Mechanisms Of Oxidised Protein Accumulation In Ageing Cells
Funder
National Health and Medical Research Council
Funding Amount
$429,000.00
Summary
Australia has one of the world's most rapidly ageing populations. It is estimated that in 30 years time over 30% of the population will be over 65; many will suffer from a debilitating, age-related disease. The diseases of ageing represent one of the major health challenges this century. Despite their increasing incidence, our understanding of the underlying causes is limited. A common feature is the accumulation of damaged proteins in cells and tissues. Damaged proteins are usually broken down ....Australia has one of the world's most rapidly ageing populations. It is estimated that in 30 years time over 30% of the population will be over 65; many will suffer from a debilitating, age-related disease. The diseases of ageing represent one of the major health challenges this century. Despite their increasing incidence, our understanding of the underlying causes is limited. A common feature is the accumulation of damaged proteins in cells and tissues. Damaged proteins are usually broken down by the cells and replaced, but in many age-related diseases this process fails. The most common source of protein damage is attack by oxygen-derived free radicals. These are by-products of our body's need for oxygen and can originate from atmospheric pollutants. Oxygen rusts metal, makes fat go rancid and can cause irreparable damage to proteins and other biological molecules. Free radical damage contributes to the development of many age-related diseases such as atherosclerosis and neurodegenerative diseases such as Alzheimer's disease. The accumulation of damaged proteins can cause cell death. Our knowledge of the mechanisms by which cells remove proteins damaged by oxygen and the reasons for their accumulation is limited. In this project we will use a novel technique we have developed to generate oxidised proteins in ageing cells. We will identify cellular mechanisms required for the efficient removal of damaged proteins and those mechanisms which fail in ageing cells. We will focus on a group of proteins which protect damaged proteins from aggregating and accumulating and we will examine how we can prevent the accumulation of oxidised proteins by stimulating the body s defence mechanisms. Since the population of Australia is ageing, diseases of ageing are going to consume an increasing amount of the national health budget. A better knowledge of these cellular mechanisms will allow us to design effective prevention and treatment strategies which are at present lacking.Read moreRead less
Lipoprotein Oxidation, Antioxidants And Atherosclerosis
Funder
National Health and Medical Research Council
Funding Amount
$281,812.00
Summary
We are studying how major blood vessels harden. This process (called atherosclerosis) is the major underlying cause of heart disease, the major single cause of death of Australians. Our research focusses on the 'Oxidation Theory', one of the most common theories of how atherosclerosis develops. Accordingly, fats in fat-carrying particles (called lipoproteins) penetrate the walls of blood vessels, where they cause disease as a result of going rancid. This is a primary reason for the general publi ....We are studying how major blood vessels harden. This process (called atherosclerosis) is the major underlying cause of heart disease, the major single cause of death of Australians. Our research focusses on the 'Oxidation Theory', one of the most common theories of how atherosclerosis develops. Accordingly, fats in fat-carrying particles (called lipoproteins) penetrate the walls of blood vessels, where they cause disease as a result of going rancid. This is a primary reason for the general public's interest in antioxidant supplements to combat heart disease. However, it is not clear at present whether rancid fats is a cause or consequence of atherosclerosis, and we recently showed that the two processes can be dissociated in an animal model of the disease. This application addresses the question of whether the process of fats going rancid can be generally dissociated from atherosclerosis, using several different animal models of the disease. We will distinguish different chemical pathways that give rise to different types of rancid fats, and between rancid fats and 'rancid' proteins. Such studies have not been carried out to date. Our underlying hypothesis is that the process of lipoprotein fat going rancid is a consequnece rather than a cause of atherosclerosis and heart disease. By testing this hypothesis, we will provide a rationale for whether antioxidant supplements aimed at preventing rancid fats from accumulating are likely of benefit in terms of preventing heart disease. This is of direct interest to public health. Our studies also address the issue of how antioxidants (if not through preventing fats from going rancid) attenuate atherosclerosis. We will focus on a particular synthetic antioxidant for which there is strong evidence that it is beneficial in preventing the re-narrowing of blood vessels in humans undergoing coronary angioplasty. These studies have the potential to provide new clues for the development of novel drugs against heart disease.Read moreRead less
Identifying The Targets Of Myeloperoxidase-derived Oxidants In Plasma And Cells
Funder
National Health and Medical Research Council
Funding Amount
$237,258.00
Summary
