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
Characterisation Of Putative Targets Of The Ubiquitin-protein Ligase, Nedd4
Funder
National Health and Medical Research Council
Funding Amount
$258,055.00
Summary
Cellular proteins are synthesised and degraded depending on the metabolic state of the cell. The normal turnover of a number of cellular proteins is mediated by a complex pathway involving a highly conserved polypeptide called ubiquitin. Ubiquitin-dependent proteolysis of a number of proteins is essential for the maintenance of the health of a cell. Many cell cycle proteins, membrane channels, receptors and products of some oncogenes are known targets of the ubiquitin-dependent turnover. Clearly ....Cellular proteins are synthesised and degraded depending on the metabolic state of the cell. The normal turnover of a number of cellular proteins is mediated by a complex pathway involving a highly conserved polypeptide called ubiquitin. Ubiquitin-dependent proteolysis of a number of proteins is essential for the maintenance of the health of a cell. Many cell cycle proteins, membrane channels, receptors and products of some oncogenes are known targets of the ubiquitin-dependent turnover. Clearly, a defect in this tightly regulated mechanism for the downregulation of proteins can result in a pathological condition and therefore it is important to understand how this pathway is regulated at molecular level. In the multistep ubiquitin pathway, some component enzymes called E3 are required for specifying the targets to be degraded. We discovered one such enzyme Nedd4. One of the proteins regulated by Nedd4 is epithelial sodium channel (ENaC). Loss of Nedd4-mediated regulation of ENaC results in Liddle's Syndrome, a genetic form of hypertension. Since Nedd4 is expressed in many tissues and during development, we predicted that Nedd4 may regulate other important proteins in addition to ENaC. We have recently identified several proteins which interact with Nedd4. Some of these proteins are likely to play important roles in cellular regulation and during development. The proposed project is designed to characterise these proteins. We believe that by studying these proteins we will learn a great deal about the cellular regulatory pathways. In summary, Nedd4 is an important protein involved in cellular regulation and has a proven role in human disease. A study of characterising targets of Nedd4 will be vital in understanding the molecular basis of cell regulation and its implication in disease.Read moreRead less
Regulation Of The Epithelial Sodium Channel By The Nedd4-like Protein KIAA0439
Funder
National Health and Medical Research Council
Funding Amount
$452,640.00
Summary
The epithelial sodium channel (ENaC) is a highly specific ion channel expressed in the apical membrane of some tissues. In the distal nephron of the kidney, ENaC activity is responsible for maintaining sodium balance, blood volume and blood pressure. In the lung ENaC function is required for fluid clearance. Delineating the molecular basis of the regulation of ENaC is vital in understanding disease mechanisms and in defining targets for novel therapeutics for the treatment of disorders that aris ....The epithelial sodium channel (ENaC) is a highly specific ion channel expressed in the apical membrane of some tissues. In the distal nephron of the kidney, ENaC activity is responsible for maintaining sodium balance, blood volume and blood pressure. In the lung ENaC function is required for fluid clearance. Delineating the molecular basis of the regulation of ENaC is vital in understanding disease mechanisms and in defining targets for novel therapeutics for the treatment of disorders that arise due to sodium imbalance. Furthermore, ENaC and the molecules involved in the channel regulatory cascade are potential candidate genes in defining the genetic causes of human hypertension and salt wasting disorders. Previous studies from our laboratories and by other groups have implicated Nedd4, a protein initially cloned by us, as a key player in regulating ENaC. Our recent data suggest that KIAA0439, a close relative of Nedd4, is also involved in ENaC control mechanisms. The work proposed in this application is an extension of our recent findings and will enable us to fully define how KIAA0439 regulates the activity of ENaC.Read moreRead less
Mechanisms Of Nedd4/Nedd4-2-mediated Regulation Of The Epithelial Sodium Channel
Funder
National Health and Medical Research Council
Funding Amount
$471,000.00
Summary
The epithelial sodium channel (ENaC) is a highly specific ion channel expressed in the apical membrane of some tissues. In the kidney, ENaC activity is responsible for maintaining sodium balance, blood volume and blood pressure. In the lung ENaC function is required for fluid clearance. Abnormal regulation of ENaC is associated with conditions such as hypertension, cystic fibrosis and pulmonary oedema. Delineating the molecular basis of the regulation of ENaC is vital in understanding disease me ....The epithelial sodium channel (ENaC) is a highly specific ion channel expressed in the apical membrane of some tissues. In the kidney, ENaC activity is responsible for maintaining sodium balance, blood volume and blood pressure. In the lung ENaC function is required for fluid clearance. Abnormal regulation of ENaC is associated with conditions such as hypertension, cystic fibrosis and pulmonary oedema. Delineating the molecular basis of the regulation of ENaC is vital in understanding disease mechanisms and in defining targets for novel therapeutics for the treatment of disorders that arise due to sodium imbalance. Furthermore, ENaC and the molecules involved in the channel regulatory cascade are potential candidate genes in defining the genetic causes of human hypertension and salt wasting disorders. Previous studies from our laboratories and by other groups have shown that Nedd4 and Nedd4-2 proteins are key players in regulating ENaC activity. Our recent NHMRC supported work has identified another important protein, Grk2, as a regulator of ENaC. The work proposed in this application is an extension of our recent findings and will enable us to fully define how Nedd4-Nedd4-2 and Grk2 regulate the activity of ENaC.Read moreRead less
Roles Of Ndfip1 And Ndfip2 As Adaptors For The Nedd4 Family Of Ubiquitin Ligases
Funder
National Health and Medical Research Council
Funding Amount
$656,395.00
Summary
Part of this proposal is to understand how the body controls iron uptake through one of the iron transporters (DMT1). We will also study how proteins called Ndfip1 and Ndfip2 that regulate DMT1, also control other cellular processes, such as protection against brain damage following trauma. The results from this study should ultimately contribute to the development of therapies for certain human pathologies.