Telomere and telomerase evolution in S. cerevisiae

项目摘要 端粒，由线性末端的重复DNA序列组成 染色体起到保护帽的作用。然而，端粒不能完全 在复制过程中复制，没有核糖核蛋白酶端粒酶。 理解端粒长度和端粒酶之间的微妙平衡 活动对人类最大的两个健康问题有着重要的影响： 衰老和癌症。端粒已被证明随着年龄的增长而缩短，起到了 “生物钟”限制了细胞可以经历的几轮分裂。绕过 这种增殖限制，超过85%的癌症异常上调端粒酶 表情。这项工作的长期目标是了解 端粒和端粒酶，以及这些细胞成分如何对 生物体的健康和寿命。开始解开这些广泛的基础 问题，将进行两条具体的调查路线，以利用强大的 酿酒酵母的遗传可操作性。首先，一个用于获得收益的屏幕- 端粒酶RNA的功能突变将识别延长端粒酶活性的新等位基因 通过增加酶的活性来调节端粒。这样的功能获得突变体将会脱落 关于端粒酶的基本RNA成分如何对 酶的整体作用。更活跃的端粒酶也将允许探索 更长的端粒是否会改变有机体的整体健康状况。第二，酵母 将对菌株进行基因工程，使其16个线性菌株中的每一个循环 染色体，允许新的实验研究的优势和 真核生物中环形染色体的缺点。这些小说 酵母菌株将为创造创新的真核生物奠定基础 所有线性染色体都循环的有机体，打开了探索的大门 端粒和端粒酶进化的大问题。

PROJECT ABSTRACT Telomeres, composed of repetitive DNA sequences at the termini of linear chromosomes, serve as protective caps. However, telomeres cannot be fully copied during replication without the ribonucleoprotein enzyme telomerase. Understanding the delicate balance between telomere length and telomerase activity has important implications for two of the biggest human health concerns: aging and cancer. Telomeres have been shown to shorten with age, acting as a “biological clock” limiting the rounds of division a cell can undergo. To circumvent this proliferative limit, over 85% of cancers aberrantly up-regulate telomerase expression. The long-term goal of this work is to understand the evolution of telomeres and telomerase, and how these cellular components contribute to the health and lifespan of an organism. To begin unraveling these broad fundamental questions, two specific lines of inquiry will be undertaken harnessing the powerful genetic manipulability of Saccharomyces cerevisiae. First, a screen for gain-of- function mutations in telomerase RNA will identify novel alleles that lengthen telomeres by increasing enzyme activity. Such gain-of-function mutants will shed new light on how the essential RNA component of telomerase contributes to the overall action of the enzyme. More active telomerase will also permit exploration of whether longer telomeres alter total fitness of the organism. Second, yeast strains will be genetically engineered to circularize each of their 16 linear chromosomes, allowing novel experimental investigation of the advantages and disadvantages of circular chromosomes in a eukaryotic organism. These novel yeast strains will build a foundation for creating an innovative eukaryotic organism with all linear chromosomes circularized, opening the door to explore big picture questions of telomere and telomerase evolution.