Telomere maintenance by Werner syndrome family proteins

描述(申请人提供)：我们将使用小鼠和酵母作为模型系统，探索端粒生物学与沃纳早衰综合征疾病之间的联系。端粒缩短伴随着人类衰老，但在人类衰老过程中起着不确定的因果作用。相比之下，很明显，预防端粒缩短是大多数癌症生长所必需的。沃纳综合征和布鲁姆综合征的特点是过早衰老和癌症发病率升高。这些综合征分别是由于相关的RecQ家族解旋酶WRN和BLm的缺失引起的。越来越多的证据表明，Werner细胞存在端粒缺陷，这可能是导致过早衰老和癌症发病率上升的原因之一，而WRN(和其他RecQ解旋酶)可能在端粒缩短的修复中发挥作用。我们将剖析酵母RecQ同源物Sgslp在端粒维持中的既定作用。我们将绘制Sgslp的结构域，在缺乏端粒酶的酵母细胞中，这些结构域是防止快速衰老和端粒缩短所必需的，以及衰老幸存者的缺陷。我们将测试解释这些缺陷的替代机制，包括不适当的重组或端粒G-DNA结构的形成。我们还将筛选与SGSLP合作维持端粒的其他遗传因素。我们还将研究WRN和BLM在由于端粒酶基因失活而导致端粒缩短的小鼠中的功能。我们会问，与单纯缺乏端粒酶或WRN和BLM一起缺乏端粒酶的小鼠相比，缺乏端粒酶和WRN和BLM的小鼠是否会发展得更早、更严重，甚至是不同的缺陷。高增殖性组织包括性腺、胃肠道系统和皮肤的萎缩和细胞凋亡将被检查。在存在或不存在功能性WRN和BLM的情况下，将比较缺乏端粒酶的组织和细胞的端粒缩短、细胞遗传学不稳定性和辐射敏感性的比率。此外，WRN和BLM在使用重组而不是端粒酶维持其端粒的细胞中的作用将被探索。这些研究将阐明WRN和BLM在人类端粒中的功能，并加深对端粒在人类自然衰老和癌症中的作用的理解。

DESCRIPTION (provided by applicant): We will explore connections between telomeres biology and diseases in the Werner premature aging syndrome, using mouse and yeast as model systems. Telomere shortening accompanies but plays an uncertain causal role in human aging. In contrast, it is clear that prevention of telomere shortening is required for the growth of most cancers. Werner syndrome and Bloom syndrome are characterized by premature features of aging and by elevated rates of cancers. The syndromes are caused by loss of the related RecQ-family helicases WRN and BLM, respectively. Evidence is accumulating that Werner cells have telomere defects, which might contribute to the premature aging and elevated cancer incidence, and WRN (and other RecQ helicases) may function in the repair of shortened telomeres. We will dissect the established role of the yeast RecQ homologue, Sgslp, in telomere maintenace. We will map the domains of Sgslp that, in yeast cells lacking telomerase, are required to prevent rapid senescence and telomere shortening, as well as defects in surivivors of senescence. We will test alternative mechanisms to explain these defects, including inappropriate recombination or the formation of G-DNA structures at telomeres. We will also screen for other genetic factors that cooperate with Sgslp in telomere maintenance. We will also examine the function of WRN and BLM in mice that have shortened telomeres due to genetic inactivation of telomerase. We will ask whether mice that lack telomerase and WRN and BLM together develop earlier, more profound or even different defects than mice that simply lack telomerase alone or WRN and BLM together. Atrophy and apoptosis in highly proliferative tissues, including the gonads, gastrointestinal system and skin, will be examined. Rates of telomere shortening, cytogenetic instability, and radiation sensitivity will compared in tissues and cells lacking telomerase in the presence or absence of functional WRN and BLM. Additionally, the role of WRN and BLM in cells that maintain their telomeres using recombination, rather than telomerase, will be explored. These studies should illuminate the function of WRN and BLM at human telomeres and improve understanding of the role of telomeres in natural human aging and cancer.