Dynamic Trafficking Of Amino Acid Transporters At Synapses And Their Role In Regulating Neurotransmission
Funder
National Health and Medical Research Council
Funding Amount
$421,219.00
Summary
Brain cells release chemical neurotransmitters to activate their neighbours. The most abundant neurotransmitter is glutamate, which mediates most of the communication in the brain. Following release, this neurotransmitter must be rapidly recycled to prevent levels being depleted and neurotransmission failing. The subject of this grant is to understand what molecules and pathways are used to recycle glutamate in the brain, and how its supply is controlled to sustain continual brain activation.
Examination Of The Molecular Pharmacology Of Anthracyclines Induced Via Their Interaction With Iron
Funder
National Health and Medical Research Council
Funding Amount
$618,401.00
Summary
Anthracyclines are highly effective anti-cancer drugs, but their use is limited by toxic effects on the heart. This is thought to be due to these drugs directly binding iron (Fe). Indeed, we showed that anthracyclines induced marked changes in the way heart cells utilise Fe (DR1-3, 38; Mol. Pharmacol. 2002, 2003, 2004, 2005). We were the first to show that anthracyclines prevent Fe release from the criticial Fe storage protein ferritin. This prevents the use of Fe for vital processes eg. DNA and ....Anthracyclines are highly effective anti-cancer drugs, but their use is limited by toxic effects on the heart. This is thought to be due to these drugs directly binding iron (Fe). Indeed, we showed that anthracyclines induced marked changes in the way heart cells utilise Fe (DR1-3, 38; Mol. Pharmacol. 2002, 2003, 2004, 2005). We were the first to show that anthracyclines prevent Fe release from the criticial Fe storage protein ferritin. This prevents the use of Fe for vital processes eg. DNA and haem synthesis. Hence, this effect probably contributes to the cytotoxic activity of anthracyclines on the heart. We showed that novel drugs developed in my lab that bind Fe called chelators show high activity in animals (DR4) and prevent anthracycline-mediated Fe accumulation in ferritin. Importantly, Fe chelators have been shown to inhibit anthracycline-mediated cardiotoxicity. Indeed, the clinically used cardioprotective agent, ICRF-187, is actually an Fe chelator (5, DR6). However, ICRF-187 is not totally successful in terms of its cardioprotective effects and can cause myelosuppression (5, DR6). While the clinically used chelator, desferrioxamine (DFO), can prevent anthracycline-mediated cardiotoxicity, its poor membrane permeability limits its effectiveness. Our chelators are highly permeable and overcome the disadvantages of DFO (DR4). Thus, they are vital to examine for preventing anthracycline-mediated cardiotoxicity. In this proposal we will examine the changes in Fe metabolism induced by anthracyclines and test the hypothesis that novel Fe chelators may prevent the cardiotoxicity of these agents. We also aim to be the first to assess if preparation of anthracyclines which cannot bind iron prevents their cardiotoxicity. This will be done by preparing metal complexes of these drugs which prevent Fe-binding eg. anthracycline-zinc complexes. These studies are important for the development of less cardiotoxic forms of these very useful anti-tumour agents.Read moreRead less
Understanding The Acute And Cumulative Metabolic Effects Of Prolonged Sitting In Adults
Funder
National Health and Medical Research Council
Funding Amount
$416,597.00
Summary
Sedentary behaviour (sitting time) has been linked to an increased risk of chronic illnesses, including type 2 diabetes and obesity, but recent evidence suggests that light-intensity activity (non-exercise activities of daily living) is associated with reduced risk. These studies will examine whether breaking up sitting time with frequent short periods of activity can overcome the negative effects of prolonged sitting on blood glucose and blood fats in overweight older adults.
