Phosphoinositide 3-kinase Signalling And Skeletal Muscle Mass.
Funder
National Health and Medical Research Council
Funding Amount
$597,598.00
Summary
Maintenance of skeletal muscle mass is essential for human health and locomotion. In ageing and cancer, loss of muscle mass leads to severe weakness and immobilization causing morbidity and mortality. This grant aims to characterise a novel gene that when deleted in mice leads to significant muscle damage. The molecular pathways within the cell that lead to the observed muscle damage will be investigated and this may provide insights into the pathways that control muscle damage and its regenerat ....Maintenance of skeletal muscle mass is essential for human health and locomotion. In ageing and cancer, loss of muscle mass leads to severe weakness and immobilization causing morbidity and mortality. This grant aims to characterise a novel gene that when deleted in mice leads to significant muscle damage. The molecular pathways within the cell that lead to the observed muscle damage will be investigated and this may provide insights into the pathways that control muscle damage and its regenerationRead moreRead less
Using Gene Delivery Technologies To Define Novel Mechanisms Of Skeletal Muscle Adaptation, And Develop Muscle-directed Interventions For Frailty And Serious Illness
Funder
National Health and Medical Research Council
Funding Amount
$631,370.00
Summary
The focus of my research is to investigate the cellular mechanisms underlying regulation of skeletal muscle size and function in health and disease. By defining these processes we can establish the events contributing to muscle wasting and frailty commonly associated with serious illness and advancing age, and develop interventions to prevent/overcome this important contributor to poor health prospects and reduced survival.
Novel Muscle Therapeutics Through Selective Beta-Adrenoceptor Signalling
Funder
National Health and Medical Research Council
Funding Amount
$603,608.00
Summary
Muscle wasting is an urgent and unmet health risk commonly associated with ageing; cancer, muscle diseases, and conditions including cardiovascular and metabolic disorders. Manipulating beta-adrenergic signalling is a therapeutic target for muscle wasting but treatments have so far been limited due to cardiaovascular side effects. Using cutting edge technologies, we will identify treatments that effectively separate beneficial effects on skeletal muscles from unwanted effects on the heart.
The Molecular Mechanisms Of Anabolic Androgen Actions In Skeletal Muscle
Funder
National Health and Medical Research Council
Funding Amount
$487,500.00
Summary
We are studying the role of male sex hormones, androgens, in controlling muscle function. Muscle wasting occurs in a variety of disorders, including cancer, burns and trauma, and also during normal ageing. Treatment with androgens helps prevent muscle wasting, and causes increased muscle size, although current therapies can also have side effects. Little is known about how androgens prevent wasting and promote muscle growth. Therefore, we propose to study the actions of male sex hormones in musc ....We are studying the role of male sex hormones, androgens, in controlling muscle function. Muscle wasting occurs in a variety of disorders, including cancer, burns and trauma, and also during normal ageing. Treatment with androgens helps prevent muscle wasting, and causes increased muscle size, although current therapies can also have side effects. Little is known about how androgens prevent wasting and promote muscle growth. Therefore, we propose to study the actions of male sex hormones in muscle. We will study the growth of mouse muscle cells in culture, and measure their rate of growth when treated with androgens. All cells contain certain factors that control their growth and replication, and we will test whether androgens activate these factors to increase growth. We will also study the effect of androgens on muscle in mice, to investigate complex effects that only occur in real muscle. We will neuter male mice, which causes muscle wasting. Neutered mice will then be treated with androgens or placebo, and we will compare the muscle growth effect of androgen treatment versus placebo. We will measure muscle strength, size, and the number of muscle cells in treated and placebo mice. We will also see if the effects of androgen require a particular protein, the androgen receptor, which acts as a lock-key mechanism in cells, to allow them to respond to androgens. We will make a strain of mouse with a non-functional version of the androgen receptor only in muscle cells. This will determine if the muscle growth effects of androgens occur through a direct action on muscle, or indirectly through acting on other tissues in the body. This information will ultimately allow us to design more targeted androgen therapies for muscle wasting, that act only on muscle.Read moreRead less
