Nuclear complementation restores mtDNA levels in cultured cells from a patient with mtDNA depletion

Am J Hum Genet. 1993 Sep;53(3):663-9.


We have studied cultured skin fibroblasts from a patient with a fatal mitochondrial disease manifesting soon after birth. These fibroblasts were found to grow only in the presence of pyruvate and uridine, a characteristic of cells lacking mtDNA (rho0 cells). Southern blot and PCR analyses confirmed that the patient's fibroblasts contained less than 2% of control levels of mtDNA. Biochemical analyses indicated that the activities of all the respiratory-chain enzymes were severely decreased in mitochondria isolated from these fibroblasts. In order to elucidate the underlying molecular defect, cell fusions were performed between enucleated fibroblasts from this patient and a human-derived rho0 cell line (rho0 A549.B2). The resulting cybrids were plated in medium lacking pyruvate and uridine, to select for the restoration of respiratory-chain function. Complementation was observed between the nuclear genome of the rho0 A549.B2 cells and the mtDNA of the patient's cells, restoring mtDNA levels and respiratory-chain function in the cybrid cells. These results indicate that mtDNA depletion in our patient is under the control of the nuclear genome.

MeSH terms

  • Cell Fusion
  • Cell Nucleus
  • Chromosome Aberrations / genetics*
  • Citrate (si)-Synthase / deficiency
  • Citrate (si)-Synthase / genetics
  • Cytochrome-c Oxidase Deficiency
  • DNA, Mitochondrial / analysis
  • DNA, Mitochondrial / genetics*
  • Electron Transport Complex I
  • Electron Transport Complex IV / genetics
  • Fibroblasts / enzymology
  • Gene Expression Regulation, Enzymologic
  • Genetic Complementation Test
  • Humans
  • Hybrid Cells
  • Infant, Newborn
  • Malate Dehydrogenase / deficiency
  • Malate Dehydrogenase / genetics
  • Male
  • Mitochondria / enzymology
  • Mitochondria / pathology*
  • Mitochondria, Muscle / enzymology
  • Mitochondria, Muscle / pathology
  • Mitochondrial Myopathies / enzymology*
  • Mitochondrial Myopathies / genetics*
  • NADH, NADPH Oxidoreductases / deficiency
  • NADH, NADPH Oxidoreductases / genetics
  • Pyruvate Dehydrogenase Complex Deficiency Disease / genetics
  • Succinate Cytochrome c Oxidoreductase / deficiency
  • Succinate Cytochrome c Oxidoreductase / genetics


  • DNA, Mitochondrial
  • Succinate Cytochrome c Oxidoreductase
  • Malate Dehydrogenase
  • NADH, NADPH Oxidoreductases
  • Electron Transport Complex IV
  • Citrate (si)-Synthase
  • Electron Transport Complex I