Regulation Of The Sarcolemmal Na-K Pump By FXYD Proteins
Funder
National Health and Medical Research Council
Funding Amount
$268,264.00
Summary
Background. Pump molecules embedded in the membranes of all cells maintain a difference in composition between the cell content and the surrounding tissue fluids. Of these, the membrane sodium-potassium pump (Na+-K+ pump) is the most important. It uses metabolic energy generated in the cell to transport 3Na+ out in exchange for 2K+ transported in, and maintains a low concentration of Na+ and a high concentration of K+ within cells. The opposite applies to the surrounding tissue fluids. The conce ....Background. Pump molecules embedded in the membranes of all cells maintain a difference in composition between the cell content and the surrounding tissue fluids. Of these, the membrane sodium-potassium pump (Na+-K+ pump) is the most important. It uses metabolic energy generated in the cell to transport 3Na+ out in exchange for 2K+ transported in, and maintains a low concentration of Na+ and a high concentration of K+ within cells. The opposite applies to the surrounding tissue fluids. The concentration gradient for Na+ serves in mechanisms that couple transport of other ions and molecules to the downhill movement of Na+ in the direction determined by its concentration gradient. The transport of ions and molecules directly and indirectly due to the operation of the membrane Na+-K+ pump is very important for the function of all cells. Objectives. It is poorly understood how cells regulate the activity of their membrane Na+-K+ pumps. We will examine if small molecules (FXYD proteins) in the cell membrane, closely associated with the pump, regulate its activity. Methods. We will use a whole-cell patch clamping technique to attach small glass pipettes to single heart cells and replace their content with solutions in the pipettes. The technique allows real-time measurement of Na+-K+ pump activity because the 3:2 Na+:K+ exchange ratio generates an electrical current that can be measured in the single cells. The FXYD proteins will be produced in bacteria, purified and introduced into the heart cells by inclusion in the pipette solution that replace the cell content. Expected outcomes. Achieving this project's objectives will greatly enhance our understanding of Na+-K+ pump regulation. This is important because high levels of Na+ in heart cells is a pivotal abnormality in heart disease. Understanding the Na+-K+ pump can be activated to reduce cell Na+ levels should help design of treatments.Read moreRead less
Physiological And Pathological Effects Of Oxidation On Contractile Function In Skeletal Muscle
Funder
National Health and Medical Research Council
Funding Amount
$613,311.00
Summary
Reactive oxygen molecules generated within muscle fibres in normal exercise and in pathological conditions, greatly affect muscle function by altering the responsiveness of the contractile proteins. This study investigates how various oxidative stresses affect particular reactive sites on key proteins controlling muscle contraction. The findings should identify key molecular changes involved in normal activity and the role oxidation plays in chronic muscle weakness in particular conditions.
Defining The Mechanisms That Control Exocytosis And Cell Signalling In Health And Disease.
Funder
National Health and Medical Research Council
Funding Amount
$473,477.00
Summary
This research focuses on pathways regulating nervous communication and hormone release. It centres on proteins that regulate this process and on the function of specific endocrine cells in health and disease. It uses unique research tools developed in this laboratory enabling the study of mechanisms regulating cell signalling. Through this research I aim to identify how the cells in our body communicate with each other and how this relates to diseases such as type 2 diabetes.
Hormone Transport By Alpha-2-Macroglobulin: Novel Roles In Regulating Hormone Activity
Funder
National Health and Medical Research Council
Funding Amount
$602,857.00
Summary
Alpha-2-macroglobulin is a large protein in the blood known to bind and transport numerous hormones in the circulation. Our previous studies published in BLOOD (2009) and JBC (2013) have discovered an important role for this molecule in the transport and regulation of a peptide hormone. The studies proposed in this application have important implications for understanding new roles of alpha-2-macroglobulin in hormone binding and regulating the activity of hormones in disease states.
Investigation Of The Roles Of Calcium-dependent Proteases In Muscle Damage And Disease
Funder
National Health and Medical Research Council
Funding Amount
$360,160.00
Summary
Muscle strength is important to the health and well-being of everyone. Skeletal muscle weakening occurs as a result of certain disease states, aging and prolonged inactivity due to illness-injury-surgery. This can result in the loss of normal activity and mobility and an increased incidence of falls and accidents, which impact considerably on health care costs. There is a family of proteins called calpains that have been linked to a number of factors affecting muscle function, however it is not ....Muscle strength is important to the health and well-being of everyone. Skeletal muscle weakening occurs as a result of certain disease states, aging and prolonged inactivity due to illness-injury-surgery. This can result in the loss of normal activity and mobility and an increased incidence of falls and accidents, which impact considerably on health care costs. There is a family of proteins called calpains that have been linked to a number of factors affecting muscle function, however it is not known how they are involved. Calpains are proteases, ie. they destroy other proteins, and they are regulated by the concentration of calcium inside a cell. The calcium concentration increases dramatically inside a muscle cell when it contracts. Inside a muscle cell it is important that there is tight regulation of the calpains to avoid them being activated inappropriately during normal use and causing muscle damage. In certain disease states, such as types of muscular dystrophy, it is known that the calcium concentration within resting muscle fibres is increased compared with healthy muscle fibres. We propose that as a consequence of this, the calpains will be less regulated and will cause damage to the muscle, which contributes to the muscle weakness seen in these diseases. Whilst calpains have been implicated with symptoms associated with muscle dystrophies, the role they play is certainly unclear. The objectives of our research proposal are to understand what factors influence i) where the calpains are located and ii) when and how much they are activated, within muscle fibres. We will compare this in healthy muscle and muscle from mdx mice, an animal model of Duchenne muscular dystrophy.Read moreRead less
Investigating Follistatin-based Interventions For Long Term-protection Against Frailty Associated With Chronic Illness And Aging
Funder
National Health and Medical Research Council
Funding Amount
$987,169.00
Summary
Effective therapies are urgently needed to combat frailty arising from muscle wasting associated with chronic illness and aging. The proposed studies will investigate the prospects of developing novel short-term interventions that can confer long-term benefits for preventing and treating muscle wasting associated with chronic illness and advanced aging.