Alternate Signalling Pathways Regulating The Human Arachidonate Epoxygenase CYP2J2 In Response To Stress Stimuli
Funder
National Health and Medical Research Council
Funding Amount
$369,000.00
Summary
Hypoxia, or oxygen deprivation, is caused by the decreased supply of blood to cells and is a component of ischaemic injury to the cardiovascular system (e.g. stroke, atherosclerosis) and numerous other organs (e.g. cancer and chemical mediated injury). It is now known that an important group of proteins that switch on specialised target genes in response to hypoxia is Activator-Protein-1 (AP-1). We have found that cytochrome P450 2J2 (CYP2J2), which is an enzyme that forms beneficial fatty acid ....Hypoxia, or oxygen deprivation, is caused by the decreased supply of blood to cells and is a component of ischaemic injury to the cardiovascular system (e.g. stroke, atherosclerosis) and numerous other organs (e.g. cancer and chemical mediated injury). It is now known that an important group of proteins that switch on specialised target genes in response to hypoxia is Activator-Protein-1 (AP-1). We have found that cytochrome P450 2J2 (CYP2J2), which is an enzyme that forms beneficial fatty acid products inside cells, is decreased in hypoxia and that this is due to increased activity of AP-1. We know that similar stressful stimuli can also result in a loss of CYP2J2. Again, AP-1 is involved but we have further evidence for the role of another pathway. This project will explore how these pathways operate individually and together to decrease CYP2J2. Studying the regulation of human genes is difficult because we can not readily monitor their levels in cells in either healthy or sick individuals. So we will make transgenic mouse models to study human CYP2J2 regulation, which will provide information on the human situation. In this project we will identify which factors switch off the CYP2J2 transgene and will analyse the signalling pathways within cells that control this response. The importance of these studies is that they will help us to design pharmacological strategies to prevent the loss of CYP2J2 in cells that are stressed. Such agents may be effective in the treatment of ischaemic injury seen in stroke and atherosclerosis. If we can maintain CYP2J2 levels we may be able to maintain the beneficial fatty acid levels in cells and have a novel therapeutic approach for keeping cells alive.Read moreRead less
The Role Of Cytochrome P-450 Metabolites Of Arachidonic Acid In Human Cardiovascular Disease
Funder
National Health and Medical Research Council
Funding Amount
$552,610.00
Summary
Alcohol consumption is known to raise blood pressure but the mechanism by which it does this is not known This project examines the role of certain fatty acid metabolites called cytochrome P450 metabolites of arachidonic acid (CYP450AA-M) during periods of alcohol consumption and periods of abstinance from alcohol. These fatty acid metabolites act on blood vessels causing them to constrict or dilate. In doing this they affect blood pressure regulation. The results of this study will determine ho ....Alcohol consumption is known to raise blood pressure but the mechanism by which it does this is not known This project examines the role of certain fatty acid metabolites called cytochrome P450 metabolites of arachidonic acid (CYP450AA-M) during periods of alcohol consumption and periods of abstinance from alcohol. These fatty acid metabolites act on blood vessels causing them to constrict or dilate. In doing this they affect blood pressure regulation. The results of this study will determine how important CYP450AA-M are in the development of alcohol related hypertension. We will study CYP450AA-M in cells as well as in plasma and urine to see if cellular levels of CYP450AA-M are better determinants of blood pressure regulation than plasma or urinary levels of CYP450AA-M. This project will help scientists decide how important these metabolites are for blood presssure regulation. If these metabolites are found to be important then it should be possible to alter their levels either by diet or drug treatment.Read moreRead less
Synergism Between Opioids And Other Agents At Central Primary Afferent Synapses
Funder
National Health and Medical Research Council
Funding Amount
$202,771.00
Summary
Opioids, such as codeine, pethidine and morphine, are the most effective pain relieving drugs known but their clinical utility is limited by hazardous and potentially lethal side effects, as well as the development of tolerance and physical dependence with associated addiction liability. Recent research in our laboratory has identified for the first time a mechanism in the mammalian brain by which the pain relieving actions of opioids can be greatly enhanced by drugs that independently modulate ....Opioids, such as codeine, pethidine and morphine, are the most effective pain relieving drugs known but their clinical utility is limited by hazardous and potentially lethal side effects, as well as the development of tolerance and physical dependence with associated addiction liability. Recent research in our laboratory has identified for the first time a mechanism in the mammalian brain by which the pain relieving actions