Collombet J M, Mandon G, Dumoulin R, Mousson B, Stepien G
Centre de Génétique Moléculaire et Cellulaire, UMR CNRS 5534, Villeurbanne, France.
Mol Gen Genet. 1996 Nov 27;253(1-2):182-8. doi: 10.1007/s004380050311.
Myoblast cultures were established from muscle biopsies of two patients harboring heteroplasmic mitochondrial (mt) DNA deletions. The accumulation kinetics of the deleted mtDNA was followed during myoblast to myotube differentiation. The percentage of deleted mtDNA was determined by quantitative PCR in myoblasts, myotubes, and muscle biopsies. The deleted form accounted for 65% of the mtDNA present in a muscle biopsy from a patient harboring a 5.6-kb deletion. The percentage of deleted mtDNA was 1.2% in myoblasts and increased progressively after differentiation, up to 12% at 21 days after the commitment time. In a second patient harboring a 2.8-kb deletion, the percentage of deleted mtDNA increased much more slowly: from 0.07% in myoblasts to 0.21% after 22 days of differentiation, as compared with 45% in the muscle biopsy. Thus, a three- and ten-fold increase, respectively, in the fraction of deleted mtDNA occurred during the differentiation of myoblasts to myotubes from the two patients. The faster accumulation of deleted mtDNA int he first patient's cells was linked to an earlier myoblast to myotube differentiation, suggesting that the level of deleted mtDNA is inversely related to the rate of cell proliferation.
从两名携带异质性线粒体（mt）DNA缺失的患者的肌肉活检样本中建立了成肌细胞培养物。在成肌细胞向肌管分化过程中，追踪缺失mtDNA的积累动力学。通过定量PCR测定成肌细胞、肌管和肌肉活检样本中缺失mtDNA的百分比。在一名携带5.6 kb缺失的患者的肌肉活检样本中，缺失形式的mtDNA占mtDNA总量的65%。成肌细胞中缺失mtDNA的百分比为1.2%，分化后逐渐增加，在分化开始21天后达到12%。在另一名携带2.8 kb缺失的患者中，缺失mtDNA的百分比增加得要慢得多：从成肌细胞中的0.07%增加到分化22天后的0.21%，而在肌肉活检样本中为45%。因此，在两名患者的成肌细胞向肌管分化过程中，缺失mtDNA的比例分别增加了三倍和十倍。在第一名患者的细胞中，缺失mtDNA积累更快，这与成肌细胞向肌管的分化更早有关，表明缺失mtDNA的水平与细胞增殖速率呈负相关。
