Caltrin As A Calcium Transport Inhibitor During Osteoclastic Bone Resorption
Funder
National Health and Medical Research Council
Funding Amount
$196,527.00
Summary
Excessive bone resorption has been observed in many common bone diseases such as osteoporosis, Paget's disease and arthritis. These are major health problems in Australia and other developed countries. Increased activation or formation of osteoclasts is responsible for the excessive bone resorption. Understanding the mechanisms by which the osteoclasts exert its function and activation is an important step toward developing strategies to combat excessive bone resorption for the treatment and pre ....Excessive bone resorption has been observed in many common bone diseases such as osteoporosis, Paget's disease and arthritis. These are major health problems in Australia and other developed countries. Increased activation or formation of osteoclasts is responsible for the excessive bone resorption. Understanding the mechanisms by which the osteoclasts exert its function and activation is an important step toward developing strategies to combat excessive bone resorption for the treatment and prevention of osteolytic disorders. This project attempts to address the important and fundamental issue of osteoclast function. We have identified caltrin, a known calcium transport inhibitor, that is likely to be biologically important in osteoclast calcium homeostasis. This project intends to investigate the role of caltrin in calcium-induced apoptosis, osteoclast bone resorption and the cellular and molecular mechanisms underlined. It will enhance our knowledge of calcium regulation in osteoclasts and provide information to facilitate the development of new anti-resorptive agents.Read moreRead less
The Role Of V-ATPase Accessory Subunit Ac45 In Osteoclasts
Funder
National Health and Medical Research Council
Funding Amount
$235,500.00
Summary
Osteoclasts are directly related to many lytic bone disorders including osteoporosis, osteoarthritis and Paget's diseases. Development of strategies to control the formation or activities of osteoclasts has been a major focus of bone research. The vacuolar proton pump (V-ATPase) located on the plasma membrane of the osteoclast is responsible for creating a low pH environment critical for bone resorption, and therefore a potential molecular target for the discovery of novel bone antiresorptive ag ....Osteoclasts are directly related to many lytic bone disorders including osteoporosis, osteoarthritis and Paget's diseases. Development of strategies to control the formation or activities of osteoclasts has been a major focus of bone research. The vacuolar proton pump (V-ATPase) located on the plasma membrane of the osteoclast is responsible for creating a low pH environment critical for bone resorption, and therefore a potential molecular target for the discovery of novel bone antiresorptive agents useful for the treatment of lytic bone disorders. The proposed research will give considerable insight into the role of the both V-ATPase accessory subunit Ac45 and V-ATPase complex in osteoclasts. Understanding the molecular and cellular mechanisms by which V-ATPases regulate osteoclast bone resorption will facilitate the development of novel and selective inhibitors for the treatment of lytic bone disorders.Read moreRead less
Osteal Macrophages: Novel Regulators Of Osteoblast Function And The Endosteal Stem Cell Niche
Funder
National Health and Medical Research Council
Funding Amount
$406,125.00
Summary
Bone diseases are a major health problem and current treatments are inadequate. We are investigating a novel role for macrophages (cells important in tissue maintenance and immune responses) in bone growth, repair and disease. Greater understanding of this will provide new ways to treat bone disease. We will also determine if these macrophages help support stem cells that reside near bone surfaces, which may provide new treatment strategies to improve bone marrow transplantation in cancer.
Vertebral Body Strength: Contribution Of Bone Mass, Bone Structure And Material Properties
Funder
National Health and Medical Research Council
Funding Amount
$434,498.00
Summary
This study will determine the contributions to vertebral body strength made by its structural and material properties. Using state-of-the-art computed-tomography scanners, digitised representations of vertebral bodies in three-dimensions will be produced, which enable measurement of bone structure. After strength testing of the vertebral bodies, the structural and material properties, which combine to predict vertebral body strength, will be identified in an aged population.
