Telomere maintainance by werner syndrome family proteins

描述（由申请人提供）：在哺乳动物中，细胞衰老和凋亡被认为与年龄相关的疾病有关，并且可以通过端粒的急剧缩短和无帽引起。在人类中，端粒缩短伴随着衰老，越来越多的证据表明，缩短损害组织稳态。虽然端粒酶对端粒的维持已经被很好地理解，但其他端粒维持途径的作用还不太清楚。人类Werner类早衰综合征是由WRN recq家族解旋酶缺乏引起的，其特征是端粒维持缺陷。包括我们自己对小鼠WRN和猪链球菌同源物Sgs1的研究在内的几项研究表明，基于同源重组（HR）和基于g -四重体（G4） dna的机制，RecQ解旋酶在端粒维持中的作用。在这里，我们将研究涉及RecQ解旋酶、G4-DNA和HR的端粒维持的新方面。这些研究将有三个具体目的：1)确定SAS2编码的组蛋白乙酰转移酶的缺失以HR依赖的方式延长端粒酶突变体寿命的机制；2)研究Sgs1的缺失如何使缺乏端粒酶和同源重组的细胞形成端粒丢失的幸存者；3)验证RecQ解旋酶可以通过调节G4-DNA形成来调节端粒维持机制的假设。这些目标将在酿酒酵母中进行，它提供了一个实验上易于处理的模型来解剖机制，然后将在小鼠和培养的小鼠和人类细胞中对酵母的发现进行测试。机制将通过使用已建立的遗传、生化、药理学、分子和细胞生物学方法进行探索。了解RecQ解旋酶、HR、G4-DNA和组蛋白乙酰转移酶如何协同调节端粒维持，将为衰老和癌症生物学提供新的见解，并为未来治疗年龄相关疾病和恶性肿瘤的治疗方法的开发提供新的靶点。公共卫生相关性：端粒，染色体的末端，在衰老和癌症的发展中发挥重要作用。我们正在研究端粒维持的新机制，包括1)DNA解旋酶的RecQ亚型的作用，当缺失时，可能导致人类早衰和癌症疾病，2)同源重组的作用，3)称为g -四联体的不寻常DNA结构的作用。这些研究将有助于阐明端粒维持的机制，从而有助于确定治疗包括癌症在内的衰老疾病的新靶点。

DESCRIPTION (provided by applicant): Cell senescence and apoptosis are thought to contribute to age-related diseases in mammals, and can be induced by critically shortened and thus uncapped telomeres. In humans, telomere shortening accompanies aging, and there is increasing evidence that shortening impairs tissue homeostasis. While maintenance of telomeres by telomerase is well understood, the roles of other telomere maintenance pathways are less well defined. The human Werner progeroid syndrome, caused by deficiency of the WRN RecQ-family helicase, is characterized by defects in telomere maintenance. Several lines of investigation, including our own work with mouse WRN and the S. cerevisiae homolog Sgs1, indicate roles for RecQ helicases in telomere maintenance by homologous recombination (HR)-based and G-quadruplex (G4) DNA-based mechanisms. Here we will investigate novel aspects of telomere maintenance involving RecQ helicases, G4-DNA, and HR. These will be investigated in three specific aims: 1) Determine the mechanisms by which deletion of the histone acetyltransferase encoded by SAS2 extends, in an HR- dependent fashion, the lifespan of telomerase mutants, 2) Investigate how the absence of Sgs1 enables cells lacking telomerase and homologous recombination to form survivors of telomere loss, and 3) Test the hypothesis that RecQ helicases can modulate telomere maintenance mechanisms via regulation of G4-DNA formation. These aims will be carried in S. cerevisiae, which provides an experimentally tractable model in which to dissect mechanisms, and findings from yeast will then be tested in mice and cultured murine and human cells. Mechanism will be explored through the use of established genetic, biochemical, pharmacological, molecular and cell biological approaches. Understanding how RecQ helicases, HR, G4-DNA, and histone acetyltransferases collaborate to regulate telomere maintenance will offer new insights into aging and cancer biology, and should provide new targets for the future development of therapeutics aimed at treating age- related diseases and malignancies. PUBLIC HEALTH RELEVANCE: Telomeres, the ends of chromosomes, play important roles in aging and the development of cancer. We are studying novel mechanisms by which telomeres are maintained, including 1) roles for the RecQ subtype of DNA helicase that, when absent, can lead to human premature aging and cancer diseases, 2) roles for homologous recombination and 3) roles for unusual DNA structures called G-quadruplexes. These studies will help illuminate mechanisms by which telomeres are maintained and will thus help identify new targets for treating diseases of aging, including cancer.