E-cadherin is one of the major proteins responsible for mediating cell-to-cell adhesion in the body. During development, E-cadherin is essential for establishing the cellular architecture of epithelial organs and for maintaining epithelial function in the adult. In this context, E-cadherin acts to establish and maintain the polarity of epithelial cells. E-cadherin is also a powerful tumour suppressor and the loss of E-cadherin expression or function is a primary event in metastasis and cancer in ....E-cadherin is one of the major proteins responsible for mediating cell-to-cell adhesion in the body. During development, E-cadherin is essential for establishing the cellular architecture of epithelial organs and for maintaining epithelial function in the adult. In this context, E-cadherin acts to establish and maintain the polarity of epithelial cells. E-cadherin is also a powerful tumour suppressor and the loss of E-cadherin expression or function is a primary event in metastasis and cancer invasion. Proteins at the surface of epithelial cells must be sorted and trafficked, or transported, to different membrane domains. E-cadherin, for instance, must be trafficked to the lateral domain of cells in order to function in cell-cell adhesion. We recently discovered that cell surface E-cadherin is re-internalized and recycled back to the surface via a pathway that is poised to contribute to the regulation of cell adhesion. Our proposed studies aim to reveal how newly-synthesized E-cadherin and recycling E-cadherin are trafficked, which molecules and which vesicle carriers accomplish this transport. E-cadherin has specific amino acids that act as targeting signals for its sorting and trafficking; we have recently identified one such signal and will now seek the signal responsible for its endocytosis. Using specifically engineered mutants of E-cadherin we will also study other proteins that interact with E-cadherin during its trafficking for sorting and regulation. One of these is polycystin, a protein that is mutated in a common inherited kidney disease. Insights into this disease and normal kidney epithelial function will emerge from this work. A growing understanding of E-cadherin function and regulation is essential for the health of epithelial organs and for controlling and preventing cancer.Read moreRead less
Identification And Characterization Of Novel PI3-kinase Signal Transducing Elements In Platelets
Funder
National Health and Medical Research Council
Funding Amount
$457,500.00
Summary
Platelets play an important role in blood clotting and blood vessel repair. Upon vessel injury, platelets rapidly adhere to the site of damage where they undergo dramatic shape change to spread over the site of injury. Activation and regulation of these processes relies on a complex network of signal transduction processes, involving the integration of multiple receptors and pathways. One pathway demonstrated to play a role in regulating platelet responses is the enzyme phosphatidylinositol 3-ki ....Platelets play an important role in blood clotting and blood vessel repair. Upon vessel injury, platelets rapidly adhere to the site of damage where they undergo dramatic shape change to spread over the site of injury. Activation and regulation of these processes relies on a complex network of signal transduction processes, involving the integration of multiple receptors and pathways. One pathway demonstrated to play a role in regulating platelet responses is the enzyme phosphatidylinositol 3-kinase (PI3-kinase) and its lipid products PtdIns(3,4,5)P3 and PtdIns(3,4)P2. However, very little is known about exactly how PI3-kinase and its products regulate the platelet responses. Our research studies aim to gain a deeper understanding into the molecular mechanisms of PI3-kinase signal transduction in platelets, through the identification and characterization of novel platelet proteins that bind to PI3-kinase lipid products, and to define what role these proteins play in platelet PI3-kinase dependent responses.Read moreRead less
The regulation of signalling molecules in Saccharomyces Cerevisiae by inositol polyphosphate 5-phosphatases. Phosphoinositide signalling molecules regulate the actin cytoskeleton, secretion, vesicular trafficking and cell growth and death. We have identified, cloned and characterised a family of signal terminating enzymes called inositol polyphosphate 5-phosphatases (5-phosphatases) that regulate phosphoinositide signalling molecules. We have cloned and characterised four distinct 5-phosphatases ....The regulation of signalling molecules in Saccharomyces Cerevisiae by inositol polyphosphate 5-phosphatases. Phosphoinositide signalling molecules regulate the actin cytoskeleton, secretion, vesicular trafficking and cell growth and death. We have identified, cloned and characterised a family of signal terminating enzymes called inositol polyphosphate 5-phosphatases (5-phosphatases) that regulate phosphoinositide signalling molecules. We have cloned and characterised four distinct 5-phosphatases in the yeast Saccharomyces Cerevisiae and demonstrated by both deletion and overexpression studies that these enzymes regulate the actin cytoskeleton, endocytosis and secretion. This research proposal aims to investigate the signalling complexes the 5-phosphatases form with specific actin binding and or regulatory proteins, investigate the complex interactions of phosphoinositide lipid phosphatases and the roles they play in regulating secretion from the endoplasmic reticulum and finally characterize a novel 5-phosphatase that we have recently identified. Collectively the outcome of these studies will provide novel information about the functionallly significant signalling pathways regulated by this important enzyme family.Read moreRead less
