Use this URL to cite or link to this record in EThOS:
Title: The cytoxocity of amyloid fibrils
Author: Hellewell, Andrew Leslie
ISNI:       0000 0004 2746 1755
Awarding Body: University of Leeds
Current Institution: University of Leeds
Date of Award: 2011
Availability of Full Text:
Access from EThOS:
Amyloid assemblies consist of an organised cross ~-sheet structure and can be formed by many proteins or peptides regardless of peptide sequence. Amyloid has been utilised by many species for a variety of functions, however, inappropriate amyloid formation is associated with a spectrum of devastating amyloid diseases. The nature of the primary cytotoxic species in amyloid disease is widely debated, with the consensus favouring pre-fibrillar, oligomeric entities over mature end-stage fibrils, despite an increasing body of evidence that suggest at least some fibrils may be associated with cytotoxicity. Amyloid fibrils can be considered as nanomaterials and, as the physical dimensions of nanomaterials can strongly influence their biological activity, this raises the possibility that fibril length may influence their cytotoxic potential. This thesis examines the role of fibril fragmentation on amyloid fibril-associated cytotoxicity and the cellular mechanisms involved. First, having introduced the themes of amyloidosis in Chapter 1 and the methods employed in this thesis in Chapter 2, in Chapter 3, ~2microglobulin amyloid fibrils are used as a model to investigate the effect of fibril fragmentation on cytotoxicity and membrane disruption. The fibrils were fragmented, reducing fibril length, with a consequent increase in cytotoxicity and membrane disruptive capacity. Amyloid fibrils generated from a range of disease specific, functional, de novo designed, and model systems were then formed and fragmented and their cytotoxicity was analysed using different cell lines. Strikingly, in each case, the amyloid fibrils were more cytotoxic following fragmentation. In Chapter 4 the cellular mechanisms associated with amyloid fibril-associated cytotoxicity were investigated. Using amyloid fibrils formed from ~2microglobulin (~2m) as a model, it was established that ~2m amyloid fibrils do "not cause cytotoxicity by plasma membrane disruption but, following internalisation, localise to and disrupt Iysosomes leading to cathepsin-- dependent cell death. Inhibition of fibril uptake or cathepsin activity was shown to protect VI against ~2m fibril-associated cytotoxicity, as well as the cytotoxicity associated with an array of other amyloid fibrils. Taken together the data suggest that amyloid fibrils cause cytotoxicity through disruption of Iysosomes, a mechanism common to many fibril types and increased by fibril fragmentation. The significance of these findings and the potential for future studies are then discussed in Chapter 5.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available