The Physiological Relevance Of Calcitonin In Osteoclast Function
Funder
National Health and Medical Research Council
Funding Amount
$437,640.00
Summary
Throughout adult life, bone tissue is continuously remodelled. The two main processes involved in bone remodelling, are bone formation and bone breakdown. Bone formation is controlled by cells known as osteoblasts and bone breakdown is controlled by cells known as osteoclasts. Under normal circumstances these two processes are tightly coupled. Excessive breakdown of bone, causes these two processes to become unbalanced and results in bone loss. This is the basis of many bone diseases such as ost ....Throughout adult life, bone tissue is continuously remodelled. The two main processes involved in bone remodelling, are bone formation and bone breakdown. Bone formation is controlled by cells known as osteoblasts and bone breakdown is controlled by cells known as osteoclasts. Under normal circumstances these two processes are tightly coupled. Excessive breakdown of bone, causes these two processes to become unbalanced and results in bone loss. This is the basis of many bone diseases such as osteoporosis, a condition in which the bones become fragile and therefore more susceptible to fracture. 1 in 2 women and 1 in 5 men aged 70 years and older suffer from osteoporosis in Australia. Despite this, the mechanisms which control osteoclast breakdown of bone are not well understood. Our laboratory is interested in how hormones affect osteoclast action. We plan to examine the role of the hormone calcitonin, thought to be important inhibitor of osteoclastic bone breakdown. This will be achieved by studying transgenic mice in which the receptor for calcitonin is specifically removed from osteoclasts. This will allow us to precisely determine the role of calcitonin in osteoclast function. Current treatment for osteoporosis involves the administration of drugs which inhibit bone breakdown. This project will increase our understanding of how calcitonin acts to regulate the function of osteoclasts. We believe that this research is of great importance as osteoporosis is becoming more prevalent as the population ages.Read moreRead less
The Mechanisms Of The Anabolic Actions Of Androgens In Bone.
Funder
National Health and Medical Research Council
Funding Amount
$470,960.00
Summary
Androgens (male sex hormones) are one of the few agents that increase bone formation. Androgens act by binding to a specific protein, the androgen receptor (AR). To understand exactly how androgens increase bone formation, we will study mice in which the AR is inactivated only in bone forming cells at specific stages of their development. Understanding the way in which androgens act on bone to increase size and strength will be of great benefit in the design of new treatments for osteoporosis.
The Role Of Androgens In Osteoblast Development And Bone Metabolism.
Funder
National Health and Medical Research Council
Funding Amount
$487,500.00
Summary
Maintenance of the skeleton involves the processes of bone formation by cells known as osteoblasts and bone breakdown by cells known as osteoclasts. When these processes become unbalanced, bone loss results, which is the basis of osteoporosis. The reduced bone mass found in osteoporosis leads to an increased susceptibility to bone fracture. 1 in 2 women and 1 in 3 men over the age of 60 will suffer a fracture due to osteoporosis. The increasing incidence of osteoporotic fractures has lead to ren ....Maintenance of the skeleton involves the processes of bone formation by cells known as osteoblasts and bone breakdown by cells known as osteoclasts. When these processes become unbalanced, bone loss results, which is the basis of osteoporosis. The reduced bone mass found in osteoporosis leads to an increased susceptibility to bone fracture. 1 in 2 women and 1 in 3 men over the age of 60 will suffer a fracture due to osteoporosis. The increasing incidence of osteoporotic fractures has lead to renewed efforts to understand the actions of hormones on bone. Androgens, the male sex hormones, have beneficial effects on skeletal growth and bone maintenance in both males and females by stimulating osteoblasts. It is believed that androgens act by binding to a specific protein known as the androgen receptor (AR), which is only found in androgen-responsive cells. Although it is well documented in human and animal models that androgens stimulate osteoblasts to increase the formation of bone, the way in which they act on osteoblasts remains poorly understood. The aim of this project is to investigate the effects of androgens at different stages of the developing osteoblast. This will be achieved by making transgenic mice in which the androgen receptor has been inactivated only in osteoblasts at specific stages of their development. We hypothesise that the inactivation of the androgen receptor will have dramatic effects on the development and function of osteoblasts. This project will help clarify the role androgens play in bone formation and will give fundamental insights into the basic biology of bone in both normal and disease processes. As androgens are one of the few agents that act to increase bone formation, understanding the way in which they act is important for the treatment of osteoporosis in males and females. We believe that this research is of great importance as osteoporosis becomes more prevalent in our aging population.Read moreRead less
The Physiological Role Of Calcitonin And Its Receptor In Bone Cell Metabolism.