The role of PtdIns(4,5)P2 in cellular responses in Saccharomyces cerevisiae. This grant application falls under the criteria of frontier technologies in genomics/phenomics and complex systems. We are characterizing a highly conserved network of signaling molecules regulated by complex large families of enzymes that regulate the bending of membranes, and cellular events including cell division in plants, yeast and mammalian cells. We have developed cutting edge novel technologies to localize sign ....The role of PtdIns(4,5)P2 in cellular responses in Saccharomyces cerevisiae. This grant application falls under the criteria of frontier technologies in genomics/phenomics and complex systems. We are characterizing a highly conserved network of signaling molecules regulated by complex large families of enzymes that regulate the bending of membranes, and cellular events including cell division in plants, yeast and mammalian cells. We have developed cutting edge novel technologies to localize signaling on specific intracellular membranes and visualise the role cellular lipids play in forming tubules in cells. This project will result in the presentation of Australian research at international forums and support the training of PhD students.Read moreRead less
The Interaction Between CD46 And PSD-95/Dlg-4: Roles In Cell Polarisation And CD46 Signalling.
Funder
National Health and Medical Research Council
Funding Amount
$70,000.00
Summary
Immune defence against pathogens is primarily achieved by the activities of a range of blood cells, including T cells. T cells have specialised functions involving direct killing of the pathogen, and recruitment and activation of other immune cells. Many of these functions require the lymphocyte to become polarised, or asymmetric, in order to concentrate the appropriate cellular machinery towards the site of activity. Examples of polarisation in lymphocytes includes (i) the formation of a single ....Immune defence against pathogens is primarily achieved by the activities of a range of blood cells, including T cells. T cells have specialised functions involving direct killing of the pathogen, and recruitment and activation of other immune cells. Many of these functions require the lymphocyte to become polarised, or asymmetric, in order to concentrate the appropriate cellular machinery towards the site of activity. Examples of polarisation in lymphocytes includes (i) the formation of a single protrusion, or uropod, that forms the basis for cell-cell interactions, (ii) the formation of an immune synapse which allows a T cell to recognise a pathogen, and (iii) the direction of the cellular killing machinery towards the target. The process of cell polarisation is best characterised in neurons and epithelial cells, both of which are asymmetric. In each cell type, a major mechanism of regulating polarisation is the expression and targeting of a family of proteins containing regions called PDZ domains. PDZ domains mediate protein-protein interactions and so allow the assembly of large molecular scaffolds which hold proteins in specific cell sites. The loss of cell polarity in some cells is thought to cause uncontrolled proliferation and tumour progression, and some of the PDZ-containing proteins are tumour suppressors. We have identified a PDZ-containing protein that is polarised in T cells, and have evidence that this protein interacts with and controls the polarisation of a cell surface receptor whose functions include the regulation of T cell function and proliferation. The aim of this proposal is to determine the mechanisms and functional consequences of polarisation of these two proteins in T cells, and to determine whether their interaction or polarisation is important for T cell proliferation.Read moreRead less
Immune defence against pathogens is primarily achieved by the activities of a range of blood cells, including T cells. T cells have specialised functions involving direct killing of the pathogen, and recruitment and activation of other immune cells. Many of these functions require the lymphocyte to become polarised, or asymmetric, in order to concentrate the appropriate cellular machinery towards the site of activity. Examples of polarisation in lymphocytes includes (i) the formation of a single ....Immune defence against pathogens is primarily achieved by the activities of a range of blood cells, including T cells. T cells have specialised functions involving direct killing of the pathogen, and recruitment and activation of other immune cells. Many of these functions require the lymphocyte to become polarised, or asymmetric, in order to concentrate the appropriate cellular machinery towards the site of activity. Examples