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 Nuclear Import Of Viral Oncoproteins And Transcription Factors By Protein-protein Interactions
Funder
National Health and Medical Research Council
Funding Amount
$650,383.00
Summary
The present application examines the controls that exerted over proteins that localize in the nucleus of eukaryotic cells. This relates relates integrally to cellular processes such as growth, development and oncogenesis. This research area is not represented elsewhere in Australia, and the particular experimental strategies to approach the problem, revolving around the use of special quantitative microscopic techniques are novel internationally. One part of the application seeks to examine tran ....The present application examines the controls that exerted over proteins that localize in the nucleus of eukaryotic cells. This relates relates integrally to cellular processes such as growth, development and oncogenesis. This research area is not represented elsewhere in Australia, and the particular experimental strategies to approach the problem, revolving around the use of special quantitative microscopic techniques are novel internationally. One part of the application seeks to examine transport within the cell of complexes of interacting proteins, rather than single proteins, under as close as possible to physiologically relevant conditions. This will be truly unique, and of great importance to our comprehension of eukaryotic cell function. This application examines particular types of negative control over protein nuclear localization. Since many proteins show such regulation, and in particular important proteins controlling cell growth and division, the results are fundamentally important to our understanding of how cells function in general. Further, this understanding may be applied in disease situations, such as viral-mediated oncogenesis. In the work we propose to do, viral proteins with functions relating to cancer will be examined in detail, as well as a cellular protein which is recognised by them - the tumor suppressor Rb. We intend to examine several viral oncoproteins which target Rb; one is a protein (E7) from the Human Papilloma Virus which has been frequently associated with cervical carcinomas and other cancers. Accordingly, the results may have direct application to viral-induced cancer, and our work may lead to understanding of the regulation of protein transport to the nucleus. This may thus afford a new approach at the pharmacological level to combat transformation.Read moreRead less
Approaches to combat AIDS and its causative agent, the human immunodeficiency virus HIV-1, have thus far proved ineffective. The proposed research program intends to investigate the nuclear import of two HIV-1 proteins which have central roles in HIV infection. We will apply our expertise in the area of the regulation of nuclear import of viral proteins, and build on our observations with respect to these proteins to attempt to establish the mechanistic basis of their nuclear import, and how thi ....Approaches to combat AIDS and its causative agent, the human immunodeficiency virus HIV-1, have thus far proved ineffective. The proposed research program intends to investigate the nuclear import of two HIV-1 proteins which have central roles in HIV infection. We will apply our expertise in the area of the regulation of nuclear import of viral proteins, and build on our observations with respect to these proteins to attempt to establish the mechanistic basis of their nuclear import, and how this differs from the conventional nuclear import pathways used by normal cellular proteins. We already have evidence that nuclear import of HIV-Tat is regulated in novel fashion by cellular factors, and intend, through determining its mechanistic basis, to be able to form the basis of a strategy to block this import pathway specifically, and thereby inhibit HIV replication. This may form the basis in the future of a new pharmaceutical approach to combat HIV-AIDS.Read moreRead less
NUCLEAR AND TRANSGOLGI TARGETING AND MEMBRANE INDUCTION BY DENGUE NS5 RNA-DEPENDENT RNA POLYMERASE INTERDOMAIN REGION
Funder
National Health and Medical Research Council
Funding Amount
$450,750.00
Summary
Dengue virus is the causative agent of a mosquito-borne disease, Dengue fever, relevant to northern Queensland, where antibodies from a previous infection can complex with virus of a different serotype in a subsequent infection, and cause a severe, potentially fatal form of the disease (Dengue haemorrhagic fever-Dengue shock syndrome). The present proposal seeks to further understanding of the role of the dengue RNA-dependent RNA polymerase NS5, which is essential for viral RNA replication, with ....Dengue virus is the causative agent of a mosquito-borne disease, Dengue fever, relevant to northern Queensland, where antibodies from a previous infection can complex with virus of a different serotype in a subsequent infection, and cause a severe, potentially fatal form of the disease (Dengue haemorrhagic fever-Dengue shock syndrome). The present proposal seeks to further understanding of the role of the dengue RNA-dependent RNA polymerase NS5, which is essential for viral RNA replication, within the viral infectious cycle. We intend to examine the subcellular targeting properties of a short central region (the interdomain) of NS5, which appears to play multiple roles in targeting to both the perinuclear Golgi-membranes and to the nucleus, as well as in inducing intracellular membranes derived from the Golgi which are the site of viral replication. We will determine how NS5 localisation-membrane induction may differ in insect and primate cells, and attempt to isolate binding partners of NS5 from the nucleus and Golgi compartment of insect and primate cells using various different approaches. Our studies should assist in understanding NS5's critical role in the Dengue infectious cycle, and contribute towards devising new anti-viral strategies such as vaccination and-or therapies targeted at the NS5 interdomain.Read moreRead less
Engineered Histones As DNA Carriers With Application In Therapeutic Gene Delivery
Funder
National Health and Medical Research Council
Funding Amount
$417,750.00
Summary
We intend to apply our knowledge of protein transport to the nucleus to enhance the delivery of DNA to target cells. This relates to the use of gene therapy to treat genetic defects such as inborn errors of metabolism, where a disease-causing lack-of-function mutation can be overcome by engineering cells within the organism which express, in the necessary quantities and in response to the appropriate regulatory signals, the particular component which is lacking. A limiting factor in gene therapy ....We intend to apply our knowledge of protein transport to the nucleus to enhance the delivery of DNA to target cells. This relates to the use of gene therapy to treat genetic defects such as inborn errors of metabolism, where a disease-causing lack-of-function mutation can be overcome by engineering cells within the organism which express, in the necessary quantities and in response to the appropriate regulatory signals, the particular component which is lacking. A limiting factor in gene therapy approaches is the low efficiency of nuclear uptake of introduced DNA, where it has been estimated that < 1% of the DNA taken up is actually expressed. Our proposal seeks to develop approaches to enhance non-viral-mediated gene delivery, in particular by optimising this critical, limiting step of the delivery of exogenous DNA to the nucleus. We intend to apply knowledge from studies of nuclear targeting and chromatin assembly to improve gene transfer technologies. We will build on our work showing that specific signals for nuclear import - nuclear targeting signals (NTSs) - can be used to enhance nuclear gene delivery and expression. Since DNA in the normal cellular context is in the form of chromatin - a specific complex with proteins such as histones - we intend to use reconstituted chromatin as the transfecting DNA, whereby histones engineered to include NTSs and other modular sequence elements will be used. Chromatin should not only enable NTSs and other sequence modules to be linked to the DNA but also protect against nuclease-mediated degradation prior to nuclear entry, condense the DNA to enable more efficient cellular-nuclear entry, and ensure expression of the transfected reporter gene by presenting it to the cell in a physiological context. Our approaches should contribute to bringing gene therapy closer to reality in the clinic.Read moreRead less