Novel Interactions Between GnRH Receptor And E2F4 Transcription Factor.
Funder
National Health and Medical Research Council
Funding Amount
$462,750.00
Summary
The reproductive endocrine system is under the control of gonadotropin-releasing hormone (GnRH), signalling via its G-protein coupled receptor (GPCR) in the anterior pituitary gland. The GnRH receptor (GnRHR) is the drug target for the treatment of a range of endocrine-related disorders as well as hormone-dependent cancers. Sustained treatment with either GnRH agonists or antagonists can block gonadotropin secretion indirectly, via down-regulation of the pituitary receptor resulting in a reducti ....The reproductive endocrine system is under the control of gonadotropin-releasing hormone (GnRH), signalling via its G-protein coupled receptor (GPCR) in the anterior pituitary gland. The GnRH receptor (GnRHR) is the drug target for the treatment of a range of endocrine-related disorders as well as hormone-dependent cancers. Sustained treatment with either GnRH agonists or antagonists can block gonadotropin secretion indirectly, via down-regulation of the pituitary receptor resulting in a reduction of gonadotropin secretion and consequent decline in steroid production. As the majority of tumours treated with GnRH analogues are hormone-dependent, this starves the tumour of the steroid support required for growth. However, the concept of a direct anti-tumour effect of GnRH, independent of the pituitary-gonadal axis, is supported by the in vitro inhibition of both cell growth and DNA synthesis in a number of tumour cell lines. Despite the wide use of GnRH analogues, the molecular basis of the growth inhibitory effects resulting from the activation of this receptor is not fully understood. Unravelling the protein interactions underlying receptor-mediated signalling events will provide valuable information towards understanding of receptor function in vivo. We have identified a novel interaction involving the GnRHR and E2F4, a transcription factor involved in suppression of the transcription of genes involved in cell cycle progression. In addition, over 80% of E2F4 knockout mice are sterile. Owing to the role of the GnRHR in the reproductive pathway we are interested in determining whether the GnRHR-E2F4 interaction has an influence on the development of the hypothalamic-pituitary-gonadal axis, hence affecting reproductive capacity. The interaction identified and studied in this proposal has implications for the treatment of reproductive tumours, such as those of the breast and prostate, and understanding the development of the hypothalamic-pituitary-gonadal axis.Read moreRead less
Overweight and obesity are at epidemic proportions in Australia, reflecting the pattern in the developed and developing world. The main cause appears to be an energy mismatch, with excessive caloric consumption. One response of the body to excessive nutrient supply is energy storage in fat tissue and to aid in this the body also generates new fat tissue, termed adipogenesis (also known in cells as fat cell differentiation). In many people who gain excess body weight, fat tissue is abnormal and d ....Overweight and obesity are at epidemic proportions in Australia, reflecting the pattern in the developed and developing world. The main cause appears to be an energy mismatch, with excessive caloric consumption. One response of the body to excessive nutrient supply is energy storage in fat tissue and to aid in this the body also generates new fat tissue, termed adipogenesis (also known in cells as fat cell differentiation). In many people who gain excess body weight, fat tissue is abnormal and does not respond well to the chemical insulin, thus causing insulin resistance. This insulin resistant fat tissue is especially present in a central body (visceral) site. Insulin resistance related to this visceral fat predisposes to both diabetes and premature death from cardiovascular disease. Understanding how fat tissue develops and how it might cause insulin resistance is thus important in human health. One of the factors in fat that prevents normal development of fat tissue and which induces insulin resistance is transforming growth factor- (TGF- ). We have generated new data showing that two proteins which are increased by TGF- , termed connective tissue growth factor (CTGF) and insulin like growth factor binding protein-3, (IGFBP-3), prevent adipogenesis. We have shown this in cultured cells, and have found that CTGF and IGFBP-3 are increased in visceral fat in animal models of obesity and insulin resistance. Our preliminary work has further indicated how CTGF and IGFBP-3 might each work in the fat cell to prevent adipogenesis. This proposal will determine if TGF- works through CTGF and IGFBP-3 to block adipogenesis, and it will define how CTGF and IGFBP-3 have their inhibitory effects on fat cell differentiation. Cells in culture will be utilised and an animal model of dietary induced obesity and insulin resistance will help to define whether CTGF and IGFBP-3 prevent adipogenesis in vivo, furthering our understanding in how abnormal fat tissue may develop.Read moreRead less
FUNCTIONAL ANALYSIS OF IGF-BINDING PROTEIN-2 MOLECULAR INTERACTIONS IN EARLY DEVELOPMENT AND DISEASE
Funder
National Health and Medical Research Council
Funding Amount
$551,328.00
Summary
Early development involves complex regulation of cell and organ growth. Cell migration and invasion are critical components of epithelial-mesenchymal transition (EMT) essential for early developmental, as well as injury repair and cancer. Common to these events is a highly expressed protein, insulin-like growth factor binding protein-2 (IGFBP-2), which appears to play a critical role in regulating the processes of cell migration and invasion. The underlying mechanisms of cellular regulation by I ....Early development involves complex regulation of cell and organ growth. Cell migration and invasion are critical components of epithelial-mesenchymal transition (EMT) essential for early developmental, as well as injury repair and cancer. Common to these events is a highly expressed protein, insulin-like growth factor binding protein-2 (IGFBP-2), which appears to play a critical role in regulating the processes of cell migration and invasion. The underlying mechanisms of cellular regulation by IGFBP-2 are major focus of this proposal, which brings together four major groups focussed on early development, neural injury repair, and cancer biology. We will use a range of in vitro and in vivo approaches to determine the underlying mechanisms of action of this critical protein. This project has the potential to point to novel therapeutic modalities in development, repair and cancer.Read moreRead less
Mineralocorticoid Receptor Blockade: Mechanisms Of Selectivity
Funder
National Health and Medical Research Council
Funding Amount
$540,270.00
Summary
The steroid hormone aldosterone controls salt balance and hence, blood pressure. It also has been shown to have a significant role in cardiac failure. Although drugs that block the aldosterone receptor are beneficial in the treatment of heart failure, they are limited by potassium retention in the kidney. In order to develop tissue-specific blockers of the aldosterone receptor, it is necessary to identify mechanisms by which the receptor can be activated and/or blocked in specific tissues.
