Coronary artery disease is the largest single cause of death in Australia, and commonly manifests as heart attack and angina. Congenital heart disease is the most common birth defect. We have identified a gene, Crim1, that is important for heart and coronary artery development. Investigating how this gene functions will lead to a greater understanding of congenital heart disease and may lay the foundation for therapeutics to regenerate damaged hear tissue.
Role Of Homeobox Gene Nkx2-5 In Heart Development And Congenital Heart Disease
Funder
National Health and Medical Research Council
Funding Amount
$143,250.00
Summary
Congenital abnormalities of the heart occur in ~1 in 100 live births and 1 in 10 still births in Western populations. The genetic pathways underlying cardiac development are now being dissected with increasing vigour in an effort to understand both the morphological progressions and genetic basis of heart defects. Mutations in a cardiac gene called Nkx2-5, which encodes a transcriptional regulatory protein, can cause heart defects in human families and isolated individuals, most predominantly at ....Congenital abnormalities of the heart occur in ~1 in 100 live births and 1 in 10 still births in Western populations. The genetic pathways underlying cardiac development are now being dissected with increasing vigour in an effort to understand both the morphological progressions and genetic basis of heart defects. Mutations in a cardiac gene called Nkx2-5, which encodes a transcriptional regulatory protein, can cause heart defects in human families and isolated individuals, most predominantly atrial septal defect (hole in the heart) associated with an abnormality in electrical activity of the heart. Nkx2-5 is expressed in the precursor cells of the muscle and other lineages that make up the heart in the embryo, then in the muscle layer of the heart throughout foetal and adult life. Mouse hearts that lack the Nkx2-5 gene altogether arrest at an early stage of heart development showing a complete block to ventricular chamber formation. Mice lacking only one copy of the Nkx2-5 gene have ASD and electrical defects, similar to the human disease. Building on these findings we have developed a suite of new genetic reagents with which to gain a deeper understanding of the role of Nkx-5 in development and disease. These include a mouse strain from which Nkx2-5-positive muscle cells can be purified away from other cell types in the heart, and another mouse strain that represents a good model for common congenital heart defects. We will further investigate the role of Nkx2-5 in allocation of cell types in the heart, chamber formation and birth defects using these reagents.Read moreRead less
Role Of Homeobox Gene Nkx2-5 In Heart Development And Congenital Heart Disease
Funder
National Health and Medical Research Council
Funding Amount
$227,340.00
Summary
This project seeks to define the developmental principles underlying chamber formation in the developing heart and how this becomes abnormal in inherited heart defects. The gene we study, Nkx2-5, encodes a protein which binds to DNA and regulates the expression of the genetic program for formation of the ventricles, the pumping chambers of the heart. We believe that Nkx2-5 is an Oexecutive regulator? of this program, controlling the timing and spatial expression of other regulators that then con ....This project seeks to define the developmental principles underlying chamber formation in the developing heart and how this becomes abnormal in inherited heart defects. The gene we study, Nkx2-5, encodes a protein which binds to DNA and regulates the expression of the genetic program for formation of the ventricles, the pumping chambers of the heart. We believe that Nkx2-5 is an Oexecutive regulator? of this program, controlling the timing and spatial expression of other regulators that then control expression of a host of genes required for muscle differentiation and the development of form (morphogenesis). Mutations in one copy of the human Nkx2-5 gene have recently been discovered to be associated with atrial septal defect, or Ohole in the heartO, a sometimes serious inherited defect in heart structure. Mouse embryos with a mutation in both copies of the gene have a much more serious defect in ventricle formation that is incompatible with life. The studies are designed to extend our understanding of the genetic regulation of chamber formation in the heart. We will firstly make a mouse model of the human disease using gene targeting technology, which allows us to make precise alteration in single genes in this animal. Secondly, we will apply new technology to the heart that will let us visualise molecular and cellular events at higher resolution. This technology, which uses fluorescent tags on cells and a laser to measure cell identity, has been used to great affect in the field of immunology, but can be adapted to the heart. We will use it to isolate and characterise the precious early cells that give rise to the heart in the embryo. It is in these cells that the human and mouse mutations have their first effects. Our studies have relevance to understanding and screening for human inherited heart abnormalities, and for understanding the general principles of heart formation that may reveal valuable ways to intervene in heart disease.Read moreRead less
