Pang C Y, Lee H C, Yang J H, Wei Y H
Department and Institute of Biochemistry, National Yang-Ming Medical College, Taipei, Taiwan, R.O.C.
Arch Biochem Biophys. 1994 Aug 1;312(2):534-8. doi: 10.1006/abbi.1994.1342.
By polymerase chain reaction technique and DNA sequencing, we demonstrated the existence of multiple deletions in the mitochondrial DNA (mtDNA) of human skin tissues obtained from different body sites of an 86-year-old male farmer. We examined four types of skin tissues of different physiologic conditions, including sun-exposed, nonexposed, precancerous, and cancerous. The results showed that the common age-related 4977-base-pair (bp)-deleted mtDNA was present in different proportions in all the tissues examined. Quantitative PCR revealed that the amount of the 4977-bp-deleted mtDNA was associated with the physiologic conditions of the skin tissues. The sun-exposed skin tissues harbored higher level of the 4977-bp-deleted mtDNA (12.5%) than the nonexposed normal aged skin tissues (0.4%). On the other hand, in all the exposed skin tissues examined, the slower growing aged skin tissues harbored higher level of the 4977-bp-deleted mtDNA than the faster growing skin tissues in cancerous and precancerous skin tissues. In addition, we found at least four new deletions in the aforementioned different body sites with sizes of 7031, 7150, 7288, and 7485 bp, respectively. These findings provide an evidence of photooxidation-induced mtDNA mutations, since the deletions deposit in different patterns and proportions in different skin tissues of the patient. These findings suggest that, besides the intrinsic formation and accumulation of mtDNA deletions in human tissues during normal aging process, physiological and environmental factors may also play important roles in eliciting the deposit of deleted mtDNA molecules in the tissue cells.
通过聚合酶链反应技术和DNA测序，我们证实了从一名86岁男性农民不同身体部位获取的人类皮肤组织的线粒体DNA（mtDNA）中存在多个缺失。我们检查了四种不同生理状态的皮肤组织，包括暴露于阳光的、未暴露于阳光的、癌前和癌性皮肤组织。结果表明，在所有检测的组织中，常见的与年龄相关的4977个碱基对（bp）缺失的mtDNA以不同比例存在。定量PCR显示，4977-bp缺失的mtDNA的量与皮肤组织的生理状态相关。暴露于阳光的皮肤组织中4977-bp缺失的mtDNA水平（12.5%）高于未暴露的正常老年皮肤组织（0.4%）。另一方面，在所有检测的暴露皮肤组织中，生长较慢的老年皮肤组织中4977-bp缺失的mtDNA水平高于癌性和癌前皮肤组织中生长较快的皮肤组织。此外，我们在上述不同身体部位发现了至少四个新的缺失，大小分别为7031、7150、7288和7485 bp。这些发现提供了光氧化诱导mtDNA突变的证据，因为缺失在患者不同皮肤组织中以不同模式和比例沉积。这些发现表明，除了在正常衰老过程中人类组织中mtDNA缺失的内在形成和积累外，生理和环境因素在引发缺失的mtDNA分子在组织细胞中的沉积方面也可能起重要作用。
