细胞DNA损伤检控系统在维持端粒稳定中的功能

真核生物的DNA损伤检控系统是维持细胞基因组稳定的一个重要机制，该系统能检测细胞在生命活动过程中出现的DNA损伤并引发细胞周期阻滞，对DNA损伤进行修复，以维持细胞遗传的稳定性。端粒是位于真核细胞染色体末端由重复DNA序列和蛋白质组成的复合物，具有保护染色体、介导染色体复制、引导减数分裂时的同源染色体配对和调节细胞衰老等作用。虽然端粒与DNA双链断裂都具有作为线性染色体末端的共同特点，但正常端粒并不像DNA双链断裂那样激活DNA损伤检控系统。另一方面，端粒又与DNA损伤相似，因为多种DNA损伤检控蛋白在端粒长度稳定中起重要作用。因此DNA损伤检控系统既参与了维持正常端粒的完整性，又可对端粒损伤作出应答。现就DNA损伤检控系统在维持端粒稳定中的作用及其对功能缺陷端粒的应答作一简要综述。

Roles of DNA Damage Checkpoint in Maintaining Telomere Stability

The DNA damage checkpoint of eukaryote is a vital mechanism to maintain genomic stability of the cell. This checkpoint can detect the DNA damages in the cell and cause cell cycle arrest, which will guarantee proper damage repair and ensure genomic stability. Telomeres are repetitive DNA-protein complex at the end of eucaryotic linear chromosomes and play a key role in protecting the chromosomes, mediating the replication of the chromosome, initiating the homolog alignment during meiosis and regulating the senescence of the cells. Telomeres and DNA double-strand breaks share the common feature of being physical ends of chromosomes. However, unlike double-strand breaks, telomeres do not activate the DNA damage checkpoint. On the other hand, telomeres resemble damaged DNA, as several DNA damage checkpoint proteins play important roles in telomere length maintenance. Therefore, DNA damage checkpoint signaling pathways not only are necessary for telomere integrity maintenance, but also play a vital role in facilitating repair of damaged telomeres. Here, we review recent studies defining the roles of DNA damage checkpoint in telomere maintenance and in response to telomere dysfunction.