X-irradiation alters the telomerase activity and the telomere length distribution of cultured human vascular endothelial cells
Toyoki Maeda, Jing-Zhi Guan, Masamichi Koyanagi, Naoki Makino
1TheDepartment ofCardiovascular,Respiratory, andGeriatricMedicine,KyushuUniversityBeppuHospital, Beppu,Oita, 874-0838, (JAPAN)
2The 309thHospital ofChinese People’s L iberation Army, Beijing, (CHINA)
To assess the effect of X-irradiation on somatic cell, we analyzed the telomeric changes of cultured human umbilical venous endothelial cells (HUVECs) induced shortly after low-dose X-irradiation. The effect of Xirradiation on HUVECs was assessed by the analysis of the changes in telomere length, telomerase activity, and the expression of telomereassociated proteins after 2 to 8Gy X-irradiation. The cell growth activity decreased, whereas the telomerase activity of the surviving cells decreased only at low X-ray doses. The expression levels of telomere-associated components, TRF1 and TRF2, increased in the surviving cells. As the Xray dose level increased, senescent cells increased. However, the mean telomere length of the surviving cells became longer, long telomeres increased, and short telomeres decreased. These observations suggested thatX-irradiatedHUVECs bore telomeric features similar to those of young cells, and the cells bearing short telomeres, i.e., aged cells, were selected out. The surviving cells that had gone through low dose X-irradiation might represent a radiation-resistant feature of telomere conditions. The telomeric changes at low dose X-ray disappeared at a high dose. Higher dose of X-irradiationmight induce a cellular protective reaction against Xray- induced cell damage through the restoration of telomerase activity and up-regulated telomere-associated proteins.
Telomere; Telomerase; Vascular endothelial cell; X-irradiation; Cell survival.