Our bodies generate a hormone called angiotensin II in response to a decrease in blood pressure (or salt in our bloodstream). This hormone increases blood pressure by causing blood vessels to constrict, by making us thirsty, and by inducing salt and fluid retention via an effect on the kidneys. In some cardiovascular diseases, the generation of angiotensin II or our sensitivity to this hormone is elevated. It is therefore crucial that we understand how angiotensin II works and how its actions in ....Our bodies generate a hormone called angiotensin II in response to a decrease in blood pressure (or salt in our bloodstream). This hormone increases blood pressure by causing blood vessels to constrict, by making us thirsty, and by inducing salt and fluid retention via an effect on the kidneys. In some cardiovascular diseases, the generation of angiotensin II or our sensitivity to this hormone is elevated. It is therefore crucial that we understand how angiotensin II works and how its actions in the body are mediated. For angiotensin II to act it must first bind to a receptor. Receptors are proteins and behave like locks that are opened by the hormone keys. Thus, cellular receptors for angiotensin II are engaged and activated by increases in angiotensin II in our blood. These receptors then produce signals which initiate a response (e.g. constriction of a blood vessel). Subsequently, the receptors are switched-off to prevent over-stimulation. The experiments proposed in this application continue our investigations into how angiotensin II receptors are regulated or switched-on and -off. A major way for receptors to be turned off is for them to be ear-marked by a modification known as phosphorylation. These modified receptors are then bound by proteins termed arrestins, which as indicated by their name play a role in preventing further receptor signalling. These arrestins also help remove activated receptors from the cell surface to the inside of the cell. How arrestins interact with receptors and regulate their function is poorly understood. This application proposes experiments to investigate the molecular mechanisms of arrestin action as it relates to the angiotensin II receptor. Results from these studies will further our understanding of angiotensin II receptors and their role in cardiovascular control.Read moreRead less
Novel G-protein Coupled Receptors LGR7 And LGR8; The Receptors For Relaxin And Insulin-like Peptide 3 (INSL3)
Funder
National Health and Medical Research Council
Funding Amount
$496,500.00
Summary
Relaxin is a hormone which has long been known to have essential roles in pregnancy and birth. However it has also been demonstrated to have far broader involvement in the functioning of the kidney, heart and central nervous system. Furthermore, mice lacking relaxin show increased collagen, or fibrosis, in their internal organs and skin as they age. This progressive fibrosis leads to problems with bodily functions. Treatment of these mice with relaxin reverses the fibrosis and restores function, ....Relaxin is a hormone which has long been known to have essential roles in pregnancy and birth. However it has also been demonstrated to have far broader involvement in the functioning of the kidney, heart and central nervous system. Furthermore, mice lacking relaxin show increased collagen, or fibrosis, in their internal organs and skin as they age. This progressive fibrosis leads to problems with bodily functions. Treatment of these mice with relaxin reverses the fibrosis and restores function, hence relaxin has great potential as a treatment for fibrotic diseases. Anti-fibrotic drugs are a major target for drug companies as suitable compounds are not currently available. Research into the mechanisms whereby relaxin exerts its cellular effects has been limited by the inability of researchers to identify its receptor. We now know that relaxin acts through a novel G-protein coupled receptor (GPCR) LGR7 and will also act on a related receptor LGR8. The LGR8 receptor is actually the receptor for a hormone with similarities to relaxin, INSL3. It is essential that an appreciation of relaxin receptor function is obtained not only for its important actions in pregnancy, but also for its clinical applications. In this regard, improved understanding of how relaxin interacts with these two receptors is essential. We will use our expertise in producing these hormones together with molecular techniques to produce the receptor, to study the interaction of relaxin and INSL3 with these receptors and the subsequent cellular events that occur. Furthermore, to more effectively use relaxin as a drug, we need to discover a smaller, more potent and orally active form of the hormone. We will develop novel technologies to aid in the discovery of the next generation of relaxin drugs. This multi-disciplinary approach will allow us to fully maximise the clinical potential of this enigmatic hormone.Read moreRead less
Molecular Attributes And Physiological Significance Of Beta1L-adrenoceptors
Funder
National Health and Medical Research Council
Funding Amount
$754,353.00
Summary
Beta-blockers are used for the management of cardiovascular diseases including heart failure. We have discovered that one group of beta-blockers not only blocks the receptor but stimulates it. To explain this we hypothesize that human beta-adrenoceptors exist in two different 'states' , high and low. We are now determining whether 1. the low state causes progression of heart failure, 2. the molecular basis of the two states and 3. we can make new compounds to block the low state.
