Role Of Calcium Channels And Small-conductance Potassium Channels In Myenteric Neurons
Funder
National Health and Medical Research Council
Funding Amount
$131,717.00
Summary
This proposal will investigate the electrical properties of neurons in the wall of the intestine that control movements of the bowel. These neurons form an extensive network that runs the length of the gastrointestinal tract and control mixing and propulsion of food along the intestine. We will determine the basic electrical properties of these neurons and investigate why some of them transmit signals in a continuous manner while others transmit signals intermittently and how these patterns of a ....This proposal will investigate the electrical properties of neurons in the wall of the intestine that control movements of the bowel. These neurons form an extensive network that runs the length of the gastrointestinal tract and control mixing and propulsion of food along the intestine. We will determine the basic electrical properties of these neurons and investigate why some of them transmit signals in a continuous manner while others transmit signals intermittently and how these patterns of activity fit into the overall activity of the gut. This study will build on a large body of data obtained from our laboratory that has shown that some of these neurons act as sensors of the presence-absence of food in the intestine while others send signals to the muscle in the wall of the intestine to either relax or contract it so that the food can be processed properly. By knowing what makes these neurons different from each other we will be able to understand what goes wrong in functional bowel disorders where motility is affected, resulting in pain and discomfort.Read moreRead less
Theoretical And Computational Studies On Voltage-Gated Potassium (Kv) Channels
Funder
National Health and Medical Research Council
Funding Amount
$427,796.00
Summary
The primary aim of the proposed projects is to understand how biological ion channels work. All electrical activities in the nervous system, including communication between cells and influences of hormones and drugs on cell function, are regulated by the opening and closing of ion channels. We will study, applying rigorous physical principles and engineering methods and using powerful supercomputers, a class of biological ion channels, known as the voltage-activated potassium channels.
Identification And Function Of Kv7-M-channels In Axons Of Cortical Neurons
Funder
National Health and Medical Research Council
Funding Amount
$324,930.00
Summary
Membrane proteins permeable to potassium ions provide an important break during hyperexcitability of nerve cells in the brain. In this proposal I will study the function of a unique member of potassium channel protein (the M-channel) located at key regions of nerve cells; the axon. The results will provide important insights into the elementary steps of nerve cell excitability, and a better understanding of M-channel related diseases including neonatal epilepsies and chronic nerve pain.
Computational Study Of Selectivity, Gating And Mutation In The Acetylcholine Receptor And Potassium Channels
Funder
National Health and Medical Research Council
Funding Amount
$301,393.00
Summary
One way cells in living organisms communicate with each other is via the passage of charged particles across the cell membrane. This takes place through ion channels, large protein molecules that span the membrane and allow small molecules or ions to pass through a central pore. Malfunction of ion channels is known to underlie a variety of disorders including epilepsy, hypertension, kidney disease, heart attack, deafness. Channels also provide promising targets for making new broad spectrum anti ....One way cells in living organisms communicate with each other is via the passage of charged particles across the cell membrane. This takes place through ion channels, large protein molecules that span the membrane and allow small molecules or ions to pass through a central pore. Malfunction of ion channels is known to underlie a variety of disorders including epilepsy, hypertension, kidney disease, heart attack, deafness. Channels also provide promising targets for making new broad spectrum antibiotics and antivirals. This project aims to study two important types of ion channel: acetylcholine receptors that convey signals between nerve and muscle cells, and potassium channels that regulate the nerve impulses themselves. The binding of the neurotransmitter acetylcholine released from a nerve cell to acetylcholine receptors in the muscle cell prompts the opening of a cation conductive pore. The resulting influx of ions initiates a cascade of events ending in the contraction of the muscle fibre. However, the way in which this channel opening is initiated and how ions move into the muscle cell remain to be determined. Potassium channels are primarily used to rapidly 'switch off' nerve impulses so that subsequent messages can be passed through the nerve cell. To do this they have to be highly discriminatory, allowing only potassium to pass across the cell membrane and not sodium that would initiate another impulse. Although we now know what these tiny proteins look like, it is not clear how they differentiate between types of ions while still allowing many millions to pass each second. We will use computer simulations to study how these two type of channel open and close, and how they discriminate between different ion types. Using sophisticated computational techniques on Australia's most powerful supercomputers we aim to elucidate this fundamental area of human biology in the hope of deriving treatments for some debilitating neuromuscular diseases.Read moreRead less
