我们已在酵母中鉴定出400多个影响端粒长度的基因。我们将对其中大部分基因进行系统生物学分析，以及分子机制的研究。我们将开展以下几个方面的研究：（1）利用突变体库，对端粒特异性转录物TERRA进行系统性遗传分析，寻找调控TERRA的基因。（2）xm1和rat1-1是影响TERRA表达的两个基因，我们将通过回复互补实验来鉴定影响TERRA表达的基因，并探索这些基因是共同发挥作用还是独立发挥作用。（3）探索TERRA是否以及如何受环境压力调控。（4）构建双突变体库，通过平行的系统的上位分析，检测这些双突变的端粒长度。（5）最终我们将把以上这些结果整合成一套新的端粒长度维持基因网络的计算模型，作进一步的探索。我们将运用分子生物学、生物化学和遗传学手段研究这些有趣的科学问题。鉴于端粒和端粒酶对细胞增殖的重要影响，我们的研究成果将有助于促进癌症治疗的研究。

Telomeres are nucleoprotein structures that protect chromosomal ends. Mammalian somatic cells lacking telomerase activity have a limited life span since they lose chromosomal information at each division. Cancer cells usually reactivate telomerase and are thus able to continue to proliferate. Telomeres also prevent the cells from recognizing the chromosomal ends as double-strand breaks and thus prevent genomic instability, which is enhanced in cancer cells and promotes carcinogenesis. Therefore, telomere biology has important implications in cancer development. .We have identified ~400 yeast genes that affect telomere length (Telomere Length Maintenance-TLM genes). The large number of genes involved require a system-level analysis, as well as a molecular dissection of the mechanisms at play. The Zhou and Kupiec lab have been working towards that end. Here we join forces and collaborate in a joint effort to dissect the TLM gene network. .Specifically, we will: 1) Carry out a systematic genetic analysis of telomere-specific transcripts, TERRA, in the telomere mutants to determine which of them may be attributed to misregulated TERRA. 2) In a complementary assay, we will carry out a telomere epistasis analysis of xrn1 and rat1-1, mutations known to affect TERRA expression. This systematic analysis, together with the previous one, should identify which of the telomere-affecting genes acts by changing TERRA levels, either with each of the nucleases, or independently. 3) Determine how TERRA transcription is regulated in terms of environmental stress. 4) Two parallel systematic epistasis analyses will be carried out by creating all possible double mutants (DMs) and measuring their telomere length. 5) Finally, we will incorporate all the results obtained into new and extant computational models of the TLM network, improving its exploration. .We will investigate these intriguing mechanisms by molecular biology, biochemical and genetic means. The basic knowledge gained by these experiments may help improve anti-cancer therapies, by combining ways in which cell proliferation could be prevented.

基因组保持稳定是细胞存活和维持正常功能必需的条件。真核细胞的基因组DNA包裹着组蛋白（H2A、H2B、H3和H4）八聚体形成核小体，以染色质形式存在。端粒是真核生物线性染色体的末端结构，对于保证DNA完整复制和维持基因组的稳定性至关重要。端粒DNA主要由特化的逆转录酶、即端粒酶复制。由于端粒DNA与一般的DNA双链断裂有相似性，它也可以通过同源重组的途径进行复制。端粒区域的染色质是典型的异染色质，其异染色质特性使附近的基因沉默。该课题主要研究了端粒结合蛋白调控端粒异染色质组装、端粒长度、端粒重组及细胞衰老的分子机制，取得了如下发现。（1）描绘端粒异染色质从头组装的动态分子过程， （2）阐述了组蛋白甲基转移酶HMT1催化H3R2非对称双甲基化的机制，（3）揭示Rad6–Bre1泛素连接酶泛素化组蛋白H2BK123而调控端粒复制的机制，（4）发现KEOPS复合物调控端粒复制与重组，其亚基Cgi121失活抑制端粒重组并延长细胞寿命，（5）发现组成型表达端粒酶促进酵母细胞时序性衰老，（6）建立了酿酒酵母非对称核小体修饰系统，并揭示了姐妹组蛋白H3独立调控基因转录，协作调控端粒的沉默效应。上述研究工作总结在6篇研究论文中，发表在eLife，Nucleic Acids Research，PLOS Genetics，Aging，Biochemical Journal和Journal of Genetics and Geneomics学术期刊上。这些研究成果的发表显示我们的研究处于国际先进水平。