The Role Of The Endothelium In Insulin's In Vivo Action Upon Skeletal Muscle Metabolism.
Funder
National Health and Medical Research Council
Funding Amount
$451,500.00
Summary
A number of studies using novel techniques developed in association with our USA collaborators, indicate that insulin has a major stimulatory effect on blood flow within muscle in both animals and humans to improve access for itself as well as nutrients such as glucose. As much as 50% of the glucose taken up by muscle in vivo during continual exposure to insulin may be attributed to this effect. Moreover, this haemodynamic effect of insulin in muscle is impaired in a number of animal models and ....A number of studies using novel techniques developed in association with our USA collaborators, indicate that insulin has a major stimulatory effect on blood flow within muscle in both animals and humans to improve access for itself as well as nutrients such as glucose. As much as 50% of the glucose taken up by muscle in vivo during continual exposure to insulin may be attributed to this effect. Moreover, this haemodynamic effect of insulin in muscle is impaired in a number of animal models and in obese humans when insulin mediated muscle glucose uptake is also impaired. What is not known is how insulin mediates this haemodynamic effect of recruiting capillary blood flow. Thus in the present study a number of aspects are to be explored, with particular focus on the cells that line the blood vessels and constitute the capillaries, the so called endothelium. First, we will explore the specific role of the endothelium in insulin's action by using the novel approach of attaching insulin to a large molecule that prevents it leaving the lumen of the blood vessel. This will mean that insulin will be confined to interacting only with insulin receptors on the muscle endothelium. Similarly, non activating anti insulin receptor antibody will be used in the presence of insulin to selectively prevent activation of the endothelial insulin receptors. In addition, we will investigate whether homocysteine, an amino acid found to impair endothelial dependent vasodilatation, impairs the haemodynamic effects of insulin. The impact that normal insulin release after a meal has upon the haemodynamic actions in muscle and the role this has in muscle glucose uptake will also be investigated by using the techniques developed in the first part of the project. Our over riding hypothesis is that the endothelium plays a key role in controlling insulin and possibly glucose access to muscle cells and thus a significant proportion of insulin mediated metabolic events in muscle.Read moreRead less
Molecular Characterisation Of Adiponectin Receptors: Implications For Adiponectin Action And Resistance
Funder
National Health and Medical Research Council
Funding Amount
$95,137.00
Summary
Adiponectin is a hormone secreted by fat cells with anti-inflammatory, anti-atherogenic and insulin sensitising properties. Adiponectin levels and actions are compromised in obesity and type 2 diabetes. Adponectin mediates its effects via two receptors but the mechanisms are poorly understood. This proposal aims to define the underlying mechanisms with the ultimate goal of identifying novel therapeutic strategies to improve adiponectin's actions.
Microvascular Complications Of Diabetes - Potential Role Of Regenerative Therapies
Funder
National Health and Medical Research Council
Funding Amount
$32,003.00
Summary
The global burden of diabetes is projected to reach more than 366 million by 2025. According to the AusDiab 2005 study, each year 0.8% of Australians develop diabetes. Diabetes is the leading cause of end-stage kidney disease in Australia. Current treatments slow damage to the kidney, but do not reverse kidney damage. We will explore the potential for adult progenitor cells (endothelial progenitor cells) to reverse damage to the kidney and restore its function.
Role Of IGF Binding Protein-3 (IGFBP-3) And IGFBP-5 As Modulators Of Nuclear Hormone Signalling
Funder
National Health and Medical Research Council
Funding Amount
$465,750.00
Summary
The insulin-like growth factors are small proteins involved in the growth of most tissues. Their actions are regulated by binding to larger proteins (known as IGFBPs) in the bloodstream and outside the cell. However, some IGFBPs are also found inside cells, where they seem to carry out other functions. We believe that two of these binding proteins, IGFBP-3 and IGFBP-5, change the way cells respond to vitamin A and vitamin D. These two vitamins are important in cell growth and in the way certain ....The insulin-like growth factors are small proteins involved in the growth of most tissues. Their actions are regulated by binding to larger proteins (known as IGFBPs) in the bloodstream and outside the cell. However, some IGFBPs are also found inside cells, where they seem to carry out other functions. We believe that two of these binding proteins, IGFBP-3 and IGFBP-5, change the way cells respond to vitamin A and vitamin D. These two vitamins are important in cell growth and in the way certain cells perform specialised functions. In test-tube experiments, IGFBP-3 and IGFBP-5 interact directly with the receptors that regulate the effects of these hormones. If the same thing happens inside the cell, IGFBP-3 and IGFBP-5 could change the way these receptors respond to signals from outside the cell. We will investigate what effect these IGFBPs have in living cells and in whole animals and how this may relate to human disease. If we are able to understand how IGFBP-3 and IGFBP-5 affect the way cells respond to vitamin A and D, then we may be able to develop new ways to treat certain human diseases.Read moreRead less
The Role Of Vitamin D In Beta Cell Function, Glucose Tolerance And Diabetes Mellitus.
