Mechanisms of cell death in Alzheimer's disease

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dc.contributor.advisor Associate-Professor Mike Dragunow en
dc.contributor.advisor Professor Richard Faull en
dc.contributor.author MacGibbon, Geraldine Anne en
dc.date.accessioned 2008-11-20T23:51:29Z en
dc.date.available 2008-11-20T23:51:29Z en
dc.date.issued 1998 en
dc.identifier.citation Thesis (PhD--Pharmacology and Clinical Pharmacolgy)--University of Auckland, 1998. en
dc.identifier.uri http://hdl.handle.net/2292/3164 en
dc.description Restricted Item. Print thesis available in the University of Auckland Library or may be available through Interlibrary Loan. en
dc.description Related published articles. MacGibbon GA, Cooper GJS, Dragunow M. Acute application of human amylin, unlike β-amyloid peptides, kills undifferentiated PC12 cells by apoptosis. NeuroReport 1997; 8:3945-3950. MacGibbon GA, Lawlor PA, Walton M, et al. Expression of Fos, Jun and Krox family proteins in Alzheimer's disease. Exp Neurol 1997; 147:316-332. MacGibbon GA, Lawlor PA, Sirimanne E et al. Bax expression in mammalian neurons undergoing apoptosis, and in Alzheimer's disease hippocampus. Brain Res 1997; 750:223-234 en
dc.description.abstract Alzheimer's disease (AD) is a progressive neurodegenerative disorder, which is characterised clinically by dementia and progressive memory loss, and pathologically by neuronal degeneration, plaques (insoluble β-amyloid (Aβ) protein) and neurofibrillary lesions (abnormally phosphorylated tau protein). The mechanisms by which cells die in AD remain largely unknown and controversial. There is some evidence to suggest that cell death in AD brains may occur by apoptosis, and that Aβ might be involved in this process. Apoptosis, a type of cell death characterised by distinct morphological and biochemical features, is often the result of 'programmed cell death' (PCD). Many gene families have been proposed to be involved in the PCD pathway, including the caspase family, inducible transcription factor (ITF) family (including Jun, Fos and Krox genes), and members of the Bcl-2 gene family (including the death promoting gene Bax). It is possible, therefore, that some of these genes may play a role in cell death in AD. The hippocampus is one of the first regions of the brain to be affected in AD, showing cell loss mainly in the CA1-2 pyramidal cell layer. In this thesis, the hippocampus from AD and Control cases has been examined for markers of apoptosis and genes thought to be involved in PCD. In addition, the actions of Aβ, human amylin (a structurally similar protein to Aβ) and the Aβ precursor protein (APP) have been examined in cell culture in an attempt to elucidate their mechanisms of action and relate this to the pathogenesis of AD. AD hippocampi showed increased DNA fragmentation as assessed by TdT-mediated dUTP-biotin nick end labelling (TUNEL), but TUNEL-positive cells in AD generally did not exhibit 'typical' apoptotic morphology, and there was no evidence of the oligonucleosomal DNA fragmentation characteristic of apoptosis. This indicates that 'typical' apoptosis may not be the predominant cell death mechanism in AD. However, there was some evidence of atypical 'broken' nuclei, which may represent a form of apoptosis that presents with a different morphology in aging tissue. This study found no conclusive evidence of increased expression of Fos or Jun family members in the CA1 region of AD hippocampi, however there were increased levels of the putative 'apoptosis-specific protein' and krox24 mRNA in this area which could be related to the cell death. There was no change in Bax expression in the CA1 region of AD brains (although increased Bax expression was observed in this region in a rat hypoxic-ischemia model where the CA1 neurons die by apoptosis). However, there was a decrease in Bax expression in the granule cells of AD hippocampi which could be related to the relative preservation of these cells in AD. Bax and ITF expression was observed in tangles, senile plaques and Hirano bodies in AD hippocampi, which may be related to the formation of these features and/or the pathogenesis of AD. There appeared to be changes in the cellular location of proteins in post-mortem tissue that made determination of ITF levels extremely difficult. In addition, patterns of ITF expression differed when different antisera directed at the same protein were used. These observations indicate that caution must be exercised when studying protein changes in post-mortem tissue. Application of insoluble Aβ to cultured cells, and overexpression of APP or familial AD-linked APP mutants in cultured cells, did not cause toxicity or alter c-Jun gene expression. However, human amylin was toxic to cultured cells, and had different effects on c-Jun gene expression depending on the cell type. This shows that structurally similar proteins do not always act by a similar mechanism, and that care must be taken when choosing a cell culture system to study disease-related events. The finding that neither insoluble Aβ nor APP/AD-linked APP mutants caused acute toxicity to cultured cells, coupled with the lack of relationship between TUNEL staining and Aβ deposits in post-mortem AD tissue, indicates that deposited insoluble Aβ and/or increased amounts of Aβ may not represent the toxic event in AD. This thesis provides a detailed investigation of several factors that could be involved in the cell death process in the hippocampus in AD. The results presented find no conclusive evidence for ‘classical’ apoptosis and/or increased ITF expression in the hippocampus in AD, but the changes in expression of krox24 mRNA, ‘apoptosis-specific protein’ and Bax suggest that programmed cell death may well be a mechanism which is involved in the pathogenesis of AD. en
dc.format Scanned from print thesis en
dc.language.iso en en
dc.publisher ResearchSpace@Auckland en
dc.relation.ispartof PhD Thesis - University of Auckland en
dc.relation.isreferencedby UoA873754 en
dc.rights Whole document restricted. Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. en
dc.rights.uri https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm en
dc.title Mechanisms of cell death in Alzheimer's disease en
dc.type Thesis en
thesis.degree.discipline Pharmacology and Clinical Pharmacology en
thesis.degree.grantor The University of Auckland en
thesis.degree.level Doctoral en
thesis.degree.name PhD en
dc.subject.marsden Fields of Research::320000 Medical and Health Sciences::320500 Pharmacology and Pharmaceutical Sciences::320503 Clinical pharmacology and therapeutics en
dc.rights.holder Copyright: The author en
pubs.local.anzsrc 11 - Medical and Health Sciences en
dc.rights.accessrights http://purl.org/eprint/accessRights/ClosedAccess en
pubs.org-id Faculty of Medical & Hlth Sci en


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