Regulation Of Voltage-Gated Potassium Channels: X-ray Structures Of Cytosolic Components Of The BK Nd Kv Families
Funder
National Health and Medical Research Council
Funding Amount
$235,500.00
Summary
This research will investigate aspects of ion channel gating (opening). Ion channels are specialised pores perforating cell membranes that facilitate transport of ions, or charged atoms, across its breadth. The flow of ions from one side to another is measurable as an electrical current. The pore, or channel, through which ions pass narrows in regions, creating an impasse, or gate , prohibiting passage. The gate is controlled by external factors, such as the binding of certain molecules (ligands ....This research will investigate aspects of ion channel gating (opening). Ion channels are specialised pores perforating cell membranes that facilitate transport of ions, or charged atoms, across its breadth. The flow of ions from one side to another is measurable as an electrical current. The pore, or channel, through which ions pass narrows in regions, creating an impasse, or gate , prohibiting passage. The gate is controlled by external factors, such as the binding of certain molecules (ligands), or, in the case of voltage-dependent ion channels, the application of a voltage to the membrane. Such perturbations widen the pore sufficiently to permit conduction. Voltage-gated potassium channels specifically transport potassium ions. They fall into multiple categories, and generally form large complexes with intracellular, as well as membrane-bound, portions. For some types, cues from intracellular chemical processes are known to regulate electrical excitability, using the intracellular domains to transfer information to the membrane. In others it is not clear if and how this might happen. Our efforts will focus on exploring this theme in two contrasting systems, Kv and BK channels. Kv channels open in response to voltage, whereas activation of BK channels requires both voltage and moderate levels of intracellular calcium. X-ray crystallography will be used to generate accurate three-dimensional images of selected potassium channel components, allowing us to visualise discrete steps in the regulation processes. Potassium channels are essential for life. They effect transmission of our nerve impulses, and are thus fundamental to central nervous system activity. This research will help us to understand the factors that control them.Read moreRead less
Inactivation Of HERG Potassium Channels: Dynamic Changes In The Outer Pore Structure
Funder
National Health and Medical Research Council
Funding Amount
$422,716.00
Summary
Sudden cardiac death, due to disturbances in the normal electrical activity of the heart, is one of the leading causes of death in Australia and its incidence is increasing. Tackling the problem of cardiac arrhythmias is therefore one of the major challenges for cardiology in the 21st century. Two factors are greatly limiting progress in this area, the inability to predict who is most at risk and a paucity of treatment options. To address these problems, we need to better understand the basic me ....Sudden cardiac death, due to disturbances in the normal electrical activity of the heart, is one of the leading causes of death in Australia and its incidence is increasing. Tackling the problem of cardiac arrhythmias is therefore one of the major challenges for cardiology in the 21st century. Two factors are greatly limiting progress in this area, the inability to predict who is most at risk and a paucity of treatment options. To address these problems, we need to better understand the basic mechanisms underlying arrhythmias. The rhythm of the heart beat is controlled by electrical signals mediated by the flow of ions through specialised proteins called ion channels. Of the channels that contribute to cardiac electrical activity, potassium ion channels encoded by the Human ether-a-go-go-related gene (HERG) have been of particular interest for three reasons. Firstly, mutations in HERG are the cause of one third of cases of congenital long QT syndrome, an inherited cause of sudden cardiac death. Secondly, HERG is the molecular target for the vast majority of drugs that cause drug-induced long QT syndrome, the commonest cause of drug-induced arrhythmias and cardiac death. Thirdly, HERG channels have very unusual biophysical properties, which has led to the suggestion that they may act as an endogenous anti-arrhythmic agent . Accordingly, the major objective of the proposed research program is to understand the molecular and structural basis of the unusual properties of HERG channels. We will use a combination of molecular and electrical techiques in conjunction with computer modeling to probe the micoscopic motions in the channel that underly the unusual biophyscial properties of these channels. This work will facilitate a better understanding of how clinically identified mutations in HERG contribute to the increased risk of cardiac arrhythmias. More generally, it will improve our understanding of how cardiac ion channels maintain the normal rhythm of the heart.Read moreRead less