Molecular Mechanisms Of G Protein-Coupled Receptor Cross Talk
Funder
National Health and Medical Research Council
Funding Amount
$256,980.00
Summary
The normal function of all living cells depends on how they respond to the multitude of physical and chemical stimuli to which they are constantly exposed. The majority of chemical stimuli acting on cells do so not by directly entering the cell, but rather by acting on specific types of receiver proteins on the cell's surface called receptors. One important family of receptors transmit their message to the inside of the cell by coupling to yet another type of protein known as the G protein. Aber ....The normal function of all living cells depends on how they respond to the multitude of physical and chemical stimuli to which they are constantly exposed. The majority of chemical stimuli acting on cells do so not by directly entering the cell, but rather by acting on specific types of receiver proteins on the cell's surface called receptors. One important family of receptors transmit their message to the inside of the cell by coupling to yet another type of protein known as the G protein. Aberrations in the normal function of these G protein-coupled receptors have been implicated in a wide variety of disorders, such as schizophrenia, pain and dementia. To date, most therapeutic approaches to treating these disorders have targeted individual types of G protein-coupled receptors thought to play a role in each disease state, but this has met with mixed success. One of the reasons for this is that each disorder actually involves more than one type of G protein-coupled receptor communicating with other types in a complex way. Our current proposal specifically focuses on some of the newer mechanisms that have been suggested to play an important role in the communication between different types of G protein-coupled receptors located in the same type of cell. An understanding of how such receptor proteins can communicate with one another in this situation is absolutely vital in unravelling processes involved in the maintenance of health, abnormalities that lead to disease and in the development of more effective treatments.Read moreRead less
The maintenance of optimum health and function of living cells, and consequently that of the whole organism, depends on how cells respond to a multitude of physical and chemical stimuli that continually bombard them. The majority of the chemical stimuli such as hormones and neurotransmitters impart their actions not by directly entering the cell, but instead, by binding to a specific receiver protein at the cell surface called a receptor. In one class of such receptors called G protein coupled r ....The maintenance of optimum health and function of living cells, and consequently that of the whole organism, depends on how cells respond to a multitude of physical and chemical stimuli that continually bombard them. The majority of the chemical stimuli such as hormones and neurotransmitters impart their actions not by directly entering the cell, but instead, by binding to a specific receiver protein at the cell surface called a receptor. In one class of such receptors called G protein coupled receptors, the transmission of the message to the interior of the cell involves yet another protein called G protein. It is extremely important to unravel how each of these components, the stimulating agent, the receptor and G protein, works in order to understand how the cells respond to various chemical signals. To make this process even more complex, it was recently shown that another newly discovered group of proteins called receptor activity modifying proteins (RAMPs) too play a critical role in some systems. Understanding what actually is the role of these new players, and how they team-up with the other components to elicit a specific response to a chemical stimulus, forms the basis of this proposal. Such knowledge is central to the unraveling of the processes involved in the maintenance of health, abnormalities that lead to disease, and in the development of new treatments.Read moreRead less
Alteration Of Glucose Metabolism By GPCR Activation
Funder
National Health and Medical Research Council
Funding Amount
$444,796.00
Summary
In type 2 diabetes the effect of insulin to stimulate glucose transport in fat cells and skeletal muscle is impaired so there is great interest in identifying insulin-independent mechanisms that increase glucose transport. Several G protein-coupled receptors (GPCRs) regulate glucose transport independently of insulin but the mechanisms involved in these effects are largely unknown. This project investigates how GPCRs regulate glucose homeostasis and will evaluate them as potential treatments.
