Human Tyrosine Hydroxylase Isoforms And Susceptibility Of Dopaminergic Neurons To Degeneration In Parkinson's Disease
Funder
National Health and Medical Research Council
Funding Amount
$359,683.00
Summary
In Parkinson's disease there is major loss of the dopaminergic neurons of the substantia nigra. We are investigating how the control of dopamine synthesis may affect the differential loss of dopaminergic neurons in Parkinson's disease. Understanding why certain dopaminergic die in Parkinson's disease and others do not will help the development of new treatment strategies for Parkinson's disease.
Differential Regulation Of Human Tyrosine Hydroxylase Isoforms And The Development Of Parkinson's Disease
Funder
National Health and Medical Research Council
Funding Amount
$325,591.00
Summary
Parkinson's disease is a common neurodegenerative disease whose major feature is loss of a dopamine containing nerves in a part of the brain called the substantia nigra. Loss of nerves within the substantia nigra is not uniform, but firstly and primarily affects the ventral cells, suggesting that particular dopaminergic neurons are more vulnerable to the disease process. A key to understanding Parkinson's disease would be to work out why these cells are more susceptible to degeneration than othe ....Parkinson's disease is a common neurodegenerative disease whose major feature is loss of a dopamine containing nerves in a part of the brain called the substantia nigra. Loss of nerves within the substantia nigra is not uniform, but firstly and primarily affects the ventral cells, suggesting that particular dopaminergic neurons are more vulnerable to the disease process. A key to understanding Parkinson's disease would be to work out why these cells are more susceptible to degeneration than other dopaminergic cells in the brain. Tyrosine hydroxylase controls the rate of dopamine synthesis. Humans are unique in that they contain four isoforms of tyrosine hydroxylase and therefore they have the potential to alter the regulation of dopamine synthesis in ways that other species do not. Recent developments in our laboratories have suggested that particular isoforms of tyrosine hydroxylase may have either a role in the susceptibility of dopaminergic neurons to degeneration in Parkinson's disease or a role in the timing of the symptoms of the disease. We have demonstrated differences in the distribution of the human TH isoforms within the substantia nigra, with certain isoforms being more prevalent in the susceptible ventral cells. We have also shown that there are major differences in the regulation of the four human tyrosine hydroxylase isoforms. Some isoforms will be more sensitive to conditions that occur with high frequency stimulation of neurons and some to low frequency sustained stimulation. This would provide a mechanism by which differential distribution of the human TH isoforms would result in altered dopamine synthesis in different parts of the human brain and this may in turn lead to either increased susceptibility to, or earlier appearance of symptoms of, Parkinson's disease.Read moreRead less
Alzheimer's Disease And Related Disorders: Mechanism Of Tau Pathology In Established And Novel Transgenic Animal Models
Funder
National Health and Medical Research Council
Funding Amount
$423,017.00
Summary
Alzheimer's disease (AD) is a devastating neurodegenerative disease for which no cure is available. It affects more than 15 million people worldwide. There are estimates that by 2040, approximately 500'000 Australians will suffer from AD, with associated health costs of about 3% of the GDP. AD is characterized by two major brain lesions, beta-amyloid plaques and neurofibrillary tangles (NFTs). The latter contain a protein called tau which is in a fibrillar and highly phosphorylated state. We wer ....Alzheimer's disease (AD) is a devastating neurodegenerative disease for which no cure is available. It affects more than 15 million people worldwide. There are estimates that by 2040, approximately 500'000 Australians will suffer from AD, with associated health costs of about 3% of the GDP. AD is characterized by two major brain lesions, beta-amyloid plaques and neurofibrillary tangles (NFTs). The latter contain a protein called tau which is in a fibrillar and highly phosphorylated state. We were the first to establish a transgenic animal model of pre-tangles and, together with Dr. Hutton's laboratory, of NFT formation. We could further show that injections of beta-amyloid into brains of our tau mutant mice enhanced the NFT pathology in these mice. By Functional Genomics we identied genes and proteins, which are induced by tau expression. The specific aim of this proposal is to determine whether oxidative stress enhances the tau pathology in our tau mutant mice and whether distinct brain areas are particularly susceptible to this kind of stress. The reason for addressing this question is twofold: On the one hand, we have found in our mice that reactive oxygen species are increased, secondly it is known that some brain areas in the AD brain are degenerating, whereas others are not. A second aim is to develop novel tau transgenic models where individual interactions of tau with cellular proteins are disturbed. Finally, we want to determine whether the two kinases BMX and FAK and the phosphatase PPV regulate tau phosphorylation in vivo. Together, we hope that our efforts lead to a better understanding of the pathogenic mechanisms in AD and related disorders. As pathocascades are likely to be shared between a range of diseases, these findings may also contribute to other fields of research, such as Parkinson's disease. Ultimately, these efforts will assist in the development of a safe treatment of AD.Read moreRead less