Expression and mitochondrial localization of frataxin, the Friedreich's ataxia gene product

P. Cavadini, C. Diblasi, S. Baratta, A. Princivalle, S. Didonato, G. Battaglia, M. Mora, F. Taroni

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Friedreich's ataxia (FA) is the most common hereditary ataxia (1:50,000). The disease gene (X25; Campuzano eraJ., 1996) encodes a 210-aa protein, termed frataxin, whose physiological role is presently unknown. To gain insights into the pathogenic mechanism leading to FA, we have expressed the HA1-epitope-tagged frataxin cDNA in transfected mammalian cells (CMT4). Experiments were performed with both an anti-HA1 monoclonal antibody and two different anti-frataxin polyclonal antibodies. Western blot analysis of transiently transfected cells showed a larger band of ≈30 kDa and a smaller band of ≈21 kDa. Interestingly, immunofluoreïcence analysis of transfected cells revealed that the signal pattern of frataxin was similar to that of two mitochondria-specific probes, CPT-II and SSBP, thus indicating a mitochondrial localization of frataxin. Immunofluorescence analysis with anti-frataxin polyclonal antibodies confirmed the characteristic 'mitochondrial' pattern also in human fibroblasts and skeletal muscle fibers. Analysis of the immunoprecipitated protein from transfected cells radiolabeled either in the presence or in the absence of valinomycin, an inhibitor of mitochondrial import, indicated that frataxin is synthesized as a larger precursor which is subsequently processed at the mitochondrial level into a smaller mature form. In situ hybridization analysis of rat neural tissue demonstrated high X25 expression in the primary sensory neurons of the dorsal root ganglia, the spinal neurons of the ventral and intermediate laminae, and the cerebellar neurons of the granular cell layer, neural structures which are selectively damaged in the human disease.

Original languageEnglish
Pages (from-to)25
Number of pages1
JournalItalian Journal of Neurological Sciences
Issue number4
Publication statusPublished - 1997

ASJC Scopus subject areas

  • Neuroscience(all)
  • Clinical Neurology


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