Insulin resistance (the inability of ordinarily insulin-sensitive tissues such as muscle and adipose tissue to respond to insulin) contributes to a number of diseases including diabetes and obesity. A key metabolic step in these tissues is the uptake of glucose from the blood stream. This step is accelerated by insulin thus allowing efficient clearance of glucose from the bloodstream after a meal. Our laboratory has played a major role in showing that insulin regulates glucose uptake into muscle ....Insulin resistance (the inability of ordinarily insulin-sensitive tissues such as muscle and adipose tissue to respond to insulin) contributes to a number of diseases including diabetes and obesity. A key metabolic step in these tissues is the uptake of glucose from the blood stream. This step is accelerated by insulin thus allowing efficient clearance of glucose from the bloodstream after a meal. Our laboratory has played a major role in showing that insulin regulates glucose uptake into muscle and adipose tissue by stimulating the movement of a glucose transport protein from inside the cell to the cell surface (see http:--www.imb.uq.edu.au-groups-james-glut4 for an animated description of this process). The purpose of this proposal is to dissect the molecular mechanisms by which this glucose transporter can be held inside the cell in the absence of insulin and then allowed to be released from this site moving to the surface in the presence of insulin. Our studies over the past 5 years have brought us much closer to understanding this process in detail. The identification of the molecules responsible for this regulatory step will not only aid our understanding of this process but it will also provide a valuable target for development of therapeutic agents that can be used to combat insulin resistance.Read moreRead less
EPITHELIAL ION TRANSPORT DEFECTS IN CYSTIC FIBROSIS: PATHOPHYSIOLOGY AND TREATMENT
Funder
National Health and Medical Research Council
Funding Amount
$290,440.00
Summary
The thin layer of fluid covering the surface of the air passages acts to protect the airway surface from drying. This fluid also allows the hair-like projections, or cilia, on the top of the airway cells to beat more effectively. The volume and composition of this fluid is determined by the movement of salt and water across the mucous membranes of the air passages. The importance of this fluid is shown by the problems that occur in Cystic Fibrosis (CF), the most common lethal inherited disease a ....The thin layer of fluid covering the surface of the air passages acts to protect the airway surface from drying. This fluid also allows the hair-like projections, or cilia, on the top of the airway cells to beat more effectively. The volume and composition of this fluid is determined by the movement of salt and water across the mucous membranes of the air passages. The importance of this fluid is shown by the problems that occur in Cystic Fibrosis (CF), the most common lethal inherited disease affecting Australians. In CF, altered salt transport causes drying of the airway surface which impairs the working of the cilia. This leads to retention of mucous in the airway with repeated bacterial infections damaging the lungs. Simple tests have been designed to directly measure the movement of salt across the surface of the nasal passage using a fine soft rubber tube. Movement of mucous in the nose is measured using other simple techniques that are currently used diagnostically. Together, these tests in the nose provide vital information about how the surface of normal human airway moves salt, water and mucous. Any differences found in CF patients will then give us a good idea of the problems found in the CF lung. We will study the interactions between calcium, sodium and chloride in the fluid lining the airways, measuring changes in salt and mucous movement. A range of testing procedures will be used in human volunteers, anaesthetised mice and isolated tissues from sheep. We have already demonstrated important links between the fluid lining the airways and salt movement, and we expect that this may lead to the development of new treatments for Cystic Fibrosis. This therapy will focus on treating the lung problems of CF patients, the major cause of disability. We anticipate that this preventative therapy may offer real benefits in the fight to cure CF.Read moreRead less
Mechanism Of Action Of Sec1p-like Proteins In Membrane Trafficking
Funder
National Health and Medical Research Council
Funding Amount
$234,936.00
Summary
One of the most important evolutionary changes that has occurred is the development of intracellular compartments. All eukaryotic cells possess numerous membrane-encased structures which provide the basis for intracellular specialisation. For example, in order to degrade unwanted components cells have developed degradative enzymes. It is vital for the cell that these enzymes are sequestered away from other cellular components to avoid destruction of valuable molecules. In addition, the cell has ....One of the most important evolutionary changes that has occurred is the development of intracellular compartments. All eukaryotic cells possess numerous membrane-encased structures which provide the basis for intracellular specialisation. For example, in order to degrade unwanted components cells have developed degradative enzymes. It is vital for the cell that these enzymes are sequestered away from other cellular components to avoid destruction of valuable molecules. In addition, the cell has developed a complex assembly line of modifications that are added to proteins in a specific order as they travel to their final destination within the cell. This necessitates the accurate passage of molecules between compartments, a process known as vesicle transport. To orchestrate the complex network of vesicular transport steps between all of the various intracellular compartments it is necessary to employ complex machinery to guide and check that these steps occur with high fidelity. The goal of our research proposal is to define the function of one of the molecules involved in this control process, the so-called Sec1p proteins. The strength of our proposal lies in the diversity of our approach. We intend to explore the molecular advantages of a relatively simple eukaryotic organism, a yeast cell, and apply the findings obtained from this cell to a more complex but highly related vesicular transport process; that of the insulin-regulated movement of a glucose transporter in mammalian fat and muscle cells. While we intend to apply our findings to the treatment of patients with diabetes, it is our ultimate goal to be able to learn more about this fundamental cell biological process so that we can apply our knowledge to understanding many different disease states.Read moreRead less
Mechanism Of Action Of Sec1p-like Proteins In Membrane Trafficking.
