Molecular Mechanisms Of Feed-forward Regulation Of Bile Acid Detoxification And Elimination In Cholestasis
Funder
National Health and Medical Research Council
Funding Amount
$334,500.00
Summary
Liver diseases in which there is obstruction to bile flow (cholestatic liver diseases) can lead to liver failure, liver cirrhosis as well as a diminished quality of life. Patients suffer from severe itching which may prove difficult to control. It is thought that may of these adverse effects of obstructed bile flow are due to the retention of a component or bile, called bile acids, within the body. Bile acids are detergent-like compounds formed from cholesterol. Some bile acids are highly toxic ....Liver diseases in which there is obstruction to bile flow (cholestatic liver diseases) can lead to liver failure, liver cirrhosis as well as a diminished quality of life. Patients suffer from severe itching which may prove difficult to control. It is thought that may of these adverse effects of obstructed bile flow are due to the retention of a component or bile, called bile acids, within the body. Bile acids are detergent-like compounds formed from cholesterol. Some bile acids are highly toxic and cause the death of cells within the liver if their concentration becomes too high. Evidence has emerged that the body has control mechanisms to try and combat rising levels of bile acids in cholestatic liver diseases. These control mechanisms are complex and include enzymes from the cytochrome P450 family as well as several specialized transport molecules. In cholestasis these mechanisms promote the removal of bile acids through the urine as well as converting very toxic bile acids to less toxic forms. The present projects builds on discoveries concerning the regulation of cytochrome P450 enzymes made by our group over the last few years, including an in-depth understanding of the way the production of CYP3As is increased by some drugs. We intend to determine in detail how defense mechanisms against toxic bile acids are engaged. In particular, we wish to identify the receptor molecules that 'sense' the rising levels of bile acids that occur in cholestatic liver diseases. An understanding of these issues will allow us to better manage patents with these diseases and develop new strategies for treating cholestatic disorders, for example, development of novel drugs that can influence bile acid detoxification in the liver and other organs.Read moreRead less
Bile Acid Detoxification By Nuclear Receptor-mediated CYP3A Regulation
Funder
National Health and Medical Research Council
Funding Amount
$196,527.00
Summary
Liver diseases in which there is obstruction to bile flow (cholestatic liver diseases) can lead to liver failure, liver cirrhosis as well as a diminished quality of life. Patients suffer from severe itching which may prove difficult to control. It is thought that many of these adverse effects of obstructed bile flow are due to the retention of a component of bile, called bile acids, within the body. Bile acids are detergent-like compounds formed from cholesterol. Some bile acids are highly toxic ....Liver diseases in which there is obstruction to bile flow (cholestatic liver diseases) can lead to liver failure, liver cirrhosis as well as a diminished quality of life. Patients suffer from severe itching which may prove difficult to control. It is thought that many of these adverse effects of obstructed bile flow are due to the retention of a component of bile, called bile acids, within the body. Bile acids are detergent-like compounds formed from cholesterol. Some bile acids are highly toxic and cause the death of cells in the liver if their concentration becomes too high. Evidence has emerged that the body has control mechanisms to try and combat rising levels of bile acids in cholestatic liver diseases. One such mechanism, which is the subject of this application, is the metabolism of bile acids to less toxic forms, by a process called hydroxylation. A particular class of liver enzymes, known as cytochromes P450 CYP3As, appear to mediate these hydroxylation reactions. Liver cytochrome P450 enzymes are important to medicine in areas as broad as drug breakdown, steroid hormone regulation and the formation or elimination of cancer causing chemicals. These enzymes are present in high concentration in the human liver, but the factors governing how much of these enzymes are produced have been poorly understood. The present projects builds on discoveries concerning the regulation of cytochrome P450 enzymes made by our group over the last few years, including an in-depth understanding of the way the production of CYP3As are increased by some drugs. We intend to determine the mechanism by which bile acids increase the level of CYP3A enzymes are how effective these enzymes are in hydroxylating bile acids. An understanding of these issues will allow us to better manage patents with cholestatic liver diseases and develop new strategies for treating these diseases, for example, development of novel drugs that increase bile acid hydroxylation in the liver.Read moreRead less
A Novel Metabolic Role For UDP Glycosyltransferase 8 (UGT8)
Funder
National Health and Medical Research Council
Funding Amount
$419,144.00
Summary
The UDP glycosyltransferases (UGTs) are a family of enzymes that remove drugs and toxins from the human body as well as control levels of naturally produced molecules such as bile acids and hormones. We found that a new member of this family called UGT8 processes bile acids in the kidney and intestine and can affect how bile acids act to regulate metabolism. Our studies uncover new roles for bile acids in liver, kidney and gut health and in metabolic disorders such as diabetes and obesity.
Inhibition Of Glucose-stimulated Insulin Secretion By Protein Kinase C Epsilon
Funder
National Health and Medical Research Council
Funding Amount
$555,693.00
Summary
Type 2 diabetes is a chronic disease which occurs when the pancreas is unable to produce enough insulin for the body to cope with rising blood glucose levels after a meal, and is strongly linked to obesity. We have discovered that fat oversupply activates an enzyme in the pancreas causing defects in insulin release due to glucose. Inhibiting this enzyme helps overcome diabetes, through poorly defined mechanisms that we aim to clarify here. Our work could lead to new therapies for diabetes.
Mechanisms Of Fatty-acid Mediated Destruction Of Pancreatic Beta Cells
Funder
National Health and Medical Research Council
Funding Amount
$510,476.00
Summary
Type 2 diabetes is associated with obesity, but not all obese individuals develop the disease. Non-diabetic obese subjects are able to compensate for diminished sensitivity to insulin (a general feature of obesity) by enhanced output of insulin from the pancreatic beta-cells of the islet of Langerhans. In diabetics this compensatory mechanism is disrupted. Obesity and Type 2 diabetes are also associated with elevated levels of fatty acids (FAs) in the bloodstream. These can be taken up by the be ....Type 2 diabetes is associated with obesity, but not all obese individuals develop the disease. Non-diabetic obese subjects are able to compensate for diminished sensitivity to insulin (a general feature of obesity) by enhanced output of insulin from the pancreatic beta-cells of the islet of Langerhans. In diabetics this compensatory mechanism is disrupted. Obesity and Type 2 diabetes are also associated with elevated levels of fatty acids (FAs) in the bloodstream. These can be taken up by the beta-cells where they exert both short and long-term effects. In the longer term FAs can be toxic to beta-cells and this is thought to be important in the failure of beta-cell compensation. The project is aimed at a better understanding of the manner by which different types of FAs influence the susceptibility of beta-cells to destruction. It builds on our preliminary results suggesting that the capacity of the beta-cell to convert saturated FAs to unsaturated FAs helps protect them from destruction. Our aim is to examine the mechanisms underlying this protection.Read moreRead less
Chronic Kidney Diseases (CKDs) present serious morbidity and mortality in our society. Kidney scarring is the final manifestation of many types of kidney diseases. Recent evidence showed that a reduced ability to generate energy during injuries leads to kidney scarring. My study is looking at how the specific changes in kidney energy production can lead to kidney scarring. The findings of my study can have potential to prevent kidney scarring and change the course of kidney diseases.
Many heart diseases are associated with impairment of energetics of the heart. Improving the heart's energetics can lead to improved survival and long-term outcomes. Perhexiline is a heart medication that works by improving the way the heart uses energy. Although effective, it is associated with long-term toxicities. Better understanding of this medication may lead to less adverse effects and also provide a basis for further investigation of drug development in the future.