Allosteric Modulation Of GPCR-mediated Intracellular Signalling In Human Embryonic Stem Cell Derived Cardiomyocytes.
Funder
National Health and Medical Research Council
Funding Amount
$324,598.00
Summary
Adenosine and muscarinic receptors are cell-surface proteins that represent promising targets for a number of conditions. However, the mechanisms linking the activation of these receptors to cellular responsiveness have not been thoroughly investigated in cells of human origin. This study will use novel cutting-edge methods to measure the effects of different classes of drugs on receptor-mediated intracellular signalling in embryonic stem cell derived human cardiac cells.
Understanding The Pharmacoregulation Of The Extracellular Calcium Sensing Receptor.
Funder
National Health and Medical Research Council
Funding Amount
$744,943.00
Summary
Calcium sensing receptors (CaSR) are important regulators of hormone release and modulators of kidney transport, digestion-absorption-satiety and bone mass. In each case, CaSRs adopt a characteristically distinct activating mechanism that we will unravel in detail sufficient for the development of novel chemotherapies e.g., for osteoporosis and obesity. We also anticipate early application of CaSR-based therapies to clinically significant genetic disorders e.g., neonatal hyperparathyroidism.
The Role Of Cellular Microdomains In G-protein Coupled Receptor Signalling.
Funder
National Health and Medical Research Council
Funding Amount
$385,297.00
Summary
Molecules communicate with cells by attaching to proteins called receptors on the outside of cells, and triggering a series of events inside the cell. These events initially include the assembly of multiple proteins at the cell surface. This project will examine the formation of receptors and other proteins into these ‘communication complexes’. This will provide novel targets for more selective drug development.
Novel Functional Domains On Adrenoceptors For Drug Interaction And Cell Signalling
Funder
National Health and Medical Research Council
Funding Amount
$801,500.00
Summary
Our work involves studying cell-surface proteins (receptors) that respond to hormones such as adrenaline or substances that transmit signals in the nervous system (neurotransmitters). These receptors play a vital role in orchestrating responses to stimuli such as stress, pain, changes in blood pressure, body temperature, fluid and energy status, and exercise. They allow communication between different organs or different parts of the nervous system. G-protein coupled receptors (GPCRs) are the ma ....Our work involves studying cell-surface proteins (receptors) that respond to hormones such as adrenaline or substances that transmit signals in the nervous system (neurotransmitters). These receptors play a vital role in orchestrating responses to stimuli such as stress, pain, changes in blood pressure, body temperature, fluid and energy status, and exercise. They allow communication between different organs or different parts of the nervous system. G-protein coupled receptors (GPCRs) are the major group of cell surface receptors that interact with hormones and neurotransmitters. Treatment of many diseases and conditions relies on the use of drugs that selectively activate or block a single type of GPCR. In fact, about 2-3 of existing therapies are based on these drugs. In designing new drugs it is important to understand as much as possible about the properties of the target receptors. There is emerging evidence concerning interactions between drugs, receptors and proteins inside cells that translate signals into responses (signalling proteins). For example, receptors have additional sites of drug action that can modulate their activity, and can also couple to multiple signalling pathways. We are studying adrenoceptors that respond to adrenaline and to the neurotransmitter noradrenaline. Our studies will use adrenoceptors as model systems to identify novel potential sites for drug interaction, to gain new insights into signalling mechanisms utilized by these receptors and to examine how a variety of phosphorylation mechanisms affect the ability of receptors to couple to particular signalling pathways.Read moreRead less