All cells have a characteristic shape (morphology), which is intrinsic to cellular function. A blood cell is designed to move in a liquid medium whereas a muscle cell is optimised for physical movement of attached bones. We are studying the mechanisms which control cell shape. We focus on the components of the cell skeleton (cytoskeleton) which are implicated in the regulation of shape. In particular, we study the actin based microfilament system. We have previously shown that two types of these ....All cells have a characteristic shape (morphology), which is intrinsic to cellular function. A blood cell is designed to move in a liquid medium whereas a muscle cell is optimised for physical movement of attached bones. We are studying the mechanisms which control cell shape. We focus on the components of the cell skeleton (cytoskeleton) which are implicated in the regulation of shape. In particular, we study the actin based microfilament system. We have previously shown that two types of these components of the cytoskeleton are able to control the structure of cells. In addition, we have found that variants of these two components (called isoforms) are used to build structures in different parts of cells. This has led us to think about the anatomy of cells and tissues in a new way. In some ways its like building a city. You create different kinds of buildings to suit their purpose. Each building uses a combination of building blocks which suit the structural demands of rooms and the overall building. In this study we are proposing to identify the specific job that one of these types of building blocks must play in order to allow normal cell growth and embryo development. To do this, we plan to change these genes in mice and then examine the impact on cell and tissue anatomy. This promises to contribute to the conversion of anatomical science and pathology from descriptive to experimental-mechanistic disciplines. This in turn will lead to a new tool set of diagnostic agents for the pathologist and the development of drugs which target specific functions of the cytoskeleton.Read moreRead less
Blimp-1: A Master Regulator Of B-lymphocyte Terminal Differentiation?
Funder
National Health and Medical Research Council
Funding Amount
$154,250.00
Summary
B lymphocytes are the antibody-producing cells of the immune system. They are formed in the bone marrow, and are exported to the body to circulate, searching for signs of infection. These circulating cells are not fully mature, but when they encounter an invader, with the help of other immune cells, they change. Most become antibody-producing cells, the final, operational cells of the B cell lineage. A few cells are set aside as memory cells that can rapidly become antibody-producing cells shoul ....B lymphocytes are the antibody-producing cells of the immune system. They are formed in the bone marrow, and are exported to the body to circulate, searching for signs of infection. These circulating cells are not fully mature, but when they encounter an invader, with the help of other immune cells, they change. Most become antibody-producing cells, the final, operational cells of the B cell lineage. A few cells are set aside as memory cells that can rapidly become antibody-producing cells should the same infection occur again. This is the basis of vaccination. The secretion of antibodies into the serum (that can bind to and eliminate an invader anywhere in the body) is the main function of B lymphocytes. This project will study the genes that allow B cells to become antibody-secreting cells (called ASC). We will focus on the gene for Blimp-1, the B lymphocyte-induced maturation protein, which has been called the master regulator of ASC formation. This claim is based largely on circumstantial evidence, and has not been directly tested genetically. We have made a mouse in which the Blimp-1 gene has been altered so that we can disable it in carefully controlled way. Using this knockout mouse, we can directly test the requirement for Blimp-1 in ASC and in other cell types. We will study these animals, using many tests that can accurately measure the behaviour of isolated cells, or the immune responses of the animals. We will examine other genes that are thought to be required for ASC to form or to perform their work, to see if loss of Blimp-1 (a known gene silencer) has impacted on these other genes. In this way, we expect to identify the genetic program that drives a B cell to become a mature ASC. Using this knowledge, we hope eventually to be able to study diseases of ASC in humans (as occur in allergy, asthma, rheumatoid arthritis and leukaemia). This information may also be used to improve the outcome of vaccination.Read moreRead less
Genetic Analysis Of Cell Death Pathways, Drug Resistance And Oncogenic Co-operativity In IL-3 Dependent Cell Lines
Funder
National Health and Medical Research Council
Funding Amount
$445,270.00
Summary
The ultimate fate of most of our cells is to die by committing suicide, because they are no longer required, are no longer functioning, or are potentially harmful. This normal physiological process is termed apoptosis . Inappropriate apoptosis can contribute to cell loss following heart attacks, stroke or neurodegenerative diseases, such as Alzheimer s or Parkinson s disease. Conversely, when cell death fails to occur, abnormal cells can accumulate and lead to cancer. In addition, because drugs ....The ultimate fate of most of our cells is to die by committing suicide, because they are no longer required, are no longer functioning, or are potentially harmful. This normal physiological process is termed apoptosis . Inappropriate apoptosis can contribute to cell loss following heart attacks, stroke or neurodegenerative diseases, such as Alzheimer s or Parkinson s disease. Conversely, when cell death fails to occur, abnormal cells can accumulate and lead to cancer. In addition, because drugs that are used to treat cancer may exert their effect by inducing apoptosis, a failure of this suicide response may cause resistance to chemotherapy. The genes of the apoptosis pathway function either to promote or inhibit cell death. We have found that some genes in the apoptosis pathway allow apoptosis to proceed rapidly, but do not decide the fate of the cell. Other genes are required for a cell to commit to die. If these genes are mutated then apoptosis does not occur and a functional cell may survive. The distinction between cells that decide fate and those that do not is crucial because it is only the genes that decide cell fate that can act as cancer genes, and are valid targets for therapy. We use a model in which apoptosis is caused by removal of a growth factor, using cell lines derived from mice that lack particular genes in the cell death pathway. These cells proliferate normally in the presence of growth factor, and allow us to determine the role of the genes when growth factor is withdrawn. Because these cells are sensitive to chemotherapeutic drugs, we can also determine the contribution these genes make to cancer drug sensitivity. Using this system, we have discovered that Puma, a gene known to be required for apoptosis in response to radiation, is also a critical activator of apoptosis following growth factor withdrawal. We will determine the manner in which Puma is regulated by growth factors, as well as identify and characterise other key components.Read moreRead less