Date of Award
12-8-2023
Degree Name
Doctor of Philosophy (PhD)
Degree Type
Dissertation
Abstract
X-linked dystonia-parkinsonism (XDP) is an adult-onset neurodegenerative disorder that results in the loss of striatal medium spiny neurons (MSNs). XDP is an X-linked disorder caused by disease-specific mutations around the TAF1 gene. This thesis highlights the utility of directly reprogrammed MSNs from fibroblasts of affected XDP as a platform that captures cellular and epigenetic phenotypes associated with XDP neurodegeneration. In addition, this thesis demonstrates the neuroprotective effect of SAK3 currently tested in other neurodegenerative diseases. XDP fibroblasts from three independent patients as well as age- and sex-matched control fibroblasts were used to generate MSNs using miRNA-9/9*-124 and the transcription factors CTIP2, DLX1-P2A-DLX2, and MYT1L. Cell death, DNA damage, and mitochondrial health assays were carried out to assess the neurodegenerative state of directly reprogrammed MSNs from XDP patients (XDP-MSNs). RNA sequencing and ATAC sequencing were performed to infer changes in the transcriptomic and chromatin landscapes of XDP-MSNs compared to those of control MSNs (Ctrl-MSNs). Our results show that XDP patient fibroblasts can be successfully reprogrammed into MSNs and XDP-MSNs display several spontaneous degenerative phenotypes, including neuronal death, DNA damage, and mitochondrial dysfunction, compared to Ctrl-MSNs reprogrammed from age- and sex-matched control individuals. In addition, XDP-MSNs showed increased vulnerability to TNFα, a known cellular stressor compared to Ctrl-MSNs. The transcriptomic and chromatin accessibility analyses indicate that pathways related to neuronal function, calcium signaling, and genes related to other neurodegenerative diseases are commonly altered in XDP-MSNs from multiple patients. This thesis also shows that the TAF1 gene that harbors the XDP-specific mutations is not downregulated in its mRNA or protein expression. However, other several genes are significantly alternatively spliced, one of which is RNF212. Interestingly, we found that SAK3, a T-type calcium channel activator, that is beneficial in other neurodegenerative diseases conferred a protective effect in XDP-MSNs. Notably, we found that SAK3-mediated alleviation of neurodegeneration in XDP-MSNs was accompanied by gene expression changes toward Ctrl-MSNs.
Language
English (en)
Chair and Committee
Andrew Yoo
Recommended Citation
Aryal, Shivani, "Modeling X-Linked Dystonia Parkinsonism (XDP) in Patient-Derived Medium Spiny Neurons" (2023). Arts & Sciences Electronic Theses and Dissertations. 3195.
https://openscholarship.wustl.edu/art_sci_etds/3195