Funder
National Health and Medical Research Council
Funding Amount
$440,250.00
Summary
One of the most important evolutionary changes that has occurred is the development of intracellular compartments. All eukaryotic cells possess numerous membrane-encased structures which provide the basis for intracellular specialisation. For example, in order to degrade unwanted components cells have developed degradative enzymes. It is vital for the cell that these enzymes are sequestered away from other cellular components to avoid destruction of valuable molecules. In addition, the cell has ....One of the most important evolutionary changes that has occurred is the development of intracellular compartments. All eukaryotic cells possess numerous membrane-encased structures which provide the basis for intracellular specialisation. For example, in order to degrade unwanted components cells have developed degradative enzymes. It is vital for the cell that these enzymes are sequestered away from other cellular components to avoid destruction of valuable molecules. In addition, the cell has developed a complex assembly line of modifications that are added to proteins in a specific order as they travel to their final destination within the cell. This necessitates the accurate passage of molecules between compartments, a process known as vesicle transport. To orchestrate the complex network of vesicular transport steps between all of the various intracellular compartments it is necessary to employ complex machinery to guide and check that these steps occur with high fidelity. The goal of our research proposal is to define the function of one of the molecules involved in this control process, the so-called Sec1p proteins. The strength of our proposal lies in the diversity of our approach. We intend to explore the molecular advantages of a relatively simple eukaryotic organism, a yeast cell, and apply the findings obtained from this cell to a more complex but highly related vesicular transport process; that of the insulin-regulated movement of a glucose transporter in mammalian fat and muscle cells. While we intend to apply our findings to the treatment of patients with diabetes, it is our ultimate goal to be able to learn more about this fundamental cell biological process so that we can apply our knowledge to understanding many different disease states.Read moreRead less
Structure-function Studies Of Ion Permeation And Selectivity In Recombinant Glycine Receptor Channels
Funder
National Health and Medical Research Council
Funding Amount
$331,300.00
Summary
Ligand-gated ion channels (LGICs) are members of a superfamily of receptor channels, with very significant structural and functional similarities, which play a major role in fast synaptic neurotransmission within the brain and spinal cord, and underlying the complex behaviour of the nervous system, but when dysfunctional can result in major neurological problems. Glycine is one of the two most important inhibitory neurotransmitters in the central nervous system. Impaired glycine-mediated neurotr ....Ligand-gated ion channels (LGICs) are members of a superfamily of receptor channels, with very significant structural and functional similarities, which play a major role in fast synaptic neurotransmission within the brain and spinal cord, and underlying the complex behaviour of the nervous system, but when dysfunctional can result in major neurological problems. Glycine is one of the two most important inhibitory neurotransmitters in the central nervous system. Impaired glycine-mediated neurotransmission underlies a range of inherited neurological diseases and already, it has been shown that the human disorder, familial Startle disease (hyperekplexia) occurs because of point mutations that have impaired the permeation and activation of the glycine receptor (GlyR). Similarly, certain epilepsies are now known to be caused by mutations in, or close to, the channel region in the excitatory acetylcholine receptors (AChRs), which affect channel activation and ion permeation. However, because of their very significant structural and functional similarities, information obtained in one member of the LGIC family of receptors has strong potential application to the other members and the GlyR with its simpler structure has certain advantages for investigation. The first aim of this project is to investigate how the molecular biological structure of these ion channels controls permeation, how it affects how different ions are selectively allowed to move through it and how it affects channel activation. A second related aim is to learn more about the process of desensitization of GlyR receptors, whereby a sustained presence of a high concentration of agonist can cause a reduction in receptor response. A third aim is to specifically investigate the mechanisms underlying the mode of molecular disruption resulting from two new Startle disease mutations, which, in addition to their own inherent clinical value, can also give general information about receptor function.Read moreRead less
The Functional Roles Of ADAMs In The Regulation Of Embryo Implantation.
