Brunel University Research Archive (BURA) >
Schools >
School of Health Sciences and Social Care >
School of Health Sciences and Social Care Theses >

Please use this identifier to cite or link to this item: http://bura.brunel.ac.uk/handle/2438/6334

Title: Investigating the pathogenesis and therapy of Friedreich Ataxia
Authors: Sandi, Chiranjeevi
Advisors: Pook, M
Keywords: Friedreich ataxia
FRDA
Frataxin
Hdac inhibitor
NSCs
Publication Date: 2010
Publisher: Brunel University School of Health Sciences and Social Care PhD Theses
Abstract: Friedreich ataxia (FRDA) is an inherited autosomal recessive neurodegenerative disorder caused by a GAA trinucleotide repeat expansion mutation within the first intron of the FXN gene. Normal individuals have 5 to 30 GAA repeats, whereas affected individuals have from approximately 70 to more than 1,000 GAA triplets. In addition to progressive neurological disability, FRDA is associated with cardiomyopathy and an increased risk of diabetes mellitus. Currently there is no effective therapy for FRDA and this is perhaps due to the lack of an effective system to test potential drugs. Therefore, the main aim of this thesis is to develop a novel cell culture system, to aid in rapid drug screening for FRDA. Firstly, I have demonstrated the establishment of novel cell culture systems, including primary fibroblasts, neural stem cells (NSC) and splenocytes, from FRDA YAC transgenic mouse models (YG8 and YG22). Then, I have shown the differentiation of NSCs into neurons, oligodendrocytes and astrocytes. The presence of these cells was confirmed by using cell specific immunofluorescence assays. I have also shown that both YG8 and YG22 rescue mice have less tolerance to hydrogen peroxide induced oxidative stress than WT mice, as similarly seen in FRDA patient fibroblasts. Recent findings indicate that FRDA is associated with heterochromatin-mediated silencing of the FXN gene accompanied by histone changes, flanking the GAA repeats. This suggested potential therapeutic use of compounds which can reduce the methylation and increase the acetylation of histone proteins. Therefore, using human and mouse primary fibroblast cell lines I have investigated the efficacy and tolerability of various DNA demethylating agents, GAA interacting compounds and class III histone deacetylase (HDAC) inhibitors. Although DNA demethylating agents showed increased FXN expression, no correlation between the level of DNA methylation and FXN expression was identified. Nevertheless, the use of GAA interacting compounds, particularly DB221, and the HDAC inhibitor, nicotinamide, have shown encouraging results, provoking us to use such compounds in future long-term in vivo studies. In addition, I have also investigated the long-term efficacy of two benzamide-type HDAC inhibitors, RGFA 136 and RGFP 109, on the FRDA YAC transgenic mice. No overt toxicity was identified with either drug, indicating a safe administration of these compounds. Both compounds produced improved functional analysis together with significantly reduced DRG neurodegeneration. However, neither of these compounds was shown to significantly increase the FXN mRNA expression. Nevertheless, elevated levels of frataxin protein in the brain tissues were obtained with RGFP 109, suggesting that RGFP 109 is capable of crossing the blood-brain barrier. I have also found increased levels of global acetylated H3 and H4 histone proteins in brain tissues, along with significant increase in aconitase enzyme activity, particularly with RGFP 109 treatments. Overall, these results support future clinical trial development with such compounds.
Description: This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.
Sponsorship: This work is financially supported by the Muscular Dystrophy Association (MDA)
URI: http://bura.brunel.ac.uk/handle/2438/6334
Appears in Collections:School of Health Sciences and Social Care Research Papers
Biological Sciences
School of Health Sciences and Social Care Theses

Files in This Item:

File Description SizeFormat
FulltextThesis.pdf6.53 MBAdobe PDFView/Open

Items in BURA are protected by copyright, with all rights reserved, unless otherwise indicated.