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
Regulation Of Pancreatic Beta-cell Number And Function By Adipocyte-released Hormones, Free Fatty Acids And Ghrelin.
Funder
National Health and Medical Research Council
Funding Amount
$256,500.00
Summary
The disease diabetes mellitus comprises a heterogeneous group of disorders all characterised by high blood glucose levels. Beta-cells in the pancreas, which secrete insulin, are central to the pathophysiology of the disease. Type 1 or insulin-dependent diabetes mellitus results from an absolute deficiency of insulin due to auto immunological destruction of the pancreatic beta cell, and accounts for 5-10% of total diabetes mellitus. In the more common type 2 or non-insulin-dependent diabetes mell ....The disease diabetes mellitus comprises a heterogeneous group of disorders all characterised by high blood glucose levels. Beta-cells in the pancreas, which secrete insulin, are central to the pathophysiology of the disease. Type 1 or insulin-dependent diabetes mellitus results from an absolute deficiency of insulin due to auto immunological destruction of the pancreatic beta cell, and accounts for 5-10% of total diabetes mellitus. In the more common type 2 or non-insulin-dependent diabetes mellitus, liver, muscle and fat cells are resistant to the action of insulin and compensatory mechanisms that are activated in the beta-cell to increase insulin secretion are not sufficient to maintain normal blood glucose levels. In Western countries including Australia, type 2 diabetes currently affects around 2% of the whole population and about 6% of adults (10% of over 60-y) and continues to grow at around 6% per annum. Type 2 diabetes often occurs in obese patients and a direct link between obesity and type 2 diabetes has been strongly suggested by research to date. It has also been found that a progressive loss of beta-cell function throughout the course of the disease results in the reduction of insulin secretion. The contribution of excessive fat tissue in obese patients to the progress of type 2 diabetes is not clear. Certain hormones from fat cells, metabolic regulatory hormone, and fatty acids have been demonstrated to influence the function of beta-cells in previous studies, including our own. We now aim to investigate in detail the effect of these on cultured beta-cells with molecular and cell biology techniques. We expect to identify a factor or factors which stimulate or inhibit the progress of beta-cell dysfunction, with the potential to identify therapeutic targets in the treatment of type 2 diabetes.Read moreRead less
Type 2 diabetes is reaching epidemic proportions across the world and is a huge burden in health care costs. We know it is a multifaceted disease with many symptoms, one of which is a reduction in insulin secretion. This proposal sets out to determine the mechanisms of insulin secretion from healthy tissue and what goes wrong in disease.