Defining The Role And Contribution Of Cdc37 To Signal Transduction And Tumourigenesis By Src-family Kinases
Funder
National Health and Medical Research Council
Funding Amount
$411,430.00
Summary
Cells respond to extracellular stimuli, such as growth factors and hormones, by activating intracellular networks of signaling molecules. It is the activation of these signaling networks that is ultimately responsible for mediating the biological responses of cells to extracellular stimuli (e.g. insulin stimulating glucose metabolism by cells). Members of the Src-family of tyrosine kinases are paramount among signaling molecules, as they are able to directly initiate the activation of a cascade ....Cells respond to extracellular stimuli, such as growth factors and hormones, by activating intracellular networks of signaling molecules. It is the activation of these signaling networks that is ultimately responsible for mediating the biological responses of cells to extracellular stimuli (e.g. insulin stimulating glucose metabolism by cells). Members of the Src-family of tyrosine kinases are paramount among signaling molecules, as they are able to directly initiate the activation of a cascade of signaling networks that regulate the activity of the cell. Significantly though, the inappropriate activation of Src-family kinases has been implicated in the development of cancer, particularly breast and colon cancer, in humans. To fulfill their signaling functions however, Src-family kinases must first be folded into an active conformation upon their synthesis in the cell then be maintained in this conformation. Although previous studies, including our own, have implicated a class of proteins called molecular chaperones in this process, little is known about how the folding of Src-family kinases by these proteins is achieved and regulated. The overall aim of this study is to determine how the folding of Hck, one member of the Src-family of tyrosine kinases, into a conformation that enables it to participate in signaling networks is achieved and regulated. It is expected that the results from this study will provide significant new insight into how this process might influence the ability of cells to respond to extracellular stimuli and potentially contribute to the conversion of a normal cell into one with tumourigenic properties. Findings from this project may be particularly important in the context of human cancer. A better knowledge of how the signaling activity of Src-family kinases is regulated by molecular chaperones might provide a new avenue of investigation for the identification of novel chemotherapeutic agents.Read moreRead less
Identification Of The Plasmodium Falciparum Translocon That Exports Parasite Proteins Into Their Erythocytic Hosts.
Funder
National Health and Medical Research Council
Funding Amount
$409,027.00
Summary
Up to 10% of the world's population will suffer from malaria in any given year and for over a million this disease will be fatal. This devastating disease is caused by the parasite Plasmodium falciparum that infects and destroys our red blood cells. Infected red cells are greatly modified by the parasites so they can feed and avoid elimination by the human immune system. We wish to investigate the red blood cell modification process and assess it as a potential target for anti-malarial drugs.
Cytokine Secretion: A Model For Protein Trafficking.
Funder
National Health and Medical Research Council
Funding Amount
$204,111.00
Summary
TNF-a is an inflammatory cytokine with important roles in host defense, tumour regulation and energy homeostatis, however the oversecretion of TNF-a is also a major cause of septic shock, rheumatoid arthritis, Chron?s disease and the cachexia of cancer. TNF-a synthesis and its release from the surface of cells are relatively well understood. However little is known about its trafficking through the secretory pathway of cells. Understanding this process has the potential to provide new ways of co ....TNF-a is an inflammatory cytokine with important roles in host defense, tumour regulation and energy homeostatis, however the oversecretion of TNF-a is also a major cause of septic shock, rheumatoid arthritis, Chron?s disease and the cachexia of cancer. TNF-a synthesis and its release from the surface of cells are relatively well understood. However little is known about its trafficking through the secretory pathway of cells. Understanding this process has the potential to provide new ways of controlling the secretion of TNF-a. In previous work we have characterized transport vesicles and cytoskeletal proteins involved in secretory pathways of epithelial cells. We now propose to focus on the characterization of transport vesicles, and the roles of actin and myosins involved in TNF-a secretion in macrophages. These studies will rely on introducing new technology to this line of research. Fluorescent tagged constructs of TNF-a will be expressed and viewed in living cells to analyse the secretory pathway and measure the transport of TNF-a from its site of accumulation in the Golgi complex to the cell surface. This work aims to identify membrane-bound vesicles and vesicle-associated proteins that target TNF-a for secretion. We will begin to investigate the role of actin and myosins, using drugs and microinjected peptides to block their function. Overall these studies will provide important cell biological information about protein trafficking in cells. Cytokine secretion is important in immunity and cancer, information important to both fields will be gained from these studies.Read moreRead less
FHA Domain-dependent Functions Of Cell Cycle Checkpoint Kinases
Funder
National Health and Medical Research Council
Funding Amount
$235,500.00
Summary
Human chromosomes as carriers of the genetic information are constantly subjected to DNA damage. This usually occurs spontaneously, simply as a result of oxidation of DNA residues as a byproduct of cellular energy consumption or as a result of errors during chromosome duplication in growing cells, and is compounded by chemical or physical agents, for example carcinogens, UV rays or X-rays. DNA damage can have severe consequences if not properly repaired, leading to genomic instability with loss ....Human chromosomes as carriers of the genetic information are constantly subjected to DNA damage. This usually occurs spontaneously, simply as a result of oxidation of DNA residues as a byproduct of cellular energy consumption or as a result of errors during chromosome duplication in growing cells, and is compounded by chemical or physical agents, for example carcinogens, UV rays or X-rays. DNA damage can have severe consequences if not properly repaired, leading to genomic instability with loss of vast tracts of DNA or inappropriate genome rearrangements, that may ultimately give rise to cancer. To prevent such dire consequences, all organisms from yeast to man contain molecular checkpoints that sense the presence of DNA damage and then activate a cellular response program that includes damage repair and prevention of cell division while damage persists. These molecular checkpoints are highly conserved throughout evolution which allows us to analyse the details involved in simple organisms such as yeast, to draw general conclusions on their function in more complex human cells. Along these lines, we are studying the function of two yeast proteins that are similar to the human Chk2 protein, a tumour suppressor that is mutated in a subset of families suffering from the Li-Fraumeni multi-cancer syndrome. We have identified new pathways by which these proteins contribute to the survival of cells after treatment with DNA damaging agents and will further charaterise these in the present proposal.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
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