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.
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
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
Role Of IGF Binding Protein-3 (IGFBP-3) And IGFBP-5 As Modulators Of Nuclear Hormone Signalling
Funder
National Health and Medical Research Council
Funding Amount
$465,750.00
Summary
The insulin-like growth factors are small proteins involved in the growth of most tissues. Their actions are regulated by binding to larger proteins (known as IGFBPs) in the bloodstream and outside the cell. However, some IGFBPs are also found inside cells, where they seem to carry out other functions. We believe that two of these binding proteins, IGFBP-3 and IGFBP-5, change the way cells respond to vitamin A and vitamin D. These two vitamins are important in cell growth and in the way certain ....The insulin-like growth factors are small proteins involved in the growth of most tissues. Their actions are regulated by binding to larger proteins (known as IGFBPs) in the bloodstream and outside the cell. However, some IGFBPs are also found inside cells, where they seem to carry out other functions. We believe that two of these binding proteins, IGFBP-3 and IGFBP-5, change the way cells respond to vitamin A and vitamin D. These two vitamins are important in cell growth and in the way certain cells perform specialised functions. In test-tube experiments, IGFBP-3 and IGFBP-5 interact directly with the receptors that regulate the effects of these hormones. If the same thing happens inside the cell, IGFBP-3 and IGFBP-5 could change the way these receptors respond to signals from outside the cell. We will investigate what effect these IGFBPs have in living cells and in whole animals and how this may relate to human disease. If we are able to understand how IGFBP-3 and IGFBP-5 affect the way cells respond to vitamin A and D, then we may be able to develop new ways to treat certain human diseases.Read moreRead less
Functional Effects Of Polymorphic Variation Of The Aromatase (CYP19) Gene On Enzyme Activity:relationship To Disease
Funder
National Health and Medical Research Council
Funding Amount
$237,708.00
Summary
After menopause, oestrogen synthesis changes from an ovarian to an adipose source by concersion of androgens to estrogens, a process catalyzed by aromatase, the product of the CYP19 gene. We will generate mutants of the CYP19 gene that we have previously found in humans by site-directed mutagenesis and observe the effects of these mutants on aromatase function. This research will help with diagnosis and treatment of breast and other cancers and osteoporosis in humans .
MALE OSTEOPOROSIS: A POPULATION-BASED STUDY IN GEELONG
Funder
National Health and Medical Research Council
Funding Amount
$432,645.00
Summary
Osteoporosis is a term used to indicate that bones have become thin and fragile. During the ageing process bone fragility increases and fractures occur more easily and more often. Fractures may also occur during normal daily activities, with fractures of the spine, forearm and hip being common. However, many other sites may fracture. This is a serious problem because fractures cause pain, disability and, sometimes, death. Although previously overshadowed by its effect in women, osteoporosis is i ....Osteoporosis is a term used to indicate that bones have become thin and fragile. During the ageing process bone fragility increases and fractures occur more easily and more often. Fractures may also occur during normal daily activities, with fractures of the spine, forearm and hip being common. However, many other sites may fracture. This is a serious problem because fractures cause pain, disability and, sometimes, death. Although previously overshadowed by its effect in women, osteoporosis is increasingly being recognised in men. In Australia, 39% of all fractures occur in men and prognosis for fracture in men is worse than in women. A consequence of increasing male longevity is that osteoporosis will affect a growing number of Australian men. It is anticipated that between 1996 and 2051, the number of men with fracture will double, with a 4-fold increase in the number of male hip fractures. Unless the problem of osteoporosis in men is addressed and effective interventions are implemented, the substantial health burden imposed by age-related fractures will continue to escalate. In this case-control study of fracture risk in men, men with fractures (cases) will be identified prospectively for 3 years from radiological reports. Controls will be selected concurrently, at random from electoral rolls. Anticipated number of cases and controls are 800 and 1400, respectively. Cases and controls will be characterised for risk factors for fracture: bone density and bone geometry will be measured, serum samples collected, and diet, lifestyle and medical history documented by questionnaire. The advantage of this type of data is that information from patients with fracture will be used to tell us about the risk of fracture in healthy, unaffected men and about the characteristics of the Australian male population at risk for fracture. The information can be used in decision making for the individual and in policy making for the whole population.Read moreRead less
Is Periosteal Bone Formation Responsible For Sexual Dimorphism In Bone Fragility
Funder
National Health and Medical Research Council
Funding Amount
$316,320.00
Summary
Men and women sustain fractures as they age because their bones become fragile. Women sustain fractures more often than men. Bone thinning occurs in both sexes but it is usually believed that this thinning or loss of bone is greater in women than men. We have evidence to suggest that this may not be correct. In fact, it is likely that men and women lose a similar amount of bone, about half what they started with, but during ageing, men lay down more bone on the outside surface of the bone than w ....Men and women sustain fractures as they age because their bones become fragile. Women sustain fractures more often than men. Bone thinning occurs in both sexes but it is usually believed that this thinning or loss of bone is greater in women than men. We have evidence to suggest that this may not be correct. In fact, it is likely that men and women lose a similar amount of bone, about half what they started with, but during ageing, men lay down more bone on the outside surface of the bone than women compensating for the similar amount lost on the inside of the bone. We also have evidence to suggest than men and women who get spine fractures do so because the process of laying down bone may fail to occur normally. We will study these processes of bone loss inside the bone and bone gain outside the bone to try to better understand why bones become weak. We will measure the bone size and its density in healthy men and women and patients with fractures to determine how the increasing size of the bone produced by laying down bone on its outside helps to keep it strong and to preserve the bone that would otherwise be lost if it didn't occur or if a disease developed that might reduce the compensatoryRead moreRead less
Investigation Of COX-2 Regulation Of Bone Turnover And Mechanically Induced Bone Formation By Genetic Overexpression.
