Structure-function And Domain Minimization Of Insulin-like Peptide 3, A Novel Member Of The Insulin Superfamily.
Funder
National Health and Medical Research Council
Funding Amount
$288,000.00
Summary
Insulin-like peptide 3 (INSL3) is a peptide hormone that is structurally similar to insulin. It is produced in both the testes and the ovaries. In the male, one of its primary roles is to initiate testes descent during fetal development via a direct action on the gubernaculum ligament. Failure of INSL3 action either directly or due to receptor malfunction causes cryptorchidism (undescended testes), one of the most common congenital defects. In the female, INSL3 is implicated in follicle selectio ....Insulin-like peptide 3 (INSL3) is a peptide hormone that is structurally similar to insulin. It is produced in both the testes and the ovaries. In the male, one of its primary roles is to initiate testes descent during fetal development via a direct action on the gubernaculum ligament. Failure of INSL3 action either directly or due to receptor malfunction causes cryptorchidism (undescended testes), one of the most common congenital defects. In the female, INSL3 is implicated in follicle selection. More recent evidence shows that the peptide has clear roles in modulating male and female germ cell maturation. These effects indicate that agonists and antagonists of INSL3 have potential as specific drugs for novel contraceptive approaches or infertility treatments in both sexes. The actions of INSL3 are mediated by interaction with a G-protein coupled receptor known as LGR8. This receptor is expressed in the testes and ovary as well as several other tissues including the brain. However, very little is known about how INSL3 interacts with LGR8 to produce its physiological responses. Consequently, we will determine the structural features of the peptide that are responsible for receptor binding. This will be achieved by use of chemical peptide synthesis of not only INSL3 but also of analogues of the peptide that contain modified residues or domains. These will be assayed for characteristic INSL3 activity and the results, together with those acquired by modern biomolecular interaction analyses, will be used to identify the receptor binding regions for INSL3. This information, together with a determination of the three-dimensional structure of INSL3 by using NMR spectroscopy, will then be disseminated using computer-assisted molecular modelling to design smaller, more stable, orally active analogues. Such mimetics of reduced size that are correspondingly cheaper and simpler to prepare and handle will have great potential for therapeutic regulators of human fertility.Read moreRead less
Elucidation Of The Molecular Requirements Of The Low Affinity 'state' Of The Beta1-adrenoceptor
Funder
National Health and Medical Research Council
Funding Amount
$535,500.00
Summary
Beta-blockers are used for the management of cardiovascular diseases including heart failure, ischaemic heart disease and high blood pressure. Beta-blockers mostly work by blocking the effects of a naturally occuring chemical called noradrenaline. Beta-blockers can be used to prevent noradrenaline induced increases in the rate and force of human heart contraction. We have discovered that one group of beta-blockers exemplified by CGP 12177 has the remarkable property of not only being able to blo ....Beta-blockers are used for the management of cardiovascular diseases including heart failure, ischaemic heart disease and high blood pressure. Beta-blockers mostly work by blocking the effects of a naturally occuring chemical called noradrenaline. Beta-blockers can be used to prevent noradrenaline induced increases in the rate and force of human heart contraction. We have discovered that one group of beta-blockers exemplified by CGP 12177 has the remarkable property of not only being able to block beta-receptors but they can also stimulate them at higher concentrations. Thus low concentrations block the effects of noradrenaline, but higher concentrations stimulate the receptor. More puzzling is that the stimulant effects of this group of beta-blockers cannot be easily blocked. To explain this we hypothesize that human beta-receptors can exist in two different 'states'. One 'state' can be stimulated by noradrenaline and blocked by low concentrations of beta-blockers such as propranolol and CGP 12177. Another 'state' of the same receptor is resistant to blockade by beta-blockers such as propranolol but can be stimulated by beta-blockers such as CGP 12177. This project seeks to investigate the molecular basis of the beta-adrenoceptor that is responsible for stimulant effects of beta-blockers. Specifically it explores the components of the beta-adrenoceptor that are critically and uniquely important for interacting with the stimulant beta-blockers. This project is an important increment in our laboratories research program to increase our understanding of the effects of beta-blockers. Our long term goal is to be able to develop beta-blockers that can block both states of the beta-adrenoceptor to provide a more effective block of the receptor and in particular for the improved management of heart failure.Read moreRead less
Understanding Cell Signalling Mechanisms Activated By Relaxin Family Peptides: Targets With Therapeutic Potential
Funder
National Health and Medical Research Council
Funding Amount
$306,842.00
Summary
