Osteoclasts (OC) are large multinucleated cells present in bone that are responsible for bone resorption. The renewal of bone and bone growth are regulated by the opposing actions of OCs and osteoblasts, cells that form new bone. Together, with other accessory cells in the bone marrow, these constitute 'bone-forming units' (BFU). Excess production or over-activation of OCs in the BFU leads to common bone conditions such as osteoporosis, Paget's disease and the bone lysis caused by bone cancers. ....Osteoclasts (OC) are large multinucleated cells present in bone that are responsible for bone resorption. The renewal of bone and bone growth are regulated by the opposing actions of OCs and osteoblasts, cells that form new bone. Together, with other accessory cells in the bone marrow, these constitute 'bone-forming units' (BFU). Excess production or over-activation of OCs in the BFU leads to common bone conditions such as osteoporosis, Paget's disease and the bone lysis caused by bone cancers. Osteoporosis causes a great deal of pain and disability and it alone costs the Australian taxpayers more than $400 million per year. OCs are formed from white blood cells that are present in the bone marrow and the blood. The recent discovery of a family of new factors that control the formation of OCs has enabled the generation of human OCs in the laboratory so now we can investigate the genes that control the process of conversion of white blood cells to OCs. An important advance in this project involves the use of cord blood that contains stem cells. These very na ve cells will enable us to study the very earliest genes that control differentiation of precursors to OC. We have found a number of genes that are regulated by these new bone-forming factors. In white blood cells the activation of particular genes can regulate OC formation. One example is vitamin D-upregulated gene, VDUP. This gene is of particular interest as it causes inhibition of the mechanism that leads to OC formation in the bone. Obviously, the ability to control a 'switch' that regulates OC formation may enable us to control the progress of bone loss in diseases such as osteoporosis. In this project, we intend to investigate how and why the genes that lead to OC formation are regulated and what influence the various bone cell factors have on the formation of bone-resorbing OCs. These studies will lead to the development of treatments for osteoporosis and other bone diseases.Read moreRead less
Histone Demethylase KDM6A Is A Novel Target For Treating Craniosynostosis In Children With Saethre-Chotzen Syndrome
Funder
National Health and Medical Research Council
Funding Amount
$548,854.00
Summary
Children with Saethre-Chotzen syndrome exhibit premature fused coronal sutures, and other skull/ skeletal malformations. Surgical intervention is the only treatment option to ensure optimal cognitive and skeletal development. Our studies have identified a candidate molecular pathway that regulates bone formation by cranial bone cells from these patients. Targeting this key molecular regulator with chemical inhibitors will help prevent the premature fusion of cranial sutures.
Tyrosine Kinase Receptor C-ros-oncogene 1 Mediates Twist-1 Haploinsufficiency Induced Craniosynostosis In Children: A Novel Therapeutic Target
Funder
National Health and Medical Research Council
Funding Amount
$562,863.00
Summary
Children with Saethre-Chotzen syndrome exhibit premature fussed coronal sutures, and other skull/ skeletal malformations. Surgical intervention is the only treatment option to ensure optimal cognitive and skeletal development. Our studies have identified a candidate molecular pathway that regulates bone formation by cranial bone cells from these patients. Targeting these key molecular signalling components with chemical inhibitors will help prevent the premature fusion of cranial sutures.
