Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.784695
Title: ALS/FTD associated C9orf72 expansions induce heat shock response activation and induce SOD1 proteinopathy
Author: Shaw, Matthew
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2019
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Abstract:
A hexanucleotide repeat expansion (HRE) within the C9orf72 gene is the most prevalent cause of amyotrophic lateral sclerosis/fronto-temporal dementia (ALS/FTD). Current evidence suggests that HREs induce neurodegeneration through the accumulation of RNA foci and/or dipeptide repeat proteins (DPRs), though there is also evidence for haploinsufficiency of the C9orf72 protein. Here, we modelled toxic gain of function disease mechanisms by generating and characterising two distinct transgenic zebrafish models. Whilst both model systems express HREs that lead to RNA foci production, only one model expresses ATG-driven DPRs. The two model systems were termed "RNA-only" and "RNA+DPR" zebrafish. As a readout of cellular stress, we utilised a fluorescent-reporter construct that expresses DsRed under the control of a heat shock promoter, which we then used to screen for potential therapeutic compounds. We also used immunoblotting techniques to characterise DPR, TDP-43 and SOD1 proteinopathies in human ALS post-mortem tissue. Our RNA-only zebrafish model did not display any evidence of reduced survival at 26 months post-fertilisation. In contrast, the RNA+DPR zebrafish model displayed muscle atrophy, motor neuron loss and reduced survival at 36 months post-fertilisation. In line with increased toxicity, we identified that RNA+DPR zebrafish activate the heat shock response (HSR), which we also found to be true in C9orf72-ALS patient samples. HSR activation correlated with disease progression in our RNA+DPR zebrafish model and, through drug screening, we found that this could be attenuated using the compounds ivermectin, selamectin and riluzole. Finally, we report that SOD1 proteinopathy is detectable in disease relevant areas of C9orf72 patients CNS, and that this correlates with TDP-43 proteinopathy. We conclude that our RNA+DPR zebrafish model system shows motor neuron pathology, and the HSR readout in this zebrafish model may prove useful as a tool for evaluating potential neuroprotective compounds prior to mammalian testing. Finally, our neuropathological findings suggest a potential link between C9orf72-HREs and SOD1 as well as TDP-43 proteinopathies.
Supervisor: Ramesh, Tennore ; Shaw, Pamela ; Higginbottom, Adrian Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.784695  DOI: Not available
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