Heterologous mitochondrial DNA recombination in human cells

We found direct evidence of recombination between these two mitochondrial DNA haplotypes

Marilena D'Aurelio

2004

Scholarcy highlights

  • Mitochondrial DNA recombination has been well documented in plants, fungi and protists and in invertebrates, and the activity of enzymes involved in homologous recombination has been identified in mammalian mitochondria
  • To exclude that these recombinant subclones were the result of a long-polymerase chain reaction artifact, we repeated the same amplification and cloning procedures using as starting templates genomic DNA from containing homoplasmic MTCO1 mutant and Cybrids homoplasmic for the MTCyB mutation parental cybrids mixed in equal proportions
  • On the basis of these polymorphisms, we determined that the three recombinant mitochondrial DNA molecules were the result of independent recombination events, because the region where the sequence transitioned from CO1MT to CyBMT differed in each of them
  • There is evidence that supports the concept that human mitochondria possess some of the enzymatic components necessary for homologous recombination and that mtDNA can undergo intra-molecular recombination
  • Our hybrid human cell system provides an ideal setting to investigate the existence of inter-molecular mtDNA recombination, because it involves mtDNA markers that can be recognized by restriction fragment length polymorphism analyses
  • We found that the majority of hybrid clones harbored recombinant molecules, which represented a significant proportion of the total mtDNA pool, and that the amount of recombination was highest in those clones where the two parental molecules had segregated in similar proportions
  • Quantification of the relative proportion of the C16278T polymorphism in the D-loop of the hybrids clones was performed on EcoRV digestion of polymerase chain reaction products amplified with the P5 – P6 primer set and radiolabeled with the ‘last cycle hot’

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