A 55–200 expansion of the CGG nucleotide repeat in the 5′-UTR of the fragile X mental retardation 1 gene (FMR1) is the hallmark of the triplet nucleotide disease known as the “premutation” as opposed to those with >200 repeats, known as the full mutation or fragile X syndrome. Originally, premutation carriers were thought to be free of phenotypic traits; however, some are diagnosed with emotional and neurocognitive issues and, later in life, with the neurodegenerative disease fragile X-associated tremor/ataxia syndrome (FXTAS). Considering that mitochondrial dysfunction has been observed in fibroblasts and post-mortem brain samples from carriers of the premutation, we hypothesized that mitochondrial dysfunction-derived reactive oxygen species (ROS) may result in cumulative oxidative-nitrative damage. Fibroblasts from premutation carriers (n = 31, all FXTAS-free except 8), compared with age- and sex-matched controls (n = 25), showed increased mitochondrial ROS production, impaired Complex I activity, lower expression of MIA40 (rate-limiting step of the redox-regulated mitochondrial-disulfide-relay-system), increased mtDNA deletions and increased biomarkers of lipid and protein oxidative-nitrative damage. Most of the outcomes were more pronounced in FXTAS-affected individuals. Significant recovery of mitochondrial mass and/or function was obtained with superoxide or hydroxyl radicals’ scavengers, a glutathione peroxidase analog, or by overexpressing MIA40. The effects of ethanol (a hydroxyl radical scavenger) were deleterious, while others (by N-acetyl-cysteine, quercetin and epigallocatechin-3-gallate) were outcome- and/or carrier-specific. The use of antioxidants in the context of precision medicine is discussed with the goal of improving mitochondrial function in carriers with the potential of decreasing the morbidity and/or delaying FXTAS onset.
Altered Redox Mitochondrial Biology in the Neurodegenerative Disorder Fragile X-Tremor/Ataxia Syndrome: Use of Antioxidants in Precision Medicine
Gyu Song,E. Napoli,Sarah Wong,R. Hagerman,Siming Liu,F. Tassone,C. Giulivi
Published 2016 in Molecular Medicine
ABSTRACT
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- Publication year
2016
- Venue
Molecular Medicine
- Publication date
2016-06-30
- Fields of study
Biology, Medicine, Environmental Science
- Identifiers
- External record
- Source metadata
Semantic Scholar, PubMed
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