Role Of The T-box Transcription Factors, Tbx5 And Tbx20, In Cardiac Development And Congenital Heart Disease
Funder
National Health and Medical Research Council
Funding Amount
$345,000.00
Summary
Structural defects in the heart are present in approximately 1 in 100 live births, and 1 in 10 still births in developed countries. Some 8% of deaths in the first year of life are caused by such abnormalities. While some defects can be repaired in childhood many go undetected and compound in later years leading to sudden death or compromised quality of life. Virtually all inherited heart defects for which the underlying genetic alteration is known are caused by mutations in genes controlling dev ....Structural defects in the heart are present in approximately 1 in 100 live births, and 1 in 10 still births in developed countries. Some 8% of deaths in the first year of life are caused by such abnormalities. While some defects can be repaired in childhood many go undetected and compound in later years leading to sudden death or compromised quality of life. Virtually all inherited heart defects for which the underlying genetic alteration is known are caused by mutations in genes controlling development of the heart in the embryo. Examples are Tbx5, a member of the T-box family of transcription factor genes mutated in Holt Oram syndrome, and Nkx2-5, a homeodomain transcription factor gene mutated in families with hole in the heart and cardiac electrical defects. We propose to investigate the involvement of a new member of the T-box gene family, Tbx20, in cardiac development and disease, and to compare and contrast its function with that of Tbx5. The Tbx5 and Tbx20 proteins interact directly with Nkx2-5 to stimulate transcription of cardiac genes, making Tbx20 a good candidate for involvement in inherited disease. We will use gene targeting technology to delete the Tbx20 gene in mice, and will analyse heart anatomy, gene expression and function to determine the effect of its loss. We will also investigate how Tbx20 interacts with other cardiac regulatory pathways, by crossing Tbx20 mutant mice with mice deficient for Nkx2-5 and Tbx5, strains that show heart abnormalities similar to those found in human patients. Microarray technology, which examines gene expression on a whole genome scale, will also be used to identify genes that are regulated by these transcription factors. Finally, we will search for mutations in the Tbx20 gene in human patients that have inherited heart abnormalities. In doing so we may improve our understanding of disease causation and predisposition thereby identifying patients at risk and providing improved genetic counselling and diagnosis.Read moreRead less
Understanding The Role That Cellular Hypoxia Plays In Normal Heart Development
Funder
National Health and Medical Research Council
Funding Amount
$522,773.00
Summary
Congenital heart defects (CHD) are the most common type of birth defects, being present in 6 out of every 1000 live births, and 10% of stillbirths. In addition to the danger of death during childhood, such heart defects also increase the risk of heart disease during adulthood. Our research project involves looking for the genetic causes of CHD. We are looking at two genes , called HIF1a and CITED2, for which we already have evidence that they are very important in allowing the heart to form norm ....Congenital heart defects (CHD) are the most common type of birth defects, being present in 6 out of every 1000 live births, and 10% of stillbirths. In addition to the danger of death during childhood, such heart defects also increase the risk of heart disease during adulthood. Our research project involves looking for the genetic causes of CHD. We are looking at two genes , called HIF1a and CITED2, for which we already have evidence that they are very important in allowing the heart to form normally within the embryo. Because the heart is the first organ to form in the embryo (during the first trimester), we cannot use humans to study this process. Instead we have two lines of mice which specifically lack either the HIF1a or CITED2 genes throughout the embryo. Both of these mouse lines have severe heart defects similar to some types of CHD seen in humans. However, removal of either of these genes also causes severe defects in other tissues, complicating our study. To overcome this problem, we will use a slightly different technique to remove either gene specifically in the entire developing heart of the embryo, while leaving the normal gene in the rest of the embryo. Thus we will be able for the first time to study the effects of these genes on the heart alone. We suspect that the defects in the hearts of such embryos will be of a particular sub-type of CHD. If this is true, in the future we hope to be able show that mutation of either of these genes will cause a specific type of human CHD. This will enable genetic screening of families with a history of CHD, assist in genetic counselling, and promote the development of therapies.Read moreRead less
Effects And Mechanisms Of Direct Cardiac Compression In Interruption Of Myocardial Remodelling In Chronic Heart Failure.
