Epigenetic Silencing Of Retroelements In Mammalian Stem Cells: A Role For RNA Interference?
Funder
National Health and Medical Research Council
Funding Amount
$296,980.00
Summary
Now that the human genome has been sequenced, all the genes which encode the bricks and mortar of our cells have been defined. A major question remains: how are all these genes controlled and co-ordinated? What turns them on or off at precisely the right time? In this project we wish to test whether a newly-discovered mechanism of turning genes off in plants and flies also works in mammals. If we demonstrate this mechanism then it may help us to improve gene therapy - a novel form of medical tre ....Now that the human genome has been sequenced, all the genes which encode the bricks and mortar of our cells have been defined. A major question remains: how are all these genes controlled and co-ordinated? What turns them on or off at precisely the right time? In this project we wish to test whether a newly-discovered mechanism of turning genes off in plants and flies also works in mammals. If we demonstrate this mechanism then it may help us to improve gene therapy - a novel form of medical treatment in which healthy genes are used to replace defective genes in cells. Both inherited diseases, like hemophilia, and acquired diseases, like cancer, have been considered appropriate targets for gene therapies. Surprisingly, however, the promises of gene therapy have not kept up with expectations. In attempting to achieve clinically relevant results, viruses (masters of forcing infected cells to do their bidding) have been harnessed to deliver healthy genes into diseased cells. A major problem has been that the modified, safe viruses used clinically have not been efficient at achieving sustained production of healthy gene products. In examining the question of what turns gene off, we will attack the problem of sustainability of gene therapy by defining the mechanisms involved in switching gene therapy viruses off. If we can understand what switches viral genes off in cells, then we should be able to devise means to avoid the 'off switch' and thereby provide durable treatments for many types of cancer. In the studies described , we will attack this problem using a number of different, but complementary approaches.Read moreRead less
Gene Transcription In Activated T Cells: A Model Of Chromatin Remodeling.
Funder
National Health and Medical Research Council
Funding Amount
$477,500.00
Summary
Cells of the immune system respond to invasion of the body by infectious or other damaging agents by switching on the production of a large array of proteins that are critical for an orchestrated immune response. Some of these proteins, referred to as cytokines, are secreted by the cells and act as intercellular messengers to affect the function of other cells need for an immune response. Switching on the production of these cytokines requires the genes that produce them to interpret the complex ....Cells of the immune system respond to invasion of the body by infectious or other damaging agents by switching on the production of a large array of proteins that are critical for an orchestrated immune response. Some of these proteins, referred to as cytokines, are secreted by the cells and act as intercellular messengers to affect the function of other cells need for an immune response. Switching on the production of these cytokines requires the genes that produce them to interpret the complex signaling pattern to which the cell has been exposed. These complex signaling patterns are interpreted in the nucleus by molecular switches that lie beside the genes in the DNA. The incorrect production of these proteins is involved in immune diseases such as autoimmunity, allergy and leukemia. Genes are housed in the nucleus of the cell, packaged into a structure known as chromatin. When the gene is not producing protein it is tightly packaged in chromatin but when it is activated to produce protein this packaging is altered to allow the gene to see the signals being received by the cell and produce protein. We have identified a protein within the nucleus that is critical in allowing certain cytokine genes to see the signals being received in the nucleus. By investigating the role of this protein (called c-Rel) in chromatin reorganization in immune cells, we hope to better define the steps required for appropriate gene activation in an immune response. This knowledge, in turn, will lead to the identification of novel therapeutic targets to control immune responsesRead moreRead less
Structure-function Analysis Of Nuclear Receptor And Cofactor Action: Evidence For A Role In Muscle.
