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Mitochondrial DNA abnormalities in skeletal muscle of patients with sporadic amyotrophic lateral sclerosis

Stefan Vielhaber, Dagmar Kunz, Kirstin Winkler, Falk R. Wiedemann, Elmar Kirches, Helmut Feistner, Hans-Jochen Heinze, Christian E. Elger, Walter Schubert, Wolfram S. Kunz
DOI: http://dx.doi.org/10.1093/brain/123.7.1339 1339-1348 First published online: 1 July 2000

Summary

Amyotrophic lateral sclerosis is a neurodegenerative disease affecting the anterior horn cells of the spinal cord and cortical motor neurons. Previous findings have suggested a specific impairment of mitochondrial function in skeletal muscle of at least a limited number of patients. Applying flavoprotein/NAD(P)H autofluorescence imaging of mitochondrial function in saponin-permeabilized muscle fibres, we detected a heterogeneous distribution of the respiratory chain defect among individual fibres in muscle biopsies of patients (11 out of 17) with sporadic amyotrophic lateral sclerosis (SALS). These findings correlate with the presence of cytochrome c oxidase (COX)-negative muscle fibres detected histologically. We established the molecular basis for the decreased activities of NADH:CoQ oxidoreductase and COX in SALS muscle. In the skeletal muscle of the investigated patients, diminished levels (13 out of 17) or multiple deletions (one out of 17) of mitochondrial DNA (mtDNA) were observed. These alterations of mtDNA seem to be related to decreased levels of membrane-associated mitochondrial Mn-superoxide dismutase. Our results support the viewpoint that an oxygen radical-induced impairment of mtDNA is of pathophysiological significance in the aetiology of at least a subgroup of patients with SALS.

  • sporadic amyotrophic lateral sclerosis
  • mitochondria
  • oxidative phosphorylation
  • mitochondrial DNA damage
  • oxygen radicals
  • Mn-SOD
  • ALS = amyotrophic lateral sclerosis
  • COX = cytochrome c oxidase
  • FALS = familial ALS
  • mtDNA = mitochondrial DNA
  • NADHTR = nicotinamide adenine dinucleotide (reduced) tetrazolium reductase
  • rDNA = ribosomal DNA
  • ROS = reactive oxygen species
  • SALS = sporadic ALS
  • SDH = succinate dehydrogenase
  • SOD = superoxide dismutase
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