Recycling Endosomes Governing Cell Polarity And Cytokine Secretion.
Funder
National Health and Medical Research Council
Funding Amount
$958,412.00
Summary
Cytokines are chemical messengers released by cells to mount inflammatory responses to fight infections. The timing and direction of cytokine release must be tightly regulated. We investigate the cellular compartments and molecules that control cytokine secretion using sophisticated live cell imaging. Uncontrolled cytokine release is the main cause of ongoing inflammation in arthritis and inflammatory bowel disease and our studies aim to identify cellular targets for new drug development.
Structural Characterisation Of Phosphopeptide Recognition By FHA Domains
Funder
National Health and Medical Research Council
Funding Amount
$257,036.00
Summary
Cells require numerous signalling pathways to keep various cellular processes coordinated and under control. One of the most important aspects of signalling is formation of complexes involving two or more different proteins. One of the recently identified players in the formation of these signalling complexes is the so-called forkhead-associated (FHA) module, FHA modules are protein sequences of ~130 amino acids that appear as a part of signalling proteins and bind to specific sequences on signa ....Cells require numerous signalling pathways to keep various cellular processes coordinated and under control. One of the most important aspects of signalling is formation of complexes involving two or more different proteins. One of the recently identified players in the formation of these signalling complexes is the so-called forkhead-associated (FHA) module, FHA modules are protein sequences of ~130 amino acids that appear as a part of signalling proteins and bind to specific sequences on signalling protein partners. Many proteins containing FHA modules are important for the repair of damaged DNA and the stability of chromosomes. The aim of our studies is to understand the molecular and atomic details of how FHA modules bind their partners. This is the first step towards designing therapeutic agents against various forms of cancer where DNA is damaged.Read moreRead less
Colorectal cancer is a common malignancy in Australia and the mutation of one gene (Apc) is implicated in >80% of the cases. We aim to understand Apc biochemistry in normal and colon cancer cells by integrating mathematics with our experimental biology program. The main outcomes for this project will be a better understanding of the regulatory systems perturbed in colon cancer. We believe that the insights gained by our research will point the way to more effective treatments of colon cancer.
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
Physiological Significance Of Cellular Translocation Of The Intestine-specific Homeodomain Protein Cdx2
Funder
National Health and Medical Research Council
Funding Amount
$196,527.00
Summary
Ulcerative colitis and Crohn's disease are debilitating inflammatory diseases of the bowel. Conservative estimates (Australian Crohn's and Colitis Association) suggest that at least 23,000 Australians are affected (>1 in 1000). Ten years after onset, there is an estimated risk of 0.5-1.0% per year of pancolitis patients developing full-blown bowel cancer. Current therapies for colon cancer are not very effective and the median survival for patients with metastatic disease is poor at 7-12 mont ....Ulcerative colitis and Crohn's disease are debilitating inflammatory diseases of the bowel. Conservative estimates (Australian Crohn's and Colitis Association) suggest that at least 23,000 Australians are affected (>1 in 1000). Ten years after onset, there is an estimated risk of 0.5-1.0% per year of pancolitis patients developing full-blown bowel cancer. Current therapies for colon cancer are not very effective and the median survival for patients with metastatic disease is poor at 7-12 months. It is therefore important to increase our understanding of the biology underlying these inflammatory conditions so that more effective treatments may be developed and fewer patients proceed to the cancerous stage. We have recently demonstrated a novel interaction between two proteins that may be relevant to intestinal inflammation. Surprisingly, the two proteins would not normally be expected to coincide with each other because of their different localisations within cells and tissues. The first protein, Cdx2, is only synthesised by intestinal lining cells and normally resides in the nucleus where it activates genes that play a role in the highly specialised absorptive functions of the intestine. The other protein, acrogranin-granulin, is more widely distributed in the body and is generally transported out of cells shortly after it has been made. It has been shown to interact with receptors on epithelial cells and blood cells and promotes their growth. In this proposal we will be investigating whether the complex formed between Cdx2 and granulin is important for normal physiology. Moreover since elevated levels of granulin are associated with inflammation, we aim to determine whether the Cdx2-granulin complex is formed during the active phase of ulcerative colitis and Crohn's disease. Specifically, we will test the hypothesis that the Cdx2-granulin complex plays an important role in repairing the damage caused to the lining of the intestine during inflammation.Read moreRead less
LPS-regulated SNAREs And Control Of Cytokine Secretion In Macrophages.