Funder
National Health and Medical Research Council
Funding Amount
$692,040.00
Summary
Hormone receptors have critical roles in almost all aspects of physiology by transducing the effects of hormones into metabolic responses. There are ~45 orphan hormone receptors encoded by distinct genes in humans, since all receptors are important in the treatment of human disease, the plethora of orphan receptors has been the catalyst for the development of a new paradigm, reverse endocrinology. Reverse endocrinology is the process whereby the orphan hormone receptor is used to search for a pr ....Hormone receptors have critical roles in almost all aspects of physiology by transducing the effects of hormones into metabolic responses. There are ~45 orphan hormone receptors encoded by distinct genes in humans, since all receptors are important in the treatment of human disease, the plethora of orphan receptors has been the catalyst for the development of a new paradigm, reverse endocrinology. Reverse endocrinology is the process whereby the orphan hormone receptor is used to search for a previously unknown hormone, and metabolic pathway. We are interested in the orphan hormone receptors, Rev-erbA and RVR, orphan members of the receptor superfamily. Rev-erb alpha expression is regulated by fibrates, widely used hypolipidemic drugs, and the circadian cycle. Rev-erbs mediate the regulation of lipid metabolism and peroxisomal beta oxidation. Furthermore, Rev-erbs are acutely induced during brain seizures, postulated to regulate cerebellar plasticity, and involved in growth control. In view of these critical regulatory roles, and the success of reverse endocrinology to date, we intend to complete the structural analysis of the Rev-erb and RVR as a tool to identify the hormone that binds this receptor. Hormone receptors recruit proteins called nuclear receptor cofactors, that function as regulators of gene expression. The cofactors regulate gene expression and development. Furthermore these cofactors, when misregulated result in the onset of disease and carcinogenesis, which underscores the need for achieving a high resolution view of their function in many tissues. Along these lines, we are interested in exmining the function of these cofactors in muscle. Understanding the molecular role of the NR cofactors during muscle differentiation will be a critical step toward elucidating the dysregulation-function of these proteins in muscle diseases, such as rhabdomyosarcoma and inflammatory myopathy that have cofactor deficiency.Read moreRead less
This is a study of the biological system of epigenetics. Every cell in our body has the same genetics, or library of information contained in the form of DNA sequence. Epigenetics is the system that controls how this DNA is used in a particular situation, or what books are opened and read. During embryonic development, cells know what they want to become, e.g., a muscle cell, and, once they take on an identity, remember that they are when they duplicate themselves during growth. Epigenetics does ....This is a study of the biological system of epigenetics. Every cell in our body has the same genetics, or library of information contained in the form of DNA sequence. Epigenetics is the system that controls how this DNA is used in a particular situation, or what books are opened and read. During embryonic development, cells know what they want to become, e.g., a muscle cell, and, once they take on an identity, remember that they are when they duplicate themselves during growth. Epigenetics does not achieve this through changing genetics the library always stays intact. Rather, it acts by using proteins or chemicals to make DNA functional in one way, or another. Genomic imprinting is a special type of epigenetics. While an embryo has received identical genetic information from each of its parents, the epigenetic information received from each parent was not entirely the same. Some genes which behave differently according to what parent they came from. For example, a gene that makes a growth factor protein is active only if received from the father. If received from the mother, it is inactive, and makes no protein. Genes behaving in this way are known as imprinted genes. We are trying to discover what epigenetic mechanisms are behind this behaviour of imprinted genes. One way we are approaching this problem is to study germ cells the cells giving rise to eggs and sperm. These cells are unusual in that their imprinted genes behave in the same way regardless of whether they were received from the mother or father, i.e., like any other gene. If we can understand why this is the case, we will be better able to understand why imprinted genes behave the way they do in the rest of the cells of the body. Broadly, the mechanisms we uncover should further our understanding of germ cell development, gene expression, and disease. Perturbations in the epigenetic profile are likely causes of human disease, including cancer.Read moreRead less
Identification Of Variably Expressed Genes In Isogenic Mice And Humans
Funder
National Health and Medical Research Council
Funding Amount
$293,080.00
Summary
