Following a meal glucose circulates in the blood and is taken up into cells via movement of an intracellular glucose transporter from the inside of the cell to fuse with the cell membrane and subsequent transfer of the glucose into the cell. This process is triggered by insulin. One of the commonest diseases resulting from a failure of this cellular process is diabetes. A common form of diabetes which occurs in many adults in Australia results from insulin resistance, whereby the effects of insu ....Following a meal glucose circulates in the blood and is taken up into cells via movement of an intracellular glucose transporter from the inside of the cell to fuse with the cell membrane and subsequent transfer of the glucose into the cell. This process is triggered by insulin. One of the commonest diseases resulting from a failure of this cellular process is diabetes. A common form of diabetes which occurs in many adults in Australia results from insulin resistance, whereby the effects of insulin are diminished and cells become increasingly unable to uptake glucose. Recent studies have demonstrated that a novel enzyme known as SHIP-2 may play a role in regulating insulin action in cells. Deletion of SHIP-2 in mice results in these animals have increased sensitivity to insulin, low blood glucose levels, and a greatly enhanced ability to take up glucose in cells in response to low dose insulin. Our laboratory has been working on the cellular mechanisms regulating SHIP-2 function. We have recently revealed the intracellular location of SHIP-2 and also demonstrated how SHIP-2 is localized in the cell. These studies have shown that SHIP-2, via interactions with other proteins, regulates the actin cytoskeleton immediately beneath the cell membrane and this may be a mechanism for facilitating cellular glucose uptake. This research proposal aims to determine how SHIP-2 facilitates glucose uptake into cells. We will make cell lines and transgenic animals which express high levels of this enzyme and determine the functional consequences on insulin stimulated glucose uptake. Collectively these studies in the long term may facilitate better treatment strategies for diabetic patients.Read moreRead less
Use Of Novel Transfection Protocols To Study Protein Trafficking In Malaria-infected Erythrocytes
Funder
National Health and Medical Research Council
Funding Amount
$211,527.00
Summary
Malaria kills between 1 and 3 million children each year. In addition, the disease debilitates the adult population in malaria-endemic areas, thereby contributing to the cycle of poverty in many third world countries. As resistance to existing antimalarial drugs increases, there is an urgent need to understand the workings of the parasite at a molecular level to enable the development of alternative antimalarial strategies. During part of its life cycle, the malaria parasite infects the erythroc ....Malaria kills between 1 and 3 million children each year. In addition, the disease debilitates the adult population in malaria-endemic areas, thereby contributing to the cycle of poverty in many third world countries. As resistance to existing antimalarial drugs increases, there is an urgent need to understand the workings of the parasite at a molecular level to enable the development of alternative antimalarial strategies. During part of its life cycle, the malaria parasite infects the erythrocytes of its human host. The parasite transports proteins to the erythrocyte membrane so as to modify the properties of its adopted cellular residence. The parasite proteins that are deposited at or in the erythrocyte membrane increase the leakiness and the stickiness of the parasitised erythrocytes. This allows more efficient uptake of nutrients and allows the parasitised erythrocytes to adhere to blood vessel walls, thereby avoiding passage through the spleen. Adherence of parasitised erythrocytes to capillaries in the brain is thought to lead to the development of the complication known as cerebral malaria. This complication is responsible for most of the deaths due to malaria. In order to traffic the adherence proteins to the erythrocyte surface, the parasite establishes a novel transport pathway for moving proteins across the erythrocyte cytoplasm. As the uninfected erythrocyte has no means, nor requirement, for moving proteins, this novel transport mechanism may represent a target for drugs that kill the malaria parasite without being toxic to humans. The pathways for the movement of proteins around the infected erythrocyte are largely unknown. We propose to use techniques to introduce foreign genes into malaria-infected erythrocytes to unravel the details of the molecular machinery and the ticketing system that the parasite uses to traffic proteins to their correct destinations in its adopted home.Read moreRead less
Identification Of Insulin Specific Signal Transduction Pathways In Adipocytes
Funder
National Health and Medical Research Council
Funding Amount
$451,980.00
Summary
Insulin resistance, which represents an inability of insulin to regulate metabolism in appropriate target tissues such as muscle and adipose tissue, 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 ....Insulin resistance, which represents an inability of insulin to regulate metabolism in appropriate target tissues such as muscle and adipose tissue, 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). In the present proposal we will pursue a number of strategies to dissect the signal transduction pathways that connect the insulin receptor to the movement of this glucose transporter. Identification of these molecules will provide the missing pieces to this important puzzle. Once solved we will have at our disposal a novel set of targets for designing drugs that will combat insulin resistant diseases.Read moreRead less
Protein Trafficking In Malaria Parasite-infected Erythrocytes
Funder
National Health and Medical Research Council
Funding Amount
$417,750.00
Summary
Malaria kills between 1 and 3 million children each year. In addition, the disease debilitates the adult population in malaria-endemic areas, thereby contributing to the cycle of poverty in many third world countries. As resistance to existing antimalarial drugs increases, there is an urgent need to understand the workings of the parasite at a molecular level to enable the development of alternative antimalarial strategies. During part of its life cycle, the malaria parasite infects the erythroc ....Malaria kills between 1 and 3 million children each year. In addition, the disease debilitates the adult population in malaria-endemic areas, thereby contributing to the cycle of poverty in many third world countries. As resistance to existing antimalarial drugs increases, there is an urgent need to understand the workings of the parasite at a molecular level to enable the development of alternative antimalarial strategies. During part of its life cycle, the malaria parasite infects the erythrocytes of its human host. The parasite transports proteins to the erythrocyte membrane so as to modify the properties of