Intrinsic Bone Qualities In Fragility Fracture Patients: Mass, Microarchitecture, Mineralization And Damage Accumulation
Funder
National Health and Medical Research Council
Funding Amount
$447,027.00
Summary
Osteoporosis drug therapies have been associated with a significant reduction in fragility fracture. Patients receiving osteoporosis drugs, which have different effects on BMD, may have similar reductions in fractures. Furthermore, patients with fragility fractures may have abnormalities in bone structural and material properties. Changes to the process of bone renewal, due to drug therapy, may explain why fracture risk decreases where no detectable change to the structure of bone has been detec ....Osteoporosis drug therapies have been associated with a significant reduction in fragility fracture. Patients receiving osteoporosis drugs, which have different effects on BMD, may have similar reductions in fractures. Furthermore, patients with fragility fractures may have abnormalities in bone structural and material properties. Changes to the process of bone renewal, due to drug therapy, may explain why fracture risk decreases where no detectable change to the structure of bone has been detected. It has also been shown that when bone renewal is suppressed microdamage accumulates in bone tissue, leading to reduced bone toughness. The toughness of bone is of primary importance in relation to fragility fractures, and it has been shown that the fatigue strength and fracture toughness (work to fracture) reduce considerably with age. This proposed study would seek to elucidate the role of bone tissue-level properties in determining bone quality for human subjects: patients with fragility hip fractures on no osteoporosis drugs therapy, hip fracture patients on osteoporosis drugs therapies, and normal age- and sex-matched individuals. Our laboratory has extensive experience in the analysis of the structure of human bone tissue. Recently, we have developed novel and unique techniques to assess bone quality, using micro-CT, backscatter SEM imaging, confocal microscopy and immunohistochemistry. This multifaceted study will identify at the bone tissue-level the structural mechanisms (micro-architecture, mineralisation, and microscopic cracking) that are indicative of the efficacy of fragility fracture drugs. Better understanding of the mechanisms by which bones are less likely to fracture will enable better targeting of osteoporosis drug therapy to individuals at risk of fragility fracture.Read moreRead less
Prostaglandin G/H Synthase-2 (PGHS-2) Is A Key Regulator Of Skeletal Adaptation And Remodelling
Funder
National Health and Medical Research Council
Funding Amount
$301,018.00
Summary
Knowledge of the biology underlying bone formation is important for developing novel approaches to stimulate new bone formation in skeletal diseases associated with ageing or disability, or for maintenance of new bone around orthopaedic or dental implants. The discovery that a prostaglandin enzyme (PGHS-2) is a key factor in activity-related bone formation and normal bone turnover, as well as a pharmacological target for reducing inflammation, has considerable clinical significance. Specific inh ....Knowledge of the biology underlying bone formation is important for developing novel approaches to stimulate new bone formation in skeletal diseases associated with ageing or disability, or for maintenance of new bone around orthopaedic or dental implants. The discovery that a prostaglandin enzyme (PGHS-2) is a key factor in activity-related bone formation and normal bone turnover, as well as a pharmacological target for reducing inflammation, has considerable clinical significance. Specific inhibition of PGHS-2 by recent anti-inflammatory drugs avoids formation of gastric ulcers, but their influence on normal bone remodelling and fracture repair is not known and must be investigated. Many such inhibitors are in advanced clinical trials, but their effect on bone metabolism has not been published. This project is important because it employs novel experimental models to advance our knowledge of prostaglandin biology in skeletal adaptation, and elucidates important clinical consequences for specific inhibition of PGHS-2 in the skeleton. This project will investigate the regulation of prostaglandin production by PGHS enzymes following mechanical loading in vivo. It will use cell, molecular and histochemical techniques to determine if the genes that regulate the enzymes are influenced by mechanical stimuli, and if they are dependent on other molecules, associated with structural proteins (stress fibres) within the cell. It will investigate if inhibition of PGHS-2 by antiinflammatory drugs or stress-fibre inhibitors, depresses normal bone turnover and healing responses. The outcome of these experiments could indicate new approaches to stimulate bone formation, preserve bone mass, or minimise adverse skeletal effects of anti-inflammatory treatments related to orthopaedic or dental procedures.Read moreRead less
