Structure Determination Of The Mammalian Ryanodine Receptor
Funder
National Health and Medical Research Council
Funding Amount
$377,397.00
Summary
Heart failure is the leading cause of death worldwide. We will determine the structure of the ryanodine receptor, a calcium channel involved in initiating contraction of cardiac and skeletal muscle. Detailed insights into the function of the ryanodine receptor will result from this work. An atomic structure of the cardiac ryanodine receptor will assist in the development of improved ryanodine receptor inhibitors to prevent and treat congestive heart failure.
Mechanisms Regulating Excitation-contraction Coupling In Skeletal Muscle
Funder
National Health and Medical Research Council
Funding Amount
$687,750.00
Summary
Muscle contraction occurs when an electrical impulse from a nerve travels over the surface of a skeletal muscle fibre and triggers the release of calcium ions from special stores inside the fibre. However, little is known about the regulatory mechanisms involved in turning on and turning off the calcium release. This project investigates the properties of the calcium release and what processes are involved in regulating it. Information about this is vital for understanding how normal muscle work ....Muscle contraction occurs when an electrical impulse from a nerve travels over the surface of a skeletal muscle fibre and triggers the release of calcium ions from special stores inside the fibre. However, little is known about the regulatory mechanisms involved in turning on and turning off the calcium release. This project investigates the properties of the calcium release and what processes are involved in regulating it. Information about this is vital for understanding how normal muscle works and why muscles show reduced performance with exercise (muscle fatigue), with aging, and in certain diseases.Read moreRead less
STRUCTURAL AND FUNCTIONAL INTERACTIONS BETWEEN THE II-III LOOP OF THE SKELETAL DHPR AND THE RYANODINE RECEPTOR
Funder
National Health and Medical Research Council
Funding Amount
$410,250.00
Summary
The project has implications for neuromuscular diseases and for muscle weakness in general and in the elderly, all of which are significant health issues. The results will elucidate molecular mechanisms in muscle contraction and will provide a basis for drug design and treatment of muscle disorders. Respiration and locomotion depend on changes in calcium concentration inside muscle cells. Cardiovascular function, neuronal activity and immune responses also depend on the release of calcium from i ....The project has implications for neuromuscular diseases and for muscle weakness in general and in the elderly, all of which are significant health issues. The results will elucidate molecular mechanisms in muscle contraction and will provide a basis for drug design and treatment of muscle disorders. Respiration and locomotion depend on changes in calcium concentration inside muscle cells. Cardiovascular function, neuronal activity and immune responses also depend on the release of calcium from internal stores. Ryanodine receptor (RyR) calcium channels, either alone or in combination with a different internal calcium channel, regulate calcium release in each of these diverse functions. The essential nature of RyRs is underlined by death at or before birth when RyR expression is defective. Genetic defects in the RyR cause cardiac arrhythmias, malignant hyperthermia and central core disease. RyR function is compromised in heart failure and fatigue. The key role of RyRs makes them a potential therapeutic target, but they are not used as such because of the limited knowledge of the nature and structure of their regulatory sites. Electrical signals from the brain are able to release calcium from internal stores in muscle and initiate muscle contraction by virtue of a physical interaction between two calcium channel proteins, a surface membrane channel and the RyR. The molecular basis of this protein-protein interaction is is not understood and is a subject of this proposal. We will (a) solve the structure of one part of the surface channel that is known to contribute to the protein-protein interaction with the RyR, (b) determine the amino acid residues that interact with each other and (c) evaluate the functional consequences of the the binding of proteins. Understanding more about RyR regulation will pave the way for rational drug design and the eventual use of the RyR as a therapeutic target.Read moreRead less
SPECIFIC MODIFICATION OF SKELETAL MUSCLE RYANODINE RECEPTOR ACTIVITY
Funder
National Health and Medical Research Council
Funding Amount
$411,000.00
Summary
The project will have implications for muscle fatigue, which is a public health issue in an aging population, and for neuromuscular diseases and muscle weakness. The ryanodine receptor (RyR) calcium release channel regulates changes in calcium concentrations inside the muscle cell that are essential for respiration and movement. Defects in expression of RyRs results in death in utero or at birth. The RyR is also important in many other tissues, where it acts either alone or in combination with a ....The project will have implications for muscle fatigue, which is a public health issue in an aging population, and for neuromuscular diseases and muscle weakness. The ryanodine receptor (RyR) calcium release channel regulates changes in calcium concentrations inside the muscle cell that are essential for respiration and movement. Defects in expression of RyRs results in death