Steroid hormones, such as estrogen and androgens, act in the body by locking onto a family of proteins (nuclear receptors) that bind directly to the DNA to regulate genes. The mechanisms underlying this process are complex and involve recruitment of additional molecules or coactivators to improve efficiency. Recently a novel coactivator was identified, termed SRA, which exerts its effects as an RNA, rather than as a protein. SRA is aberrantly expressed in breast cancer, raising the possibility t ....Steroid hormones, such as estrogen and androgens, act in the body by locking onto a family of proteins (nuclear receptors) that bind directly to the DNA to regulate genes. The mechanisms underlying this process are complex and involve recruitment of additional molecules or coactivators to improve efficiency. Recently a novel coactivator was identified, termed SRA, which exerts its effects as an RNA, rather than as a protein. SRA is aberrantly expressed in breast cancer, raising the possibility that it plays an important role in breast cancer cell proliferation. To better understand how estrogen signals in breast cancer and identify proteins that bind to SRA in cancer cells, we established a collaboration with the O'Malley group at Baylor College of Medicine in Texas (who discovered SRA). We have identified several novel SRA-binding proteins, each of which plays an important role to regulate estrogen and androgen action. Up to this point, we have used a model that has enabled proof of principle studies in the same cancer cells from which SRA was discovered (non-breast or prostate cancer). However, we now need to carefully study the role of these proteins in cancer cells relevant to breast and prostate cancer. Thus, we plan to investigate how these proteins interact with SRA, how they influence nuclear receptor activity and breast and prostate cancer cell proliferation, examine their role in activating other pathways of cell growth in cancer cells, assay the levels of each protein in a series of human breast cancer specimens and solve the physcial 3-D structure of these proteins complexed to the SRA RNA. This work will provide novel insight into several key areas of hormone action in breast and prostate cancer. We hope to identify new markers that can be used for improved diagnosis and for prognosis, and provide structural information for the development of novel therapeutics.Read moreRead less
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
Determinants Of Tissue- And Ligand-Specific Responses At The Mineralocorticoid Receptor
Funder
National Health and Medical Research Council
Funding Amount
$668,485.00
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.