Altered Redox Mitochondrial Biology in the Neurodegenerative Disorder Fragile X-Tremor/Ataxia Syndrome: Use of Antioxidants in Precision Medicine

• Main Authors: Gyu Song (Author), Eleonora Napoli (Author), Sarah Wong (Author), Randi Hagerman (Author), Siming Liu (Author), Flora Tassone (Author), Cecilia Giulivi (Author)
• Format: Book
• Published: BMC, 2016-06-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.
• Notes: 10.2119/molmed.2016.00122; 1076-1551; 1528-3658
• Keywords: Therapeutics. Pharmacology; RM1-950; Biochemistry; QD415-436
• Source: Molecular Medicine, Vol 22, Iss 1, Pp 548-559 (2016)

Abstract 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.