Funder
National Health and Medical Research Council
Funding Amount
$102,820.00
Summary
A significant proportion of Australians are deficient in Vitamin D, a vitamin obtained from sunlight exposure and to a lesser extent from food. Vitamin D deficiency has been associated with increased risk of Type 2 diabetes. This study aims to demonstrate the mechanisms through which vitamin D affects the insulin-producing cells of the pancreas and to determine whether deficiency affects the body's handling of glucose and subsequent risk of Type 2 diabetes and diabetes in pregnancy.
Understanding The Cause And Consequence Of Impaired Insulin Secretion In The NZO Mouse A Model Of Diabetes.
Funder
National Health and Medical Research Council
Funding Amount
$711,224.00
Summary
Type 2 diabetes is a major health problem affeting over 1 million Australians. A key feature of this disease is reduced secretion of the pancreratic hormone insulin which results in high blood sugar levels. We are using a naturally occurring animal model of diates called the NZO mouse to understand why the pancreas secretes less insulin and the consequences of this defect. This project has the potential of providing better therapeutic strategies for patients with Type 2 diabetes.
Expansion, Differentiation And Functional Analysis Of In Vitro Derived Pdx1+ Pancreatic Progenitors
Funder
National Health and Medical Research Council
Funding Amount
$540,075.00
Summary
Type 1 diabetes is a condition that arises when the body's immune system destroys insulin-producing beta cells within the pancreas. Recent studies have shown that normal glucose control can be restored by replacing the missing beta cells by transplantation of cells from deceased donors. However, the demand for transplant material outweighs supply. The work described in this application seeks to define how insulin-producing beta cells can be derived in the laboratory from embryonic stem cells .
Investigations Of Beta Cell Dysfunction And Death In Type 2 Diabetes
Funder
National Health and Medical Research Council
Funding Amount
$314,433.00
Summary
Diabetes is a disease that affects 100 million people worldwide and this number is expected to double in the next twenty years. This disease is characterised by high blood sugar levels which over prolonged periods of time can affect the function of the kidneys and eyes as well as causing heart attacks and strokes. A main contributing factor to diabetes is the inability of the pancreas to secrete insulin, the hormone that is responsible for keeping blood sugar levels in the normal range. The reas ....Diabetes is a disease that affects 100 million people worldwide and this number is expected to double in the next twenty years. This disease is characterised by high blood sugar levels which over prolonged periods of time can affect the function of the kidneys and eyes as well as causing heart attacks and strokes. A main contributing factor to diabetes is the inability of the pancreas to secrete insulin, the hormone that is responsible for keeping blood sugar levels in the normal range. The reason for this inability of the pancreas to secrete enough insulin is not known. It is known however, that both genetic and environmetal factors are responsible. The aim of this investigation is to determine the biochemical and genetic reason for decreased insulin secretion from an animal model of diabetes called DBA-2J mouse. Specifically we will be studying the effects of long-term increased sugar and fat on the function of the insulin producing cells of the pancreas, in order to identify the biochemical pathway responsible for reduced insulin secretion. In parallel we will be investigating the gene or genes in DBA-2J mice that are responsible for decreased insulin secretion and pancreatic cell death. This will provide clues as to the genes that may be responsible for diabetes in humans. This project will provide crucial information on the cause of reduced insulin secretion both at the cellular and genetic level, and will lead to a better understanding of the cause of diabetes.Read moreRead less
The Role Fructose-1,6-bisphosphatase On The Regulation Of Hepatic Gluconeogenesis
Funder
National Health and Medical Research Council
Funding Amount
$212,485.00
Summary
Type 2 or adult onset diabetes is a disease characterised by high blood sugar that causes damage to the kidneys, eyes and to the circulation and many patients die from heart attack or stroke. There is an increase in the prevalence of diabetes in Australia and a substantial portion of the health budget is utilised by caring for people with diabetes. Determining what exactly causes the increase in blood sugar levels is critical in the treatment of the disease. It is known that the sugar produced a ....Type 2 or adult onset diabetes is a disease characterised by high blood sugar that causes damage to the kidneys, eyes and to the circulation and many patients die from heart attack or stroke. There is an increase in the prevalence of diabetes in Australia and a substantial portion of the health budget is utilised by caring for people with diabetes. Determining what exactly causes the increase in blood sugar levels is critical in the treatment of the disease. It is known that the sugar produced and released by the liver is an important contributor to the high blood sugar levels found in patients with diabetes. The main biochemical pathway responsible for this is called gluconeogenesis, a complex arrangement of enzymes, which convert amino acids and fat into sugar. Although it is known that this pathway is overactive in patients with diabetes, the exact reason for this is not clearly understood. The aim of this proposal is to produce a transgenic mouse that has an increase in liver sugar production as a result of an increase in gluconeogenesis, and to study its effects on blood sugar levels. Furthermore, studies will be performed to understand the regulation of this pathway by infusing the transgenic mice with insulin, the hormone that inhibits gluconeogenesis. The mechanism of action of insulin will be determined by the measurement of key enzymes that regulate gluconeogenesis. The significance of this grant is to identify possible sites for the development of new drugs or gene therapy that will lead to a decrease in the production of sugar by the liver. This will lead to better control of blood sugar levels and slow down or even prevent the onset of diabetes complications.Read moreRead less