Novel Transcriptional Regulation In Skeletal Muscle Development And Disease
Funder
National Health and Medical Research Council
Funding Amount
$344,592.00
Summary
It has been assumed that once genes are activated in a particular type of cell, they remain 'on'. From work described in this laboratory, we now know that gene activity may come and go. Instead of the analogy of a light switch that has been turned on and stays on, it appears that at least in muscle, gene activity is more like blinking lights. If you take an image of muscle tissue, which is just a snapshot in time, a gene may not appear to be activated if it was temporarily 'flashing off' at the ....It has been assumed that once genes are activated in a particular type of cell, they remain 'on'. From work described in this laboratory, we now know that gene activity may come and go. Instead of the analogy of a light switch that has been turned on and stays on, it appears that at least in muscle, gene activity is more like blinking lights. If you take an image of muscle tissue, which is just a snapshot in time, a gene may not appear to be activated if it was temporarily 'flashing off' at the time of viewing. This may occur in all tissue types, but it is more easily detected in muscle because the cell is large with many nuclei, rather than small with a single nucleus. Another reason why this phenomenon is more readily detectable in muscle cells is that they are very dynamic cells that can undergo fairly radical changes in shape. An actively growing or hypertrophying muscle cell may have all of its genes at a high pitch of transcriptional activity to support rapid growth. However, once a muscle cell has reached its appropriate size, then muscle genes switch to a flashing mode of transcription to maintain rather than build structures. SIGNIFICANCE: (1) This may be a fundamental mechanism of gene regulation that occurs in virtually all cell types. As such, our finding will open an area of research into the types of molecules involved in this novel mechanism. (2) Our studies will result in a better understanding of the mechanisms of muscle cell hypertrophy in response to excercise and drugs, as well as atrophy due to nerve damage or inherited muscle disease. (3) This mechanism may explain the expression of foreign DNA in muscle cells delivered via gene therapy approaches. Our findings could result in a more efficacious means of expressing the introduced gene that might require tricking the muscle fibre into believing that it is in a perpetual growth mode.Read moreRead less
Skeletal muscle responds to exercise or mechanical load, in a process known as hypertrophy. Hypertrophy is initiated by a population of immature muscle cells known as myoblasts which fuse to form myotubes, and then mature to form muscle fibers (differentiation). Many proteins involved in a cascade of activation and-or deactivation are important for regulating hypertrophy (hypertrophic signaling). Failure of skeletal muscle to induce hypertrophy can lead to muscle degeneration. The FHL proteins a ....Skeletal muscle responds to exercise or mechanical load, in a process known as hypertrophy. Hypertrophy is initiated by a population of immature muscle cells known as myoblasts which fuse to form myotubes, and then mature to form muscle fibers (differentiation). Many proteins involved in a cascade of activation and-or deactivation are important for regulating hypertrophy (hypertrophic signaling). Failure of skeletal muscle to induce hypertrophy can lead to muscle degeneration. The FHL proteins are highly expressed in skeletal muscle. FHL proteins are molecular scaffolds which direct assembly of protein complexes to form the muscle contraction machinery (sarcomere). We propose FHL proteins will initiate-regulate skeletal muscle hypertrophy. Increased levels of FHL1 correlate with skeletal muscle hypertrophy. However, it is unclear if increased FHL1 is alone sufficient to induce hypertrophy directly. We have genetically engineered mice to express elevated levels of FHL1 specifically in skeletal muscles (FHL1 transgenic mice) and these mice show muscle enlargement. FHL1 transgenic mice have larger muscle fibers and are >7-fold stronger than non-transgenic littermates. We are currently examining which cell signaling pathways are