Genetics of telomerase in C. elegans

描述（由申请人提供）：端粒酶将端粒重复序列逆转录到染色体末端。本项目的长期目标是开发线虫C. elegans作为端粒酶和端粒生物学研究的系统。C.秀丽线虫具有全着丝粒染色体，其有利于在端粒酶缺乏时发生的初始端对端染色体融合事件的遗传分离。从各种遗传背景中分离和分析端到端融合将为它们的起源提供前所未有的见解，并可能揭示与正常端粒相互作用的一些DNA损伤反应蛋白的意想不到的功能。基因筛选已经确定了四种蛋白质，这些蛋白质是端粒酶在酵母中端粒处发挥作用所必需的，而我们的正向基因筛选表明，在C. elegans线虫and perhaps也许in other multicellular多细胞organisms有机体.该领域的一个模型表明，端粒可能会在端粒酶募集之前被检测到DNA双链断裂。然而，我们已经确定，MRT-1核酸酶，它有助于DNA链间交联修复，是端粒酶作用于C。elegans端粒。因此，端粒酶可能通过一种可以响应DNA链间交联的途径被募集到端粒。我们怀疑这一假设可能与端粒的进化有关，并计划使用遗传和生物化学方法来测试这种可能性。此外，我们将确定和表征四个新的突变，导致缺乏端粒酶活性在体内C。elegans（279，222g，36f和3211e）。最后，将进行进一步的突变体筛选，以使体内端粒酶活性所需的基因饱和。在细胞周期中，端粒酶只在短暂的时刻作用于端粒，所以C。elegans可能有助于在多细胞生物体内鉴定负责端粒酶活性的基因组。 端粒酶缺乏导致致命的人类遗传性疾病，如再生障碍性贫血、先天性睾丸发育不良和肺纤维化：该研究项目可能会定义导致这些人类疾病的基因突变。鉴于大多数癌症表达端粒酶，而大多数正常的体细胞不表达端粒酶，我们的研究也可能有助于确定蛋白质和/或途径，这些蛋白质和/或途径可能是治疗各种癌症的有用靶点。最后，该项目可能定义与端粒诱导的基因组不稳定性相关的重组中间体和途径，这可能促进肿瘤的发展。

DESCRIPTION (provided by applicant): Telomerase reverse transcribes telomere repeats onto chromosome termini. The long- term goal of this project is to develop the nematode C. elegans as a system for the study of telomerase and telomere biology. C. elegans possesses holocentric chromosomes that facilitate genetic isolation of initial end-to-end chromosome fusion events that occur when telomerase is deficient. Isolation and analysis of end-to-end fusions from various genetic backgrounds will provide unprecedented insight into their genesis and may reveal unexpected functions of some DNA damage response proteins that interact with normal telomeres. Genetic screens have identified four proteins that are required for telomerase to function at telomeres in yeast, whereas our forward genetic screens indicate that 10 or more proteins are required in C. elegans and perhaps in other multicellular organisms. One model in the field suggests that telomeres may be sensed as DNA double-strand breaks prior to recruitment of telomerase. However, we have determined that the MRT-1 nuclease, which facilitates DNA interstrand crosslink repair, is required for telomerase to act at C. elegans telomeres. Thus, telomerase may be recruited to telomeres via a pathway that can respond to DNA interstrand crosslinks. We suspect that this hypothesis may be relevant to telomere evolution and plan to test this possibility using genetic and biochemical approaches. In addition, we shall identify and characterize four new mutations that result in deficiency for telomerase activity in vivo in C. elegans (279, 222g, 36f and 3211e). Finally, further mutant screens will be performed in an effort to saturate for genes required for telomerase activity in vivo. Telomerase only acts at telomeres for a fleeting moment during the cell cycle, so the powerful genetics of C. elegans may help to identify the suite of genes responsible for telomerase activity in vivo in multicellular organisms. PUBLIC HEALTH RELEVANCE Deficiency for telomerase causes lethal human hereditary disorders such as aplastic anemia, dyskeritosis congenita and pulmonary fibrosis: genes that mutate to cause these human diseases may be defined by this research project. Given that most cancers express telomerase whereas most normal somatic cells do not, our studies may also help to define proteins and/or pathways that may be useful targets for treatment of a wide variety of cancers. Finally, this project may define recombination intermediates and pathways that are relevant to telomere-induced genome instability, which may promote tumor development.