Novel Metabolic Actions Of HDL With Therapeutic Potential For Type 2 Diabetes
Funder
National Health and Medical Research Council
Funding Amount
$559,471.00
Summary
Our proposal investigates a novel approach to treat type 2 (late onset) diabetes. We have identified an important link between HDL (good) cholesterol and glucose metabolism. The current proposal is to conduct studies in humans to determine whether therapies which increase HDL result in sustained reduction of blood glucose. Given the escalating global prevalence of obesity and type 2 diabetes, this work is potentially of great significance.
Understanding Sphingolipid Mediators Of Insulin Resistance
Funder
National Health and Medical Research Council
Funding Amount
$643,447.00
Summary
Sphingolipids are a class of lipid metabolites that have a variety of functions within cells. It has been known for some time that an accumulation of excess lipid, including certain sphingolipids, can adversely impact insulin action and glucose metabolism in cells. In this project we will a combination of strategies to test the hypothesis that the sphingolipid profile can be manipulated to have favourable effects on metabolism.
Targeting Ceramide Metabolism To Improve Lipid-induced Insulin Resistance
Funder
National Health and Medical Research Council
Funding Amount
$604,327.00
Summary
We have shown that the buildup of ceramide in muscle plays a key role in the inhibition of normal insulin action when the body is exposed to excessive amounts of fat, which leads to poor control of blood sugar levels and Type 2 diabetes. Using mass spectrometry we will now measure different ceramide types, to investigate which contribute to defects in insulin action. We will also examine whether enzymes involved in ceramide formation or degradation can be targeted to improve insulin responses.
Novel Interplay Of Oestrogen And Growth Hormone In Regulating Lipid Metabolism
Funder
National Health and Medical Research Council
Funding Amount
$673,045.00
Summary
These studies provide insights into the mechanisms and role of oestrogen in regulating whole body and liver fat metabolism. Oestrogen-related medications that modify the action or tissue availability of oestrogen are widely used therapeutics and can predispose to obesity and fat accumulation in the liver. Whether the effect is direct or through interplay with other metabolic hormones is unknown. This proposal examines their metabolic consequences and impact on obesity and liver health.
Ceramide Metabolism And ER Stress In Fatty-acid Mediated Destruction Of Pancreatic Beta Cells
Funder
National Health and Medical Research Council
Funding Amount
$549,092.00
Summary
The underlying cause of Type 2 diabetes is the failure of pancreatic beta cells to secrete sufficient insulin to overcome the insulin resistance that is associated with obesity. Beta cell failre is associated with both defective insulin secretion and loss of beta cell mass. This proposal focuses on the cellular mechanisms and stress pathways whereby too much fatty acid promotes beta cell death.
Inosine-5' Monophosphate Dehydrogenase (IMPDH) is an enzyme responsible for providing a form of energy to cells, so that they may undertake their correct functions. Recently, we have demonstrated that IMPDH also has a role in the formation of fat droplets within cells, when they are exposed to excessive nutrients. In mammals, excess consumed energy is stored as fat droplets within all cells. In fat cells, the energy is stored in very large droplets, and we see this as extra body fat. This is som ....Inosine-5' Monophosphate Dehydrogenase (IMPDH) is an enzyme responsible for providing a form of energy to cells, so that they may undertake their correct functions. Recently, we have demonstrated that IMPDH also has a role in the formation of fat droplets within cells, when they are exposed to excessive nutrients. In mammals, excess consumed energy is stored as fat droplets within all cells. In fat cells, the energy is stored in very large droplets, and we see this as extra body fat. This is sometimes associated with an alteration in the hormone production of the cells, leading to problems such as diabetes. In other cells, the excess energy is stored as tiny fat droplets (lipid bodies) that can adversely affect the function of the cell. We have shown that blocking the action of IMPDH can interfere with the accumulation of fat in both fat cells and other types of cell. This suggests that IMPDH has an important role in the development of obesity and associated problems such as diabetes. In this study we aim to investigate in detail the role of IMPDH in the accumulation of fat droplets in cells. We will do this by looking at the effects of different forms of IMPDH in different cell types, including human fat cells. We will also study cells and animals with increased or decreased amounts of IMPDH, and investigate the effects of this on the development of increased fat stores and insulin resistance. These studies will increase our understanding of the role of IMPDH in the development of obesity, and may lead to identification of new avenues of treatment for obesity and type 2 diabetes.Read moreRead less
Biochemical Basis Of Islet Beta-cell Compensation And Failure In Normal Pregnancy And Gestational Diabetes Mellitus
Funder
National Health and Medical Research Council
Funding Amount
$480,828.00
Summary
The factors causing the current world-wide crisis of rapidly rising diabetes prevalence remain poorly understood. Of potential major importance, however, is the hypothesis that abnormalities in the maternal metabolic environment, as occur in gestational diabetes (GDM) (diabetes that develops in pregnancy), result in abnormal development of metabolic systems in the baby resulting in higher risk of adult onset diabetes in the babies. Therefore, it is of importance to understand the mechanisms caus ....The factors causing the current world-wide crisis of rapidly rising diabetes prevalence remain poorly understood. Of potential major importance, however, is the hypothesis that abnormalities in the maternal metabolic environment, as occur in gestational diabetes (GDM) (diabetes that develops in pregnancy), result in abnormal development of metabolic systems in the baby resulting in higher risk of adult onset diabetes in the babies. Therefore, it is of importance to understand the mechanisms causing GDM, such that effective measures can be developed to counter this passing on of diabetes risk from mother to baby. It is known that a key factor causing GDM is failure of maternal pancreatic islet beta-cells to compensate for increased demands for insulin production in pregnancy. Poorly understood, however, are the cellular mechanisms of islet beta-cell compensation in normal pregnancy and failure of this compensation in GDM pregnancy. We have recently shown that there is a pathway of fat metabolism (triglyceride- free fatty acid cycle) within the islet beta-cell that has an important role in amplyfing insulin secretion necessary to maintain normal blood glucose and protecting the islets from failure in obese rats. The major focus of this project is to test the hypothesis that this pathway has a key role in the adaptation of pancreatic islets to normal pregnancy and its dysfunction contributes to the causation of GDM. Of great interest from preliminary findings is that a master regulator of glucose and fat metabolism, PGC1alpha, is markedly reduced in islets during normal pregnancy. Studies will also be directed to PGC1alpha's role in islet adaptation to pregnancy and failure in GDM. We expect that successful completion of this project will lead to the development of highly targeted counter measures to prevent GDM and to slow and reverse the current epidemic of diabetes.Read moreRead less
Mechanisms Of The Insulin-sensitising Effects Of AMPK Activation In Liver And Muscle.