Funder
National Health and Medical Research Council
Funding Amount
$211,527.00
Summary
The initiation of pregnancy in humans and rodents hinges upon the ability of the embryo to attach to the wall of the uterus and invade into the uterine tissue. This process of embryo implantation is tightly regulated and depends on the secretion of enzymes and regulators of these enzymes. A newly identified family of enzymes which might be important in this process is the ADAMs family. These enzymes have the potential to facilitate both cell attachment and cell invasion and also to activate othe ....The initiation of pregnancy in humans and rodents hinges upon the ability of the embryo to attach to the wall of the uterus and invade into the uterine tissue. This process of embryo implantation is tightly regulated and depends on the secretion of enzymes and regulators of these enzymes. A newly identified family of enzymes which might be important in this process is the ADAMs family. These enzymes have the potential to facilitate both cell attachment and cell invasion and also to activate other enzymes and growth factors. Recent studies in our laboratory have shown the ADAMs to be expressed both at the most invasive time of implantation and when invasion is being down-regulated. This project will examine the role of the ADAMs in embryo implantation facilitating attachment and invasion into the uterus by acting enzymatically on the uterine tissue and by activating other enzymes. It will also determine the role of ADAMs in down-regulating invasion potentially by activating a growth factor, TNF-alpha. Knowledge of this process and particularly its regulation is important for the treatment of pregnancy associated diseases that arise from improper implantation. These include infertility, placenta accreta, choriocarcinoma, miscarriage and pre-eclampsia. Furthermore, an understanding of the regulation of implantation will contribute to the treatment of other conditions associated with cell invasion such as cancer metastasis.Read moreRead less
Therapeutic Implications Of A Molecular Link Between Survivin And Telomerase Reverse Transcriptase
Funder
National Health and Medical Research Council
Funding Amount
$547,970.00
Summary
A unifying feature of all types of cancer cells is that they are immortal. Our investigations will build upon our recent results that showed the gene survivin is involved in cancer cell immortalisation. We will characterise a molecular link between survivin and the enzyme telomerase, which is central to cancer cell immortality. Furthermore, we will demonstrate the therapeutic potential of turning off both survivin and telomerase as a novel approach to halting the growth of cancer cells.
Immunising Aboriginal Mothers With Pneumococcal Polysaccharide Vaccine To Prevent Infant Ear Disease And Carriage
Funder
National Health and Medical Research Council
Funding Amount
$1,131,530.00
Summary
Aboriginal children experience the highest rates of acute and chronic ear infections in the world, with resultant permanent ear damage, hearing loss and educational disadvantage. These infections are mainly bacterial, and Streptococcus pneumoniae (pneumococcus) is the predominant pathogen. Pneumococcal colonisation and infection begins within days of birth, many months before any potential immunological protection from infant pneumococcal conjugate vaccine may be expected. New strategies are nee ....Aboriginal children experience the highest rates of acute and chronic ear infections in the world, with resultant permanent ear damage, hearing loss and educational disadvantage. These infections are mainly bacterial, and Streptococcus pneumoniae (pneumococcus) is the predominant pathogen. Pneumococcal colonisation and infection begins within days of birth, many months before any potential immunological protection from infant pneumococcal conjugate vaccine may be expected. New strategies are needed to eliminate, or at least delay, this early-onset pneumococcal colonisation. One such strategy is the administration to the mother of pneumococcal vaccine, which may protect the newborn infant by leading to higher titres of transplacental or breast milk pneumococcal antibodies and-or by reducing carriage (and transmission to the infant) of maternal pneumococci. Previous small studies using this strategy have been encouraging, but there have been no studies properly evaluating carriage or disease endpoints in infants. The polysaccharide pneumococcal vaccine is currently recommended for all Aboriginal and Torres Islander persons aged 15 years or more in the Northern Territory but uptake of the vaccine has been poor. We propose to conduct a pilot study to determine if maternal immunisation with this vaccine, either in the third trimester of pregancy of immediately following delivery, can reduce pneumococcal carriage and the prevalence of middle ear disease among Aboriginal infants at seven months of age. We aim to recruit 210 Aboriginal women who have uncomplicated pregnancies from Darwin and remote communities in the Top End of the Northern Territory. Each subject and their infant offspring will be followed-up after vaccination and at birth, one , two and seven months after birth.Read moreRead less
Glycine Transporters regulate the concentration of glycine in the spinal cord and brain. It has been suggested that elevating glycine levels in these regions may be useful in treating pain and schizophrenia. This project will provide the basis for the development of new glycine transport inhibitors that may be used to treat these conditions.
Regulation Of Secretion Of The Fungal Virulence Determinant, Phospholipase B
Funder
National Health and Medical Research Council
Funding Amount
$487,500.00
Summary
Serious systemic infections due to fungi have increased dramatically in the past few years, especially in people with poorly functioning immune systems. Treatment of these conditions is problematic because the few drugs which are available are not highly effective, and-or cause significant side-effects. Little is understood of how fungi cause disease, and this problem must be addressed if these infections are to be contained. We have discovered that the enzyme, phospholipase B (PLB), is secreted ....Serious systemic infections due to fungi have increased dramatically in the past few years, especially in people with poorly functioning immune systems. Treatment of these conditions is problematic because the few drugs which are available are not highly effective, and-or cause significant side-effects. Little is understood of how fungi cause disease, and this problem must be addressed if these infections are to be contained. We have discovered that the enzyme, phospholipase B (PLB), is secreted by the disease-causing fungus, Cryptococcus neoformans, and that it is important in enabling the fungus to invade the host's cells and spread around the body from the lungs to the brain, where it can cause meningoencephalitis. PLB is also produced by other disease-causing fungi. The mechanism of PLB secretion is completely unknown. In this project we aim to determine the pathways involved in PLB secretion with the intention of exploiting steps unique to pathogenic fungi, for the future design of new anti-fungal drugs.Read moreRead less