Funder
National Health and Medical Research Council
Funding Amount
$470,750.00
Summary
TNF(tumour necrosis factor alpha) is a potent proinflammatory cytokine secreted by immune activated macrophages. TNF has essential roles in host defense, tumour killing and energy metabolism. Excessive secretion of TNF in acute and chronic inflammatory conditions, such as septic shock, Crohn s disease, rheumatoid arthritis and in cancer has many severe, even fatal, consequences. Improved anti-TNF therapeutics are needed for clinical management in all of these conditions. Our studies are focused ....TNF(tumour necrosis factor alpha) is a potent proinflammatory cytokine secreted by immune activated macrophages. TNF has essential roles in host defense, tumour killing and energy metabolism. Excessive secretion of TNF in acute and chronic inflammatory conditions, such as septic shock, Crohn s disease, rheumatoid arthritis and in cancer has many severe, even fatal, consequences. Improved anti-TNF therapeutics are needed for clinical management in all of these conditions. Our studies are focused on investigating how macrophages synthesize and secrete TNF, with the ultimate goal of characterizing the molecules and vesicles in the TNF secretory pathway. Our recent findings show the expression of SNARE proteins, part of the vesicle docking and fusion machinery, is regulated in concert with cytokine secretion and other trafficking changes in activated macrophages. We identified the proteins Syntaxin4, Munc-18c and SNAP-23 as the specific t-SNARE complex that regulates TNF delivery to the cell surface. In the proposed studies we will investigate how SNAREs are regulated during macrophage activation by studying their gene expression and protein modifications. We have developed a single-cell assay to measure TNF trafficking in macrophages; this allows the identification of molecules with roles in TNF secretion and it will be used in a series of experiments to identify the specific v-SNARE proteins that partner the t-SNARE for TNF delivery. Finally we will use live cell imaging to investigate how and where TNF is delivered to the macrophage cell surface and membrane fractionation to examine a role for membrane microdomains in organizing SNARE-mediated TNF secretion. Manipulation of SNAREs, using data generated by these studies, holds potential for the development of new anti-TNF therapies.Read moreRead less
Role Of FHA Domains As Protein-protein Interaction Modules In Cell Signalling
Funder
National Health and Medical Research Council
Funding Amount
$191,973.00
Summary
The proper processing of information in cells involves the association of different proteins to signalling complexes. We will decipher the role the so-called FHA module plays in the formation of protein complexes. FHA modules are present in several proteins that are important for the repair of damaged DNA and the stability of chromosomes. Understanding the structure and function of this module will be relevant for various forms of cancer where DNA is damaged.
Regulation Of PtdIns(3,4,5)P3 By Inositol Polyphosphate 5-phosphatases
Funder
National Health and Medical Research Council
Funding Amount
$200,880.00
Summary
Growing cells respond to growth factors by dividing and proliferating. Uncontrolled cell growth leads to cancer. Signals are released from the cell membrane following growth factor stimulation, that communicate via a complex network of intracellular signalling molecules, that instruct the nucleus to divide. One critical signalling network that mediates cell growth are the phosphoinositide messenger molecules. These signals are switched off by a family of proteins called inositol polyphosphate 5- ....Growing cells respond to growth factors by dividing and proliferating. Uncontrolled cell growth leads to cancer. Signals are released from the cell membrane following growth factor stimulation, that communicate via a complex network of intracellular signalling molecules, that instruct the nucleus to divide. One critical signalling network that mediates cell growth are the phosphoinositide messenger molecules. These signals are switched off by a family of proteins called inositol polyphosphate 5-phosphatases. We propose the 5-phosphatases are essential for normal cell growth. Several studies have suggested in their absence tumour formation may occurr. We have identified a new member of this enzyme family called SHIP-2. This proposal aims to investigate the mechanisms by which this enzyme family metabolises signalling molecules and thereby regulates cell growth. We will also characterize how the 5-phosphatases control the normal pathways by which primitive cells differeniate into mature cells.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
Regulation Of Body Composition And Glucose Homeostasis By The Adaptor Protein Grb10.
Funder
National Health and Medical Research Council
Funding Amount
$617,256.00
Summary
Resistance to the hormone insulin underlies the development of Type 2 Diabetes. Loss of muscle mass in the elderly contributes to insulin resistance. Recently we identified Grb10 as a new regulator of insulin action and muscle mass. In this proposal, we aim to study how Grb10 affects development and growth of muscle and fat, and the underlying molecular mechanisms. This may lead to new strategies for improving body composition and treating the insulin resistance associated with Type 2 Diabetes.