bims-cytox1 Biomed News
on Cytochrome oxidase subunit 1
Issue of 2019‒07‒28
two papers selected by
Gavin McStay
Staffordshire University

  1. Int J Med Sci. 2019 ;16(7): 931-938
    Germain N, Dessein AF, Vienne JC, Dobbelaere D, Mention K, Joncquel M, Dekiouk S, Laine W, Kluza J, Marchetti P.
      The diagnosis of mitochondrial diseases is a real challenge because of the vast clinical and genetic heterogeneity. Classically, the clinical examination and genetic analysis must be completed by several biochemical assays to confirm the diagnosis of mitochondrial disease. Here, we tested the validity of microscale XF technology in measuring oxygen consumption in human skin fibroblasts isolated from 5 pediatric patients with heterogeneous mitochondrial disorders. We first set up the protocol conditions to allow the determination of respiratory parameters including respiration associated with ATP production, proton leak, maximal respiration, and spare respiratory capacity with reproducibility and repeatability. Maximum respiration and spare capacity were the only parameters decreased in patients irrespective of the type of OXPHOS deficiency. These results were confirmed by high-resolution oxygraphy, the reference method to measure cellular respiration. Given the fact that microscale XF technology allows fast, automated and standardized measurements, we propose to use microscale oxygraphy among the first-line methods to screen OXPHOS deficiencies.
    Keywords:  mitochondria; mitochondrial diseases; oxidative metabolism; reserve capacity; respiratory chain complex
  2. Sci Rep. 2019 Jul 22. 9(1): 10549
    Shimura M, Nozawa N, Ogawa-Tominaga M, Fushimi T, Tajika M, Ichimoto K, Matsunaga A, Tsuruoka T, Kishita Y, Ishii T, Takahashi K, Tanaka T, Nakajima M, Okazaki Y, Ohtake A, Murayama K.
      Mitochondrial respiratory chain complexes II, III, and IV and cytochrome c contain haem, which is generated by the insertion of Fe2+ into protoporphyrin IX. 5-Aminolevulinic acid (ALA) combined with sodium ferrous citrate (SFC) was reported to enhance haem production, leading to respiratory complex and haem oxygenase-1 (HO-1) upregulation. Here, we investigated the effects of different concentrations of ALA and SFC alone or in combination (ALA/SFC) on fibroblasts from 8 individuals with mitochondrial diseases and healthy controls. In normal fibroblasts, expression levels of oxidative phosphorylation (OXPHOS) complex subunits and corresponding genes were upregulated only by ALA/SFC. Additionally, the increased oxygen consumption rate (OCR) and ATP levels in normal fibroblasts were more obvious after treatment with ALA/SFC than after treatment with ALA or SFC. OXPHOS complex proteins were enhanced by ALA/SFC, whereas OCR and ATP levels were increased in 6 of the 8 patient-derived fibroblasts. Further, HO-1 protein and mRNA levels were enhanced by ALA/SFC in all fibroblasts. The relative mtDNA copy number was increased by ALA/SFC. Thus, our findings indicate that ALA/SFC is effective in elevating OXPHOS, HO-1 protein, and mtDNA copy number, resulting in an increase in OCR and ATP levels, which represents a promising therapeutic option for mitochondrial diseases.