The Role Of Apolipoprotein E In High Density Lipoprotein Metabolism
Funder
National Health and Medical Research Council
Funding Amount
$151,208.00
Summary
Coronary heart disease is a major cause of death and disability in Australia. A high level of blood cholesterol increases the risk of developing coronary heart disease. This increase in coronary risk is caused by the cholesterol that is carried in low density lipoproteins (LDL). However, not all cholesterol is bad. A proportion of the cholesterol in blood is carried high density lipoproteins (HDL), which are powerful protectors against heart disease. People with high blood levels of HDL have a s ....Coronary heart disease is a major cause of death and disability in Australia. A high level of blood cholesterol increases the risk of developing coronary heart disease. This increase in coronary risk is caused by the cholesterol that is carried in low density lipoproteins (LDL). However, not all cholesterol is bad. A proportion of the cholesterol in blood is carried high density lipoproteins (HDL), which are powerful protectors against heart disease. People with high blood levels of HDL have a significantly reduced risk of developing heart disease. HDL consist of several different types of particles that contain lipids (or fats) and proteins. Not all HDL protect equally against coronary heart disease. Our ability to determine which HDL are the most cardioprotective is limited because it is difficult to separate the different types of particles from each other. One thing we do know is that the cardioprotective properties and metabolism of HDL are influenced by the proteins they contain. A considerable amount is known about the effects of the two main HDL proteins on the metabolism and cardioprotective properties of HDL. However, HDL contain several other proteins which are also important in this regard. This project is concerned with one of those other proteins called apolipoprotein E. The evidence that apolipoprotein E protects against heart disease is indisputable. Despite this, almost nothing is known about its role in HDL metabolism. This is because it is difficult to isolate large amounts of apolipoprotein E-containing HDL from plasma. In order to overcome these problems I have developed a novel method for preparing HDL which contain apolipoprotein E. These preparations are comparable to the apoE-containing HDL in human plasma. They will be used in this project to study the influence of apolipoprotein E on HDL metabolism.Read moreRead less
Genetic Programs Regulated By The Nuclear Hormone Receptor, LXR, In Muscle: Control Of Cholesterol And Lipid Metabolism
Funder
National Health and Medical Research Council
Funding Amount
$425,250.00
Summary
The heightened occurrence of cardiovascular disease has been linked to disorders in lipid metabolism. Obesity, insulin resistance, and atherosclerosis are prevalent diseases associated with these dyslipidemias. Lipid homeostasis is regulated by dietary intake, de novo synthesis and catabolism. Disorders of lipid metabolism are associated with cardiovascular disease, insulin resistance-diabetes, obesity and hypertension. Raised levels of serum TGs, and low high density lipoprotein (HDL) cholester ....The heightened occurrence of cardiovascular disease has been linked to disorders in lipid metabolism. Obesity, insulin resistance, and atherosclerosis are prevalent diseases associated with these dyslipidemias. Lipid homeostasis is regulated by dietary intake, de novo synthesis and catabolism. Disorders of lipid metabolism are associated with cardiovascular disease, insulin resistance-diabetes, obesity and hypertension. Raised levels of serum TGs, and low high density lipoprotein (HDL) cholesterol levels are characteristic of lipotoxic diseases. HDLs have a defensive role in the prevention of atherogenic dyslipidemia by mediating cholesterol efflux from peripheral tissues through the hormone -dependent ATP-binding cassette (ABC) transporters back to the liver for excretion and elimination. Agents that raise the levels of high density lipoprotein cholesterol (HDLc) through cholesterol efflux provide a pharmaceutical solution for the prevention of hypercholesterolemia, atherogenic and cardiovascular disease. These hormone dependent cholesterol and lipid effluxing proteins are regulated by a protein named LXR. Understanding the functional role of LXR in skeletal muscle, a peripheral tissue that accounts for 40% of total body weight is of paramount importance in understanding whole body cholesterol homeostasis and lipid metabolism. Furthermore, LXR and LXR target genes that facilitate cholesterol efflux and consequently raise HDLc levels are important pharmaceutical targets. Identification of novel LXR targets in skeletal muscle, which has a significant role in insulin sensitivity and the blood lipid profile provides an additional platform for therapeutic intervention.Read moreRead less
Role Of Impaired Insulin Signalling In Fatty Acid-induced Muscle Insulin Resistance In Vivo
Funder
National Health and Medical Research Council
Funding Amount
$481,500.00
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 in tissues). As well as diabetes, insulin resistance is closely associated with obesity, dyslipidaemia, hypertension and cardiovascular diseases (Syndrome X). While genetic factors play a role, a high caloric intake (particularly with a high fat content) and a sedentary lifestyle are extremely important environmental contr ....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 in tissues). As well as diabetes, insulin resistance is closely associated with obesity, dyslipidaemia, hypertension and cardiovascular diseases (Syndrome X). While genetic factors play a role, a high caloric intake (particularly with a high fat content) and a sedentary lifestyle are extremely important environmental contributors to Syndrome X and diabetes. From evidence that we and others have obtained over the last few years it is now evident that an important mediator of insulin resistance is the quantity of fat molecules which accumulate in muscle and liver. This project examines mechanisms whereby this fat accumulation can disrupt the signalling mechanism normally causing increased glucose metabolism in response to insulin. While basic experiments in cell systems have identified some candidates, a need exists to demonstrate whether they actually cause the insulin resistance in the whole animal or human, or are merely associated with it. We will combine metabolic-physiological studies with a novel technique we have recently established in our laboratory for introducing DNA into skeletal muscle of laboratory animal models. We now aim to exploit this approach to obtain more definitive data about the importance of insulin signalling changes to insulin resistance. Two major steps in insulin signalling will be investigated, involving the insulin receptor substrate proteins and the kinase Akt-PKB, both strongly implicated in lipid-induced insulin resistance. This knowledge will be invaluable in improving strategies to lessen or prevent lipid-associated insulin resistance, a major contributor to the metabolic derangement in Type 2 diabetes and Syndrome X.Read moreRead less