Myeloperoxidase (MPO) is a haem enzyme, released by activated white blood cells, that catalyses the production of highly damaging chlorinated oxidants. These oxidants are known to play a major role in the human immune system by killing bacteria and other invading pathogens. However, excessive or misplaced generation of these oxidants results in tissue damage. This damage has been implicated in development of disease. For example, there is strong evidence for the involvement of MPO, and the oxida ....Myeloperoxidase (MPO) is a haem enzyme, released by activated white blood cells, that catalyses the production of highly damaging chlorinated oxidants. These oxidants are known to play a major role in the human immune system by killing bacteria and other invading pathogens. However, excessive or misplaced generation of these oxidants results in tissue damage. This damage has been implicated in development of disease. For example, there is strong evidence for the involvement of MPO, and the oxidants that it produces, in atherosclerosis. This disease is responsible for the death of around 40 % of the Australian population. There is no doubt that the oxidants produced by MPO cause major damage to tissues and extensive cell death. However, the mechanisms involved in this process remain to be established, due to a lack of sensitive and specific techniques for examining oxidant-mediated damage to individual target molecules. This study will identify the key targets of MPO-derived oxidants in plasma and cells using novel labelling techniques. This will provide valuable information about the mechanisms of oxidative damage and cytotoxicity. This will be important in the design of potential therapeutic agents to modulate and prevent the progression of degenerative diseases, such as atherosclerosis, that are linked with MPO.Read moreRead less
Mechanisms Of Proteolysis Of Proteins Containing Oxidised Amino Acids
Funder
National Health and Medical Research Council
Funding Amount
$406,320.00
Summary
There is evidence that during ageing, and age-related diseases, proteins which have been chemically modified by oxidation accumulate in the body, and may have deleterious effects. Oxidation of proteins is a process akin to that by which fats go rancid. It has been demonstrated by the applicants to be an important process in formation of cataracts, and in development of the blood vessel disease, atherosclerosis, which is responsible for most heart attacks and stroke. Other important age-related d ....There is evidence that during ageing, and age-related diseases, proteins which have been chemically modified by oxidation accumulate in the body, and may have deleterious effects. Oxidation of proteins is a process akin to that by which fats go rancid. It has been demonstrated by the applicants to be an important process in formation of cataracts, and in development of the blood vessel disease, atherosclerosis, which is responsible for most heart attacks and stroke. Other important age-related diseases, such as Alzheimer s disease and other neurological disorders, are also claimed to be associated with deranged protein oxidation, and accumulation of oxidised products. There is clear evidence that certain defensive mechanisms, such as those acting to remove invading organisms and clear wounds, are also associated with an enhanced production of oxidised proteins. Perhaps the most important component of defense against oxidised proteins is their removal by complete breakdown to constituent components, and excretion. Normally, the machinery for breakdown of proteins is in vast excess over the required rate of degradation. However, clearly in these conditions of accumulation of oxidised proteins, this is no longer the case, or no longer suffices. Mechanisms by which oxidised proteins are degraded are poorly understood, and quite controversial. Therefore, the present studies bring to bear a new approach to studying this issue, which has been developed by the applicants. The aim is to reveal mechanisms involved in the breakdown of proteins containing oxidised amino acids, both in cellular systems, and in vivo. Such an understanding may allow us to envisage how to remove oxidised proteins by therapeutic means and therefore interfere with the development of age-related diseases such as Alzheimer s disease and cataract formation and the diseases of the blood vessels associated with attack and stroke.Read moreRead less
Oxidation Of Arterial Extracellular Matrix By Myeloperoxidase-derived Oxidants
Funder
National Health and Medical Research Council
Funding Amount
$183,266.00
Summary
It is well established that changes occur in the composition and nature of the extracellular matrix present in the artery wall during the development of atherosclerosis. The changes that occur in this matrix affect both the mechanical and physical properties of the arterial wall (e.g. its ability to cope with the high pressures genrated by the pumping of blood from the heart) and the adhesion of cells. It is well established that certain key cell types do not adhere well, or grow properly, on al ....It is well established that changes occur in the composition and nature of the extracellular matrix present in the artery wall during the development of atherosclerosis. The changes that occur in this matrix affect both the mechanical and physical properties of the arterial wall (e.g. its ability to cope with the high pressures genrated by the pumping of blood from the heart) and the adhesion of cells. It is well established that certain key cell types do not adhere well, or grow properly, on altered or damaged matrix and this can result in either the loss of key cell types from the artery wall (e.g. loss of endothelial cells) and - or the proliferation and invasion of cells from other sources (e.g. smooth muscle cell invasion into the intimal space). There is circumstantial evidence that some of these changes occur via the formation of oxidants by the heme enzyme myeloperoxidase which is released from activated white cells. In this study we will employ recently developed analytical techniques to examine the nature of the alterations that are present in atherosclerotic plaques in comparison to normal human artery samples, and investigate the mechanisms by which such alterations arise. We will seek evidence for, or against, the involvement of myeloperoxidase-derived oxidants in the observed changes using specific markers which we have developed for the presence of such damage. This information will allow the rational design of strategies to interfere with the progression of atherosclerosis, which is the major killer of Australians.Read moreRead less