Université Claude Bernard, Lyon, France.
Cell Cycle. 2011 Apr 1;10(7):1037-42. doi: 10.4161/cc.10.7.15071.
A critical function of telomeres is to prevent the ligation of chromosome ends by DNA repair enzymes. In most eukaryotes, telomeric DNA consists in large arrays of G-rich tandem repeats that are recognized by DNA binding capping proteins. Drosophila telomeres are unusual as they lack short tandem repeats. However, Drosophila capping proteins can bind chromosome extremities in a DNA sequence-independent manner. This epigenetic protection of fly telomeres has been essentially studied in somatic cells where capping proteins such as HOAP or HP1 are essential in preventing chromosome end-to-end fusions. HipHop and K81 are two recently identified paralogous capping proteins with complementary expression patterns. While HipHop is involved in telomere capping in somatic cells, K81 has specialized in the protection of telomeres in post-meiotic male germ cells. Remarkably, K81 is required for the stabilization of HOAP and HP1 at telomeres during the massive paternal chromatin remodeling that occurs during spermiogenesis and at fertilization. We thus propose that the maintenance of capping proteins at Drosophila sperm telomeres is crucial for the transmission of telomere identity to the diploid zygote. :
端粒的一个关键功能是防止 DNA 修复酶连接染色体末端。在大多数真核生物中，端粒 DNA 由大量富含 G 的串联重复序列组成，这些序列被 DNA 结合封端蛋白识别。果蝇的端粒很特殊，因为它们缺乏短串联重复序列。然而，果蝇的封端蛋白可以以 DNA 序列非依赖的方式结合染色体末端。这种对果蝇端粒的表观遗传保护主要在体细胞中进行研究，在体细胞中，HOAP 或 HP1 等封端蛋白对于防止染色体端到端融合是必不可少的。HipHop 和 K81 是两种最近鉴定的具有互补表达模式的同源封端蛋白。虽然 HipHop 参与体细胞中端粒的封端，但 K81 专门参与保护减数后雄性生殖细胞中的端粒。值得注意的是，K81 对于在精子发生过程中和受精时发生的大量父本染色质重塑期间 HOAP 和 HP1 在端粒处的稳定是必需的。因此，我们提出，在果蝇精子端粒处维持封端蛋白对于将端粒身份传递给二倍体合子是至关重要的。
