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
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
New inhibitors of HIV based on cellular enzymes. Over 39 million people are infected with HIV worldwide. However, none of the most highly affected countries have yet reached the peak in AIDS-related illness and death, thus the global impact of HIV/AIDS will get significantly worse, before it gets better.
In Australia, HIV is again on the rise. Ironically, improved treatments that have extended life expectancy will cause the number of HIV infected Australians to rise for many years to come. ....New inhibitors of HIV based on cellular enzymes. Over 39 million people are infected with HIV worldwide. However, none of the most highly affected countries have yet reached the peak in AIDS-related illness and death, thus the global impact of HIV/AIDS will get significantly worse, before it gets better.
In Australia, HIV is again on the rise. Ironically, improved treatments that have extended life expectancy will cause the number of HIV infected Australians to rise for many years to come. Therefore many Australians will suffer from the combined impact of the AIDS illness itself, opportunistic infections, the side-effects of treatment and natural aging. We aim to develop new drugs to combat this disease to help people everywhere lead happier, healthier and more productive lives.Read moreRead less
Sensing atmosphere: Understanding the HNOX-protein gas-sensing capability and how it is affected by heme-oxidation. The project investigates how gas sensing heme-proteins from the novel HNOX (Heme-Nitric Oxide) family are able to discriminate between different gaseous ligands such as O2 and NO and how oxidation of the heme alters this response. The gas-sensing capability of the HNOX proteins is crucial for organisms ranging from bacteria to humans. Thus, understanding of these signalling mechani ....Sensing atmosphere: Understanding the HNOX-protein gas-sensing capability and how it is affected by heme-oxidation. The project investigates how gas sensing heme-proteins from the novel HNOX (Heme-Nitric Oxide) family are able to discriminate between different gaseous ligands such as O2 and NO and how oxidation of the heme alters this response. The gas-sensing capability of the HNOX proteins is crucial for organisms ranging from bacteria to humans. Thus, understanding of these signalling mechanisms will have a strong impact on many scientific fields from the control of pathogen growth to human blood pressure regulation. This collaboration will establish Australian scientists and as world-leading in the field of NO and redox signalling. This development will also be of substantial benefit for the training of the next generation of Australian students and scientists.Read moreRead less
Hierarchical Phosphorylation of Tyrosine Hydroxylase is Dependent on the Activation Sequence of Signaling Pathways. Protein phosphorylation is a fundamental process in biology. It controls protein expression and function in all cells. Hierarchical phosphorylation is defined as the phosphorylation of a protein at one site leading to an altered phosphorylation at another site on the same protein and an altered biological outcome. We have discovered that the enzyme tyrosine hydroxylase undergoes a ....Hierarchical Phosphorylation of Tyrosine Hydroxylase is Dependent on the Activation Sequence of Signaling Pathways. Protein phosphorylation is a fundamental process in biology. It controls protein expression and function in all cells. Hierarchical phosphorylation is defined as the phosphorylation of a protein at one site leading to an altered phosphorylation at another site on the same protein and an altered biological outcome. We have discovered that the enzyme tyrosine hydroxylase undergoes a form of hierarchical phosphorylation not previously reported. Here we examine hierarchical phosphorylation in rat and human tyrosine hydroxylase and its functional consequence in intact cells. The approaches and methods developed will also be applicable to investigation of hierarchical phosphorylation in other proteins.Read moreRead less
The regulation of signalling molecules in Saccharomyces Cerevisiae by inositol polyphosphate 5-phosphatases. Phosphoinositide signalling molecules regulate the actin cytoskeleton, secretion, vesicular trafficking and cell growth and death. We have identified, cloned and characterised a family of signal terminating enzymes called inositol polyphosphate 5-phosphatases (5-phosphatases) that regulate phosphoinositide signalling molecules. We have cloned and characterised four distinct 5-phosphatases ....The regulation of signalling molecules in Saccharomyces Cerevisiae by inositol polyphosphate 5-phosphatases. Phosphoinositide signalling molecules regulate the actin cytoskeleton, secretion, vesicular trafficking and cell growth and death. We have identified, cloned and characterised a family of signal terminating enzymes called inositol polyphosphate 5-phosphatases (5-phosphatases) that regulate phosphoinositide signalling molecules. We have cloned and characterised four distinct 5-phosphatases in the yeast Saccharomyces Cerevisiae and demonstrated by both deletion and overexpression studies that these enzymes regulate the actin cytoskeleton, endocytosis and secretion. This research proposal aims to investigate the signalling complexes the 5-phosphatases form with specific actin binding and or regulatory proteins, investigate the complex interactions of phosphoinositide lipid phosphatases and the roles they play in regulating secretion from the endoplasmic reticulum and finally characterize a novel 5-phosphatase that we have recently identified. Collectively the outcome of these studies will provide novel information about the functionallly significant signalling pathways regulated by this important enzyme family.Read moreRead less
The role of PtdIns(4,5)P2 in cellular responses in Saccharomyces cerevisiae. This grant application falls under the criteria of frontier technologies in genomics/phenomics and complex systems. We are characterizing a highly conserved network of signaling molecules regulated by complex large families of enzymes that regulate the bending of membranes, and cellular events including cell division in plants, yeast and mammalian cells. We have developed cutting edge novel technologies to localize sign ....The role of PtdIns(4,5)P2 in cellular responses in Saccharomyces cerevisiae. This grant application falls under the criteria of frontier technologies in genomics/phenomics and complex systems. We are characterizing a highly conserved network of signaling molecules regulated by complex large families of enzymes that regulate the bending of membranes, and cellular events including cell division in plants, yeast and mammalian cells. We have developed cutting edge novel technologies to localize signaling on specific intracellular membranes and visualise the role cellular lipids play in forming tubules in cells. This project will result in the presentation of Australian research at international forums and support the training of PhD students.Read moreRead less
Mitochondrial proteases and their contribution to protein homeostasis. This research will examine how a critically important cellular organelle known as the mitochondrion maintains its functional integrity by sensing and signalling protein perturbations. As mitochondrial dysfunction is central to a number of neurodegenerative diseases understanding the molecular biology of this fundamentally important cellular process could, in the future, provide for better health outcomes for an aging Australi ....Mitochondrial proteases and their contribution to protein homeostasis. This research will examine how a critically important cellular organelle known as the mitochondrion maintains its functional integrity by sensing and signalling protein perturbations. As mitochondrial dysfunction is central to a number of neurodegenerative diseases understanding the molecular biology of this fundamentally important cellular process could, in the future, provide for better health outcomes for an aging Australian population. The training of post-graduate students is an integral component of this study and thus will contribute to building national research capacity. International collaborations and new discoveries will also contribute to the recognition of Australian research.Read moreRead less