of polarisation in lymphocytes includes (i) the formation of a single protrusion, or uropod, that forms the basis for cell-cell interactions, (ii) the formation of an immune synapse which allows a T cell to recognise a pathogen, and (iii) the direction of the cellular killing machinery towards the target. The process of cell polarisation is best characterised in neurons and epithelial cells, both of which are asymmetric. In each cell type, a major mechanism of regulating polarisation is the expression and targeting of a family of proteins containing regions called PDZ domains. PDZ domains mediate protein-protein interactions and so allow the assembly of large molecular scaffolds which hold proteins in specific cell sites. The loss of cell polarity in some cells is thought to cause uncontrolled proliferation and tumour progression, and some of the PDZ-containing proteins are tumour suppressors. We have identified a PDZ-containing protein that is polarised in T cells, and have evidence that this protein interacts with and controls the polarisation of a cell surface receptor whose functions include the regulation of T cell function and proliferation. The aim of this proposal is to determine the mechanisms and functional consequences of polarisation of these two proteins in T cells, and to determine whether their interaction or polarisation is important for T cell proliferation.Read moreRead less
Investigation of a Phagocytic Synapse in the Uptake of Apoptotic Cells. Rapid clearance of cells that die by apoptosis is crucial for embryonic development, tissue turnover, and after inflammatory events. Specialised phagocytes engulf the apoptotic cell corpses in a way that minimises inflammation and prevents autoimmunity. Genetic studies have identified the key evolutionary receptors involved, but the molecular basis of this phagocytosis is still poorly understood. We have developed, and seek ....Investigation of a Phagocytic Synapse in the Uptake of Apoptotic Cells. Rapid clearance of cells that die by apoptosis is crucial for embryonic development, tissue turnover, and after inflammatory events. Specialised phagocytes engulf the apoptotic cell corpses in a way that minimises inflammation and prevents autoimmunity. Genetic studies have identified the key evolutionary receptors involved, but the molecular basis of this phagocytosis is still poorly understood. We have developed, and seek to establish, an integrated model that incorporates new findings to explain how the distinctive functions of specialised receptors can be orchestrated to achieve this function. A successful outcome to the project will provide new knowledge of value to human health.Read moreRead less
Regulation Of Signal Transduction By Cbl: Investigation Of Effects On The Cytoskeleton, Cell Adhesion And Cell Motility
Funder
National Health and Medical Research Council
Funding Amount
$256,527.00
Summary
Changes in cell adhesion and motility have been implicated in a wide range of human pathologies (e.g. immune, reproductive, mental, and cancerous disorders) . Cell adhesion and motility are tightly regulated by a group of proteins known as Rho-GTPases. Novel pharmacological agents that target signalling by Rho-GTPases have been demonstrated to profoundly affect tumour metastasis, as well as central nervous system regeneration following injury. Further exploitation of Rho-GTPase signal modulation ....Changes in cell adhesion and motility have been implicated in a wide range of human pathologies (e.g. immune, reproductive, mental, and cancerous disorders) . Cell adhesion and motility are tightly regulated by a group of proteins known as Rho-GTPases. Novel pharmacological agents that target signalling by Rho-GTPases have been demonstrated to profoundly affect tumour metastasis, as well as central nervous system regeneration following injury. Further exploitation of Rho-GTPase signal modulation, by detailed studies of the molecular mechanisms involved, could lead to significant advances in medical sciences. In particular, treatment of cancer and spinal injuries are likely to benefit from further development of Rho-signalling research.Read moreRead less
Regulation of MHC-I and ICAM-1 by flavivirus, West Nile. This project investigates the intracellular signalling pathway responsible for the expression of genes which are critical to our immune response. We have demonstrated in a mouse model that high levels of expression of two of these genes in flavivirus encephalitis are associated with a survival advantage. We would expect this project to provide basic new information about the mechanisms of expression of these genes as well as information ab ....Regulation of MHC-I and ICAM-1 by flavivirus, West Nile. This project investigates the intracellular signalling pathway responsible for the expression of genes which are critical to our immune response. We have demonstrated in a mouse model that high levels of expression of two of these genes in flavivirus encephalitis are associated with a survival advantage. We would expect this project to provide basic new information about the mechanisms of expression of these genes as well as information about the interaction of this family of viruses, flavivirus with the host.Read moreRead less