Immunohistochemical detection of human mtDNA polymerase gamma and of humanmitochondrial transcription factor A in cytochrome-c-oxidase-deficient oxyphil cells of hyperfunctional parathyroids

Immunohistochemical studies were performed in 18 hyperfunctional parathyroi ds with oxyphil cell aggregates for the detection of cytochrome-c-oxidase ( complex IV of the respiratory chain), mitochondrial DNA polymerase gamma an d human mitochondrial transcription factor A (h-mtTFA). Seventy-three oxyph il areas exhibiting a defect of cytochrome-c-oxidase were found. The defect involved both the mitochondrially coded subunits II/III and the nuclear de rived subunits Vab. There was no loss of mtDNA polymerase gamma or of h-mtT FA in these foci, corresponding to a high content of mtDNA revealed by in s itu hybridization. Isolated defects of h-mtTFA were also not found. In cont rast, isolated defects of mtDNA polymerase gamma were present in 22 oxyphil foci. These results show that defects of cytochrome-c-oxidase in oxyphil c ells are not due to altered expression of h-mtTFA or DNA polymerase gamma, indicating that other nuclear factors involved in the generation of the res piratory chain may be impaired. The low incidence of defects of mtDNA polym erase gamma and the absence of alterations of h-mtTFA and cytochrome-c-oxid ase in these foci suggest that defects of mtDNA polymerase gamma are of min or pathogenetic significance.