Kao S H, Liu C S, Wang S Y, Wei Y H
Department of Biochemistry, National Yang-Ming University, Taipei, Taiwan, Republic of China.
Biochem Mol Biol Int. 1997 Jun;42(2):285-98. doi: 10.1080/15216549700202681.
Hair follicles plucked from the bi-temporal region of the scalp of 433 Chinese subjects of different ages were used for the examination of ageing-associated mutations of human mitochondrial DNA (mtDNA). By use of PCR techniques, we detected the 4,977 bp and 7,436 bp deletions of mtDNA in hair follicles from aged individuals. The frequencies of occurrence of both mtDNA deletions were found to increase with age of the subject. Moreover, we employed a semi-quantitative PCR method to determine the proportion of the 4,977 bp deleted mtDNA (dmtDNA) in hair follicles. The results showed that the average proportion of the 4,977 bp dmtDNA in hair follicles were 0.05% +/- 0.01%, 0.00%, 0.55% +/- 0.05%, 0.52% +/- 0.24%, 0.65% +/- 0.17%, 1.33 +/- 0.25%, and 1.89% +/- 0.81% for the subjects in the age groups of 21-30, 31-40, 41-50, 51-60, 61-70, 71-80, and 81-99, respectively. Furthermore, we screened all the subjects harboring the 4,977 bp and/or 7,436 bp deletions for tandem duplications in the D-loop region of mtDNA by PCR with back-to-back primers. The results showed that none of the previously reported tandem duplications were present in all the hair follicles examined. This indicates that tandem duplications do not predispose to large-scale deletions of mtDNA. However, the data suggest that mtDNA deletions occur and accumulate in hair follicles during human ageing. As hair follicles can be easily and non-invasively obtained from the human, we suggest that the aged-dependent accumulation of dmtDNAs in hair follicles may be used for the monitoring of human ageing process.
从433名不同年龄的中国受试者头皮双侧颞部采集毛囊，用于检测人类线粒体DNA（mtDNA）与衰老相关的突变。通过PCR技术，我们在老年个体的毛囊中检测到了mtDNA的4977 bp和7436 bp缺失。发现这两种mtDNA缺失的发生率均随受试者年龄的增加而升高。此外，我们采用半定量PCR方法测定毛囊中4977 bp缺失的mtDNA（dmtDNA）的比例。结果显示，21 - 30岁、31 - 40岁、41 - 50岁、51 - 60岁、61 - 70岁、71 - 80岁和81 - 99岁年龄组受试者毛囊中4977 bp dmtDNA的平均比例分别为0.05%±0.01%、0.00%、0.55%±0.05%、0.52%±0.24%、0.65%±0.17%、1.33±0.25%和1.89%±0.81%。此外，我们通过使用背对背引物的PCR技术，对所有携带4977 bp和/或7436 bp缺失的受试者的mtDNA D环区域进行串联重复筛查。结果显示，在所有检测的毛囊中均未发现先前报道的串联重复。这表明串联重复不会导致mtDNA的大规模缺失。然而，数据表明在人类衰老过程中，mtDNA缺失在毛囊中发生并积累。由于毛囊可以从人体轻松且无创地获取，我们建议毛囊中与年龄相关的dmtDNA积累可用于监测人类衰老过程。
