Inter-mitochondrial complementation: Mitochondria-specific system preventing mice from expression of disease phenotypes by mutant mtDNA

Nat Med. 2001 Aug;7(8):934-40. doi: 10.1038/90976.


Here we investigated the pathogenesis of deletion mutant mitochondrial (mt)DNA by generating mice with mutant mtDNA carrying a 4696-basepair deletion (DeltamtDNA4696), and by using cytochrome c oxidase (COX) electron micrographs to identify COX activity at the individual mitochondrial level. All mitochondria in tissues with DeltamtDNA4696 showed normal COX activity until DeltamtDNA4696 accumulated predominantly; this prevented mice from expressing disease phenotypes. Moreover, we did not observe coexistence of COX-positive and -negative mitochondria within single cells. These results indicate the occurrence of inter-mitochondrial complementation through exchange of genetic contents between exogenously introduced mitochondria with DeltamtDNA4696 and host mitochondria with normal mtDNA. This complementation shows a mitochondria-specific mechanism for avoiding expression of deletion-mutant mtDNA, and opens the possibility of a gene therapy in which mitochondria possessing full-length DNA are introduced.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cells, Cultured
  • DNA, Mitochondrial / genetics*
  • Electron Transport Complex IV / metabolism
  • Genetic Complementation Test*
  • Male
  • Mice
  • Microscopy, Electron
  • Mitochondria / enzymology
  • Mitochondria / genetics*
  • Phenotype


  • DNA, Mitochondrial
  • Electron Transport Complex IV