Characterization of genes isolated in a novel screen for mutants with altered mitotic lifespan in yeast

引言：为什么所有的生物体年龄一直是一个最有趣的问题几个世纪。使用简单的模型系统，如苍蝇，蠕虫和酵母，已经确定了单个保守基因，极大地影响细胞和整个动物的寿命。单细胞和多细胞生物体的健康是衡量细胞维持寿命的能力。每个细胞都经历一系列的分裂，直到达到分化或衰老状态。 最新进展：我们已经设计并实施了第一个全基因组筛选酵母突变体，这些突变体在衰老之前经历了细胞分裂数量的改变。筛选产生了48个寿命增加的突变体和87个寿命减少的突变体。许多已鉴定的突变体定义了以前与调节寿命无关的细胞过程，并涉及蛋白质运输和铁运输相关的基因。 目的：该提案将重点测试我们的中心假设，即i）蛋白质运输是酵母细胞寿命的一个不可或缺的决定因素，ii）铁吸收和细胞运输受损导致酵母过早老化。 方法：采用复制寿命试验（RLS）对筛选出的突变体进行寿命表型的确认。最初的表征将涉及相互作用的遗传分析，以确定功能途径。表征遗传相互作用和潜在上位性被用于将因子放置在等级通路内，这是我们过去广泛依赖的方法。加拿大光源（CLS）的同步加速器将用于旨在确定游离铁是否在突变体中积累的研究，并表征通常随年龄积累的铁种类。 影响：我们在酵母中发现的基因也在人类中发现，这表明我们在酵母中的发现将允许在高等真核系统的衰老研究中探索新的研究途径。

INTRODUCTION: Why all living organisms age has been a most intriguing question for centuries. Using simple model systems, such as flies, worms, and yeast, single conserved genes have been identified that greatly impact cellular and whole animal lifespan. The health of single cell and multicellular organisms is a measure of cellular capacity to maintain lifespan. Every cell undergoes a series of divisions until a differentiated or senescent state is reached. RECENT PROGRESS: We have designed and implemented the first genome-wide screen for yeast mutants that experience an altered number of cell divisions prior to senescence. The screen yielded 48 mutants with increased lifespan and 87 with reduced lifespan. Many of the identified mutants define cellular processes that have not been previously linked with regulating lifespan, and implicate genes involved in protein trafficking and iron transport. OBJECTIVES: This proposal will focus on testing our central hypotheses that i) protein trafficking is an integral determinant of cellular lifespan in yeast, and ii) that impaired iron uptake and cellular transport results in premature aging in yeast. METHODS: The lifespan phenotypes of mutants identified in the screen will be confirmed using the replicative lifespan assay (RLS). The initial characterization will involve a genetic analysis of interactions to work out functional pathways. Characterizing genetic interactions and potential epistasis is utilized for placement of factors within hierarchical pathways, an approach that we have extensively relied on in the past. The synchrotron at the Canadian Light Source (CLS) will be employed in studies aimed at determining whether free iron accumulates in the mutants and to characterize the iron species that normally accumulate with age. IMPACT: The genes we have identified in yeast are also found in humans, suggesting that our findings in yeast will allow new avenues of research to be explored in aging studies in higher eukaryotic systems.