Sorting Nexins And Their Role In Endosomal Trafficking
Funder
National Health and Medical Research Council
Funding Amount
$331,000.00
Summary
Cells are able to internalise molecules via membrane-bound vesicles, a process known as endocytosis. Endocytosis is fundamental for many cellular processes, including receptor signalling, uptake of many essential nutrients and the ability to mount an effective lymphocyte response to foreign antigens. Once internalised, cargo is then sorted to different intracellular destinations of the endosomal transport system. The ultimate destination depends on the particular cargo molecule. The importance o ....Cells are able to internalise molecules via membrane-bound vesicles, a process known as endocytosis. Endocytosis is fundamental for many cellular processes, including receptor signalling, uptake of many essential nutrients and the ability to mount an effective lymphocyte response to foreign antigens. Once internalised, cargo is then sorted to different intracellular destinations of the endosomal transport system. The ultimate destination depends on the particular cargo molecule. The importance of the endosomal transport system is also highlighted by the discovery that many human diseases, including various cancers, lysosomal storage diseases and hypercholesterolemia, are linked to defects in trafficking along the endocytic pathway. Furthermore, a number of viral pathogens, such as HIV, and toxins, such as shiga toxin, exploit the endosomal system to gain entry into a cell. Understanding the molecular details of the sorting events within the endosomal system is necessary to be able to consider therapeutic manipulation of the trafficking of specific cargo molecules. The study seeks to understand the molecular details of the endosomal sorting machinery, knowledge that will underpin future efforts to develop drugs to manipulate movement of proteins within the endosomal system. In the long term, this could allow for the manipulation of a variety of cellular functions including the inhibition of proliferative signals in tumour cells.Read moreRead less
Functional Characterisation Of N4WBP5 And N4WBP5A, Novel Nedd4-interacting Proteins
Funder
National Health and Medical Research Council
Funding Amount
$480,750.00
Summary
The proteins that make up a cell must be correctly localised in order to perform their normal function. Specialised cellular activities are carried out in distinct compartments within a cell and proteins must correctly localise in them and traffic between them. Intracellular protein trafficking is a highly regulated process involving many components. Recent findings have shown that intracellular trafficking is regulated in many cases by distinct protein modifications. One such modification is ta ....The proteins that make up a cell must be correctly localised in order to perform their normal function. Specialised cellular activities are carried out in distinct compartments within a cell and proteins must correctly localise in them and traffic between them. Intracellular protein trafficking is a highly regulated process involving many components. Recent findings have shown that intracellular trafficking is regulated in many cases by distinct protein modifications. One such modification is tagging of a small protein called ubiquitin to proteins that are being trafficked. A focus of research in our laboratory is the study of a protein, called Nedd4, which directly tags proteins with ubiquitin. We have recently identified two novel proteins that interact with Nedd4 and localise to distinct subcellular compartments that are sites for the correct sorting and delivery of proteins trafficking within the cell. The main aim of our proposal is to characterise how these proteins function. We propose that these proteins are involved in intracellular trafficking and that they may function by targeting Nedd4 to the cellular trafficking machinery. This may be required for Nedd4 to tag molecules with ubiquitin that are involved in intracellular trafficking. Our experiments will test the functional relationship between Nedd4 and the novel proteins and determine the particular trafficking pathways in which these proteins are involved. Defects in cellular processes regulated by Nedd4 and other similar proteins cause a number of human diseases including an inherited form of hypertension and a specific group of cancers. In addition, a large number of human diseases result directly from defects which disrupt intracellular trafficking pathways. The results of this study will provide further insight into this essential cellular process and may ultimately contribute to the development of therapies for diseases resulting from defects in intracellular trafficking.Read moreRead less
Functional Characterization Of Caveolae And Caveolins
Funder
National Health and Medical Research Council
Funding Amount
$140,660.00
Summary
