalitis, Australian encephalitis and the related hepatitis C virus) which annually infect hundreds of millions of people worldwide, particularly in tropical and sub-tropical areas, and cause major public health problems. WNV is endemic in the Middle East, parts of Africa and Europe, but recent epidemics in Israel (1998), Romania (1996), United States (1999), and UK (2003) have been characterized by severe symptoms , severe neurological pathology, and fatalities. In the USA alone there were 4,156 infections and 284 deaths in 2002, 9122 infections and 223 deaths in 2003, and this mosquito borne virus has quickly spread since 1999 through all USA states and into Canada and Mexico (http:--www.cdc.gov-ncidod-dvbid-westnile-index.htm). No treatments or vaccines are available. This project focuses on an enzyme, known as the West Nile Virus NS3 protease, that is essential for replication of the virus. By studying the enzyme in the laboratory we can design small molecules that can block its function and these have real potential as leads for development of drug treatments for people infected by this virus. A precedent is the success of inhibitors of HIV-1 protease that are the most effective treatment for humans with HIV-infections. Our studies will also be used to develop potential vaccines. The science involves experts on protease enzymes, drug design and development, virology including West Nile virology, and vaccine development. We expect to generate drug and vaccine candidates and new information for their development that is at the cutting edge of West Nile Virus research.Read moreRead less
Biochemical Analysis Of Akt 3-specific Signal Transduction
Funder
National Health and Medical Research Council
Funding Amount
$349,375.00
Summary
The Akt family of enzymes consists of 3 protein kinases (Akt 1,2 and 3) and has been shown to regulate many normal cellular processes such as cell proliferation, growth, survival and motility, as well as the growth of new blood vessels. All these processes are critical for cancers to grow. However, few studies have distinguished the roles of the individual family members. Our preliminary data revealed Akt3 is far more active than the other two forms. Furthermore, using our unique Akt3 specific a ....The Akt family of enzymes consists of 3 protein kinases (Akt 1,2 and 3) and has been shown to regulate many normal cellular processes such as cell proliferation, growth, survival and motility, as well as the growth of new blood vessels. All these processes are critical for cancers to grow. However, few studies have distinguished the roles of the individual family members. Our preliminary data revealed Akt3 is far more active than the other two forms. Furthermore, using our unique Akt3 specific antibody, we find Akt 3 protein and activity levels are high in rapidly proliferating ovarian cancer cell lines and in primary ovarian tumours. The aim of this proposal is to characterise the mode and role of signalling via Akt3, including the identification of targeted substrates and signaling pathways and the outcomes of Akt3 driven signaling on cellular properties. These studies will provide important clues to understanding how this family member functions in both health and disease. Elucidation of the basis of Akt3 dependent signalling will open the possibility for the development of drugs that interfere with Akt3 function (for example in high Akt 3 expressing tumours like those of the ovary). In the long term, extension of our profiling studies to other tumour types will give a novel insight into the extent of Akt3 de-regulation as a key mediator of cancer formation.Read moreRead less
The Molecular Mechanism Of Sphingosine Kinase Activation
Funder
National Health and Medical Research Council
Funding Amount
$442,500.00
Summary
Many cell processes like growth, death and differentiation are controlled by hormones and other molecules that interact with receptors on the outside of the cell. When this type of molecule binds to a receptor, it often triggers the production of signaling molecules inside the cell that initiate a change in the cells behaviour. The lipid molecule, sphingosine phosphate has been identified as such a signaling molecule that appears to be involved in the regulation of a diverse array of important m ....Many cell processes like growth, death and differentiation are controlled by hormones and other molecules that interact with receptors on the outside of the cell. When this type of molecule binds to a receptor, it often triggers the production of signaling molecules inside the cell that initiate a change in the cells behaviour. The lipid molecule, sphingosine phosphate has been identified as such a signaling molecule that appears to be involved in the regulation of a diverse array of important mammalian cellular processes. Recent studies have found that sphingosine phosphate is involved in the inflammation of cells, and if its production can be blocked, inflammation is not seen. Therefore, this provides a potential target for therapeutic intervention in the inflammation process. However, the manner by which cells regulate sphingosine phosphate levels is not well known. It is known that sphingosine phosphate is produced by the enzyme sphingosine kinase, and strong evidence suggests that changes in this enzyme's activity in the cell regulate sphingosine phosphate levels. However, how the cell changes the levels of sphingosine kinase activity is completely unknown. This study will investigate this problem with the view that understanding this process will allow the development of new drugs to block increases in sphingosine kinase activity, preventing increases in sphingosine phosphate levels, and it turn, preventing cellular inflammation.Read moreRead less
