Modelling Huntington’s Disease Using Direct Cell Reprogramming

Huntington’s disease (HD) is a neurodegenerative disorder characterised by the progressive decline of motor, cognitive, and psychiatric functions. HD results from an autosomal dominant mutation that causes a trinucleotide CAG repeat expansion and the production of a mutant Huntingtin protein (mHTT). There are currently no effective treatments to prevent or delay HD progression as the knowledge surrounding the specific mechanisms through which mHTT results in the preferential degeneration of striatal medium spiny neurons (MSNs) is limited. This may be due to the challenge of generating a representative model of HD. Cell reprogramming is a revolutionary technology that can generate live, human neurons in vitro from the somatic cells of individuals with HD. Our research group was the first to demonstrate the direct reprogramming of adult human dermal fibroblasts (HDFs) into induced neural precursor cells (iNPs) that differentiate into neurons using chemically-modified mRNA (cmRNA) encoding the neural development factors SOX2 and PAX6. Importantly, cell reprogramming enables the study of early disease mechanisms and could facilitate the identification of novel therapeutic interventions for HD. The work conducted for this thesis sought to investigate the generation of iNPs and MSNs from HD HDFs using cmRNA-mediated reprogramming. The protocols to generate iNPs and MSNs were optimised in normal cell lines, involving hypoxic culture, BrainPhysTM neuronal medium, and the refinement of a multi-step striatal differentiation protocol. HD iNPs and MSNs were generated from HD HDFs using this refined protocol, and HD neurons exhibited significant alterations in neuronal morphology and electrophysiological properties. These findings were consistent with impaired neuronal maturation in HD. The expression of genes involved in HD neuropathogenesis were examined and found to be similar in normal and HD. An investigation of brain-derived neurotrophic factor and associated receptor signalling in the presentation of an HD phenotype suggested a role for altered receptor signalling in HD neuropathogenesis. The work of this thesis demonstrated for the first time the generation of iNPs from HD HDFs and the differentiation of HD iNPs into a population of MSNs for disease modelling. Future research confirming that HD neurons exhibit altered neuronal maturation may highlight this model of HD as a novel platform for investigating preventative therapeutic interventions.

Name thesis:degree_name

PhD

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Biomedical Science

Grantor dc:publisher

ResearchSpace@Auckland

Year dc:date.issued

2020

Author dc:creator

• Monk, Ruth

Advisors dc:contributor.advisor

• Connor, B
• Jones, K

Statement dc:rights

• Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher.

Licence dc:rights.uri

• https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm

Handle dc:identifier.uri

https://hdl.handle.net/2292/52508

OAI identifier oai:identifier

oai:researchspace.auckland.ac.nz:2292/52508