One of the most powerful ways that the activity of the cells that make up the tissues and organs of the body can be changed is by the interaction of chemicals with proteins called receptors located at the cell surface. The commonest type of receptor is called a G-protein coupled receptor as it is linked to mechanisms inside the cell by the G-proteins. These receptors are the most commonly targeted by pharmaceutical companies that wish to alter the responses of cells for therapeutic purposes and ....One of the most powerful ways that the activity of the cells that make up the tissues and organs of the body can be changed is by the interaction of chemicals with proteins called receptors located at the cell surface. The commonest type of receptor is called a G-protein coupled receptor as it is linked to mechanisms inside the cell by the G-proteins. These receptors are the most commonly targeted by pharmaceutical companies that wish to alter the responses of cells for therapeutic purposes and almost 2-3 of all drugs currently marketed work through these proteins. This project will examine the mechanisms whereby certain types of G-protein coupled receptor produce signals in cells and determine what are the critical areas of the receptor for these interactions. The receptors involved have been discovered only in the last 4 years and little is known of the ways these change the activity of cells. The substances acting on these receptors have potential for development as targets for drugs that have the potential to treat fibrosis which is a feature of many diseases including cardiac failure, kidney failure and lung disease.Read moreRead less
Chronic pain affects 1 in 5 Australians and neuropathic pain is among the most severe forms of chronic pain. Several peptides derived from cone snail venoms have attracted recent attention as potential therapeutic agents for the treatment of neuropathic pain. One of these, conotoxin MVIIA, has recently been approved in the US and Europe and others, including CVID and ACVI, are in various stages of clinical investigation. These small disulfide rich peptides share the attractive features of peptid ....Chronic pain affects 1 in 5 Australians and neuropathic pain is among the most severe forms of chronic pain. Several peptides derived from cone snail venoms have attracted recent attention as potential therapeutic agents for the treatment of neuropathic pain. One of these, conotoxin MVIIA, has recently been approved in the US and Europe and others, including CVID and ACVI, are in various stages of clinical investigation. These small disulfide rich peptides share the attractive features of peptides in general of having exquisite selectivity for particular receptors, but also share the general disadvantages of peptides of short biological half-lives and poor bioavailablility. Stabilisation of these conotoxins has the potential to substantially increase their therapeutic potential. In preliminary studies we have shown that by introducing a circular petide backbone into a conotoxin using a linker sequence we can increase its stability and resistance to enzymatic degradation. We therefore propose that it will be possible to cyclise a wide range of conotoxin molecules and thereby improve their drug like properties. In this project we will use our cyclisation approach to develop new potential treatments for pain from two classes of conotoxins. One of the lead molecules shows oral bioavailability in an animal pain model and potentially represents a major breakthrough in the field of peptide drug delivery.Read moreRead less
Determinants Of Binding And Activity Of G-protein Coupled Receptors RXFP1 And RXFP2; The Receptors For Relaxin And INSL3
Funder
National Health and Medical Research Council
Funding Amount
$531,696.00
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. It is currently in clinical trials with our commercial partner BAS Medical for the treatment of congestive heart failure, cervical ripening and preeclampsia. Furthermore, relaxin shows enormous promise as an antifibrotic agent which has far-reaching therapeutic conse ....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. It is currently in clinical trials with our commercial partner BAS Medical for the treatment of congestive heart failure, cervical ripening and preeclampsia. Furthermore, relaxin shows enormous promise as an antifibrotic agent which has far-reaching therapeutic consequences since fibrosis is a hallmark of all forms of progressive cardiovascular and renal disease and obstructive airway disease (asthma), which collectively contribute to 40-50% of deaths in developed countries. 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) Relaxin Family Peptide Receptor (RXFP) RXFP1 and will also acts on a related receptor RXFP2. The RXFP2 receptor is actually the receptor for a hormone with similarities to relaxin, INSL3. It is essential that an appreciation of RXFP 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 and INSL3 interact with their receptors and how these receptors function is essential. We will continue our previously successful approaches to study the interaction of relaxin and INSL3 with these receptors and the mechanisms by which the receptors function. The knowledge gained will aid in the design of smaller, more potent and orally active forms of relaxin and INSL3 for future clinical applications. This multi-disciplinary approach will allow us to fully maximise the clinical potential of this enigmatic hormone.Read moreRead less
Helix VIII Of G Protein Coupled Receptors Is A Lipid-activated Signalling Sensor
Funder
National Health and Medical Research Council
Funding Amount
$389,250.00
Summary
G protein-coupled receptors (GPCRs) are the largest superfamily of membrane-embedded receptors and represent prime targets for drug development. The molecular basis for their activation and regulation is poorly understood, particularly the contribution of the membrane environment to receptor function. Using a range of molecular and biophysical approaches and the angiotensin receptor as a model GPCR, studies are proposed to understand the role of the cell membrane in GPCR activation. The results ....G protein-coupled receptors (GPCRs) are the largest superfamily of membrane-embedded receptors and represent prime targets for drug development. The molecular basis for their activation and regulation is poorly understood, particularly the contribution of the membrane environment to receptor function. Using a range of molecular and biophysical approaches and the angiotensin receptor as a model GPCR, studies are proposed to understand the role of the cell membrane in GPCR activation. The results will provide important new information on the molecular mechanism of GPCR regulation and exciting new approaches for drug design.Read moreRead less