Characterization Of 72 And 52 KDa Inositol Polyphosphate 5-phosphatases: Role In Vesicular Trafficking And Cell Death
Funder
National Health and Medical Research Council
Funding Amount
$408,055.00
Summary
Cells respond to the external environment, stress, hormones and grow th factors by generating messages inside the cell that send a signal to the nucleus that stimulates cell growth. One such signalling network is that produced by membrane lipids known as phosphoinositides. Enzymes or kinases that modify these membrane lipids in particular an enzyme known as the PI 3-kinase generate potent signalling molecules that regulate cell growth. It has been shown by many studies that signals generated by ....Cells respond to the external environment, stress, hormones and grow th factors by generating messages inside the cell that send a signal to the nucleus that stimulates cell growth. One such signalling network is that produced by membrane lipids known as phosphoinositides. Enzymes or kinases that modify these membrane lipids in particular an enzyme known as the PI 3-kinase generate potent signalling molecules that regulate cell growth. It has been shown by many studies that signals generated by the PI 3-kinase are amplified in certain human cancers. Inherited cancer syndromes have been described in which the cell has lost the ability to switch off these lipid messenger molecules. The current project aims to investigate two recently identified enzymes called 5-phosphases that have the ability to terminate PI 3-kinase membrane signals. Both these enzymes were isolated and characterized by the host laboratory and it is predicted they will play distinct roles in the cell. The 72 kDa 5-phosphatase is predicted to regulate protein and vesicular trafficking to the surface of cell. This proposal aims to investigate if the 72 kDa 5-phosphatase can regulate the intracellular sorting of new proteins within the cell. We have also noted the 72 kDa 5-phosphatase may play a role in the development of the nervous system in particular the ability of nerves to send branches out and differentiate. This proposal will investigate this hypothesis. The second enzyme that we have isolated is a 52 kDa 5-phosphatase. This enzyme is present in many cells. We have compelling evidence that the enzyme forms a complex with a recently decribed protein called SODD that stops cells from dying in response to inappropropirate signals. We predict the 52 kDa 5-phosphatase may function to prevent prolonged cell survival as is observed in cancer. We will investigate if this enzyme regulates the cell death pathway and if increased or decreased levels of the 52 kDa 5-phosphatase alter cell survivalRead moreRead less
Structural And Functional Studies On Glutamate Decarboxylase.
Funder
National Health and Medical Research Council
Funding Amount
$500,460.00
Summary
This proposal aims to determine the molecular structure of the two known isoforms of Glutamate Decarboxylase (GAD65 and GAD67). GAD in an essential human enzyme that is responsible for synthesising the primary inhibitory neurotransmitter gamma-aminobutyric acid (GABA). GABA functions in the human Central Nervous System (CNS) to dampen down excitatory signals. Proper control of GABA synthesis is important and perturbations in GABA levels lies behind human diseases such as intractable epilepsy, de ....This proposal aims to determine the molecular structure of the two known isoforms of Glutamate Decarboxylase (GAD65 and GAD67). GAD in an essential human enzyme that is responsible for synthesising the primary inhibitory neurotransmitter gamma-aminobutyric acid (GABA). GABA functions in the human Central Nervous System (CNS) to dampen down excitatory signals. Proper control of GABA synthesis is important and perturbations in GABA levels lies behind human diseases such as intractable epilepsy, depression and schizophrenia. As a result of this role, numerous common therapeutics (for example benzodiazepines) target proteins involved in the GABA neurotransmitter system. The goal of this proposal is to use the molecular structures of GAD to understand how to achieve fine control of GABA production. In addition to its role in the CNS, GAD is an important human autoantigen. Antibodies to one isoform of GAD, GAD65, are found in most patients with type I diabetes as well as certain patients with the movement disorder stiff person syndrome and related diseases of the CNS. It is suggested that the development of auto-antibodies may play a key role in the pathophysiology of these conditions. Despite sharing >80% sequence similarity with GAD65, autoantibodies to the other isoform of GAD, GAD67, are rarely found in patients with disease. The aim of this grant is to characterise the region of GAD that is targetted by autoantibodes. These data will allow us to understand why certain autoantibodes are able to inhibit GAD enzyme activity and why GAD65, but not GAD67 is recognised by autoantibodes.Read moreRead less
Alternate Splicing Of Tryptase Genes Regulates Their Specificity
Funder
National Health and Medical Research Council
Funding Amount
$294,250.00
Summary
Tryptases are enzymes implicated in inflammatory disorders including arthritis, inflammatory bowel disease (IBD) and asthma. Specific tryptase inhibitors are effective in treating these diseases. We have discovered that each human tryptase gene is processed into two different protein products via a mechanism called alternate splicing. We will investigate the structure and function of these.
