Mechanism Of Action Of Sec1p-like Proteins In Membrane Trafficking.
Funder
National Health and Medical Research Council
Funding Amount
$440,250.00
Summary
One of the most important evolutionary changes that has occurred is the development of intracellular compartments. All eukaryotic cells possess numerous membrane-encased structures which provide the basis for intracellular specialisation. For example, in order to degrade unwanted components cells have developed degradative enzymes. It is vital for the cell that these enzymes are sequestered away from other cellular components to avoid destruction of valuable molecules. In addition, the cell has ....One of the most important evolutionary changes that has occurred is the development of intracellular compartments. All eukaryotic cells possess numerous membrane-encased structures which provide the basis for intracellular specialisation. For example, in order to degrade unwanted components cells have developed degradative enzymes. It is vital for the cell that these enzymes are sequestered away from other cellular components to avoid destruction of valuable molecules. In addition, the cell has developed a complex assembly line of modifications that are added to proteins in a specific order as they travel to their final destination within the cell. This necessitates the accurate passage of molecules between compartments, a process known as vesicle transport. To orchestrate the complex network of vesicular transport steps between all of the various intracellular compartments it is necessary to employ complex machinery to guide and check that these steps occur with high fidelity. The goal of our research proposal is to define the function of one of the molecules involved in this control process, the so-called Sec1p proteins. The strength of our proposal lies in the diversity of our approach. We intend to explore the molecular advantages of a relatively simple eukaryotic organism, a yeast cell, and apply the findings obtained from this cell to a more complex but highly related vesicular transport process; that of the insulin-regulated movement of a glucose transporter in mammalian fat and muscle cells. While we intend to apply our findings to the treatment of patients with diabetes, it is our ultimate goal to be able to learn more about this fundamental cell biological process so that we can apply our knowledge to understanding many different disease states.Read moreRead less
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
Prof Parton is a cell biologist studying how the plasma membrane functions in health and in disease. These studies have provided new insights into potential vehicles that can be used to introduce therapeutic agents into cells.
Regulation Of BRCA1 And APC Tumour Suppressor Functions By Nuclear Export
Funder
National Health and Medical Research Council
Funding Amount
$433,500.00
Summary
Cancer cells are unique, in that their ability to divide and grow is no longer controlled. Moreover, the DNA of cancer cells is less stable, and vital control genes often gain small mutations which culminate in a more aggressive or malignant cancer cell. Cancers from different tissues progress and respond in different ways to treatment, and the eventual development of tailored treatments or therapies will require a detailed understanding of how cancers from different tissues arise. Our laborator ....Cancer cells are unique, in that their ability to divide and grow is no longer controlled. Moreover, the DNA of cancer cells is less stable, and vital control genes often gain small mutations which culminate in a more aggressive or malignant cancer cell. Cancers from different tissues progress and respond in different ways to treatment, and the eventual development of tailored treatments or therapies will require a detailed understanding of how cancers from different tissues arise. Our laboratory studies two proteins, BRCA1 and APC, which are encoded by the genes most often associated with breast and colon cancer, respectively. We have made important discoveries linking the movement and location of these proteins inside the cell with their cancer-causing activity. In this project, we will continue to study how and why APC and BRCA1 move between different compartments inside cancer cells, and how this movement can sometimes signal cancer cells to die. Detailed understanding of these processes is essential for the eventual design of drug, peptide or gene therapies aimed at correcting defects in the expression or localisation of APC or BRCA1 in breast or colon cancer cells, and hopefully provide clues for that magic bullet that specifically targets and kills cancer cells.Read moreRead less
Protein / Protein Interactions Important For AMP-activated Protein Kinase Regulation
Funder
National Health and Medical Research Council
Funding Amount
$242,545.00
Summary
