Year: 2013
Type: dissertation
Abstract: Friedreich ataxia (FRDA) is an autosomal recessive neurodegenerative disorder, caused by a GAA repeat expansion mutation within intron 1 of the FXN gene, resulting in reduced level of frataxin protein.Normal individuals have 5 to 40 GAA repeat sequences, whereas affected individuals have approximately 70 to more than 1000 GAA triplets.Frataxin is a mitochondrial protein involved in iron-sulphur cluster and heme biosynthesis.The reduction in frataxin expression leads to oxidative stress, mitochondrial iron accumulation and consequential cell death with the primary sites of neurons of the dorsal root ganglia and the dentate nucleus of the cerebellum.FRDA, which is the most common inherited ataxia, affecting 1:50,000 Caucasians, is characterised by neurodegeneration, cardiomyopathy, diabetes mellitus and skeletal deformities.To investigate FRDA molecular disease mechanisms and therapy, several human FXN YAC transgenic mouse models have been established: Y47R, containing normal-sized (GAA) 9 repeats; YG8R and YG22R, which initially contained expanded GAA repeats of 90-190 units and 190 units, respectively, but which have subsequently been bred to now contain expanded GAA repeats of 120-220 units and 170-260 units, respectively, and YG8sR (YG8R with a small GAA band) that was recently generated from YG8R breeding.To determine the FXN transgene copy number in the enhanced GAA repeat expansion-based FRDA mouse lines, a TaqMan qPCR assay was developed.The results demonstrated that the YG22R and Y47R lines had a single copy of the FXN transgene while the YG8R line had two copies.The YG8s lines showed less than one copy of the target gene, suggesting potential deletion of the FXN gene.Single integration sites of all transgenes were confirmed by fluorescence in situ hybridisation (FISH) analysis of metaphase and interphase chromosomes.However, in the YG8s line, at least 25% of the YG8s cells had no signals, while the remaining cells showed one signal corresponding to the transgenic FXN gene.In addition, the analysis of FXN exons in YG8s rescue mice by PCR confirmed the presence of all FXN exons in these lines, suggesting the incidence of somatic mosaicism in these lines.Extended functional analysis was carried out on these mice from 4 to 12 months of age.Coordination ability of YG8R, YG8sR and YG22R 'FRDA-like' mice, together with Y47R and C57BL6/J wild-type control mice, was assessed using accelerating rotarod I would also like to thank Dr.
Author: Anjomani Virmouni, Sara
Language: English
Subfield: Cellular and Molecular Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W7066305441