adPEO mutations in ANT1 impair ADP-ATP translocation in muscle mitochondria

Hibiki Kawamata, Valeria Tiranti, Jordi Magrané, Christos Chinopoulos, Giovanni Manfredi

Research output: Contribution to journalArticlepeer-review


Mutations in the heart and muscle isoform of adenine nucleotide translocator 1 (ANT1) are associated with autosomal-dominant progressive external opthalmoplegia (adPEO) clinically characterized by exercise intolerance, ptosis and muscle weakness. The pathogenic mechanisms underlying the mitochondrial myopathy caused by ANT1 mutations remain largely unknown. In yeast, expression of ANT1 carrying mutations corresponding to the human adPEO ones causes a wide range of mitochondrial abnormalities. However, functional studies of ANT1 mutations in mammalian cells are lacking, because they have been hindered by the fact that ANT1 expression leads to apoptotic cell death in commonly utilized replicating cell lines. Here, we successfully express functional ANT1 in differentiated mouse myotubes, which naturally contain high levels of ANT1, without causing cell death. We demonstrate, for the first time in these disease-relevant mammalian cells, that mutant human ANT1 causes dominant mitochondrial defects characterized by decreased ADP-ATP exchange function and abnormal translocator reversal potential. These abnormalities are not due to ANT1 loss of function, because knocking down Ant1 in myotubes causes functional changes different from ANT1 mutants. Under certain physiological conditions, mitochondria consume ATP to maintain membrane potential by reversing the ADP-ATP transport. The modified properties of mutant ANT1 can be responsible for disease pathogenesis in adPEO, because exchange reversal occurring at higher than normal membrane potential can cause excessive energy depletion and nucleotide imbalance in ANT1 mutant muscle cells.

Original languageEnglish
Article numberddr200
Pages (from-to)2964-2974
Number of pages11
JournalHuman Molecular Genetics
Issue number15
Publication statusPublished - Aug 2011

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)
  • Molecular Biology


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