Flores Ignacio, Benetti Roberta, Blasco Maria A
Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Centre (CNIO), 28029 Madrid, Spain.
Curr Opin Cell Biol. 2006 Jun;18(3):254-60. doi: 10.1016/j.ceb.2006.03.003. Epub 2006 Apr 17.
Telomerase expression is restricted to a few cell types of the adult organism, most notably germ cells and stem/progenitor cells. Telomerase activity in germ cells is sufficient to prevent telomere shortening with age. Stem cells, however, do not have sufficient telomerase to prevent telomere shortening associated with continuous tissue renewal with increasing age. Indeed, telomerase levels in the adult organism are thought to be rate-limiting for longevity. This is supported by rare human syndromes caused by mutations in telomerase components, which are characterized by premature loss of tissue renewal and premature death. More recently, the role of telomerase and telomere length in stem cells is starting to be elucidated.
端粒酶的表达仅限于成年生物体的少数细胞类型，最显著的是生殖细胞和干细胞/祖细胞。生殖细胞中的端粒酶活性足以防止端粒随年龄增长而缩短。然而，干细胞没有足够的端粒酶来防止与年龄增长相关的连续组织更新所导致的端粒缩短。事实上，成年生物体中的端粒酶水平被认为是寿命的限速因素。这一点得到了由端粒酶成分突变引起的罕见人类综合征的支持，这些综合征的特征是组织更新过早丧失和过早死亡。最近，端粒酶和端粒长度在干细胞中的作用开始得到阐明。