Mitochondrial Iron Overload And Friedreich's Ataxia: The Role Of Frataxin In Iron And Haem Metabolism
Funder
National Health and Medical Research Council
Funding Amount
$285,990.00
Summary
Friedreich's ataxia (FA) is due to the lack of a protein known as frataxin. Recent studies using Baker's yeast have shown that the deletion of frataxin results in the accumulation of toxic iron in the mitochondrion. More recently, a variety of studies have shown that FA patients have iron loading within their cells. The iron build-up may cause severe damage. At present, the role of frataxin in mammalian mitochondrial iron metabolism is unknown. Our preliminary studies demonstrate that frataxin i ....Friedreich's ataxia (FA) is due to the lack of a protein known as frataxin. Recent studies using Baker's yeast have shown that the deletion of frataxin results in the accumulation of toxic iron in the mitochondrion. More recently, a variety of studies have shown that FA patients have iron loading within their cells. The iron build-up may cause severe damage. At present, the role of frataxin in mammalian mitochondrial iron metabolism is unknown. Our preliminary studies demonstrate that frataxin is down-regulated by either erythroid differentiation or the haem precursor protoporphyrin IX (Becker and Richardson, submitted). These data strongly suggest a role for frataxin in iron metabolism. In the present study we will continue to assess if frataxin plays a role in the way cells handle iron. Using a unique model of mitochondrial iron overload developed in my lab (Richardson et al. (1996) BLOOD 87:3477), we will extensively investigate the iron metabolism of the mitochondrion in order to determine the function of frataxin and its role in Friedreich's ataxia. In addition, we have developed a series of new drugs known as iron chelators that can enter the mitochondrion due to their high lipid solubility (Becker and Richardson 1999 J. Lab. Clin. Med. 134:510). These latter drugs are far more effective than the chelator currently used to treat iron overload, desferrioxamine (DFO). Indeed, our chelators have been designed to result in high iron chelation efficacy but low toxicity (see Becker and Richardson, 1999). This exciting research may be crucial in understanding the development of FA and in creating new therapies such as the use of iron chelators.Read moreRead less
A unified model of amino acid homeostasis. This project aims to develop a unified model of amino acid homeostasis in mammalian cells and apply it to brain cells. The model will be underpinned by a mathematical algorithm that allows predicting amino acid levels in the cytosol based on fundamental parameters such as transport and metabolism. This project should provide the significant benefit of enabling the prediction of essential functions such as cell growth and survival.
Mitochondrial Iron Overload And Friedreich's Ataxia: The Role Of Frataxin In Iron And Haem Metabolism
Funder
National Health and Medical Research Council
Funding Amount
$606,000.00
Summary
Friedreich's ataxia (FA) is due to the lack of a protein known as frataxin. A variety of studies using Baker's yeast and conditional frataxin knockout (KO) mice have shown that deletion of frataxin leads to the accumulation of toxic iron in their mitochondrion. More recently, a variety of studies have shown that FA patients have iron-loading within their mitochondrion. Iron in the highly redox active environment of the mitochondrion could contribute to the generation of cytotoxic radicals that c ....Friedreich's ataxia (FA) is due to the lack of a protein known as frataxin. A variety of studies using Baker's yeast and conditional frataxin knockout (KO) mice have shown that deletion of frataxin leads to the accumulation of toxic iron in their mitochondrion. More recently, a variety of studies have shown that FA patients have iron-loading within their mitochondrion. Iron in the highly redox active environment of the mitochondrion could contribute to the generation of cytotoxic radicals that cause severe damage. Further, cells deficient in frataxin are sensitive to oxidant stress and Fe chelators rescue oxidant-mediated death of cells from FA patients. Indeed, free radical scavengers have shown to be of use in the treatment of this disease. Studies in DR's lab during this NHMRC grant have shown that frataxin is down-regulated by erythroid differentiation or the haem precursor, protoporphyrin IX (BLOOD 2002;99:3813-22). These data indicate a role for frataxin in Fe metabolism and the pathogenesis of FA. In this study we will continue to examine the role of frataxin in the way cells handle Fe using experimental models developed under the current NHMRC grant. These include transfected cell lines with low frataxin expression generated using an expression vector containing anti-sense frataxin cDNA. Further we obtained the frataxin conditional KO mouse and generated a breeding colony. These animals display many of the pathological features of FA and are the best current model of the disease. Indeed, they will be critical for assessing the role of frataxin in Fe metabolism and as a model to test the ability of Fe-binding drugs to prevent the pathology observed. We designed lipid-soluble chelators that can enter the mitochondrion to bind Fe (Biochim Biophys Acta 2001;1536:133-140) and these ligands will be tested to prevent disease progression in the KO mice. This exciting research is crucial for understanding the pathogenesis of FA and in creating new therapies.Read moreRead less
Alpha-2-Macroglobulin And The Transport And Uptake Of The Hormone, Hepcidin
Funder
National Health and Medical Research Council
Funding Amount
$533,541.00
Summary
Hepcidin is a peptide hormone that is a major regulator of iron metabolism. It has been suggested that hepcidin is free in the blood. However, we recently identified that hepcidin binds with alpha-2-macroglobulin (a2-M) in the plasma and this increases the efficacy of this peptide. The demonstration that a2-M plays a role in hepcidin biology will lead to a better understanding of hepcidin physiology, the development of methods for its measurement and improved treatment of iron related diseases.
