Structure-function Studies Of Ion Permeation And Selectivity In Recombinant Glycine Receptor Channels
Funder
National Health and Medical Research Council
Funding Amount
$331,300.00
Summary
Ligand-gated ion channels (LGICs) are members of a superfamily of receptor channels, with very significant structural and functional similarities, which play a major role in fast synaptic neurotransmission within the brain and spinal cord, and underlying the complex behaviour of the nervous system, but when dysfunctional can result in major neurological problems. Glycine is one of the two most important inhibitory neurotransmitters in the central nervous system. Impaired glycine-mediated neurotr ....Ligand-gated ion channels (LGICs) are members of a superfamily of receptor channels, with very significant structural and functional similarities, which play a major role in fast synaptic neurotransmission within the brain and spinal cord, and underlying the complex behaviour of the nervous system, but when dysfunctional can result in major neurological problems. Glycine is one of the two most important inhibitory neurotransmitters in the central nervous system. Impaired glycine-mediated neurotransmission underlies a range of inherited neurological diseases and already, it has been shown that the human disorder, familial Startle disease (hyperekplexia) occurs because of point mutations that have impaired the permeation and activation of the glycine receptor (GlyR). Similarly, certain epilepsies are now known to be caused by mutations in, or close to, the channel region in the excitatory acetylcholine receptors (AChRs), which affect channel activation and ion permeation. However, because of their very significant structural and functional similarities, information obtained in one member of the LGIC family of receptors has strong potential application to the other members and the GlyR with its simpler structure has certain advantages for investigation. The first aim of this project is to investigate how the molecular biological structure of these ion channels controls permeation, how it affects how different ions are selectively allowed to move through it and how it affects channel activation. A second related aim is to learn more about the process of desensitization of GlyR receptors, whereby a sustained presence of a high concentration of agonist can cause a reduction in receptor response. A third aim is to specifically investigate the mechanisms underlying the mode of molecular disruption resulting from two new Startle disease mutations, which, in addition to their own inherent clinical value, can also give general information about receptor function.Read moreRead less
Mechanism Of Signal Transduction And Receptor Activation In Ligand Gated Ion Channel Receptors
Funder
National Health and Medical Research Council
Funding Amount
$551,560.00
Summary
This project seeks to provide fundamental new information about the means by which neurotransmitter receptors, which mediate fast synaptic neurotransmission, operate. This knowledge is important since the Cys-loop family of ligand gated ion channel receptors are responsible for a wide range of neuronal signalling and the control of both excitatory and inhibitory receptors. The Cys-loop receptors are modulated by both therapeutic drugs (eg. benzodiazepines, barbiturates, antiemetics) and by recre ....This project seeks to provide fundamental new information about the means by which neurotransmitter receptors, which mediate fast synaptic neurotransmission, operate. This knowledge is important since the Cys-loop family of ligand gated ion channel receptors are responsible for a wide range of neuronal signalling and the control of both excitatory and inhibitory receptors. The Cys-loop receptors are modulated by both therapeutic drugs (eg. benzodiazepines, barbiturates, antiemetics) and by recreational drugs (eg. alcohol, nicotine). They are also targets for development of new therapeutic drugs, such as allosteric modulators of nAChR for memory enhancement, or modulating GlyR to relieve spasticity or chronic pain. The project will use a range of molecular advances made by this and other laboratories to clarify how neurotransmitters enable their receptors to activate and signal. This fundamental information is of major medical significance as defective synaptic transmission, caused by mutations in ligand gated ion channel receptors, gives rise to a number of neurological and psychiatric disease states. The ligand gated receptors are also major targets for therapeutic drugs and the information gained in this study may also provide insights into new ways in which drugs could be used to enhance or inhibit synaptic signalling.Read moreRead less
Dissecting a hematopietic transcription factor complex. The development of mature active cells is a highly complex and coordinated process that is controlled largely by groups of interacting regulatory proteins. We are trying to understand, at a very detailed level, how a specific group of these proteins interact to regulate both normal blood cell development and the onset of childhood leukemias. Using this information we will try to develop reagents that can be used to inhibit these interaction ....Dissecting a hematopietic transcription factor complex. The development of mature active cells is a highly complex and coordinated process that is controlled largely by groups of interacting regulatory proteins. We are trying to understand, at a very detailed level, how a specific group of these proteins interact to regulate both normal blood cell development and the onset of childhood leukemias. Using this information we will try to develop reagents that can be used to inhibit these interactions and be used as lead compounds for treatments for disease.Read moreRead less
The role of the transcription factor Runx2 during mammary gland development and lactation. This proposal will further our understanding of mammary gland development and lactation and the mechanisms controlling mammary cell fate decisions such as differentiation. Regulation of cell fate lies at the core of most aspects of cell biology from normal development to dysfunction such as cancer. The knowledge gleamed from this project also has the potential to make economic gains for Australia by increa ....The role of the transcription factor Runx2 during mammary gland development and lactation. This proposal will further our understanding of mammary gland development and lactation and the mechanisms controlling mammary cell fate decisions such as differentiation. Regulation of cell fate lies at the core of most aspects of cell biology from normal development to dysfunction such as cancer. The knowledge gleamed from this project also has the potential to make economic gains for Australia by increasing the profitability and ensuring the sustainability of both the dairy and meat industries. Better understanding of the mechanisms controlling mammary epithelial cell differentiation should enable augmentation of lactation such as increasing milk protein content, using marker assisted selection (of targets such as Runx2) in cattle.Read moreRead less
Oxidative Damage and Cell Ageing. This research will benefit Australia by providing a fundamental understanding of how cells age. This will have immediate international impact at the scientific level and will inform strategies to reduce the rate of ageing and alleviation of age-related disorders. In the longer term the research may provide commercial and social outcomes by identifying antioxidant systems that will provide a genuine benefit in reducing ageing.