Funder
National Health and Medical Research Council
Funding Amount
$440,750.00
Summary
This project is important because it uses novel experimental models to advance our knowledge of prostaglandin biology in normal and pathological bone remodelling, and the response of the skeleton to increased physical activity. We expect that a genetic modification in mice to increase the normal production of key prostaglandin enzymes, cyclooxygenase-2 (COX-2), in bone cells will increase the number of cells that remove bone (osteoclasts), and increase bone loss and the rate of bone turnover whe ....This project is important because it uses novel experimental models to advance our knowledge of prostaglandin biology in normal and pathological bone remodelling, and the response of the skeleton to increased physical activity. We expect that a genetic modification in mice to increase the normal production of key prostaglandin enzymes, cyclooxygenase-2 (COX-2), in bone cells will increase the number of cells that remove bone (osteoclasts), and increase bone loss and the rate of bone turnover when compared to normal mice. We believe this will occur via the effect of prostaglandins on expression of genes that control osteoclast formation. This will be tested by examining the structure of the skeleton, and the expression of certain genes, in transgenic mice at different ages from 2-8 months. These effects may be exacerbated in conditions of increased bone turnover, such as postmenopausal bone loss. This will be tested by examining the bone structure and gene expression in adult mice following removal of their ovaries. Due to the role of COX-2 in adaptation of bone to mechanical loading, we also expect the load-bearing skeleton to be more sensitive to increased weight-bearing activity. We will investigate this hypothesis by applying mechanical loads to the tibiae of mice in a controlled manner and then analysing the bone structure. Knowledge of specific pathways by which bone formation can be stimulated is important for developing novel approaches to induction and augmentation of osteogenesis in skeletal diseases associated with ageing or disability, or for maintenance of new bone around implants. The discovery that COX-2 is a key enzyme in mechanotransduction and osteoclastogenesis in bone, and a pharmacological target for modulating inflammation, has considerable clinical significance. Exploiting this knowledge requires precise knowledge of the role of this enzyme in bone remodelling and adaptation and our experiments will contribute significantly to that knowledgeRead moreRead less
The Effect Of Loading On The Size, Shape And Strength Of Cortical Bone During Different Stages Of Maturation
Funder
National Health and Medical Research Council
Funding Amount
$180,000.00
Summary
Osteoporosis is a condition in which the skeleton becomes fragile and susceptible to fractures. It is a public health problem that affects both men and women over the age of sixty. Although osteoporosis affects the elderly, the most opportune time to prevent osteoporosis may be during childhood. Physical activity is a lifestyle factor known to affect the strength of the skeleton. Bone density is commonly used as a measure of bone strength because it is easily measured and is related to the break ....Osteoporosis is a condition in which the skeleton becomes fragile and susceptible to fractures. It is a public health problem that affects both men and women over the age of sixty. Although osteoporosis affects the elderly, the most opportune time to prevent osteoporosis may be during childhood. Physical activity is a lifestyle factor known to affect the strength of the skeleton. Bone density is commonly used as a measure of bone strength because it is easily measured and is related to the breaking strength of bones. However changes in the shape of bones can also affect bone strength with or without an increase in bone density. Changes in bone shape in response to exercise in children or adults have rarely been investigated, and little is known about the effects of exercise on bone shape during different stages of growth. This study is the first to investigate how exercise during childhood may affect bone strength by changing bone shape. 45 elite female tennis players aged between 6 to 18 years have completed two years of this study. 90 novice and competitive male tennis players aged between 6 to 20 years and 60 healthy age matched controls will be asked to participate in this study. Measurements will be made annually for three years. The bone shape and density of the dominant and non-dominant arms of the players will be compared with the children who don't play tennis - comparisons will also be made between i) different stages of puberty and ii) girls and boys. The findings of this study are important because the lifestyle of children today may predispose them to a greater risk of osteoporosis late in life. Physical activity may be the most important modifiable protective factor against fragile bones in old age. The findings of this study will be the first to provide insight into whether there is a unique time during growth when exercise will result in the greatest increase in bone strength by changing bone shape.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.