真核生物的端粒（Telomere）对于保证染色体正常复制以及维持基因组的稳定性有重要作用，也是研究基因组中异染色质（Heterochromatin）结构的重要模型。
9月19日，Nucleic Acids Research在线发表了中科院上海生命科学研究院生化与细胞所周金秋研究组揭示酵母转录中介复合物调控端粒机制的最新研究结果。研究生彭晶以酿酒酵母为模式生物，阐述了转录中介复合物（Mediator complex）调控端粒异染色质结构的分子机制。转录中介复合物的尾部模块通过帮助异染色质核心组分Sir蛋白在端粒上的结合和扩散参与端粒异染色质的维持，从而保证亚端粒区域基因的沉默。转录中介复合物直接结合在端粒上，可能作为端粒染色质的组分之一发挥功能。此外，该复合物还参与了端粒长度的调控。
这一工作揭示了转录中介复合物这一经典的转录调控因子在端粒调控中的特殊功能。
该研究得到了科技部和国家自然科学基金委的经费资助。（生物谷 Bioon.com）
doi:10.1093/nar/gkr757
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The tail-module of yeast Mediator complex is required for telomere heterochromatin maintenance
Jing Peng and Jin-Qiu Zhou
Eukaryotic chromosome ends have a DNA–protein complex structure termed telomere. Integrity of telomeres is essential for cell proliferation. Genome-wide screenings for telomere length maintenance genes identified several components of the transcriptional regulator, the Mediator complex. Our work provides evidence that Mediator is involved in telomere length regulation and telomere heterochromatin maintenance. Tail module of Mediator is required for telomere silencing by promoting or stabilizing Sir protein binding and spreading on telomeres. Mediator binds on telomere and may be a component of telomeric chromatin. Our study reveals a specific role of Mediator complex at the heterochromatic telomere and this function is specific to telomeres as it has no effect on the HMR locus.
