Lysosomal storage disease phenotypes in induced pluripotent stem cell models of Huntington’s disease

Kelly, Brendan 2022. Lysosomal storage disease phenotypes in induced pluripotent stem cell models of Huntington’s disease. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Huntington’s disease (HD) is a heritable, autosomal dominant, neurodegenerative disease associated with the loss of medium spiny neurons (MSNs), cognitive and motor defects, and ultimately death. Though it is a monogenic disease and is caused by an expanded CAG trinucleotide repeat in the huntingtin gene (HTT), the precise pathomechanism underlying HD is unknown. However, lysosomal expansion, lipid dyshomeostasis, defects in autophagy, and mitochondrial function, have all been reported in HD. These phenotypes are commonly observed in lysosomal storage disorders (LSDs) and in particular, similarities with Niemann Pick Type C disease (NP-C), suggest a link between the two diseases. Thus, the repurposing of n-butyl-deoxy-nojirimycin (miglustat), a competitive inhibitor of glycosphingolipid synthesis, which is currently used for treatment of NP-C, Gaucher, and Pompe diseases, has been suggested for treatment of HD. This thesis aimed to assess lysosomal storage in HD, by using neural progenitors and neurons differentiated from HD patient-derived iPSCs, to compare HD cells to isogenic-corrected versions. We identified phenotypic differences in HD lines relative to the isogenic control cells, related to endolysosomal structure, lipid dyshomeostasis, autophagy, and mitochondrial structure and function. Miglustat treatment was associated with moderate improvement related to mitochondrial length, lipid storage, and autophagosome accumulation. Finally, we report the generation of two HTT knockout lines, one of which was generated from the aforementioned HD patient-derived iPSCs. The HTT knockouts facilitated investigation into wildtype huntingtin function and conferred the ability to make three-way comparisons with which gain or loss of HTT function in HD could be approached. Importantly, the HTT knockouts allowed for interrogation into the relationship between HTT and Niemann-Pick type C1 (NPC1), the protein that is defective in NP-C disease. The results here failed to evidence a wildtype role for HTT related to NPC1, or to the lysosomal or late endosomal compartments. However, dysregulation in autophagy and gene expression related to development were identified in HTT knockouts, which could help to iv resolve wildtype HTT function. Together, this data has expanded the basic cell biology of HD and supplied new tools with which huntingtin function might be examined.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Biosciences
Subjects:	Q Science > Q Science (General)
Date of First Compliant Deposit:	31 August 2023
Last Modified:	06 Sep 2023 08:55
URI:	https://orca.cardiff.ac.uk/id/eprint/161926

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