Generation and Characterisation of Friedreich Ataxia YG8R Mouse Fibroblast and Neural Stem Cell Models

Abstract

BackgroundFriedreich ataxia (FRDA) is an autosomal recessive neurodegenerative disease caused by GAA repeat expansion in the first intron of the FXN gene, which encodes frataxin, an essential mitochondrial protein. To further characterise the molecular abnormalities associated with FRDA pathogenesis and to hasten drug screening, the development and use of animal and cellular models is considered essential. Studies of lower organisms have already contributed to understanding FRDA disease pathology, but mammalian cells are more related to FRDA patient cells in physiological terms.Methodology/Principal FindingsWe have generated fibroblast cells and neural stem cells (NSCs) from control Y47R mice (9 GAA repeats) and GAA repeat expansion YG8R mice (190+120 GAA repeats). We then differentiated the NSCs in to neurons, oligodendrocytes and astrocytes as confirmed by immunocytochemical analysis of cell specific markers. The three YG8R mouse cell types (fibroblasts, NSCs and differentiated NSCs) exhibit GAA repeat stability, together with reduced expression of frataxin and reduced aconitase activity compared to control Y47R cells. Furthermore, YG8R cells also show increased sensitivity to oxidative stress and downregulation of Pgc-1α and antioxidant gene expression levels, especially Sod2. We also analysed various DNA mismatch repair (MMR) gene expression levels and found that YG8R cells displayed significant reduction in expression of several MMR genes, which may contribute to the GAA repeat stability.Conclusions/SignificanceWe describe the first fibroblast and NSC models from YG8R FRDA mice and we confirm that the NSCs can be differentiated into neurons and glia. These novel FRDA mouse cell models, which exhibit a FRDA-like cellular and molecular phenotype, will be valuable resources to further study FRDA molecular pathogenesis. They will also provide very useful tools for preclinical testing of frataxin-increasing compounds for FRDA drug therapy, for gene therapy, and as a source of cells for cell therapy testing in FRDA mice.

Mitoferrin modulates iron toxicity in a Drosophila model of Friedreich׳s ataxia

“…The reduced tolerance of FRDA flies to iron overload is in agreement with the negative impact of iron in other FRDA models [35,[58][59][60] and the frataxin-mediated protection against elevated iron concentration [61]. The strong upregulation of Fer1HCH expression after iron feeding confirmed the activation of the iron homeostasis machinery.…”

Bone marrow transplantation stimulates neural repair in Friedreich's ataxia mice

“…Frataxin deficiency results in dysregulation in cellular antioxidant defenses,32 with deficiencies in key antioxidant regulators including PGC‐1alpha and Nrf2 33, 34. BMT in YG8R mice was associated with significant increases in PGC‐1alpha expression.…”

Cytokine therapy‐mediated neuroprotection in a Friedreich's ataxia mouse model

“…34 In line with previous studies YG8R mice had reduced protein levels of PGC-1a and Nrf2 in either the spinal cord and/or cerebellum. 35,36 This was associated with global reductions in expression of antioxidant enzymes and enzymatic activity of the iron-sulphur protein aconitase within the cerebellum 28 (Table). Untreated YG8R mice also showed increases in the lipid peroxidation product, 4-HNE, within the cerebellum and spinal cord (see Table).…”