Epithelium-fibroblast Interactions In Response To Allergic Airway Inflammation
Funder
National Health and Medical Research Council
Funding Amount
$235,526.00
Summary
The airways of an asthmatic patient undergo dramatic structural changes over time. This remodelling is thought to be responsible for producing the changes in lung function that are frequently observed in someone with the disease. However, in contrast to normal wound repair, it is unclear why in the majority of asthmatics, inflammation leads to ongoing remodelling rather than a self limiting healing process. In this context, cells that line the airways (epithelium) as well as cells that sit immed ....The airways of an asthmatic patient undergo dramatic structural changes over time. This remodelling is thought to be responsible for producing the changes in lung function that are frequently observed in someone with the disease. However, in contrast to normal wound repair, it is unclear why in the majority of asthmatics, inflammation leads to ongoing remodelling rather than a self limiting healing process. In this context, cells that line the airways (epithelium) as well as cells that sit immediately beneath them (fibroblasts) are important sources of mediators and structural matrix proteins that contribute to these processes. Under normal conditions, signals from these structural proteins are transmitted to the cells via specific adhesion molecules. However, in asthma epithelial cells are frequently damaged and detached, and fibroblasts appear to proliferate and undergo changes in their appearance. This projects aims to investigate the expression and function of specific cell adhesion molecules in the epithelium and fibroblasts following airway inflammation. Specifically, this proposal aims to determine which adhesion molecules are associated with upregulated proliferation and production of matrix proteins. We will also examine the effects of two novel mediators, thought to play a role in remodelling on the expression and function of these adhesion molecules. Proliferation of these cells and the altered deposition of matrix proteins may be a key feature of airway wall thickening and hyperreactivity that is a characteristic feature of asthma. The balance of deposition and breakdown of matrix proteins is regulated by a variety of mediators. Defining what regulates the expression and activity of adhesion molecules is of fundamental importance in determining how the normal repair processes may evolve into airway wall remodelling.Read moreRead less
Understanding The Mechanisms Used By G-protein Coupled Receptors To Regulate Insulin-independent Glucose Transport
Funder
National Health and Medical Research Council
Funding Amount
$105,590.00
Summary
In type 2 diabetes, stimulation of glucose transport in fat cells and skeletal muscle by insulin is impaired. As a result there is great interest in identifying insulin-independent mechanisms that increase glucose transport. Several G-protein coupled receptors (GPCRs) regulate glucose transport independently of insulin but the mechanisms involved in these effects are largely unknown. This project investigates how GPCRs regulate glucose transport for potential as treatments.
Clozapine Toxicity: Role Of Pharmacogenetic Variation In CYP Enzymes And Bioactivation Mechanisms In Patient Neutrophils
Funder
National Health and Medical Research Council
Funding Amount
$336,000.00
Summary
The treatment of mental disorders such as schizophrenia involves the administration of potent drug combinations to patients. Some individuals, however, do not respond to commonly-used antipsychotic drugs and their condition only improves with a unique drug called clozapine. The major problem with clozapine is its toxicity toward blood cells, heart and other organs. All people who receive clozapine must be monitored closely, especially in the first 3-4 months after starting therapy. Several new d ....The treatment of mental disorders such as schizophrenia involves the administration of potent drug combinations to patients. Some individuals, however, do not respond to commonly-used antipsychotic drugs and their condition only improves with a unique drug called clozapine. The major problem with clozapine is its toxicity toward blood cells, heart and other organs. All people who receive clozapine must be monitored closely, especially in the first 3-4 months after starting therapy. Several new drugs have been suggested to be safer versions of clozapine but these are all ineffective. Clozapine is the only agent that is effective in people who do not respond to the other drugs used to treat schizophrenia. Thus, clozapine toxicity, which necessitates discontinuation of the drug, is a devastating outcome because there is no alternative treatment that is available. Another significant problem with clozapine is that its rate of removal from the body is slowed down by many other drugs that are used concurrently. The problems with clozapine occur in some but not all individuals. This suggests that the patient's genetic makeup and their exposure to drugs and environmental agents determine the incidence of toxicity. The present project looks at how clozapine is removed from the body and how it is converted into a toxic product that damages cells. These processes will be examined, with emphasis on differences between individual patients, and strategies to protect cells from damage from the toxic derivative will be tested. Corresponding studies will be done in patients who are receiving clozapine as treatment for psychoses. We will be able to compare experimental and clinical findings in order to identify those patients who appear to be at risk. This will be possible before the toxic effects occur and will help us to identify subjects in whom the drug should only be used with great care. We may also devise strategies that will minimise the incidence of toxicity.Read moreRead less