TRANSCRIPTIONAL AND FUNCTIONAL CONSEQUENCES OF STAT3 ACTIVATION IN THE HEART
Funder
National Health and Medical Research Council
Funding Amount
$413,694.00
Summary
Recent statistics show that the disease known commonly as heart failure accounts for about 3000 deaths each year in Australia. Worldwide, a staggering 10 million people are thought to currently suffer from heart failure, with this number continuing to rise despite decreasing numbers of people suffering from other forms of heart and blood vessel disease. What causes a healthy heart to fail remains unclear, although in some circumstances failure is known to be initiated by genetic factors, viral f ....Recent statistics show that the disease known commonly as heart failure accounts for about 3000 deaths each year in Australia. Worldwide, a staggering 10 million people are thought to currently suffer from heart failure, with this number continuing to rise despite decreasing numbers of people suffering from other forms of heart and blood vessel disease. What causes a healthy heart to fail remains unclear, although in some circumstances failure is known to be initiated by genetic factors, viral factors, alcoholism, high blood pressure, or when the heart is damaged in a heart attack. We are interested in the molecular mechanisms that underlie the progression of the normal heart to failure. In 2003 we reported on altered signalling pathways in the failing human heart, and noted the increased phosphorylation of a spliceform of the transcription factor STAT3 in patients with heart failure. In this project, we will evaluate a larger group of heart failure patients for changes in phosphorylation of their STAT3 proteins. We will also increase the expression of an activated form of the STAT3 proteins in rat heart cells, and check whether there are accompanying changes in gene expression profiles that indicate a potential role in heart failure, or whether these cells are now predisposed to die. This will be extended with the use of transgenic animals (mice) engineered to overexpress activated STAT3 proteins. Again, we will focus on gene expression profiles. We will also evaluate whether the hearts of these animals are more likely to fail, either as the animals age, or when external stresses are experienced. With this information, we will be able to state whether STAT3 is a contributor to heart failure, and therefore whether it is an attractive target for future therapies aimed at reducing the morbidity and mortality of heart failure worldwide.Read moreRead less
Enhancing The Cardioprotective Effect Of Diadenosine Tetraphosphate: Designing Inhibitors Against Ap4A Hydrolase
Funder
National Health and Medical Research Council
Funding Amount
$442,500.00
Summary
Ischemia describes the condition where blood flow in the blood vessels of the heart is decreased or blocked, preventing delivery of oxygen and nutrients to the heart. Ischemic preconditioning is a phenomenon where short bursts of ischemia, followed by reperfusion, actually protect the heart from a subsequent longer period of ischemia. The biochemical signalling events involved in preconditioning are complex and incompletely defined, but most likely involve multiple pathways, although the mitocho ....Ischemia describes the condition where blood flow in the blood vessels of the heart is decreased or blocked, preventing delivery of oxygen and nutrients to the heart. Ischemic preconditioning is a phenomenon where short bursts of ischemia, followed by reperfusion, actually protect the heart from a subsequent longer period of ischemia. The biochemical signalling events involved in preconditioning are complex and incompletely defined, but most likely involve multiple pathways, although the mitochondrial ATP-dependent potassium channel may be in common with most pathways. Pretreatment with the compound diadenosine tetraphosphate (Ap4A) mimics ischemic preconditioning with noticeable reductions in tissue necrosis (cell death). This treatment has been shown in experimental work to protect the heart during periods of stress such as in heart surgery or recovery from an ischemic event. The biological site of action by Ap4A may be the mitochondria ATP-dependent potassium channel or an associated protein. Ap4A can be degraded by enzymes located inside and on the outside of heart cells, notably by two forms of Ap4A hydrolase. We will use antibody assays to understand the specific localization and amount of Ap4A hydrolase before and after ischemia and after ischemic preconditioning in human heart muscle and blood vessels. We propose to determine the structure of the enzyme and use novel computer methods to screen databases for potential inhibitors. These inhibitors of Ap4A hydrolase activity could aid the design of a potent inhibitor that would prevent Ap4A hydrolase from degrading Ap4A and therefore enhance the cardioprotective properties of Ap4A as well as minimizing side effects from the break down of Ap4A. We will also use these inhibitors and other known non-degradable Ap4A analogues in bioassays to test the relative significance of Ap4A hydrolase present in different cellular locations.Read moreRead less
Substrate Mapping And Ablation Of Ventricular Tachycardia
Funder
National Health and Medical Research Council
Funding Amount
$444,129.00
Summary
Sudden death is a tragic occurrence and can afflict Australians of all ages, racial and ethnic backgrounds. This research will aim to understand abnormalities in the heart muscle that cause dangerous heart rhythm abnormalities, which is the most common cause of sudden death. We will study ways to improve the technology of keyhole cardiac procedures so that it can be used to prevent these arrhythmias from occurring in the first place, and in improving the chance of long-term successful cure.