This project aims to study the cellular machinery that allows a cell to respond to its external environment. Specifically, this project focusses on the function of a family of membrane proteins, called caveolins, which are the major protein components of caveolae small pits which cover the surface of many mammalian cells. Caveolins are believed to regulate signalling from the external environment to the cell interior and loss of this regulation leads to uncontrolled growth leading to cancer. Sig ....This project aims to study the cellular machinery that allows a cell to respond to its external environment. Specifically, this project focusses on the function of a family of membrane proteins, called caveolins, which are the major protein components of caveolae small pits which cover the surface of many mammalian cells. Caveolins are believed to regulate signalling from the external environment to the cell interior and loss of this regulation leads to uncontrolled growth leading to cancer. Signalling from the cell surface relies on organisation of signalling components into modules. Our studies suggest that these modules are dependent on specific lipid molecules which form discrete patches, called lipid rafts, on the cell surface. We have hypothesised that caveolins control the lipid molecules associated with lipid rafts and so, indirectly, control signalling pathways. In particular, we have shown that caveolin is important in the regulation of cellular cholesterol, a vital molecule involved in maintaining the function of lipid raft domains. As numerous human diseases are associated with cholesterol imbalance, studies of caveolins can give fundamental new insights into this process, and the previously unidentified links between the cellular lipid balance and signal transduction. This project aims to use mutant caveolin molecules to disrupt caveolin function and so determine the role of caveolin in lipid regulation and in signal transduction. We will then use a lower vertebrate model system, which is amenable to experimental manipulation, to determine the role of caveolins and rafts in the development of the whole embryo.Read moreRead less
Inhibition Of Nef-activated Src-family Kinases By CHK
Funder
National Health and Medical Research Council
Funding Amount
$514,307.00
Summary
HIV hijacks infected blood cells to produce its own proteins. Nef is one of these proteins and Nef alone is sufficient to cause an AIDS-like disease. Recently, we discovered that a protein called CHK can inhibit Nef. Our research will determine how CHK inhibits Nef and test the feasibility of drugs based on CHK. Such drugs would slow AIDS progression, assisting conventional therapies and patients' immune systems to combat the infection, leading to longer, healthier, more productive lives.
Inside our cells is a complex traffic system. The vehicles are vesicles that come in different shapes and sizes and travel to specific destinations in the cell to deliver cargo such as: surface growth factor receptors that are to have their signalling terminated, proteins and lipids destined for the cell wall for growth or development (like neurite outgrowth) and proteins and hormones destined for secretion (like neurotransmitter release). More than 100 human genetic disorders map to defects in ....Inside our cells is a complex traffic system. The vehicles are vesicles that come in different shapes and sizes and travel to specific destinations in the cell to deliver cargo such as: surface growth factor receptors that are to have their signalling terminated, proteins and lipids destined for the cell wall for growth or development (like neurite outgrowth) and proteins and hormones destined for secretion (like neurotransmitter release). More than 100 human genetic disorders map to defects in one of the components of this system. Proteins called small GTPases provide order for this traffic and allow specific cargo to reach specific destinations. They regulate cell functions by acting as switches, turning biochemical processes on and off inside the cell. Ral is a small GTPase enzyme found in brain and broadly distributed in other cells. We have discovered that Ral is part of a large signalling complex. When activated Ral stimulates effectors, either the exocyst or RalBP1. In turn, mild oxidative stress controls a Ral inhibitor protein called ERp57. The research proposed aims to establish the functional role for the Ral signalling complex in cells. We will determine with which vesicle trafficking events Ral is associated, which effector it utilises in that pathway, and how that effector directs the traffic. We will also map the steps that may lead to inactivation of Ral via ERp57 in cells, and propose that this is mediated by mild oxidative stress. Techniques of molecular biology, biochemistry, molecular biology, proteomics and microscopy will be used to establish these functions. The research will lead to increased knowledge of the significance of this protein to cellular and particularly neuronal cell function. This forms the basis for understanding normal cell function and for identification of further factors causing diseases of vesicle transport. In time, such research aids in the development of specific therapies for sufferers of such diseases.Read moreRead less
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