Cellular Responses to Oxidative Damage: Cell Aging. The aim of this project is to identify the mechanisms by which oxidative stress and free radical damage cause cell aging. This work will make a significant contribution to our understanding of the aging process in cells by identifying the major reactive oxygen species that contribute to cell aging, which defence systems and antioxidants provide the greatest degree of protection, what damage accumulates as cells age and which genetic systems ar ....Cellular Responses to Oxidative Damage: Cell Aging. The aim of this project is to identify the mechanisms by which oxidative stress and free radical damage cause cell aging. This work will make a significant contribution to our understanding of the aging process in cells by identifying the major reactive oxygen species that contribute to cell aging, which defence systems and antioxidants provide the greatest degree of protection, what damage accumulates as cells age and which genetic systems are activated as during the process.Read moreRead less
The effect of nitrogen monoxide on intracellular iron metabolism. We discovered that the crucial signalling molecule nitrogen monoxide (NO) mediates iron (Fe) and glutathione (GSH) release by the transporter MRP1 probably as an NO-Fe-GSH complex [DR(2006) PNAS USA 103:7670-5]. During our current ARC grant we have markedly extended these findings by showing that another molecule, GST Pi and MRP1 form part of a coordinated system that stores and transports NO as complexes of Fe and GSH, markedly e ....The effect of nitrogen monoxide on intracellular iron metabolism. We discovered that the crucial signalling molecule nitrogen monoxide (NO) mediates iron (Fe) and glutathione (GSH) release by the transporter MRP1 probably as an NO-Fe-GSH complex [DR(2006) PNAS USA 103:7670-5]. During our current ARC grant we have markedly extended these findings by showing that another molecule, GST Pi and MRP1 form part of a coordinated system that stores and transports NO as complexes of Fe and GSH, markedly extending NO half-life from milliseconds to hours. This has broad implications for understanding NO activity in many processes which have major vital health implications, including tumour cell killing by macrophages and blood pressure control.Read moreRead less
The Effect of Nitrogen Monoxide on Intracellular Iron Metabolism. For the first time, we discovered that nitric oxide (NO) is actively transported from cells by a protein that is known to also transport glutathione (GSH). This is important, as NO was thought to passively diffuse from cells. Active transport overcomes the problems of diffusion which is inefficient and non-targeted. Moreover, NO is released as a complex with iron and GSH which markedly increases its half-life. These findings have ....The Effect of Nitrogen Monoxide on Intracellular Iron Metabolism. For the first time, we discovered that nitric oxide (NO) is actively transported from cells by a protein that is known to also transport glutathione (GSH). This is important, as NO was thought to passively diffuse from cells. Active transport overcomes the problems of diffusion which is inefficient and non-targeted. Moreover, NO is released as a complex with iron and GSH which markedly increases its half-life. These findings have broad implications for understanding the activity of NO in many processes which have major health implications, including tumour cell killing by macrophages, blood pressure etc.Read moreRead less
The effect of nitrogen monoxide on intracellular iron metabolism. During our current ARC grant we discovered a novel relationship between energy metabolism and NO-mediated Fe efflux and showed that glutathione (GSH) is vital for this release mechanism (DR5,6). Intriguingly, this transport process is part of the cytotoxic effector machinery of activated macrophages against tumours, and requires further elucidation. We also showed that CO affects Fe metabolism by binding to Fe, and CO may modulate ....The effect of nitrogen monoxide on intracellular iron metabolism. During our current ARC grant we discovered a novel relationship between energy metabolism and NO-mediated Fe efflux and showed that glutathione (GSH) is vital for this release mechanism (DR5,6). Intriguingly, this transport process is part of the cytotoxic effector machinery of activated macrophages against tumours, and requires further elucidation. We also showed that CO affects Fe metabolism by binding to Fe, and CO may modulate NO's function. We will:-
(1) Examine if NO-mediated Fe release results in GSH efflux
(2) Identify the mechanism of NO-mediated Fe efflux.
(3) Assess the effect of inducing haem oxygenase 1 on Fe metabolism
Read moreRead less
LIM-homeodomain interactions in neuronal development. The loss of central nervous system function, through accident or disease, is devastating for affected individuals and their families. Our current inability to stimulate the regeneration of nervous tissue is a result of the lack of detailed knowledge of the complex processes that must take place, at the molecular and cellular levels, during neuronal development. We are determining how a group of cellular proteins that have key roles in motor n ....LIM-homeodomain interactions in neuronal development. The loss of central nervous system function, through accident or disease, is devastating for affected individuals and their families. Our current inability to stimulate the regeneration of nervous tissue is a result of the lack of detailed knowledge of the complex processes that must take place, at the molecular and cellular levels, during neuronal development. We are determining how a group of cellular proteins that have key roles in motor neuron development interact with each other and with DNA. With this information we are developing reagents that can be used to further probe central nervous system function and may ultimately be used to regenerate damaged nerves.Read moreRead less