Funder
National Health and Medical Research Council
Funding Amount
$496,446.00
Summary
Throughout adult life, bone tissue is continuously remodelled. The two main processes involved in bone remodelling, are bone formation and bone breakdown. Bone formation is controlled by cells known as osteoblasts and bone breakdown is controlled by cells known as osteoclasts. Under normal circumstances these two processes are tightly coupled. Excessive breakdown of bone, causes these two processes to become unbalanced and results in bone loss. This is the basis of many bone diseases such as ost ....Throughout adult life, bone tissue is continuously remodelled. The two main processes involved in bone remodelling, are bone formation and bone breakdown. Bone formation is controlled by cells known as osteoblasts and bone breakdown is controlled by cells known as osteoclasts. Under normal circumstances these two processes are tightly coupled. Excessive breakdown of bone, causes these two processes to become unbalanced and results in bone loss. This is the basis of many bone diseases such as osteoporosis, a condition in which the bones become fragile and therefore more susceptible to fracture. 1 in 2 women and 1 in 3 men aged 70 years and older suffer from osteoporosis in Australia. Despite this, the mechanisms which control osteoclast breakdown of bone are not well understood. Our laboratory is interested in how hormones affect osteoclast action. We plan to examine the role of the hormone calcitonin, an important inhibitor of osteoclastic bone breakdown. This will be achieved by studying transgenic mice in which the receptor, or target, for calcitonin is specifically removed from osteoclasts. This will allow us to precisely determine the role of calcitonin in osteoclast function. Data generated by our research group indicates that calcitonin is also involved in controlling bone formation, however, the way in which calcitonin acts on osteoblasts remains poorly understood. Therefore, studying our transgenic mice will also help clarify the role calcitonin plays in bone formation. Current treatment for osteoporosis involves the administration of drugs which inhibit bone breakdown. This project will increase our understanding of how calcitonin acts to regulate bone breakdown and bone formation and may assist in the design of new therapies for osteoporosis. We believe that this research is of great importance as osteoporosis is becoming more prevalent as the population ages.Read moreRead less
Role Of Non-classical Actions Of Androgens In Musculoskeletal Physiology
Funder
National Health and Medical Research Council
Funding Amount
$703,664.00
Summary
Androgens (male sex hormones) are important for growth-maintenance of muscle and bone. The classical action of androgens is to bind the androgen receptor (AR) and regulate target genes. They can also act via non-classical AR mechanisms through other cellular pathways. To understand the role of non-classical actions in the musculoskeletal system we will study mice in which androgens can only act via this pathway. This knowledge is important for the treatment of osteoporosis and muscle wasting.
We have found that leptin, a new hormone produced by fat cells which regulates appetite and metabolism, is a powerful inhibitor of osteoclast formation. Osteoclasts are large cells present in bone which are responsible for bone resorption and therefore these cells contribute to common bone conditions such as osteoporosis, Paget's disease and bone cancer. Osteoporosis causes a great deal of pain and disability and it alone costs the Australian taxpayers more than $400 million per year. Persons wh ....We have found that leptin, a new hormone produced by fat cells which regulates appetite and metabolism, is a powerful inhibitor of osteoclast formation. Osteoclasts are large cells present in bone which are responsible for bone resorption and therefore these cells contribute to common bone conditions such as osteoporosis, Paget's disease and bone cancer. Osteoporosis causes a great deal of pain and disability and it alone costs the Australian taxpayers more than $400 million per year. Persons who are overweight tend to have higher circulating blood levels of leptin and also tend to have denser bones, which suggests that there might be a relationship between blood leptin and bone density or strength. Furthermore, leptin is produced in the bone marrow which is where osteoclasts are produced. Osteoclasts are formed from white blood cells which are present in the bone marrow and the blood. Very recent discoveries have identified a family of new factors which play a key role in the formation of osteoclasts. One of these factors has been called osteoprotegerin and is an inhibitor of osteoclast formation. Mutant mice lacking osteoprotegerin have greatly increased numbers of osteoclasts and severe osteoporosis whereas mutants with too much osteoprotegerin have bones which are much denser than normal. The availability of these factors now allows the generation of human osteoclasts in the laboratory which enables the further study of how the process is regulated. We have found that leptin increases the amount of osteoprotegerin produced by white blood cells and we believe that this is the major way that leptin inhibits osteoclast generation. In this project, we intend to further investigate how and why leptin is able to influence the generation and function of osteoclasts as leptin may be a suitable treatment for osteoporosis and other bone diseases.Read moreRead less