Monozygotic twins are known to have different phenotypic characteristics even though they contain identical genetic information. It is not uncommon for identical twins to have different coloured eyes and to show discordance for genetic diseases. While there is no definitive explanation for these differences they are generally thought to be caused by subtle changes in environmental conditions. We believe however, that these differences are set up during early embryonic development by the establis ....Monozygotic twins are known to have different phenotypic characteristics even though they contain identical genetic information. It is not uncommon for identical twins to have different coloured eyes and to show discordance for genetic diseases. While there is no definitive explanation for these differences they are generally thought to be caused by subtle changes in environmental conditions. We believe however, that these differences are set up during early embryonic development by the establishment of epigenetic modifications to the DNA. An epigenetic modification is a mark which determines whether a gene is expressed (switched on) or silent (switched off). The establishment of the mark appears to be a stochastic event which can result in different physical characteristics between genetically identical individuals. We would like to study this process in inbred mouse strains and in humans. Inbred mouse strains are maintained by inbreeding (brother-sister mating) to ensure that all individuals of the strain are isogenic (genetically identical) and in such a way that environmental variation is minimised. We will use established molecular techniques to find genes which are variably expressed among isogenic mice and humans. This work will enable us to discover genes which are sensitive to epigenetic modifications and whose epigenotype must be known if we are able to predict phenotype or disease state.Read moreRead less
All cells in the blood are the descendants of a single cell type, the stem cell. Stem cells are found in the bone marrow and throughout life have the unique ability to generate more of themselves (termed self-renewal) as well as to produce the functional cell types of the blood, ie. red and white blood cells. This project concentrates on the processes by which these stem cells can achieve these two functions. What are the genes that enable a stem cell to have this self-renewal characteristic and ....All cells in the blood are the descendants of a single cell type, the stem cell. Stem cells are found in the bone marrow and throughout life have the unique ability to generate more of themselves (termed self-renewal) as well as to produce the functional cell types of the blood, ie. red and white blood cells. This project concentrates on the processes by which these stem cells can achieve these two functions. What are the genes that enable a stem cell to have this self-renewal characteristic and conversely what are the genes that are activated when a cell becomes committed to become, for example, a white blood cell ? We have identified a gene, Pax5, which is essential in the process whereby a stem cell commits to become a lymphocyte . Our aim is to understand the function of Pax5 as a model for understanding how the commitment process as a whole works in the blood. These studies, as well as having an underlying fundamental scientific importance, are relevant to the clinical development of a number of stem cell therapies which rely on boosting stem cell production in procedures such as bone marrow transplantation for leukaemia and immune deficiency. In addition a number of characterised human blood malignancies indicate that inappropriate lineage commitment may be a factor in cancer.Read moreRead less
Molecular Regulation Of CRH Gene Expression In The Human Placenta
Funder
National Health and Medical Research Council
Funding Amount
$70,285.00
Summary
Approximately 70% of infant death is a result of premature birth. Preterm delivery occurs in 6-10% of pregnancies, and there has been no reduction in this rate in the last 30 years. This is largely because we remain ignorant of how normal and preterm birth is controlled. Understanding the physiology of human pregnancy is a critical step in the development of ways to detect and prevent preterm birth. Our group has demonstrated a link between production of a hormone (corticotropin releasing hormon ....Approximately 70% of infant death is a result of premature birth. Preterm delivery occurs in 6-10% of pregnancies, and there has been no reduction in this rate in the last 30 years. This is largely because we remain ignorant of how normal and preterm birth is controlled. Understanding the physiology of human pregnancy is a critical step in the development of ways to detect and prevent preterm birth. Our group has demonstrated a link between production of a hormone (corticotropin releasing hormone, CRH) in the placenta and the length of time the baby is carried in the mother. In women who will deliver prematurely the rise in CRH production occurs earlier and more rapidly, while in women who deliver late the rise occurs more slowly. This work has led to the concept of a biological clock that determines the length of time the fetus will be carried by the mother before birth, and in which production of CRH in the placenta plays a central role. We have been studying how the CRH gene is controlled in placental cells. We have discovered some regions in the DNA of the CRH gene which have important roles in controlling how much CRH is made by the placenta. The experiments described in this project will determine the molecular mechanisms that control the production of CRH in the human placenta. This will be done by examining the DNA sequences involved in controlling the CRH gene and by identifying the proteins that actually perform the regulating functions that result in either increased or decreased amounts of CRH being produced by the placenta. This important information will help us better understand how normal and preterm birth is controlled, and from that knowledge new ways to detect and prevent premature birth can be developed.Read moreRead less
The Role Of The Microphthalmia Transcription Factor Family In Macrophage Differentiation.