of opioids can be greatly enhanced by drugs that independently modulate biochemical processes distinct from those altered by opioids. Exploitation of these mechanisms has great potential for the development of new pharmacotherapies for effective pain relief with minimised side effects. These synergistic mechanisms appear to be at least as important for pain relief in the spinal cord as in brain, so the proposed studies will first examine the basis for synergism with opioid mediated pain relief in spinal cord. There is also strong evidence that the mechanisms to be studied in the proposed work are pivotal in the development of debilitating, chronic pain conditions that involve heightened sensitivity to painful stimuli and-or painful responses to normally innocuous stimuli such as light touch. Such aberrant responses can persist long after initial tissue damage has recovered. It is known that opioids can limit somewhat the initial steps in the induction of these abnormal responses but the mechanisms involved are unknown. The proposed studies will contribute to resolution of these mechanisms. Better understanding of the basis of these pathological processes will lead to better strategies for retarding or preventing the development of chronic pain conditions.Read moreRead less
The Effect Of Cytochrome P450 Genotype On Blood Pressure And 20-HETE Responses To Lifestyle Interventions
Funder
National Health and Medical Research Council
Funding Amount
$743,665.00
Summary
The effectiveness of treatments to reduce heart disease risk can vary enormously between individuals. This is partly due to a persons genetic makeup. Fatty acid metabolites called cytochrome P450 metabolites of arachidonic acid (CYP450-AAM) can act on blood vessels and the kidney to regulate blood pressure. We will study the effect of having a variation in a gene that regulates CYP450-AAM on blood pressure and heart disease risk in combination with a high salt diet or weight reduction.
Deciphering The Molecular Steps Leading To The Potentiation Of Neuronal Exocytosis By Arachidonic Acid
Funder
National Health and Medical Research Council
Funding Amount
$273,000.00
Summary
Release of hormones and neurotransmitters relies on a process called exocytosis which involves SNARE proteins: syntaxin1A and SNAP-25 on the target plasma membrane and VAMP on the vesicular membrane. Availability of the t-SNARE on the plasma membrane is believed to play a major role in controlling the amount of exocytosis. Syntaxin1A bound to Munc18 constitute an 'unproductive-reserve' pool of closed Syntaxin that cannot interact with SNAP-25. Intracellular messengers capable of releasing Syntax ....Release of hormones and neurotransmitters relies on a process called exocytosis which involves SNARE proteins: syntaxin1A and SNAP-25 on the target plasma membrane and VAMP on the vesicular membrane. Availability of the t-SNARE on the plasma membrane is believed to play a major role in controlling the amount of exocytosis. Syntaxin1A bound to Munc18 constitute an 'unproductive-reserve' pool of closed Syntaxin that cannot interact with SNAP-25. Intracellular messengers capable of releasing Syntaxin1A from Munc18 thereby making it available to interact with SNAP-25, are foreseen to play a major role in potentiating exocytosis - a process with ramification for memory and learning. We have identified arachidonic acid, a lipidic messenger which fullfil this role. For the first time we are in a position to manipulate at the molecular level different pools of SNARE proteins with direct implications for our understanding of the mechanism of secretion. Very few models are currently available to understand how learning and memory occur in the brain. Our research points to a new direction: the amount of 'active' and 'unproductive-reserve' pools of SNARE proteins present on the plasma membrane of neurosecretory cells are in dynamic equilibrium and arachidonic acid, a second messenger capable of trans-synaptic action, can modify this equilibrium resulting in an increase of the amount of 'active' SNARE thereby potentiating the amount of transmitter-hormone released by exocytosis. Importantly, this research lays the basis for a dynamic view of the secretory mechanism with important implications for treatment of diseases such as diabetes and neurodegenerative diseases. Our hope is that by understanding at the molecular level how secretory cells regulate the amount of their secretion, we will be in a position to modify these parameters in order to counteract illnesses of the nervous system.Read moreRead less
Cytochrome P450-mediated Epoxides Of Polyunsaturated Fatty Acids That Regulate Cell Death And Survival
Funder
National Health and Medical Research Council
Funding Amount
$495,710.00
Summary
Omega-3 polyunsaturated fatty acids (PUFAs) decrease cancer risk in man whereas omega-6 PUFA, which are common in western diets, increase risk. In cells cytochrome P450 converts PUFAs to epoxides. Omega-6 epoxides stimulate growth of cells and tumours but we have found that epoxides of the omega-3 eicosapentaenoic acid inhibit cell growth. We will now evaluate the mechanisms of these effects, which could lead to new anticancer treatments, perhaps based on altered diet.
