title: Redox state and mitochondrial respiratory chain function in skeletal muscle of LGMD2A patients.
abstract: BACKGROUND
  Calpain-3 deficiency causes oxidative and nitrosative stress-induced damage in skeletal muscle of LGMD2A patients, but mitochondrial respiratory chain function and anti-oxidant levels have not been systematically assessed in this clinical population previously.
  
  
  METHODS
  We identified 14 patients with phenotypes consistent with LGMD2A and performed CAPN3 gene sequencing, CAPN3 expression/autolysis measurements, and in silico predictions of pathogenicity. Oxidative damage, anti-oxidant capacity, and mitochondrial enzyme activities were determined in a subset of muscle biopsies.
  
  
  RESULTS
  Twenty-one disease-causing variants were detected along the entire CAPN3 gene, five of which were novel (c.338 T>C, c.500 T>C, c.1525-1 G>T, c.2115+4 T>G, c.2366 T>A). Protein- and mRNA-based tests confirmed in silico predictions and the clinical diagnosis in 75% of patients. Reductions in antioxidant defense mechanisms (SOD-1 and NRF-2, but not SOD-2), coupled with increased lipid peroxidation and protein ubiquitination, were observed in calpain-3 deficient muscle, indicating a redox imbalance primarily affecting non-mitochondrial compartments. Although ATP synthase levels were significantly lower in LGMD2A patients, citrate synthase, cytochrome c oxidase, and complex I+III activities were not different from controls.
  
  
  CONCLUSIONS
  Despite significant oxidative damage and redox imbalance in cytosolic/myofibrillar compartments, mitochondrial respiratory chain function is largely maintained in skeletal muscle of LGMD2A patients.
authors: Department of Pediatrics and Medicine, Neuromuscular Clinic, McMaster University Hospital, Hamilton, Ontario, Canada.
authors: Mats I
authors: MI
authors: Nilsson
authors: Department of Pediatrics and Medicine, Neuromuscular Clinic, McMaster University Hospital, Hamilton, Ontario, Canada.
authors: Lauren G
authors: LG
authors: Macneil
authors: Department of Pediatrics and Medicine, Neuromuscular Clinic, McMaster University Hospital, Hamilton, Ontario, Canada.
authors: Yu
authors: Y
authors: Kitaoka
authors: Department of Pediatrics and Medicine, Neuromuscular Clinic, McMaster University Hospital, Hamilton, Ontario, Canada.
authors: Fatimah
authors: F
authors: Alqarni
authors: Department of Pediatrics and Medicine, Neuromuscular Clinic, McMaster University Hospital, Hamilton, Ontario, Canada.
authors: Rahul
authors: R
authors: Suri
authors: Department of Pediatrics and Medicine, Neuromuscular Clinic, McMaster University Hospital, Hamilton, Ontario, Canada.
authors: Mahmood
authors: M
authors: Akhtar
authors: Department of Pediatrics and Medicine, Neuromuscular Clinic, McMaster University Hospital, Hamilton, Ontario, Canada.
authors: Maria E
authors: ME
authors: Haikalis
authors: Department of Pediatrics and Medicine, Neuromuscular Clinic, McMaster University Hospital, Hamilton, Ontario, Canada.
authors: Pavneet
authors: P
authors: Dhaliwal
authors: Department of Pediatrics and Medicine, Neuromuscular Clinic, McMaster University Hospital, Hamilton, Ontario, Canada.
authors: Munim
authors: M
authors: Saeed
authors: Department of Pediatrics and Medicine, Neuromuscular Clinic, McMaster University Hospital, Hamilton, Ontario, Canada.
authors: Mark A
authors: MA
authors: Tarnopolsky
mesh_terms: D002154:Calpain / Q000235:genetics; D004579:Electron Transport; D005260:Female; D006801:Humans; D008297:Male; D008928:Mitochondria / Q000378:metabolism*; D009124:Muscle Proteins / Q000235:genetics; D018482:Muscle, Skeletal / Q000378:metabolism*; D049288:Muscular Dystrophies, Limb-Girdle / Q000378:metabolism*; D009154:Mutation; D010084:Oxidation-Reduction; D018384:Oxidative Stress
chemical_list: D009124:Muscle Proteins; C105884:CAPN3 protein, human; D002154:Calpain