Heartbeats are considered to arise through specialised pacemaker cells establishing rhythmically generated (i.e. pacemaker) action potentials, which then trigger propagating action potentials in heart muscle causing contraction and pumping of blood. This research proposal aims to challenge the physical model that is used to describe this pacemaker process and resultant heart conduction. Our reasons for doing this derive from our discovery of an alternative pacemaker-conduction mechanism, which w ....Heartbeats are considered to arise through specialised pacemaker cells establishing rhythmically generated (i.e. pacemaker) action potentials, which then trigger propagating action potentials in heart muscle causing contraction and pumping of blood. This research proposal aims to challenge the physical model that is used to describe this pacemaker process and resultant heart conduction. Our reasons for doing this derive from our discovery of an alternative pacemaker-conduction mechanism, which we have shown to operate in various smooth muscles. This mechanism, termed store-based pacemaking, is entirely different to the currently held cardiac model but could readily achieve the same outcome. We will investigate the hypotheses that this pacemaker mechanism is also fundamental to mammalian heart pacemaking and conduction. Positive support for our hypotheses, as indicated by our findings on amphibian hearts and from pilot findings, may severely challenge the present model for cardiac pacemaking. Such an outcome will have major ramifications on present interpretation of cardiac function in health and disease and will be particularly important to interpretation of disorders associated with cardiac arrhythmias and heart conduction.Read moreRead less
Atrial fibrillation (AF) is the most common cause for an irregular heart beat. Catheter ablation is the only potential cure and involves passing wires via veins in the leg into the heart to deliver discrete small burns(ablation) around the pulmonary veins (PV), the major source for AF. Unfortunately 30-50% of patients have recurrent arrhythmia due to reestablishment of electrical connections. This multicentre internation trial examines whether more (maximal) ablation will improve the outcomes of ....Atrial fibrillation (AF) is the most common cause for an irregular heart beat. Catheter ablation is the only potential cure and involves passing wires via veins in the leg into the heart to deliver discrete small burns(ablation) around the pulmonary veins (PV), the major source for AF. Unfortunately 30-50% of patients have recurrent arrhythmia due to reestablishment of electrical connections. This multicentre internation trial examines whether more (maximal) ablation will improve the outcomes of the procedure.Read moreRead less
Regulation Of RyR2 Channels By Calmodulin In Healthy And Diseased Hearts
Funder
National Health and Medical Research Council
Funding Amount
$614,421.00
Summary
In the heart, RyR2 is responsible for intracellular Ca2+ release. The RyR2 is comprised of a Ca2+ channel and accessory proteins such as CaM that regulate channel activity. Evidence suggests that RyR2 regulation by CaM is altered in heart failure and human arrhythmia syndromes, but there has been no direct evidence for this. We will provide this direct evidence plus determine how CaM regulates RyR2 channels and intracellular Ca2+ release and how this leads to cardiac arrhythmias.
Ryanodine Receptor Inhibitors As Therapy For Ca2+ Store Overload Induced Arrhythmias
Funder
National Health and Medical Research Council
Funding Amount
$555,892.00
Summary
This study investigates a new therapeutic action recently discovered for flecainide, an antiarrhythmic agent that we find to completely prevent and inherited form of stress-induced arrhythmias called CPVT. The findings will provide the first detailed mechanistic understanding of an antiarrhythmic drug, findings that will also give a new direction for drug design to control common arrhythmias such as occur in diseases such as coronary artery disease.
Type 2 diabetes is the most common endocrine disease in the world and up to 60% of diabetic patients have heart disease. Heart disease is the most expensive heath condition and biggest cause of death in Australia. Diabetic patients often accumulate fat (triglyceride) within their heart cells, leading to diabetic heart disease. The present study sought to determine if diabetic patients with increased fat within their heart cells have more scarring which eventually results heart muscle dysfunction ....Type 2 diabetes is the most common endocrine disease in the world and up to 60% of diabetic patients have heart disease. Heart disease is the most expensive heath condition and biggest cause of death in Australia. Diabetic patients often accumulate fat (triglyceride) within their heart cells, leading to diabetic heart disease. The present study sought to determine if diabetic patients with increased fat within their heart cells have more scarring which eventually results heart muscle dysfunction.Read moreRead less
Atrial Fibrillation And Hypertension: Reverse Cardiac Remodelling Post Renal Denervation
Funder
National Health and Medical Research Council
Funding Amount
$90,144.00
Summary
Patients with hypertension are at increased risk of heart rhythm disorders, yet little is known if treatment of high blood pressure will improve abnormal rhythm. Renal denervation is a new and effective treatment for severe hypertension; this study will assess the adverse changes in heart structure and function due to severe hypertension, and investigate whether renal denervation can ameliorate these changes on a structural and electrical level.
Genetic Predisposition To Abnormal Atrial Substrate In Atrial Fibrillation (GENE-AF Study)
Funder
National Health and Medical Research Council
Funding Amount
$100,531.00
Summary
Atrial fibrillation (AF) is the most common heart rhythm disorder worldwide and its incidence is growing. Our world-first research aims to demonstrate that individuals who carry specific genetic variants are more likely to develop abnormal electrical and structural changes in the heart, which predispose to AF. In doing so, we intend to find the link between genetics and AF, paving the way for research into novel targeted therapies to better manage this complex and difficult to treat disease.