Structural And Functional Analyses Of Rat Receptor Activator Of NF-kb Ligand
Funder
National Health and Medical Research Council
Funding Amount
$226,320.00
Summary
Rat RANKL (Xu and Zheng, rat RANKL, AustraliaProvisional Patent PQ3147) has a variety of biological activities including osteoclast differentiation and polarization, and dendritic cell function. Overproduction or increased activity of RANKL can result in excessive osteoclast formation, activation, and bone resorption. This process contributes to many common bone lytic disorders such as osteoporosis, Paget's disease, bone metastatic diseases, arthritis, aseptic bone loosening and non-union of fra ....Rat RANKL (Xu and Zheng, rat RANKL, AustraliaProvisional Patent PQ3147) has a variety of biological activities including osteoclast differentiation and polarization, and dendritic cell function. Overproduction or increased activity of RANKL can result in excessive osteoclast formation, activation, and bone resorption. This process contributes to many common bone lytic disorders such as osteoporosis, Paget's disease, bone metastatic diseases, arthritis, aseptic bone loosening and non-union of fractures. This proposal addresses the important and fundamental issue of RANKL regarding the role of molecular structure on its biological function. We have established that the TNF-like core domain is the functional domain, important for osteoclastogenesis, osteoclast polarisation and protecting against Fas-triggered apoptosis. This proposal will further characterise the mutant forms of the TNF-like core domain of RANKL using site directed mutagenesis and protein truncation analysis, and assess their respective binding activities to OPG and RANK, and their biological activities both in vitro and in vivo. It will lead us into better understanding of the structure-function relationship of RANKL. Ideally, we would like to develop a relative agent for the suppression of osteolysis in orthopaedic related diseases including osteoporosis. Such an optimized molecule could become a potent therapeutic agent that selectively inhibits osteoclast formation and bone resorption.Read moreRead less
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
Cartilage Destruction In Joint Disease: Studies With ADAMTS-4 And ADAMTS-5 Deficient Mice
Funder
National Health and Medical Research Council
Funding Amount
$540,600.00
Summary
In healthy joints the proteoglycan, aggrecan, gives cartilage compressive resilience to permit weight bearing, but in disease aggrecan is degraded by ADAMTS enzymes. The challenges to the field are to determine which ADAMTS is involved, when these enzymes are active and precisely where they come from. We hypothesise that ADAMTS-4 and-or ADAMTS-5 is involved in cartilage pathology. To test this hypothesis we aim to [1] Generate mice containing mutant ADAMTS-4 and-or -5 in all cells, or [2] in car ....In healthy joints the proteoglycan, aggrecan, gives cartilage compressive resilience to permit weight bearing, but in disease aggrecan is degraded by ADAMTS enzymes. The challenges to the field are to determine which ADAMTS is involved, when these enzymes are active and precisely where they come from. We hypothesise that ADAMTS-4 and-or ADAMTS-5 is involved in cartilage pathology. To test this hypothesis we aim to [1] Generate mice containing mutant ADAMTS-4 and-or -5 in all cells, or [2] in cartilage cells only. [3] Analyse mutant mice for changes in skeletal architecture, changes in ADAMTS mRNA and protein, and changes in aggrecan breakdown products. [4] Assess disease severity in mutant mice in in vivo models of joint disease. We already have mice with ADAMTS-4, or -5, mutated in all tissues and we are generating the double mutants now. We will also generate single and double mutants with dysfunctional enzymes in cartilage only. We will examine skeletal structure by histology and X-ray at all ages and monitor for expression of ADAMTS-1 and -9 to detect any compensatory over-production of other potential 'aggrecanases'. We will also do co-culture experiments in which cartilage and synovial cells from combinations of mutant and control mice will be incubated together to determine whether synovial ADAMTS can penetrate and degrade aggrecan in cartilage. Finally we will induce arthritis in mutant and control mice and monitor them to detect differences in the time of disease onset, the rate of disease progression and overall disease severity. A comparison of whole-mouse with cartilage only mutants in the in vivo models will complement the in vitro co-culture studies and determine whether other joint tissues such as synovium and joint capsule can also produce ADAMTS enzymes that destroy cartilage. This is not known. Together these experiments will reveal if, where and when ADAMTS-4 and-or -5 are active, and whether indeed they are the best targets for drug development.Read moreRead less