The study of telomere repair capacity of UV-irradiated mammalian cells

• Main Authors: Ching-Ting Chen, 程靜婷
• Other Authors: 陳一村
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/48364112962730898980

碩士 === 國立陽明大學 === 醫學生物技術研究所 === 90 === Abstract Telomeres are essential for maintaining the integrity and stability of eukaryotic genomes. There is increasing evidence that dysfunctional telomeres may contribute to the development of aging or cancer. Telomeres may be rendered dysfunctional by UV irradiation. UV induces formation of the photoproducts which are generated from two closing pyrimidines in the same DNA strand. Deficiency in repair of these photoproducts may result in DNA mutation, and accumulation of mutation is related to high incidence of aging and cancer. In this study, we have explored the effects of UV irradiation on telomeric DNA repair in both 5-years-old skin fibroblasts and HepG2 hepatoma cells. First, southern blot was applied for measuring mean telomere length between these two cell lines. Our result indicates that telomeres were 3 ~ 4 kb longer in 5-years-old skin fibroblasts compared to those from HepG2 cells. We have also observed that the ratio of telomeric DNA to genomic DNA in HepG2 cells was 1 : 105 ~ 106. In addition, we have established a method for the detection of the telomeric DNA damage and its repair in human cells by T4 endonuclease V and alkaline southern blot analysis. Our preliminary data indicates that damaged telomeres were repaired gradually 0 — 24 hours after UV irradiation in 5-years-old skin fibroblasts, whereas damaged telomeres were repaired gradually during 0 — 12 hours following UV irradiation in HepG2 cells. Whether or not that the telomerase or NER repair system may participate in repair of UV-irradiated telomeres remains to be determined.