affected by elevated FHL1. We are also investigating the role of another family member FHL3 in the differentiation of immature myoblasts, a process essential for both embryonic and postnatal skeletal muscle (hypertrophy) development. In the cell nucleus, FHL2 regulates genes which control cell growth and death and increased nuclear levels of FHL2 been detected in prostate cancer biopsies. Recently we demonstrated that FHL2 binds and is sequestered from the nucleus, by a protein, filamin. We are investigating the FHL2-mediated regulation of genes in human melanoma cells, which due to gene mutation are devoid of filamin and will determine how this affects FHL2 function in muscle.Read moreRead less
Adaptation Of Muscle To Eccentric Exercise And Its Clinical Applications 194272
Funder
National Health and Medical Research Council
Funding Amount
$196,410.00
Summary
Work in this laboratory has concentrated on Delayed Onset Muscle Soreness (DOMS), the soreness felt for several days after unaccustomed exercise. This is particularly so when the exercise involves stretching of active muscle, called eccentric exercise, at longer muscle lengths. DOMS is due to microscopic muscle damage. A rapid training effect, leading to reduced soreness from a subsequent bout of similar exercise, has been identified by us as due to a specific structural adaptation. This results ....Work in this laboratory has concentrated on Delayed Onset Muscle Soreness (DOMS), the soreness felt for several days after unaccustomed exercise. This is particularly so when the exercise involves stretching of active muscle, called eccentric exercise, at longer muscle lengths. DOMS is due to microscopic muscle damage. A rapid training effect, leading to reduced soreness from a subsequent bout of similar exercise, has been identified by us as due to a specific structural adaptation. This results in the optimum length for tension generation moving to longer muscle length so that the muscle is less likely to be damaged during subsequent stretches. Hypothesizing that gross muscle tears arise from the microscopic damage, we have begun investigating whether eccentric exercise training can prevent hamstring muscle injuries. We have shown that eccentric exercise shifts the optimum length for contraction in human hamstring muscles. We are now examining athletes with past injuries, known to be likely to re-injure. Other experiments are designed to show that sports that cause injury do indeed include eccentric exercise of the hamstring muscles. We are also investigating the effectiveness of eccentric exercise in treating apparently normal children who compulsively walk on their toes. We have built monitoring equipment and are monitoring both conventional and exercise based treatments designed to shift muscle optimum length to longer lengths to allow the children to place their heels on the ground. Finally, most muscles contain different fibre types, distinguished mainly by their speed of contraction. It has been suggested that they are not all uniformly susceptible to damage from eccentric exercise, a result not predicted by our theory. However, we hypothesize that secondary factors, particularly the length for generating optimum tension, may be responsible for these differences. We plan to test this idea by measuring properties of different types of motor units.Read moreRead less
Establishing STARS As A Therapeutic Target To Reduce Muscle Wasting And Improve Muscle Function
Funder
National Health and Medical Research Council
Funding Amount
$446,189.00
Summary
Muscle wasting occurs rapidly with disuse after injuries occurring at work, during sport, with chronic disease and in road accidents. It is also a consequence of ageing. Muscle wasting and reduced muscle function places considerable financial strain on our health care system. We aim to use gene therapy and pharmacological interventions to increase the levels of a protein called STARS. We hypothesize that STARS will reduce disuse-induced muscle wasting, increase recovery and improve function.
Clarifying Molecular Role Of IGF-1:Ea Isoforms In Skeletal Muscle Hypertrophy And Atrophy
Funder
National Health and Medical Research Council
Funding Amount
$394,718.00
Summary
The growth factor IGF-1 is proposed as a therapeutic agent to increase muscle mass and to reduce muscle wasting resulting from denervation, disuse, ageing and dystrophy. Understanding the precise mechanisms of IGF-1 action is essential for the potential therapeutic use of this factor. This research is focused on the molecular role of IGF-1 in healthy muscle and in the conditions of muscle wasting and degeneration.