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
The project aims to understand how a factor responsible for the production of a type of white blood cell interacts with its receptor. If we knew the molecular details of how this factor works then we would be able to control better diseases, such as osteoporosis and arthritis, where such cells can play havoc by destroying tissue. The project also has implications for certain leukaemias which lose growth control mechanisms in response to this factor.
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.
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
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
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
Regulators Of G Protein Signalling On The Golgi Complex
Funder
National Health and Medical Research Council
Funding Amount
$666,116.00
Summary
The secretion of proteins from cells involves a host of regulatory and signalling proteins. G proteins, signal transducers, located on the Golgi membranes, participate in the budding of transport vesicles in the secretory pathway. A newly-discovered family of Regulators of G Protein Signalling (RGS) proteins perform the critical function of turning off signals generated by G proteins. RGS proteins are powerful, but as yet, ill-defined regulatory molecules. In this study we will identify and char ....The secretion of proteins from cells involves a host of regulatory and signalling proteins. G proteins, signal transducers, located on the Golgi membranes, participate in the budding of transport vesicles in the secretory pathway. A newly-discovered family of Regulators of G Protein Signalling (RGS) proteins perform the critical function of turning off signals generated by G proteins. RGS proteins are powerful, but as yet, ill-defined regulatory molecules. In this study we will identify and characterize RGS proteins in macrophages that are located on Golgi membranes and help to regulate cytokine secretion and other immune functions. More detailed studies on selected RGS proteins will include mutational analysis of functional domains within the proteins and identification of other proteins that interact with RGS proteins. Overall these studies will lead us to understand how specific RGS proteins interact with G proteins and other molecules to regulate signalling in the secretory pathway. Anomalies in cell signalling have severe consequences in a variety of diseases and can cause cancer. Similarly, abnormal secretion in cells contributes to inflammation, diabetes and other disease processes. Information forthcoming from our studies on RGS proteins will have wide-reaching implications and the potential to reveal new targets for therapeutics in these diseases.Read moreRead less
Structural Studies On Cell Signalling Via The LIF Receptor And Gp130
Funder
National Health and Medical Research Council
Funding Amount
$453,943.00
Summary
The cytokines play important roles in the immune system during blood cell development and inflammation, and in nerve growth, bone remodeling, reproduction and heart development. Cell responses are initiated by a cytokine bringing together on the cell surface a receptor complex made up of multiple molecules. This project will investigate the atomic structure of the cell surface macromolecular complex, and hence the underlying mechanism by which cytokine signals are initiated.