Identification and analysis of genetic determinants of natural telomere length variation

 描述（由申请人提供） 端粒是位于真核生物线性染色体物理末端的进化上保守的蛋白质-DNA复合物。在大多数人类细胞中，出生时重复端粒DNA的初始长度随着年龄的增长而缩短，因此可以作为增殖历史的标志并预先确定细胞寿命。端粒维持基因的突变导致过早衰老和许多与年龄相关的疾病。平均端粒长度在人类中表现出相当大的个体间差异，似乎是在强大的遗传控制下，但建立端粒长度设定点的因素的确切性质仍然难以捉摸。在这里，我们提出了确定和表征遗传因素建立端粒长度设定点的模式植物拟南芥。在我们的初步结果中，我们表明，类似于人类和酵母，自然拟南芥种群显示端粒长度设定点的显着变化，我们确定了5号染色体上的端粒长度QTL的主要影响。该建议的主要方法利用了最近在拟南芥QTL定位中的重大技术突破，使用遗传上先进的重组近交MAGIC品系来发现建立群体特异性端粒长度设定点的遗传因素。目的1利用天然拟南芥群体的显著遗传多样性和用于精确监测端粒长度的简单测定。我们将继续测量MAGIC群体中的端粒长度，并使用候选基因方法和群体范围的比较序列和表达分析的组合来精细定位一个主要和几个次要QTL。在目标2中，我们将利用多种基因检测，如敲除和转基因拯救实验，功能上表征候选基因，并验证其在端粒生物学中的作用。我们的研究结果将导致更好地了解自然拟南芥种群中端粒长度多态性的遗传差异，也可能为人类不同衰老速率的分子基础和衰老相关疾病的易感性提供重要的见解。

 DESCRIPTION (provided by applicant) Telomeres are evolutionarily conserved protein-DNA complexes at the physical ends of linear eukaryotic chromosomes. The initial length of the repetitive telomeric DNA set at birth shortens with age in most human cells, thus serving as a marker of proliferation history and pre-determining cellular lifespan. Mutations in telomere maintenance genes lead to premature aging and a number of age-related disorders. Mean telomere length in humans shows considerable inter-individual variation and appears to be under strong genetic control, but the exact nature of factors establishing telomere length set point remains elusive. Here we propose to identify and characterize genetic factors establishing telomere length set point in the model plant Arabidopsis thaliana. In our preliminary results, we show that, similar to humans and yeast, natural Arabidopsis populations display significant variation in telomere length set point, and we identify a major effect telomere length QTL on chromosome 5. The main approach of this proposal takes advantage of the major recent technical breakthroughs in Arabidopsis QTL mapping using genetically advanced Recombinant Inbred MAGIC Lines to discover genetic factors establishing population-specific telomere length set point. Aim 1 takes advantage of the remarkable genetic diversity of natural Arabidopsis populations and the easy assays for precise monitoring of telomere length. We will continue measuring telomere length in the MAGIC population and fine-map one major and several minor QTL using a combination of candidate gene approach and population- wide comparative sequence and expression analysis. In Aim 2, we will utilize multiple genetic assays, such as knock-out and transgenic rescue experiments, to functionally characterize candidate genes and validate their role in telomere biology. Our results will lead to better understanding of genetic differences underlying telomere length polymorphism in natural Arabidopsis populations, and may also provide important insights into the molecular basis for different rates of aging among humans and predisposition to aging-associated diseases.