its adopted cellular residence. The parasite proteins that are deposited at or in the erythrocyte membrane increase the leakiness and the stickiness of the parasitised erythrocytes. This allows more efficient uptake of nutrients and allows the parasitised erythrocytes to adhere to blood vessel walls, thereby avoiding passage through the spleen. Adherence of parasitised erythrocytes to capillaries in the brain is thought to lead to the development of the complication known as cerebral malaria. This complication is responsible for most of the deaths due to malaria. In order to traffic the adherence proteins to the erythrocyte surface, the parasite establishes novel transport pathways for moving proteins across the erythrocyte cytoplasm. As the uninfected erythrocyte has no means, nor requirement, for moving proteins, this novel transport mechanism may represent a target for drugs that kill the malaria parasite without being toxic to humans. The pathways for the movement of proteins around the infected erythrocyte are largely unknown. We propose to use cell biology techniques and techniques to introduce foreign genes into malaria-infected erythrocytes to unravel the details of the molecular machinery and the ticketing system that the parasite uses to traffic proteins to their correct destinations in its adopted home.Read moreRead less
Structural Studies On SNARE Proteins Involved In Insulin Action
Funder
National Health and Medical Research Council
Funding Amount
$308,263.00
Summary
Diabetes mellitus, a disease characterised by high blood glucose levels, is caused by a relative or absolute deficiency in the activity of insulin. The blood-glucose lowering action of insulin is a result of its ability to stimulate glucose uptake by fat and muscle cells. A major goal of Professor James' laboratory is to identify molecules that are involved in this insulin-regulated uptake of glucose. Professor James has identified and characterised the glucose transporter, GLUT4, a protein that ....Diabetes mellitus, a disease characterised by high blood glucose levels, is caused by a relative or absolute deficiency in the activity of insulin. The blood-glucose lowering action of insulin is a result of its ability to stimulate glucose uptake by fat and muscle cells. A major goal of Professor James' laboratory is to identify molecules that are involved in this insulin-regulated uptake of glucose. Professor James has identified and characterised the glucose transporter, GLUT4, a protein that is normally stored inside muscle and fat cells. In response to insulin stimulation, GLUT4 moves to the cell surface where it functions to transport glucose into the cell. Over the past 5 years Professor James laboratory has, in conjunction with other groups, discovered several key proteins that are involved in the insulin-regulated movement of GLUT4 within the cell. We plan to exploit the therapeutic potential of this biological system by obtaining high resolution three dimensional structures of these key proteins. The resulting structural information will allow us to develop compounds that modify the function of these key proteins. Such compounds could prove useful as novel therapeutic agents in the treatment of diabetes. The purpose of this proposal is to begin to implement this goal. By combining the knowledge and reagents coming out of the work on insulin-regulated glucose transport in Professor James' laboratory with the molecular and structural biology expertise in Dr Martin's, Dr Halliday's and Prof Craik's laboratories we are in a unique position to achieve this highly significant goal.Read moreRead less
Analysis Of The Role Of Vesicle Docking/Fusion Proteins In Trafficking Of The Glut4 Glucose Transporter In Adipocytes
Funder
National Health and Medical Research Council
Funding Amount
$212,036.00
Summary
The objective of these studies is to understand the molecular mechanisms that are involved in the control of blood glucose levels by the hormone insulin. Elevated blood glucose levels following a meal stimulate the pancreas to release insulin into the circulation. Insulin acts to reduce blood sugar levels by stimulating the uptake of glucose into fat and muscle and suppressing glucose production by the liver. Defects in insulin action in these tissues are the primary cause of Type II diabetes. T ....The objective of these studies is to understand the molecular mechanisms that are involved in the control of blood glucose levels by the hormone insulin. Elevated blood glucose levels following a meal stimulate the pancreas to release insulin into the circulation. Insulin acts to reduce blood sugar levels by stimulating the uptake of glucose into fat and muscle and suppressing glucose production by the liver. Defects in insulin action in these tissues are the primary cause of Type II diabetes. The debilitating effects of Type II diabetes, the dramatic increase its incidence, and the expense of treating the symptoms of diabetic complications have lead to the realization that the disease represents a major health problem requiring substantial research and development efforts. The project will focus on insulin regulation of glucose uptake in fat cells. Insulin promotes glucose uptake into fat by activating an intracellular signaling pathway that triggers the translocation of a unique glucose transporter protein (Glut4) from storage sites inside the cell to the cell surface. Glut4 translocation is mediated by small membrane vesicles that function to sequester the glucose transporter inside cells in the absence of insulin, and to shuttle Glut4 to the cell surface in response to the hormone. Despite the central importance of this event to the maintenance of normal blood glucose levels, it is poorly understood. The studies will be directed towards investigating the cellular machinery involved in the latter stages of insulin-stimulated glucose uptake- the vesicle-mediated delivery of Glut4 to the cell surface. The objective of these studies is to better understand the molecular basis for Glut4 translocation, and regulation by the insulin signaling cascade. Accomplishment of this goal may suggest potential drug intervention strategies aimed at enhancing insulin-stimulated Glut4 translocation and promoting improved control of blood glucose levels in Type II diabetes.Read moreRead less
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
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
Regulation Of Body Composition And Glucose Homeostasis By The Adaptor Protein Grb10.
Funder
National Health and Medical Research Council
Funding Amount
$617,256.00
Summary
Resistance to the hormone insulin underlies the development of Type 2 Diabetes. Loss of muscle mass in the elderly contributes to insulin resistance. Recently we identified Grb10 as a new regulator of insulin action and muscle mass. In this proposal, we aim to study how Grb10 affects development and growth of muscle and fat, and the underlying molecular mechanisms. This may lead to new strategies for improving body composition and treating the insulin resistance associated with Type 2 Diabetes.