YEAST GENES IN RNA PROCESSING & NUCLEUS/CYTOSOL EXCHANGE

细胞器（生化专业化区域）的存在，通过以下方式彼此分开 膜表征真核细胞。这种细胞组织需要精心设计的机制， 在适当的条件下，有效地将正确的大分子递送到正确的位置， 以及细胞器的生物发生、维持和遗传机制。我们的重点是 原子核利用遗传方法，我们的模式真核生物，酵母菌 酿酒酵母，我们以前确定Loslp。Loslp及其同源物（Xpo-t）在tRNA核内的功能 出口然而，LOS^/Xpo-t是所有生物体中的一个非必需基因，它已经可以消除其 这需要细胞具有Loslp非依赖性tRNA核输出途径。目标1 拟议的工作采用候选人和全基因组技术来揭示Loslp独立 tRNA核输出途径。直到最近，tRNA的运动被认为是单向的， 核合成位点到胞质功能位点。然而，我们发现， 发生。事实上，大量的tRNA从细胞质中快速而可逆地进入细胞核 在特定的生理条件下或特别是酵母突变体下。这种“逆行tRNA核 输入途径”很可能是所有真核生物基因表达新发现的水平。目的2 旨在了解管理逆行途径的机制及其与细胞的协调， 新陈代谢.在目标3中，我们采用全基因组方法来了解复杂和动态的 核被组织成不被膜彼此分开的域。迄今为止，我们 发现了N-乙酰化和一个完整的膜蛋白的必要作用，以适当地束缚我们的细胞， 报告细胞的核膜。我们试图找出其他这样的基因产物，并了解是否 那些已经确定的在亚核组织中扮演一般角色。我们预计， 收集的信息将在人类疾病中有重要的应用，例如癌症，Emery-Dreifuss肌肉疾病， 营养不良和Hutchison-Gilford早衰综合征是由不适当的细胞核/细胞质引起的 动力学和核组织。

The presence of organelles, areas of biochemical specialization, separated from one another other by membranes characterize eukaryotic cells. Such cellular organization necessitates elaborate mechanisms to effectively deliver the correct macromolecules to the correct locations, under the appropriate conditions, as well as mechanisms for the biogenesis, maintenance and inheritance of the organelles. Our focus is on the nucleus. Using genetic approaches available for our model eukaryotic organism, yeast Saccharomyces cerevisiae we previously identified Loslp. Loslp and its homologues (Xpo-t) function in tRNA nuclear egress. However, LOS^/Xpo-t is an unessential gene in all organisms that it has been possible to ablate its function, requiring that cells possess Loslp-independent tRNA nuclear export pathway(s). Aim 1 of the proposed work employs both candidate and genome-wide technologies to uncover the Loslp-independent tRNA nuclear export pathway(s). Until recently tRNA movement was regarded to be unidirectional from the nuclear site of synthesis to the cytosolic site of function. However, we discovered that the reverse also occurs. In fact, large pools of tRNA imported from cytoplasm quickly and reversibly reside in the nucleus under particular physiological conditions or in particular yeast mutants. This "retrograde tRNA nuclear import pathway" is likely a newly discovered level of gene expression for all eukaryotic organisms. Aim 2 seeks to understand the mechanisms that govern the retrograde pathway and its coordination with cellular metabolism. In Aim 3 we employ genome-wide approaches to learn how the complicated and dynamic nucleus is organized into domains that are not separated from each other by membranes. To date, we discovered necessary roles for N-acetylation and an integral membrane protein to appropriately tether our reporter to the inner nuclear membrane. We seek to identify other such gene products and to learn whether those already identified fulfill general roles in subnuclear organization. We anticipate that the information gleaned will have significant application in human disorders, such as cancers, Emery-Dreifuss muscular dystrophy and Hutchison-Gilford Progeria syndrome that result from inappropriate nucleus/cytosol dynamics and nuclear organization.