Molecular Biological Studies on Telomere Structure, Function and Maintenance

利用裂解酵母、非洲爪哇卵提取物和哺乳动物培养细胞对端粒结构和功能进行了研究。之所以选择这些模式生物，是因为它们分别高度服从遗传、生化和细胞生物学分析。在裂解酵母中发现了新的端粒成分spRap1、SpRif1、Ccq1、Poz1。在非洲爪蛙卵提取液中发现端粒DNA结合蛋白TRF1以细胞周期依赖的方式与染色质结合和解离。利用SV40复制系统对末端复制问题的分子机制进行了分析。研究发现，端粒DNA本身和端粒染色质都不是复制反应的良好底物。利用携带温度敏感DNA聚合酶a的小鼠细胞，发现端粒包含对复制压力最脆弱的基因组区域之一。这些研究揭示了端粒结构和功能的新方面，这将扩大我们对衰老和癌细胞中明显的随机染色体行为的理解。此外，显而易见的是，“元生物学”，即并行研究不同的模式生物，以跨物种互动的方式促进研究，是高效和多产的。

Telomere structures and functions were studied using fission yeast, Xenopus egg extracts and mammalian cultured cells. These model organisms were chosen because they are highly amenable to genetic, biochemical and cell biological analyses, respectively.1. Novel telomeric components, spRap1,SpRif1,Ccq1,Poz1,were identified in fission yeast.2. Telomere DNA-binding protein TRF1 was found to associate with and dissociate from chromatin in a cell-cycle-dependent manner in Xenopus egg extracts.3. Using the SV40 replication system, the molecular mechanism of the end replication problem was analyzed. It was found that telomeric DNA by itself as well as telomere chromatin is not a good substrate for replication reactions.4. Using murine cells harboring temperature-sensitive DNA polymerase a, it was found that the telomere comprises one of the most vulnerable genomic regions to replication stresses.5. It was found that epigenetic as well as genetic mechanisms cooperate to maintain the telomere functions.These studies revealed new aspects of telomere structures and functions, which will extend our understanding of apparently stochastic chromosomal behaviors in aging and cancer cells. Moreover, it became evident that "meta-biology", studying different model organisms in parallel to promote the research in an cross-species interactive manner is highly efficient and productive.