GLUCOCORTICOID EFFECTS ON BONE: THE ROLE OF THE OSTEOBLAST
Funder
National Health and Medical Research Council
Funding Amount
$464,520.00
Summary
Glucocorticoids (usually referred to as cortisone) are used as therapeutic agents in almost all fields of medicine, where they have been proven to be of great benefit to countless patients suffering from diseases such as rheumatoid arthritis, asthma, inflammatory bowel disease and malignancies. Glucocorticoids are also of live saving benefit to patients who have undergone organ transplantation. It is, however, well known that glucocorticoids may also exert deleterious effects on bone, muscle, ca ....Glucocorticoids (usually referred to as cortisone) are used as therapeutic agents in almost all fields of medicine, where they have been proven to be of great benefit to countless patients suffering from diseases such as rheumatoid arthritis, asthma, inflammatory bowel disease and malignancies. Glucocorticoids are also of live saving benefit to patients who have undergone organ transplantation. It is, however, well known that glucocorticoids may also exert deleterious effects on bone, muscle, cartilage and skin, causing osteoporosis, muscle wasting and skin damage. As a matter of fact, cortisone-induced muscle and bone disease is one of the most frequent and serious side effects associated with glucocorticoid treatment, and substantially affects quality of life and co-morbidity in many patients. In the present project, we aim to develop new strategies for the understanding and prevention of costisone-induced bone disease. The first step is to investigate the mechanisms of actions of glucocorticoids in bone. To this aim, we have generated a model in which a cortisone- inactivating enzyme is produced in excess in the bone forming cells (osteoblasts). Previous studies have shown that these cells are protected against the effects on cortisone, while other cells not producing this enzyme remained vulnerable. We now intend to use this model to study the mechanisms of glucocorticoid action on bone and muscle under normal and diseased conditions (e.g. in a model of glucocorticoid excess and in a model of rheumatoid arthritis). We also intend to study how internal glucocorticoids affect the development of bone forming cells. Our long-term aim is to uncover new ways to target drug action to the desired tissues and cells, while protecting other tissues and cells from deleterious side effects.Read moreRead less
Molecular Characterisation Of The Ligand-binding Domain Of The Mineralocorticoid Receptor
Funder
National Health and Medical Research Council
Funding Amount
$215,183.00
Summary
The steroid hormone aldosterone regulates blood pressure by controlling sodium retention. The important role of this hormone in blood pressure control is underlined by the fact that all known monogenetic hypertensive conditions involve aldosterone or sodium reabsorption. Aldosterone works by activating an intracellular 'receptor' protein that in turn switches on specific genes. The products of these genes act to produce sodium retention. Antagonists (blockers) of this receptor are used in the tr ....The steroid hormone aldosterone regulates blood pressure by controlling sodium retention. The important role of this hormone in blood pressure control is underlined by the fact that all known monogenetic hypertensive conditions involve aldosterone or sodium reabsorption. Aldosterone works by activating an intracellular 'receptor' protein that in turn switches on specific genes. The products of these genes act to produce sodium retention. Antagonists (blockers) of this receptor are used in the treatment of hypertension but have undesirable side effects. The design of new, more specific, antagonists has been slow because we do not understand how these drugs bind to the receptor and what effect they have on the protein. How the aldosterone receptor functions is poorly understood. This project aims to investigate the receptor in detail. We are in the process of determining regions of the receptor structure important for hormone binding. This information is vital for the design of new antagonists. The aldosterone receptor is unusual in that it is also activated by cortisol, a steroid hormone involved in stress and inflammation. By examining hormone binding it may be possible to determine if the two steroids activate the receptor in the same way. An understanding of how both natural hormones and synthetic antagonists function is impossible without thorough study of the receptor itself. We intend to examine fundamental aspects of aldosterone receptor function. In particular we wish to identify proteins that interact with the receptor. These proteins either enhance or inhibit the ability of the receptor to switch on genes and are vital to explaining the actions of both natural hormones and synthetic antagonists. Results from these experiments should advance our understanding of the basic biology of aldosterone action and its role in cardiovascular biology, and lead to the design of better receptor antagonists for use in the treatment of hypertension and cardiac fibrosis.Read moreRead less
The Involvement Of Bone Cells In The Adverse Side-effects Associated With Therapeutic Glucocorticoid Use
Funder
National Health and Medical Research Council
Funding Amount
$290,032.00
Summary
Long-term use of cortisone (glucocorticoids) often leads to significant health problems such as diabetes and obesity. We have convincing preliminary data suggesting these side effects are, at least in part, mediated via bone cells. Inhibiting cortisone action in these cells, in mice treated with cortisone, results in a significant reduction of the negative side effects of this drug on fuel metabolism (eg glucose and lipid levels). The current aim is to investigate how this pathway is involved in ....Long-term use of cortisone (glucocorticoids) often leads to significant health problems such as diabetes and obesity. We have convincing preliminary data suggesting these side effects are, at least in part, mediated via bone cells. Inhibiting cortisone action in these cells, in mice treated with cortisone, results in a significant reduction of the negative side effects of this drug on fuel metabolism (eg glucose and lipid levels). The current aim is to investigate how this pathway is involved in cortisone-induced obesity and diabetes.Read moreRead less