Arachidonic Acid Modulation Of Glutamate Transporters
Funder
National Health and Medical Research Council
Funding Amount
$286,980.00
Summary
Neurotransmitter transporters play a key role in regulating the dynamics of neurotransmission and are also the targets for a number of very important drugs. Glutamate is the predominant neurotransmitter responsible for fast excitatory neurotransmission and glutamate transporters are responsible for controlling glutamate concentrations to maintain normal neurotransmission. The failure of glutamate transporters has been implicated as playing a key role in brain damage following a stoke and also fo ....Neurotransmitter transporters play a key role in regulating the dynamics of neurotransmission and are also the targets for a number of very important drugs. Glutamate is the predominant neurotransmitter responsible for fast excitatory neurotransmission and glutamate transporters are responsible for controlling glutamate concentrations to maintain normal neurotransmission. The failure of glutamate transporters has been implicated as playing a key role in brain damage following a stoke and also for long term neurological disorders such as Alzheimer's disease. In this project we shall investigate a novel mechanism for regulating the activity of glutamate transporters and explore the possibility of pharmacologically manipulating glutamate transporters. This work may lead to the development of novel compounds that improve transporter function and reduce the pathological consequences of impaired transporter function. Such compounds may have therapeutic potential as neuroprotectants in the treatment of neurological disorders such ischaemic brain damage or neurodegenerative disorders such Alzheimer's disease.Read moreRead less
Novel Omega-3 Fatty Acid Epoxides And The Activation Of Cellular Survival Pathways
Funder
National Health and Medical Research Council
Funding Amount
$457,267.00
Summary
Recent studies have reported that foods and oils containing high levels of omega-3 fatty acids have beneficial effects in patients with arthritis and cardiovascular disease. The mechanisms by which these dietary changes produce health benefits are unclear but it is known that omega-3 fatty acids can replace omega-6 and other fatty acids in cells; these omega-6 acids are more common in western diets. A number of enzymes in cells convert fatty acids to oxygenated derivatives and some of these have ....Recent studies have reported that foods and oils containing high levels of omega-3 fatty acids have beneficial effects in patients with arthritis and cardiovascular disease. The mechanisms by which these dietary changes produce health benefits are unclear but it is known that omega-3 fatty acids can replace omega-6 and other fatty acids in cells; these omega-6 acids are more common in western diets. A number of enzymes in cells convert fatty acids to oxygenated derivatives and some of these have potent protective effects that allow cells to survive in the presence of toxic stimuli. We have found that epoxides formed from the omega-3 fatty acid stearidonic acid are extremely potent protective agents in cells - more so that epoxides from omega-6 acids like arachidonic acid. The present project seeks to identify omega-3 fatty acid epoxides with potent and long-lived beneficial effects in cells, relate these properties to those of omega-6 fatty acid epoxides and then understand how the omega-3 epoxides enhance cell survival. The findings will provide a rational basis from which to understand the beneficial effects of dietary modification already seen in clinical studies. By understanding the biochemical and molecular events in cells that are activated by omega-3 fatty acid epoxides we may be able to design therapies, most likely involving changes in dietary fat intake, that could benefit individuals with arthritic, cardiovascular and other conditions. Given the high incidence of these conditions in this country the potential impact of the findings from this project could be highly significant and are consistent with the national research priority healthy ageing.Read moreRead less
HYPOXIA AND THE TRANSCRIPTIONAL REGULATION OF CYP GENES IN CELLS
Funder
National Health and Medical Research Council
Funding Amount
$211,527.00
Summary
Hypoxia, or oxygen deprivation caused by the decreased supply of blood to cells, is a component of ischaemic injury of the cardiovascular system (as in angina or atherosclerosis) and numerous other organs (e.g. in cancer and chemical-mediated injury). It is now known that the content of certain proteins that activate specialised target genes is increased rapidly in cells in response to oxygen deprivation. Some of the most important of these proteins are hypoxia-inducible factor-1 (or HIF-1) and ....Hypoxia, or oxygen deprivation caused by the decreased supply of blood to cells, is a component of ischaemic injury of the cardiovascular system (as in angina or atherosclerosis) and numerous other organs (e.g. in cancer and chemical-mediated injury). It is now known that the content of certain proteins that activate specialised target genes is increased rapidly in cells in response to oxygen deprivation. Some of the most important of these proteins are hypoxia-inducible factor-1 (or HIF-1) and activator protein-1 (or AP-1). We have identified a novel target gene that is activated in hypoxia. This gene produces an enzyme, termed cytochrome P450 2J2, that acts on fatty acids which are present in cell membranes and converts them into molecules that control the flow of potassium and calcium ions into cells. Alterations in the flow of such ions into cells have been observed previously in hypoxia but the mechanism of this effect is unclear. Thus, cytochrome P450 2J2 is switched on in hypoxia and generates fatty acid metabolites that control protective ion fluxes in cells.Read moreRead less