How do apicomplexan parasites steal amino acids from their hosts? The single-celled parasites that cause malaria and toxoplasmosis are adept at stealing nutrients from the host animals that they infect. How they do this is, however, poorly understood. This project seeks to identify the processes by which these parasites scavenge amino acids, an essential class of nutrient, from their hosts. Using innovative experimental approaches, the project aims to identify and characterise the parasite prote ....How do apicomplexan parasites steal amino acids from their hosts? The single-celled parasites that cause malaria and toxoplasmosis are adept at stealing nutrients from the host animals that they infect. How they do this is, however, poorly understood. This project seeks to identify the processes by which these parasites scavenge amino acids, an essential class of nutrient, from their hosts. Using innovative experimental approaches, the project aims to identify and characterise the parasite proteins that mediate the uptake of different amino acids into the parasite. The intended outcomes of the project are to provide comprehensive insights into a fundamental aspect of parasite biology, and inform strategies to treat the diseases caused by these parasites by cutting off their nutrient supply.Read moreRead less
Regulating nutrient uptake in intracellular parasites. Parasites impose a major economic and medical burden on human societies. In order to grow and reproduce, parasites scavenge nutrients from their animal or human hosts. As they move within and between hosts they encounter different levels of nutrients; how they adapt to these differences is poorly understood. This project aims to investigate the mechanisms by which the model parasite Toxoplasma senses and responds to the nutrients in its envi ....Regulating nutrient uptake in intracellular parasites. Parasites impose a major economic and medical burden on human societies. In order to grow and reproduce, parasites scavenge nutrients from their animal or human hosts. As they move within and between hosts they encounter different levels of nutrients; how they adapt to these differences is poorly understood. This project aims to investigate the mechanisms by which the model parasite Toxoplasma senses and responds to the nutrients in its environment, thereby shedding light on how they adapt to the different environments that they inhabit and, in the longer term, informing novel treatment strategies that aim to limit the parasites’ nutrient supply.Read moreRead less
Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0237729
Funder
Australian Research Council
Funding Amount
$735,000.00
Summary
A proteomics facility for Queensland researchers. The successful completion of sequencing of the genomes of many organisms, including man, has thrown emphasis back on the identification of proteins involved in the complex events that sustain cellular life. Our aim is to set up a world-class facility for proteomics research which will allow a large cohort of scientists at several institutions to identify individual proteins in vanishingly small samples of very complex mixtures. This facility wi ....A proteomics facility for Queensland researchers. The successful completion of sequencing of the genomes of many organisms, including man, has thrown emphasis back on the identification of proteins involved in the complex events that sustain cellular life. Our aim is to set up a world-class facility for proteomics research which will allow a large cohort of scientists at several institutions to identify individual proteins in vanishingly small samples of very complex mixtures. This facility will enable investigation of the control of gene expression, the intricate organisation of proteins within cells, and proteins which are potential drug targets. This equipment is an essential resource for Queensland research groups.Read moreRead less