in utero or at birth. The RyR is also important in many other tissues, where it acts either alone or in combination with a second type of calcium channel, to regulate the changes in the concentrations of calcium ions within the cell, which are essential for a variety of processes including cardiac contraction, vascular constriction, neuronal activity and immune responses. Despite its importance, little is known about the regulation of the RyR channel opening during contraction in skeletal muscle or the mechanisms of ion movement through its pore. It is often difficult to define the specific role of RyRs in intact tissues because of the lack of specific probes for the channel. The RyR is an obvious target for therapeutic drugs to modify muscle contraction, but has not been used as such because of the lack of specific and reversible drugs. Muscle performance is reduced, and fatigue is rapid, in neuromuscular disease. Performance can be improved by variety of drugs like anabolic steroids which unfortunately have additional adverse actions. The aims of the project are (a) to discover more about the regulation of, and ion conduction pathway through, the skeletal muscle RyR channel, (b) to identify compounds that can be used as specific probes for RyR activity and (c) to identify compounds that might in the future provide the basis for development of the RyR as a therapeutic target.Read moreRead less
TEMPERATURE AS MODIFIER OF MAMMALIAN SKELETAL MUSCLE FUNCTION AND OF MUSCLE RESPONSIVENESS TO PHYSIOLOGICAL FACTORS
Funder
National Health and Medical Research Council
Funding Amount
$256,018.00
Summary
Contracting muscles are a major source of heat production in the body. Heat produced by contracting muscles can cause muscle damage if muscle temperature increases above 44oC. Also, overheating from external sources can cause an increase in muscle temperature in the upper physiological range of temperature (37-44oC) which can so readily happen to humans and animals caught in blistering sun or in closed cars parked in the sun. However, very little is known about what happens to the ability of the ....Contracting muscles are a major source of heat production in the body. Heat produced by contracting muscles can cause muscle damage if muscle temperature increases above 44oC. Also, overheating from external sources can cause an increase in muscle temperature in the upper physiological range of temperature (37-44oC) which can so readily happen to humans and animals caught in blistering sun or in closed cars parked in the sun. However, very little is known about what happens to the ability of the skeletal muscle to contract when the temperature increases in this upper physiological range of temperature. This project seeks to fill in this important gap in our knowledge and increase our understanding about the existence of protective mechanisms in muscle to prevent heat-induced damage to the muscle. Such mechanisms would allow the body to operate very close to the lethal range of temperature and may be mainly responsible for the severe muscle weakness in overheated individuals. Results obtained from the project can have far reaching implications for human physiology in general and muscle and exercise physiology in particular and for developing new strategies in the treatment of collapse from body overheating. The project will also produce new knowledge regarding the mechanism of action of drugs used in the treatment of certain mental disorders but which can trigger, in susceptible individuals, uncontrolled contraction of muscles and overheating.Read moreRead less
Controlling the concentration of calcium inside cells is extremely important for normal cell function. For example, a brief increase in calcium concentration inside muscle cells is essential for muscle contraction and the normal heart beat. This calcium is kept stored in sacs inside cells and is rapidly released when needed through calcium channels known as ryanodine receptors. We have discovered that some proteins (glutathione transferases and intracellular chloride channel proteins) inside cel ....Controlling the concentration of calcium inside cells is extremely important for normal cell function. For example, a brief increase in calcium concentration inside muscle cells is essential for muscle contraction and the normal heart beat. This calcium is kept stored in sacs inside cells and is rapidly released when needed through calcium channels known as ryanodine receptors. We have discovered that some proteins (glutathione transferases and intracellular chloride channel proteins) inside cells can affect how much calcium flows through these calcium channels. The proteins were thought to have other functions and our discovery of their effect on ryanodine receptor calcium channels has caused considerable excitement. We now plan to explore how they do this. We will mutate specific regions of the proteins to discover which regions are important and which are not. We will also look at whether closely related proteins have similar effects. The new class of ion channel modulator that we are studying has the capacity to alter not only respiration, movement and cardiac contraction, but also other aspects cardiovascular function, neuronal activity and immune responses. Understanding the way in which soluble proteins can interact with ion channels may reveal a novel target for drugs that affect ryanodine receptor calcium channel function and allow the rational design of specific drugs to regulate ion channels or ion channel modulators.Read moreRead less