Balajee A S, Oh H J, Natarajan A T
MGC Department of Radiation Genetics and Chemical Mutagenesis, State University of Leiden, Sylvius Laboratories, The Netherlands.
Mutat Res. 1994 May 1;307(1):307-13. doi: 10.1016/0027-5107(94)90304-2.
The interstitial telomeric sequences have been suggested to be more susceptible to chromosome breakage and rejoining. In the present study, we tested this possibility by analysing the behavior of intra-chromosomal telomeric sequences in restriction enzyme-treated CHO and CHE cells. These cell lines show large blocks of internal telomeric repeats adjacent to the centromeric regions of the chromosomes. In CHO cells, (TTAGGG)n repeats are localised only near the centromeric regions of many of the chromosomes while in CHE cells the telomeric repeat sequences are found at both the terminal and centromeric regions of the chromosomes. In CHO cells, 26% of the total aberrations induced by AluI and 22% of those induced by HinfI were found to be involved with internal telomeric repeat sequences. In CHE cells, which possess telomeric repeats at both the terminal and interstitial regions, 39% of the aberrations induced by AluI and PvuII showed telomeric repeat signals. The proportion of acentric fragments with a telomeric repeat signal was higher in CHE than in CHO cells. Some of the damaged cells displayed an intense signal indicating the possible amplification of these repeats by telomerase. These results are in accordance with the suggestion that non-telomeric locations of telomeric repeat sequences are more prone to chromosome breakage and misrepair.
有人提出，间质端粒序列更容易发生染色体断裂和重新连接。在本研究中，我们通过分析经限制性内切酶处理的中国仓鼠卵巢（CHO）细胞和中国仓鼠胚胎（CHE）细胞中染色体内部端粒序列的行为来检验这种可能性。这些细胞系在染色体着丝粒区域附近显示出大片内部端粒重复序列。在CHO细胞中，(TTAGGG)n重复序列仅位于许多染色体的着丝粒区域附近，而在CHE细胞中，端粒重复序列在染色体的末端和着丝粒区域均有发现。在CHO细胞中，发现由AluI诱导的总畸变中有26%以及由HinfI诱导的总畸变中有22%与内部端粒重复序列有关。在末端和间质区域均具有端粒重复序列的CHE细胞中，由AluI和PvuII诱导的畸变中有39%显示出端粒重复信号。具有端粒重复信号的无着丝粒片段的比例在CHE细胞中高于CHO细胞。一些受损细胞显示出强烈信号，表明这些重复序列可能通过端粒酶进行了扩增。这些结果与以下观点一致，即端粒重复序列的非端粒位置更容易发生染色体断裂和错误修复。
