Ras Signalling And Cholesterol Efflux From Late Endosomes
Funder
National Health and Medical Research Council
Funding Amount
$276,598.00
Summary
Accumulation of cholesterol is a hallmark of early atherosclerotic lesions, known as foam cell formation. Hence the stimulation of cholesterol removal (efflux) from macrophages has great therapeutic potential. High Density Lipoproteins (HDL) and apolipoprotein A-I (apoA-I) stimulate efflux via activation of HDL-apoA-I receptors and poorly understood signalling pathways. This application is investigating the role of the Ras-MAPK signalling pathway in promoting efflux from late endosomes.
Regulation Of Hedgehog Signalling Through Intracellular Trafficking Events
Funder
National Health and Medical Research Council
Funding Amount
$220,500.00
Summary
The hedgehog signalling cascade plays a role in forming almost every organ of the body during development of an embryo. Perturbation of the function of key members of this pathway during embryonic development often results in death in utero or severe childhood abnormalities. In addition, disruption to this pathway also results in a range of cancers, most notably the extremely common skin cancer basal cell carcinoma. In this proposal we aim to investigate in detail the regulatory mechanisms which ....The hedgehog signalling cascade plays a role in forming almost every organ of the body during development of an embryo. Perturbation of the function of key members of this pathway during embryonic development often results in death in utero or severe childhood abnormalities. In addition, disruption to this pathway also results in a range of cancers, most notably the extremely common skin cancer basal cell carcinoma. In this proposal we aim to investigate in detail the regulatory mechanisms which operate to ensure that this complex pathway of interacting molecules functions correctly during embryonic development. By understanding how this regulation occurs we will gain valuable insight into how disruption of this pathway results in such a range of disease, as well as into how agents which modulate this pathway may potentially act in a therapeutic setting.Read moreRead less
Functional Characterization Of Caveolae And Caveolins
Funder
National Health and Medical Research Council
Funding Amount
$140,660.00
Summary
This project aims to study the cellular machinery that allows a cell to respond to its external environment. Specifically, this project focusses on the function of a family of membrane proteins, called caveolins, which are the major protein components of caveolae small pits which cover the surface of many mammalian cells. Caveolins are believed to regulate signalling from the external environment to the cell interior and loss of this regulation leads to uncontrolled growth leading to cancer. Sig ....This project aims to study the cellular machinery that allows a cell to respond to its external environment. Specifically, this project focusses on the function of a family of membrane proteins, called caveolins, which are the major protein components of caveolae small pits which cover the surface of many mammalian cells. Caveolins are believed to regulate signalling from the external environment to the cell interior and loss of this regulation leads to uncontrolled growth leading to cancer. Signalling from the cell surface relies on organisation of signalling components into modules. Our studies suggest that these modules are dependent on specific lipid molecules which form discrete patches, called lipid rafts, on the cell surface. We have hypothesised that caveolins control the lipid molecules associated with lipid rafts and so, indirectly, control signalling pathways. In particular, we have shown that caveolin is important in the regulation of cellular cholesterol, a vital molecule involved in maintaining the function of lipid raft domains. As numerous human diseases are associated with cholesterol imbalance, studies of caveolins can give fundamental new insights into this process, and the previously unidentified links between the cellular lipid balance and signal transduction. This project aims to use mutant caveolin molecules to disrupt caveolin function and so determine the role of caveolin in lipid regulation and in signal transduction. We will then use a lower vertebrate model system, which is amenable to experimental manipulation, to determine the role of caveolins and rafts in the development of the whole embryo.Read moreRead less
The Role Of Cholesterol In Patched/hedgehog Signalling During Mammalian Development.
Funder
National Health and Medical Research Council
Funding Amount
$198,660.00
Summary
Fluctuations in levels of cholesterol during development of the mammalian embryo have been shown to have catastrophic affects leading to gross deformities particularly in terms of brain and facial development. The requirement of the developing embryo for cholesterol has been linked to the patched-hedgehog signalling pathway which we have previously shown to be central to mammalian development as well as tumour formation. In particular, the patched protein which is responsible for regulating sign ....Fluctuations in levels of cholesterol during development of the mammalian embryo have been shown to have catastrophic affects leading to gross deformities particularly in terms of brain and facial development. The requirement of the developing embryo for cholesterol has been linked to the patched-hedgehog signalling pathway which we have previously shown to be central to mammalian development as well as tumour formation. In particular, the patched protein which is responsible for regulating signalling through this complex cascade of protein interactions has a domain similar to that which in other proteins has been shown to detect and respond to intracellular levels of cholesterol. The patched protein binds to hedgehog at the surface of the cell and mediates the transduction of the the hedgehog signal into the cell. By analogy to the role of sterol sensing domains in other proteins, we hypothesise that this domain in patched detects fluctuations in intracellular cholesterol levels which in turn alter trafficking of patched to the cell surface where it can participate in the hedgehog receptor complex. This hypothesis is supported by our preliminary data which suggests that patched is normally localised both at the cell surface and intracellularly. We are proposing a series of experiments to test our hypothesis, most of which deal with determing the localisation of patched in a cell culure system exposed to agents aimed at varying the intracellular levels of cholesterol. Subcellular localisation of patched will be analysed by immunofluorescence, electron microscopy and immunoblotting analysis. We will also test the ability of patched to aggregate at the cell surface with other molecules important in receiving and sending the hedgehog signal. The experiments in this proposal are likely to give the first clues as to the function of the sterol sensing domain in patched and its role in mediating the vital link between cholesterol and embryonic development.Read moreRead less