Factors Regulating The Temporal And Spatial Assembly Of G-protein Coupled Receptor-mediated Arrestin Complexes
Funder
National Health and Medical Research Council
Funding Amount
$472,770.00
Summary
G-protein coupled receptors are proteins that are present at the surface of most cells in the human body. They recognise and bind to specific molecules, such as hormones, the act of which results in a specific signal being transmitted into the cell. This signal alters the function of the cell and so it is critical that it is appropriate, both in type and duration. G-protein coupled receptors and the molecules that activate them provide an essential function within the human body for communicatin ....G-protein coupled receptors are proteins that are present at the surface of most cells in the human body. They recognise and bind to specific molecules, such as hormones, the act of which results in a specific signal being transmitted into the cell. This signal alters the function of the cell and so it is critical that it is appropriate, both in type and duration. G-protein coupled receptors and the molecules that activate them provide an essential function within the human body for communicating between cells, and consequently between organs. They are a major mechanism by which nerve signals are transmitted and hormones regulate bodily functions. They are therefore an important target for pharmaceuticals, with up to 50% of ethical drugs and many drugs of abuse acting upon them. It is critical to understand how these receptors alter cellular function once they receive an appropriate signal, but it is also essential to know how such responses are switched off. Arrestins are proteins within cells that interact with G-protein coupled receptors to 'arrest' their signalling. They desensitise the cell to continuous stimulation, but also act to resensitise the cell to respond to future, separate signals. Recently, they have also been shown to provide alternative mechanisms of altering cellular activity by interacting with other cellular proteins. These interactions greatly increase the potential ways in which a cell can respond once a G-protein coupled receptor is activated. Understanding the resulting complexity is essential if we are to fully exploit the vast therapeutic potential of this important receptor family.Read moreRead less
ATR-X Syndrome: Role Of ATRX In Testicular Growth And Spermatogenesis
Funder
National Health and Medical Research Council
Funding Amount
$650,881.00
Summary
Infertility is surprisingly common and affects 1 in 20 Australian men. Testosterone and its receptor, the androgen receptor, are well known to be essential for spermatogenesis and fertility. We have identified an important regulator protein (ATRX) of androgen receptor activity and show that loss of function of ATRX in testes of mice leads to spermatogenesis defects. Identifying the molecular action of ATRX will lead to a better understanding of the underlying causes of infertility in men.
Investigation Of Pancreatic Insulin-secreting Cell Function And Survival
Funder
National Health and Medical Research Council
Funding Amount
$375,750.00
Summary
Diabetes remains a major health problem in Australia. Both type 1 and type 2 diabetes is eventually due to pancreatic insulin-producing beta-cell destruction, which is caused mainly by the cell death, so called 'apoptosis' or programmed suicide of the cells. Thus, attempting to protect beta-cells against death and rescue their insulin secretory function is emerging as a strategy for the treatment of diabetes. However, how the beta-cells undergo death and how to protect the cell death are still n ....Diabetes remains a major health problem in Australia. Both type 1 and type 2 diabetes is eventually due to pancreatic insulin-producing beta-cell destruction, which is caused mainly by the cell death, so called 'apoptosis' or programmed suicide of the cells. Thus, attempting to protect beta-cells against death and rescue their insulin secretory function is emerging as a strategy for the treatment of diabetes. However, how the beta-cells undergo death and how to protect the cell death are still not completely understood. We have recently discovered a new protein, named sphingosine kinase, that is a strong protector against cell death. We also found that this enzyme is involved in process of insulin secretion. Thus, this application seeks to establish a dual role of this enzyme in protecting beta-cells from death and promoting insulin secretion by the cells. This will ultimately allow us to create new therapeutic strategy to target this protein for the management of diabetes.Read moreRead less