AIMS: Oxidative stress is thought to be involved in Friedreich's ataxia (FRDA), yet it has not been demonstrated in the target neurons that are first to degenerate. Using the YG8R mouse model of FRDA, microarray and neuritic growth experiments were carried out in the dorsal root ganglion (DRG), the primary site of neurodegeneration in this disease. RESULTS: YG8R hemizygous mice exhibited defects in movement, and DRG neurites had growth defects. Microarray of DRG tissue identified decreased transcripts encoding the antioxidants, including peroxiredoxins, glutaredoxins, and glutathione S-transferase, and these were confirmed by immunoblots and quantitative real-time PCR. Because the decreased gene transcripts are the known targets of the antioxidant transcription factor nuclear factor-E2-related factor-2 (Nrf2), Nrf2 expression was measured; it was significantly decreased at the transcript and protein level in both the DRG and the cerebella of the YG8R hemizygous mouse; further, frataxin expression was significantly correlated with Nrf2 expression. Functionally, in YG8R hemizygous DRG, the total glutathione levels were reduced and explanted cells were more sensitive to the thioredoxin reductase (TxnRD) inhibitor auranofin, a thiol oxidant. In cell models of FRDA, including Schwann and the DRG, frataxin deficiency caused a decreased expression of the Nrf2 protein level in the nucleus, but not a defect in its translocation from the cytosol. Further, frataxin-deficient cells had decreased enzyme activity and expression of TxnRD, which is regulated by Nrf2, and were sensitive the TxnRD inhibitor auranofin. INNOVATION AND CONCLUSION: These results support a mechanistic hypothesis in which frataxin deficiency decreases Nrf2 expression in vivo, causing the sensitivity to oxidative stress in target tissues the DRG and the cerebella, which contributes to the process of neurodegeneration.
AIMS: Oxidative stress is thought to be involved in Friedreich's ataxia (FRDA), yet it has not been demonstrated in the target neurons that are first to degenerate. Using the YG8R mouse model of FRDA, microarray and neuritic growth experiments were carried out in the dorsal root ganglion (DRG), the primary site of neurodegeneration in this disease. RESULTS: YG8R hemizygous mice exhibited defects in movement, and DRG neurites had growth defects. Microarray of DRG tissue identified decreased transcripts encoding the antioxidants, including peroxiredoxins, glutaredoxins, and glutathione S-transferase, and these were confirmed by immunoblots and quantitative real-time PCR. Because the decreased gene transcripts are the known targets of the antioxidant transcription factor nuclear factor-E2-related factor-2 (Nrf2), Nrf2 expression was measured; it was significantly decreased at the transcript and protein level in both the DRG and the cerebella of the YG8R hemizygous mouse; further, frataxin expression was significantly correlated with Nrf2 expression. Functionally, in YG8R hemizygous DRG, the total glutathione levels were reduced and explanted cells were more sensitive to the thioredoxin reductase (TxnRD) inhibitor auranofin, a thiol oxidant. In cell models of FRDA, including Schwann and the DRG, frataxin deficiency caused a decreased expression of the Nrf2 protein level in the nucleus, but not a defect in its translocation from the cytosol. Further, frataxin-deficient cells had decreased enzyme activity and expression of TxnRD, which is regulated by Nrf2, and were sensitive the TxnRD inhibitor auranofin. INNOVATION AND CONCLUSION: These results support a mechanistic hypothesis in which frataxindeficiency decreasesNrf2 expression in vivo, causing the sensitivity to oxidative stress in target tissues the DRG and the cerebella, which contributes to the process of neurodegeneration.
Authors: J B Schulz; T Dehmer; L Schöls; H Mende; C Hardt; M Vorgerd; K Bürk; W Matson; J Dichgans; M F Beal; M B Bogdanov Journal: Neurology Date: 2000-12-12 Impact factor: 9.910
Authors: F Piemonte; A Pastore; G Tozzi; D Tagliacozzi; F M Santorelli; R Carrozzo; C Casali; M Damiano; G Federici; E Bertini Journal: Eur J Clin Invest Date: 2001-11 Impact factor: 4.686
Authors: K Chantrel-Groussard; V Geromel; H Puccio; M Koenig; A Munnich; A Rötig; P Rustin Journal: Hum Mol Genet Date: 2001-09-15 Impact factor: 6.150
Authors: H Puccio; D Simon; M Cossée; P Criqui-Filipe; F Tiziano; J Melki; C Hindelang; R Matyas; P Rustin; M Koenig Journal: Nat Genet Date: 2001-02 Impact factor: 38.330
Authors: Mittal J Jasoliya; Marissa Z McMackin; Chelsea K Henderson; Susan L Perlman; Gino A Cortopassi Journal: Hum Mol Genet Date: 2017-07-15 Impact factor: 6.150
Authors: Belén Mollá; Diana C Muñoz-Lasso; Pablo Calap; Angel Fernandez-Vilata; María de la Iglesia-Vaya; Federico V Pallardó; Maria Dolores Moltó; Francesc Palau; Pilar Gonzalez-Cabo Journal: Neurotherapeutics Date: 2019-04 Impact factor: 7.620
Authors: Tslil Ast; Joshua D Meisel; Shachin Patra; Hong Wang; Robert M H Grange; Sharon H Kim; Sarah E Calvo; Lauren L Orefice; Fumiaki Nagashima; Fumito Ichinose; Warren M Zapol; Gary Ruvkun; David P Barondeau; Vamsi K Mootha Journal: Cell Date: 2019-04-25 Impact factor: 41.582
Authors: Jonathan Jones; Alicia Estirado; Carolina Redondo; Jesus Pacheco-Torres; Maria-Salomé Sirerol-Piquer; José M Garcia-Verdugo; Salvador Martinez Journal: Mol Ther Date: 2014-07-29 Impact factor: 11.454