The AMP-activated protein kinase (AMPK) is an enzyme that monitors the energy levels of the body. When oxygen and nutrient levels decrease, the energy levels of a cell also decrease leading to activation of the AMPK. This results in activation of energy-producing pathways and inhibition of energy-consuming pathways, allowing cells to match supply with demand to ensure their survival. The AMPK comprises of three proteins that together form a functional enzyme. In this application I aim to obtain ....The AMP-activated protein kinase (AMPK) is an enzyme that monitors the energy levels of the body. When oxygen and nutrient levels decrease, the energy levels of a cell also decrease leading to activation of the AMPK. This results in activation of energy-producing pathways and inhibition of energy-consuming pathways, allowing cells to match supply with demand to ensure their survival. The AMPK comprises of three proteins that together form a functional enzyme. In this application I aim to obtain a thorough understanding of the molecular basis of how the AMPK functions. I will determine how and where the three proteins interact with each other and determine where in a cell at any given time the AMPK can be found. This is an important question to answer because many proteins are inactive within the cytoplasm but when they are bound to the plasma membrane they are active. I have previously found the AMPK to be localized to the cytoplasm, membrane and nuclear compartments of the cell, but little is known about the AMPK s function in these different locations. Activation of the AMPK is known to depend on another protein that is also activated when cellular energy levels decrease. This protein has remained elusive to many researchers over the past few years. I plan to identify this protein using new bioinformatics together with the vast amount of information provided by the sequencing of the human genome. Exercise and reduced caloric intake activate the AMPK, these are associated with health benefits and reduce the risk of cardiovascular and neurodegenerative diseases, diabetes and obesity. For these reasons information on the role of the AMPK may improve our understanding of the reasons these diseases develop.Read moreRead less
Regulation Of The Tumour Suppressors APC And BRCA1 By Nuclear Export
Funder
National Health and Medical Research Council
Funding Amount
$530,874.00
Summary
Cancer cells lack the ability to control their own growth, and thus continously divide in their local environment, leading to tumour formation. Tumour suppressor proteins, like APC and BRCA1, normally function as regulators to help cells respond to outside signals and to stop growing when necessary. The inactivation and altered cellular localisation of tumour suppressor proteins can contribute to cancer development. We have found that the APC and BRCA1 proteins, whose inactivation leads to devel ....Cancer cells lack the ability to control their own growth, and thus continously divide in their local environment, leading to tumour formation. Tumour suppressor proteins, like APC and BRCA1, normally function as regulators to help cells respond to outside signals and to stop growing when necessary. The inactivation and altered cellular localisation of tumour suppressor proteins can contribute to cancer development. We have found that the APC and BRCA1 proteins, whose inactivation leads to development of colon cancer and breast cancer, respectively, contain signals that dictate their movement within the cell. Our novel preliminary findings reveal that APC and BRCA1 are able to move in and out of the cell nucleus. We aim to define how this occurs, and examine how the regulation of their cellular location affects the normal function of these cancer-suppressing proteins. Finally, abnormalities in the nuclear passage of APC or BRCA1 might explain their altered cellular location in cancer cells.Read moreRead less
Structural Studies On SNARE Proteins Involved In Insulin Action
Funder
National Health and Medical Research Council
Funding Amount
$308,263.00
Summary
Diabetes mellitus, a disease characterised by high blood glucose levels, is caused by a relative or absolute deficiency in the activity of insulin. The blood-glucose lowering action of insulin is a result of its ability to stimulate glucose uptake by fat and muscle cells. A major goal of Professor James' laboratory is to identify molecules that are involved in this insulin-regulated uptake of glucose. Professor James has identified and characterised the glucose transporter, GLUT4, a protein that ....Diabetes mellitus, a disease characterised by high blood glucose levels, is caused by a relative or absolute deficiency in the activity of insulin. The blood-glucose lowering action of insulin is a result of its ability to stimulate glucose uptake by fat and muscle cells. A major goal of Professor James' laboratory is to identify molecules that are involved in this insulin-regulated uptake of glucose. Professor James has identified and characterised the glucose transporter, GLUT4, a protein that is normally stored inside muscle and fat cells. In response to insulin stimulation, GLUT4 moves to the cell surface where it functions to transport glucose into the cell. Over the past 5 years Professor James laboratory has, in conjunction with other groups, discovered several key proteins that are involved in the insulin-regulated movement of GLUT4 within the cell. We plan to exploit the therapeutic potential of this biological system by obtaining high resolution three dimensional structures of these key proteins. The resulting structural information will allow us to develop compounds that modify the function of these key proteins. Such compounds could prove useful as novel therapeutic agents in the treatment of diabetes. The purpose of this proposal is to begin to implement this goal. By combining the knowledge and reagents coming out of the work on insulin-regulated glucose transport in Professor James' laboratory with the molecular and structural biology expertise in Dr Martin's, Dr Halliday's and Prof Craik's laboratories we are in a unique position to achieve this highly significant goal.Read moreRead less