The Effect Of Antiepileptic Medication On Indices Of Bone Health And Risk Factors For Falls And Fractures
Funder
National Health and Medical Research Council
Funding Amount
$469,605.00
Summary
Epilepsy is a common brain disorder and most patients with epilepsy take anti-epileptic drugs (AEDs) for many years. These patients have high rates of bone fractures, but the reasons are uncertain. Earlier studies identifying an association between AED use and bone disease were performed on institutionalised patients, and more recent studies on outpatient populations have been conflicting. A better understanding of this problem is critical for designing potential preventive measures and treatmen ....Epilepsy is a common brain disorder and most patients with epilepsy take anti-epileptic drugs (AEDs) for many years. These patients have high rates of bone fractures, but the reasons are uncertain. Earlier studies identifying an association between AED use and bone disease were performed on institutionalised patients, and more recent studies on outpatient populations have been conflicting. A better understanding of this problem is critical for designing potential preventive measures and treatments. One important additional mechanism by which AEDs may increase fracture risk is impairment of gait and balance, leading to a high risk of falls. We have novel data demonstrating the power of a Twin and Matched Sibling approach to study this important problem. This study showed that chronic AED use was associated with significant deficits in bone mineral density (BMD), a key predictor of the risk of fractures. The proposed project will ask the following questions: 1. Is BMD and estimated bone strength lower in the bones most at risk for fracture in women and men chronically taking AEDs? 2. Is the loss of bone in measurements over time greater in patients continuing to take AEDs? 3. Is the risk of bone loss greater for certain types of AEDs, and is the risk influenced by length of exposure, age and menopausal status? 4. How does AED treatment lead to reductions in BMD and bone strength? 5. Are measures of muscle strength, gait and balance impaired in patients taking AEDs compared with matched people not taking AEDs? The proposed study will utilise twins and pairs of siblings to investigate the effects of the long-term use of AEDs for epilepsy on measures of bone mass and strength, indices of bone turnover, vitamin D status, calcium regulating hormones, mineral levels, sex hormone levels, and measures of muscle strength, gait and balance function. In addition, a group of patients newly commencing AED treatment for epilepsy will be studied over 2 years.Read moreRead less
Osteoblast Control Of Mesenchymal Progenitor Cell Differentiation: The Role Of Glucocorticoids And Wnt Signalling.
Funder
National Health and Medical Research Council
Funding Amount
$443,131.00
Summary
Osteoporosis is an important and growing health issue. Reduced ability to make new bone is an important cause of osteoporosis. In this project we will study how the immature cells which eventually make bone are recruited and controlled. In particular, we will study how genes coding for important growth factors are regulated so that the proper signals are sent to young cells to induce them to become bone-making rather than fat-making cells.
Long-term Effects Of Very Low Energy Diet Versus Conventional Diet On Adiposity, Lean Body Mass, Muscle Strength And Bone Density In Obese Adults, And Mechanisms Promoting Changes
Funder
National Health and Medical Research Council
Funding Amount
$925,990.00
Summary
Very low energy diets (VLEDs) are increasingly used to treat obesity. Of concern is the fact that VLEDs induce adaptive responses that can inhibit loss of – and promote regain of – fatness (particularly belly fat) while decreasing lean body mass, muscle strength and bone density. This project will therefore determine whether VLEDs could have negative effects on body composition that increase the risk of metabolic disease, sarcopenia or osteoporosis, and if so, what are the mechanisms involved.
Effects Of Fast Versus Slow Weight Loss On Fat, Muscle And Bone In Postmenopausal Women
Funder
National Health and Medical Research Council
Funding Amount
$316,450.00
Summary
Very low energy diets (VLED) are increasingly used to treat obesity. Of concern is the fact that VLED induce adaptive responses that can inhibit loss of, and promote regain of, abdominal fat while decreasing lean body mass, muscle strength and bone density. This project will therefore determine whether VLEDs could have negative effects on body composition that increase the risk of metabolic disease, sarcopenia or osteoporosis, and if so, what mechanisms are involved.