Funder
National Health and Medical Research Council
Funding Amount
$454,500.00
Summary
Type 2 diabetes represents an escalating global health problem. In Australia 7.5% of the population has diabetes and another 16% insulin resistance (impaired action of insulin). Insulin resistance is closely associated with obesity, dyslipidemia, hypertension and cardiovascular diseases (Syndrome X) as well as diabetes. A high caloric intake (particularly with a high fat content) and a sedentary lifestyle are extremely important environmental contributors to Syndrome X and diabetes. One of the m ....Type 2 diabetes represents an escalating global health problem. In Australia 7.5% of the population has diabetes and another 16% insulin resistance (impaired action of insulin). Insulin resistance is closely associated with obesity, dyslipidemia, hypertension and cardiovascular diseases (Syndrome X) as well as diabetes. A high caloric intake (particularly with a high fat content) and a sedentary lifestyle are extremely important environmental contributors to Syndrome X and diabetes. One of the most exciting developments in the past few years has been the discovery that an enzyme, AMP kinase (AMPK), normally activated by exercise, may be involved in its beneficial effects. We have contributed to this exciting field by showing in an animal model that one dose of AICAR, a chemical agent which can activate AMPK, ameliorates the effects of insulin resistance in muscle and liver. Further very recent work has linked AMPK with various drugs (particularly glitazones and metformin) and hormones which can enhance insulin sensitivity. The goal of the experiments in this project is to determine the overall mechanism by which AMPK has ameliorating effects on counteracting insulin resistance. We hypothesize that the mechanism for this involves an effect of AMPK to reduce fat molecules accumulating within muscle and liver cells, and our studies will examine this hypothesis. Our studies should lead to a better understanding of how exercise and pharmacological activators of AMPK help in management of diabetes and insulin resistant states. In addition because AMPK activation enhances glucose metabolism by a separate pathway to insulin, it offers promise of developing compounds able to bypass metabolic steps impaired by insulin resistance. Our studies should help in the design of new therapeutic agents which can counteract insulin resistance.Read moreRead less
ERRgamma And Skeletal Muscle: Insights Into Lipid Utilization And Catabolism
Funder
National Health and Medical Research Council
Funding Amount
$357,936.00
Summary
The significance of Nuclear hormone receptors (NRs) in disease is underscored by the range of pharmacopoeia for the treatment of NR-associated disorders (e.g 16% of the top 100 drugs target NRs). ERRgamma receptors are abundantly expressed in skeletal muscle, a major mass periperal tissue that acconts for ~40% of total body weight, and energy expenditure. Muscle is the major site of glucose metabolism and, fatty acid oxidation. Consequently, it has a significant role in insulin sensitivity, the ....The significance of Nuclear hormone receptors (NRs) in disease is underscored by the range of pharmacopoeia for the treatment of NR-associated disorders (e.g 16% of the top 100 drugs target NRs). ERRgamma receptors are abundantly expressed in skeletal muscle, a major mass periperal tissue that acconts for ~40% of total body weight, and energy expenditure. Muscle is the major site of glucose metabolism and, fatty acid oxidation. Consequently, it has a significant role in insulin sensitivity, the blood lipid profile, lipid metabolism and obesity. Understanding the functional role of the orphan ERR receptors in skeletal muscle in the context of inflammation, lipid and energy homeostasis is of paramount importance in further understanding the mechanistic basis of dyslipidemia, chronic inflammation, insulin sensitivity, diabetes and obesity. Identification of novel ERRgamma targets that regulate metabolism in a major mass peripheral tissue, and positively influence the risk factors for cardiovascular disease, provides platforms for potential therapeutic intervention. Cardiovascular disease is the foremost cause of global mortality, and was responsible for >15 million deaths in 2003.Read moreRead less