Zalenskaya Irina A, Zalensky Andrei O
Department of Biological Chemistry, School of Medicine, University of California, Davis 95616, USA.
Int Rev Cytol. 2002;218:37-67. doi: 10.1016/s0074-7696(02)18011-9.
Telomeres are terminal chromosomal domains that protect chromosome ends from degradation and fusion and promote complete replication of DNA. Telomeres are involved in the regulation of cellular replicative lifespan and tumorigenesis. These important functions of the telomeres have evoked high interest: numerous studies have resulted in a detailed description of telomere composition and structure in somatic cells. Much less is known about telomeres in germline cells. Emerging novel features and unique behavior of telomeres in the process of gamete differentiation suggest that they may have additional germline-specific function(s). This review describes recent studies revealing changes in the telomere organization in the course of differentiation from the germline stem cells to mature sperm in mammals. Similarities and differences between somatic and spermatogenic cells in telomere nuclear localization, protein composition, DNA length, telomerase activity, and chromatin structure are discussed. The exceptional features of the germline telomeres may be important for regulation of telomerase activity during spermatogenesis, homologous chromosome pairing during recombination, as well as for male pronucleus development and ordered chromosome withdrawal post-fertilization.
端粒是染色体末端结构域，可保护染色体末端免于降解和融合，并促进DNA的完全复制。端粒参与细胞复制寿命和肿瘤发生的调控。端粒的这些重要功能引起了人们的高度关注：大量研究详细描述了体细胞中端粒的组成和结构。而对于生殖细胞中的端粒，人们了解得较少。端粒在配子分化过程中出现的新特征和独特行为表明，它们可能具有额外的生殖细胞特异性功能。本综述描述了最近的研究，揭示了哺乳动物从生殖系干细胞到成熟精子分化过程中端粒组织的变化。讨论了体细胞和生精细胞在端粒核定位、蛋白质组成、DNA长度、端粒酶活性和染色质结构方面的异同。生殖系端粒的特殊特征可能对精子发生过程中端粒酶活性的调控、重组过程中同源染色体配对以及受精后雄原核发育和有序染色体撤离很重要。
