Severe impairment of complex I-driven adenosine triphosphate synthesis in leber hereditary optic neuropathy cybrids

Arch Neurol. 2005 May;62(5):730-6. doi: 10.1001/archneur.62.5.730.


Background: Leber hereditary optic neuropathy (LHON) is a maternally inherited form of central vision loss associated with mitochondrial DNA point mutations that affect the ND subunits of complex I.

Objective: To elucidate the bioenergetic consequences of complex I dysfunction in LHON.

Design: The biochemical phenotypes of LHON mutations have been investigated using the transmitochondrial cytoplasmic hybrid (cybrid) cell model derived from the osteocarcoma parental cell line 143B.TK-.

Setting: Research laboratories at neuroscience and biochemistry departments at the University of Bologna, Scientific Institute "E. Medea," and University of College Medical School.

Participants: Fibroblast cell lines were obtained from patients affected with LHON, as defined by the presence of 1 pathogenic mutation, and from healthy volunteers as controls to construct cybrid cell lines.

Main outcome measures: Complex I (glutamate-malate)- and complex II (succinate)-dependent adenosine triphosphate (ATP) synthesis, their respective respiratory rates, and total cellular ATP content were investigated using digitonin permeabilized cybrid cells. Multiple cybrid cell lines were constructed, introducing into osteosarcoma-derived rho(0) cells either wild-type or LHON mutant mitochondria carrying each of the 3 common mutations at positions 11778/ND4, 3460/ND1, and 14484/ND6.

Results: All 3 LHON mutations impaired ATP synthesis and the respiratory control ratio driven by complex I substrates. In contrast, succinate-driven ATP synthesis, respiration rates, and respiratory control ratios were not affected. However, the defective ATP synthesis with complex I substrates did not result in reduced ATP cellular content, indicating a compensatory mechanism.

Conclusions: The LHON pathogenic mutations profoundly impair complex I-dependent synthesis of ATP, providing a common biochemical feature that may play a major role in LHON pathogenesis. Stratification of the results by mutation suggests that the 11778/ND4 mutation may induce an uncoupling of cybrid respiration, whereas the other 2 mutations impair the oxygen consumption rate.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / metabolism*
  • Cells, Cultured
  • Citric Acid / metabolism
  • DNA, Mitochondrial / genetics*
  • Electron Transport Complex I / genetics
  • Electron Transport Complex I / metabolism*
  • Fibroblasts / enzymology
  • Glutamates / metabolism
  • Humans
  • Hybrid Cells
  • Mutation*
  • Optic Atrophy, Hereditary, Leber / enzymology
  • Optic Atrophy, Hereditary, Leber / genetics*
  • Oxygen Consumption / genetics
  • Succinic Acid / metabolism


  • DNA, Mitochondrial
  • Glutamates
  • Citric Acid
  • Adenosine Triphosphate
  • Succinic Acid
  • Electron Transport Complex I