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
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.
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
The Structural Basis Of Cytokine Signalling Inhibition
Funder
National Health and Medical Research Council
Funding Amount
$239,473.00
Summary
Cell-cell communcation is vital for the correct functioning of the body. Cells need to be told the correct time to divide, to produce certain enzymes or chemicals, to migrate and also when to apoptose, or die. Cells receive these signals through the binding of small soluble proteins called cytokines. Cytokines bind to specialized receptors on the surface of the cell and initiate an intracellular signaling cascade that passes the correct message to the nucleus. It is important that cells react to ....Cell-cell communcation is vital for the correct functioning of the body. Cells need to be told the correct time to divide, to produce certain enzymes or chemicals, to migrate and also when to apoptose, or die. Cells receive these signals through the binding of small soluble proteins called cytokines. Cytokines bind to specialized receptors on the surface of the cell and initiate an intracellular signaling cascade that passes the correct message to the nucleus. It is important that cells react to these protein messengers however it is just as vital that they don't overreact. Many human diseases, especially inflammatory diseases such as rheumatoid arthritis and type II diabetes, are due to aberrant cytokine signaling. To ensure this doesn't occur, cells have evolved a mechanism to quickly switch off the signaling cascade after it has started. This mechanism involves an entire family of proteins, the Suppressors of Cytokine Signalling (SOCS) family. These proteins can act via two distinct mechanisms. The first is to directly block the JAK-STAT proteins, proteins that initiate the intracellular part of the signaling cascade. The second mechanism has been less well studied, it involves the SOCS proteins upregulating the degradation of signaling intermediates. The SOCS proteins can do this through the action of a 40 residue domain called the SOCS box. The SOCS box directs proteins bound to other domains of the SOCS proteins to be degraded by interacting with a complex called an E3 ubiquitin ligase. This project involves determining the three-dimensional atomic structure of the SOCS-E3 ligase interaction and investigating biophysical aspects of the interaction. This information will lead to a fuller understanding of the mechanism of signaling inhibition and will provide information crucial to the design of SOCS inhibitors. Such inhibitors would be therapeutically important in the treatment of a number of human diseases such as cancer, arthritis and type II diabetes.Read moreRead less
Specificity Of Smad Proteins In Transforming Growth Factor-beta Signaling
Funder
National Health and Medical Research Council
Funding Amount
$212,036.00
Summary
Transforming growth factor-betas (TGF-beta) regulate a fascinating array of cellular processes including cell proliferation, differentiation, migration, organization and death, as well as affect a wide range of biological functions, such as embryonic development, hematopoiesis and immune and inflammatory responses. Given the multifunctional nature of TGF-beta action, it is not surprising that the disruptions of TGF-beta functions have been implicated in many human disorders, particularly in colo ....Transforming growth factor-betas (TGF-beta) regulate a fascinating array of cellular processes including cell proliferation, differentiation, migration, organization and death, as well as affect a wide range of biological functions, such as embryonic development, hematopoiesis and immune and inflammatory responses. Given the multifunctional nature of TGF-beta action, it is not surprising that the disruptions of TGF-beta functions have been implicated in many human disorders, particularly in colorectal and pancreatic cancers. The Smad proteins (there are ten of them) are critical components of TGF-beta cellular actions. In fact, Smad4 also called DPC4 for deleted in pancreatic carcinoma locus 4. This project addresses how each Smad protein works at molecular level in the cell, and which part of biological functions it regulates. Collectively, the outcomes of the project may provide clear and specific molecular targets to treat TGF-beta related diseases such as colorectal and pancreatic cancers.Read moreRead less