Funder
National Health and Medical Research Council
Funding Amount
$367,193.00
Summary
Macrophages are large white blood cells that are also found in all the tissues of the body. They are a major part of the front line defence against infection and malignancy, but they also cause much of the pathology of many diseases particularly those in which there is chronic inflammation. Macrophages, like all the cells of the blood, are produced from the bone marrow. In the process of macrophage production a suite of genes must be switched on so that the mature macrophage can carry out its fu ....Macrophages are large white blood cells that are also found in all the tissues of the body. They are a major part of the front line defence against infection and malignancy, but they also cause much of the pathology of many diseases particularly those in which there is chronic inflammation. Macrophages, like all the cells of the blood, are produced from the bone marrow. In the process of macrophage production a suite of genes must be switched on so that the mature macrophage can carry out its functions. This project aims to understand the process of selective gene expression in macrophages. It is based upon the identification of four members of a gene family, called the microphthalmia gene family, as candidate master genes that control the overall process of macrophage production. We seek to understand how the products of genes interact.Read moreRead less
Post Transcriptional Regulation Of Plasminogen Activator Inhibitor Type 2 Gene Expression
Funder
National Health and Medical Research Council
Funding Amount
$318,000.00
Summary
The process of wound healing, cell migration and the spread of cancers requires the recruitment of specialised proteases to the cell surface . These proteases act to degrade other proteins, mainly in the extracellular space, which in turn allows cells to move around, wounds to close, and blood clots to disappear. The plasminogen activating system is one of the enzyme systems involved in these events. One of the proteases that cleaves plasminogen to its active form, plasmin, is urokinase (u-PA) a ....The process of wound healing, cell migration and the spread of cancers requires the recruitment of specialised proteases to the cell surface . These proteases act to degrade other proteins, mainly in the extracellular space, which in turn allows cells to move around, wounds to close, and blood clots to disappear. The plasminogen activating system is one of the enzyme systems involved in these events. One of the proteases that cleaves plasminogen to its active form, plasmin, is urokinase (u-PA) and the activity of u-PA is regulated by its natural inhibitor called plasminogen activator inhibitor type 2 (PAI-2). u-PA is strongly implicated in the progression of metastatic cancer and high levels of PAI-2 relative to u-PA is regularly seen as a positive prognostic indicator for metastatic cancer. In this situation, PAI-2 acts to limit the activity of u-PA thereby restricting the migration potential of the cancer. PAI-2 is unusual because it exists both inside and outside the cell. Outside the cell, PAI-2 acts to inhibit u-PA activity, while inside the cell, PAI-2 also plays a role in the inhibition of cell growth and differentiation. It is therefore important to understand how the production of PAI-2 is regulated in cells. A significant component of PAI-2 regulation occurs post-transcriptionally, particularly at the level of mRNA stability. We have identified some of the proteins that bind to PAI-2 mRNA and influence its longevity in the cell. This project aims to further undertand how these as well as other PAI-2 mRNA binding proteins influence the expression of the PAI-2 gene.Read moreRead less
Functional Analysis Of The P160 Myb-binding Protein - A Regulator Of Multiple Transcription Factors?
Funder
National Health and Medical Research Council
Funding Amount
$376,697.00
Summary
The c-myb gene is a key molecular regulator of normal blood cell production, but alterations to this gene can also lead to leukaemia. The protein (Myb) encode by the c-myb gene acts as a transcription factor, ie, it controls the activity of other genes. There is good evidence that interactions with other proteins can regulate the activity of Myb. Our laboratory has identified what we believe is one such protein - p160 - that binds to a part of Myb that reduces its activity, and thus that is like ....The c-myb gene is a key molecular regulator of normal blood cell production, but alterations to this gene can also lead to leukaemia. The protein (Myb) encode by the c-myb gene acts as a transcription factor, ie, it controls the activity of other genes. There is good evidence that interactions with other proteins can regulate the activity of Myb. Our laboratory has identified what we believe is one such protein - p160 - that binds to a part of Myb that reduces its activity, and thus that is likely to be responsible for regulating Myb. However, it has recently become apparent that p160 interacts with a number of other transcription factors in addition Myb. The primary aim of this project is to elucidate precisely how p160 interacts with Myb and what the consequences of this interaction are. A range of experimental approaches, which range from in vitro to genetic studies, will be employed to do this. We will test a specific role of p160 suggested by our preliminary studies - that of a transporter of transcription factors between the nucleus and the cytoplasm of the cell. Because of the wide range of transcription factors that p160 interacts with, its effects on the function of the cell are likely to be profound. For this same reason, it is difficult to specifically predict the possible medical-health implications of this work However, what we know to date is consistent with a role for p160 as a tumour suppressor gene. Moreover, parts of this project aim to generate genetic information and tools which will help in determining whether p160 does play such a role and generally, in identifying any other associations of p160 with particular diseases.Read moreRead less