端粒酶和细胞衰老

端粒是真核细胞染色体末端的一种特殊结构 ,由端粒 DNA和端粒蛋白质组成。端粒DNA是富含 G的高度保守的重复核苷酸序列 ,人和其他哺乳动物的端粒 DNA序列均由 5′-3′,方向 (TTAGGG) n 反复串联组成 ,它参与 DNA复制 ,对维持染色体的稳定和完全复制有重要作用。正常动物细胞 DNA的端粒随着细胞分裂而缩短 ,当缩短到一定长度时细胞将停止增殖并死亡。细胞中的端粒酶在正常细胞不表达 ,只在生殖细胞、干细胞和肿瘤细胞中表达。文章介绍了细胞衰老的细胞生物学机制、端粒酶和细胞衰老的关系 ,讨论了端粒酶和克隆动物的早衰现象的关系

Telomerase and Cell Aging

Telomere is specialized DNA protein structures found at the end of eukaryotic chromosomes. Telomere DNA is characterized by an array of randomly repeated, G rich DNA sequences that are highly conserved during evolution (human repeat sequence: TTAGGG). Telomerase is believed to play a critical role in protecting the genomic DNA from degradation and deleterious recombination events such as end to end fusion, rearrangements, chromosomal translocations and chromosomal loss. Most of normal animal somatic cells can divide only a number of times and inevitably become senescent. Telomere is an enzyme that imparts replicative immortality by maintaining the length of the telomere when expressed in reproductive and cancer cells. This paper introduced the cell biological mechanism of cell aging and the relation of telomerase with cell aging,and also the relation of telomerase with pre mature aging in cloned animal was diseused.