The Activation Of Lipoprotein Lipase By Apolipoprotein C-II
Funder
National Health and Medical Research Council
Funding Amount
$250,500.00
Summary
Abnormalities in blood lipid levels are common in our society. Treatment of these conditions adds a heavy burden to national health-care costs. Lipoprotein lipase is a plasma enzyme that plays a central role in maintaining safe blood lipid levels. The action of lipoprotein lipase in subjects on a western diet leads to the hydrolysis of about 150g of plasma triacylglycerol daily. Naturally occurring mutations in lipoprotein lipase, associated with a complete loss of enzyme activity, result in a h ....Abnormalities in blood lipid levels are common in our society. Treatment of these conditions adds a heavy burden to national health-care costs. Lipoprotein lipase is a plasma enzyme that plays a central role in maintaining safe blood lipid levels. The action of lipoprotein lipase in subjects on a western diet leads to the hydrolysis of about 150g of plasma triacylglycerol daily. Naturally occurring mutations in lipoprotein lipase, associated with a complete loss of enzyme activity, result in a high blood-lipids that can lead to premature atherosclerosis. Regulation of lipoprotein lipase occurs via an interaction with the regulatory protein apolipoprotein C-II. Individuals with apolipoprotein C-II deficiency also exhibit abnormal plasma lipid levels with an associated increased risk of coronary heart disease. These considerations demonstrate that the activation of lipoprotein lipase by apolipoprotein C-II is pivotal to the maintenance of normal blood lipid levels. The present proposal will establish the structure and orientation of apolipoprotein C-II in a lipid environment and provide a structural model for the activation of lipoprotein lipase by apolipoprotein C-II. These molecular details will serve as a model for the regulatory interactions of other apolipoproteins within lipoprotein particles and will generate leads for the development of new strategies for the treatment of blood lipid irregularities.Read moreRead less
Regulation Of Synthesis, Dimerisation And Secretion Of The Amyloidogenic Protease Inhibitor Cystatin C
Funder
National Health and Medical Research Council
Funding Amount
$423,565.00
Summary
The cells that compose our tissues are embedded in a complex mesh of extracellular proteins (for example collagen) that provide support, strenght and elasticity to the tissues. This extracellular matrix is not static; it is constantly remodelled when, for example, the cells of the immune system move through interstitial spaces to monitor the healthiness of the tissues. When infections or injuries occur, the inflammatory reactions that develop, and the processes involved in tissue repair, also in ....The cells that compose our tissues are embedded in a complex mesh of extracellular proteins (for example collagen) that provide support, strenght and elasticity to the tissues. This extracellular matrix is not static; it is constantly remodelled when, for example, the cells of the immune system move through interstitial spaces to monitor the healthiness of the tissues. When infections or injuries occur, the inflammatory reactions that develop, and the processes involved in tissue repair, also involve profound changes in the composition of the extracellular matrix. Such processes are also important for tumour growth; the cancer cells need to clear their way through interstitial space to escape to circulation and metastasize. During all these processes, the cells release to the extracellular space proteases that degrade collagen and the other components of the extracellular matrix. Obviously, these proteases must be tightly regulated to prevent them running out of control, so the cells also produce inhibitors of the proteases. The amount of proteases and inhibitors contained in the extracellular space must be maintained properly. If this equilibrium is disrupted, this can lead to pathology For instance, atherosclerosis is caused in part by excessive proteolysis of the blood vessel wall. In this project we want to study the mechanisms of one of the most abundant and important inhibitors of extracellular proteolysis: Cystatin C. We have discovered that certain cells of the immune system called dendritic cells posses interesting mechanisms to regulate how much Cystatin C they secrete. Furthermore, one of this mechanisms, which consists of pairing the protein to produce inactive dimers, may be the cause of some diseases characterised by accumulation of Cystatin C in the extracellular space. Our study may allow us to design therapies for the treatment of pathologies associated with defective or excessive production of Cystatin C.Read moreRead less
Multi-domain Regulation Of DNA Damage Response Kinases
Funder
National Health and Medical Research Council
Funding Amount
$313,427.00
Summary
DNA damage plays a key role in the onset of cancer and the response to cancer therapies. Mutations in the Chk2 DNA damage response kinase are associated with increased cancer risk. We will study detailed mechanisms how phosphorylation of Chk2-like kinases contributes to normal copying of our DNA every time a cell divides, and how it regulates how Chk2 is activated. The studies will improve our understanding how cancer may originate and how cancer cells respond to chemo- or radiation therapy.