The Role Of P62/A170 In Pathological Bone Destruction
Funder
National Health and Medical Research Council
Funding Amount
$276,000.00
Summary
Approximately up to 30% of patients are admitted to public hospitals in Australia for reasons related to skeletal disorders, including trauma, osteoarthritis, osteoporosis, primary and secondary bone tumours, genetic and metabolic disorders. Abnormal bone resorption contributes to most of these diseases and conditions. Based on the clinical evidence of P62 mutation in patients with Paget's Disease of bone and our observation of the involvement of P62 in RANKL-induced NF-Kb signaling, we propose ....Approximately up to 30% of patients are admitted to public hospitals in Australia for reasons related to skeletal disorders, including trauma, osteoarthritis, osteoporosis, primary and secondary bone tumours, genetic and metabolic disorders. Abnormal bone resorption contributes to most of these diseases and conditions. Based on the clinical evidence of P62 mutation in patients with Paget's Disease of bone and our observation of the involvement of P62 in RANKL-induced NF-Kb signaling, we propose that intracellular molecule P62-A172 may play an important part in the switch off-on signals necessary for bone resorbing cells to resorb bone. To this end, we will study the molecular mechanism of P62 in action, and the interaction with its possible partners for the facilitation of abnormal bone resorption. The clinical significance of this project is to: 1) enhance understanding of abnormal bone resorption in Orthopaedic related diseases and conditions. 2) provide a strategy of drug development for the treatment of these disease and conditions.Read moreRead less
Molecular Determinants Of Bone Remodelling In The Bone Microenvironment
Funder
National Health and Medical Research Council
Funding Amount
$317,640.00
Summary
There is little information regarding the expression of specific molecules in human bone tissue or their role in skeletal disease. The process of bone remodelling is fundamental for the maintenance of skeletal integrity. Our understanding of the molecular signalling involved in activating bone remodelling is principally derived from tissue culture and animal experiments. We will study human cancellous bone samples donated by patients undergoing surgery, and with the consent of the next-of-kin, t ....There is little information regarding the expression of specific molecules in human bone tissue or their role in skeletal disease. The process of bone remodelling is fundamental for the maintenance of skeletal integrity. Our understanding of the molecular signalling involved in activating bone remodelling is principally derived from tissue culture and animal experiments. We will study human cancellous bone samples donated by patients undergoing surgery, and with the consent of the next-of-kin, taken at autopsy. These molecular and histomorphometric studies will determine whether the understanding derived from tissue culture and animal experiments is consistent with associations demonstrable in the human cancellous bone microenvironment. The elucidation of the molecular signalling in the human bone microenvironment is essential for the effective diagnosis and treatment of bone disease. Recently reported studies have shown very persuasively that fatigue microdamage accumulates in the skeleton and is targeted for repair by remodelling. Our preliminary data shows that microcrack length is positively correlated with IL-11 mRNA gene expression. We will further investigate mRNA gene expression of a number of cytokines involved in bone cell signalling and their association with the level of microdamage in the bone. Using a animal model of controlled bone microdamage induction we will seek to determine the bone remodelling causal relationship between microdamage and cytokine signalling. Furthermore, the cellular and molecular mechanisms that lead to trabecular structures are not well understood. These studies will provide new insight into the processes that determine trabecular structures. This project will investigate these mechanisms and increase our understanding of bone cell function, essential for diagnosis and design of rational treatment for bone diseases.Read moreRead less
The Characterisation Of The Genetic Basis Of Paget's Disease Of Bone
Funder
National Health and Medical Research Council
Funding Amount
$266,402.00
Summary
Paget's disease is a bone disease in which the normal process of bone being formed and then broken down doesn't take place in the usual way. This results in bones that are enlarged, misshapen, dense and fragile. Paget's disease usually affects people of middle age or older. Although some cases are asymptomatic, Paget's disease is a major cause of bone pain and deformity. In Australia, 3-5% of people aged 40 years and over have Paget's disease. Paget's disease usually affects one of the long bone ....Paget's disease is a bone disease in which the normal process of bone being formed and then broken down doesn't take place in the usual way. This results in bones that are enlarged, misshapen, dense and fragile. Paget's disease usually affects people of middle age or older. Although some cases are asymptomatic, Paget's disease is a major cause of bone pain and deformity. In Australia, 3-5% of people aged 40 years and over have Paget's disease. Paget's disease usually affects one of the long bones in the leg, the pelvic bone, the skull or the spine. One of the most serious complications of Paget's disease is the devlopment of bone cancer. A genetic predisposition is an important factor in the development of Paget's disease. At least a quarter of patients with Paget's disease have at least one close relative with the same condition. Although it is more than 100 years since Sir James Paget first described Paget's disease, the underlying cause remains unknown. We have identified a large family with over 200 members in which there are 35 subjects affected by Paget's disease. The pattern of inheritance in this family is consistent with an autosomal dominant disorder. We have identified a discrete genetic region that is linked with the inheritance of Paget's disease in this family, indicating that a suscpetibility gene for Paget's disease lies in this region. The research program outlined in this application will refine this localisation and will define and characterise this susceptibility gene for Paget's disease. This research program is of great clinical relevance as the identification of the causative gene will open up new approaches for the treatment and prevention of this disease.Read moreRead less
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
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
I am a biochemical geneticist working on inherited disorders that affect the musculoskeletal system. My major focus is determining the molecular basis of muscular dystrophies and bone and cartilage disorders.