Funder
National Health and Medical Research Council
Funding Amount
$392,250.00
Summary
Heart failure (HF) is a disease where the heart pumping function is insufficient to provide adequate blood supply to the rest of the body. It is a highly debilitating disease affecting nearly 10 million people worldwide and has a <50% one-year survival in severe cases. Despite significant advances in pharmacotherapy, heart transplant is the only alternative for severe HF but is restricted by lack of donor organs to only ~ 5% of those requiring it. Research has shown that progression of HF is ....Heart failure (HF) is a disease where the heart pumping function is insufficient to provide adequate blood supply to the rest of the body. It is a highly debilitating disease affecting nearly 10 million people worldwide and has a <50% one-year survival in severe cases. Despite significant advances in pharmacotherapy, heart transplant is the only alternative for severe HF but is restricted by lack of donor organs to only ~ 5% of those requiring it. Research has shown that progression of HF is related to many subsequent changes after an initial insult. In addition to pumping failure, HF is associated with deranged compensatory responses such as neurohumoral over-activation, heart chamber enlargement, loss of functional cells, increase of inflammatory mediators and changes in cardiac skeleton (extracellular matrix). The changes in the heart are collectively known as remodelling. Mechanical heart assist is now considered a potential destination therapy for severe HF, superior to pharmacotherapy alone. Improvement of cardiac pumping function and even successful weaning from devices has been reported, along with observations of reverse remodelling. The success of this approach has been limited however, particularly with HF due to coronary disease, the most prevalent form. We developed a novel HeartPatch mechanical assist device to compress the heart from its outer surface. It gives support to both main chambers and avoids blood contact, a feature of currently available devices associated with complications such as blood clotting and infection. Our device has proved effective in animals with acute HF and even with cardiac arrest. We propose to study the effects of our device on the process of remodelling in HF with coronary disease in a controlled manner. The project will enhance understanding of the mechanisms involved in reverse remodelling and further the development of a device which may potentially benefit many severe HF patients.Read moreRead less
Function Of The S100A1 Ca2+-binding Protein Under Physiological And Pathological Conditions
Funder
National Health and Medical Research Council
Funding Amount
$452,545.00
Summary
The S100A1 protein is one of the most abundant proteins in human heart muscle cells. It binds calcium ions and may play a role in the regulation of heart function. S100A1 levels are reduced in human heart failure, but it is unclear whether this reduction contributes to worsening of the disease. To study this, we have generated a genetically modified mouse strain that cannot make the S100A1 protein. We will use these mice to study how important the protein is for heart function under normal condi ....The S100A1 protein is one of the most abundant proteins in human heart muscle cells. It binds calcium ions and may play a role in the regulation of heart function. S100A1 levels are reduced in human heart failure, but it is unclear whether this reduction contributes to worsening of the disease. To study this, we have generated a genetically modified mouse strain that cannot make the S100A1 protein. We will use these mice to study how important the protein is for heart function under normal conditions, and how it contributes to the development of heart failure. Preliminary data indicate that adult mice with reduced S100A1 protein levels develop a form of heart disease that significantly reduces the efficiency of the pump function of the heart.Read moreRead less
Differences Between Physiological And Pathological Cardiac Hypertrophy Offer New Strategies For Treating Heart Failure
Funder
National Health and Medical Research Council
Funding Amount
$335,473.00
Summary
The heart becomes large both in athletes as well as in patients with heart disease and failure. In the first instance, the large (hypertrophied) heart has normal or even increased pumping ability (function) whereas in the patient with heart disease the function is depressed and the heart may fail. My studies are directed towards finding out what is the difference in these 2 situations and what mechanisms are responsible for making one big heart pump well and the other big heart pump poorly. Spec ....The heart becomes large both in athletes as well as in patients with heart disease and failure. In the first instance, the large (hypertrophied) heart has normal or even increased pumping ability (function) whereas in the patient with heart disease the function is depressed and the heart may fail. My studies are directed towards finding out what is the difference in these 2 situations and what mechanisms are responsible for making one big heart pump well and the other big heart pump poorly. Specifically my project hopes to identify the genes and proteins responsible for the differences. I have already identified one such gene and I now plan to manipulate this gene by overexpressing it in animals (transgenic mice) with heart failure. I predict that overexpression of this gene will improve heart function in models of heart failure. If the hypothesis is correct, activating genes that are activated in the athlete's heart maybe a potential tool for improving heart function, quality of life and life span in patients with heart failure.Read moreRead less
Cardiac-specific Therapy Targeting Hypertrophy And Apoptotis
Funder
National Health and Medical Research Council
Funding Amount
$542,683.00
Summary
We have discovered that certain pathological responses in the heart are mediated by an unusual type of signalling protein. The aim of the proposed studies is to determine whether this unusual signalling mechanism can provide a good target for development of new therapeutic approaches to prevent or treat heart failure.