Repopulation of rho(0) cells with mitochondria from a patient with a mitochondrial DNA point mutation in tRNA(Gly) results in respiratory chain dysfunction

Familial hypertrophic ventricular cardiomyopathy has been demonstrated to b e associated with a number of mitochondrial DNA (mtDNA) mutations. A fibrob last cell line carrying a mutation in its mtDNA at position 9997 in the gen e encoding tRNA glycine was obtained from a patient with hypertrophic cardi omyopathy, To demonstrate that the etiology of this disease was a result of the mtDNA mutation, cybrid clones were constructed by fusion of enucleated patient skin fibroblasts to rho(0) osteosarcoma cells, Clones carrying hig h levels of mutant mtDNA showed predominantly cytochrome c oxidase and comp lex I deficiency as well as an elevated lactate/pyruvate (L/P) ratio, a bio chemical marker characteristic of respiratory chain deficiencies. Pulse-lab eling experiments demonstrated a strong negative correlation between the le vels of newly synthesized mtDNA-encoded polypeptides and glycine content. T hese data suggest that the T9997C mutation in mtDNA is causative of respira tory chain dysfunction when present at high levels of heteroplasmy, Hum Mut at 13:245-254, 1999, (C) 1999 Wiley-Liss, Inc.