YEAST GENES IN RNA PROCESSING & NUCLEUS/CYTOSOL EXCHANGE

描述(申请人提供)：细胞器的存在，生化特化的区域，由膜彼此隔开，是真核细胞的特征。这种细胞组织需要复杂的机制来在适当的条件下将正确的大分子有效地输送到正确的位置，以及细胞器的生物发生、维持和遗传的机制。我们的重点是原子核。利用我们的模式真核生物酵母酿酒酵母的遗传方法，我们以前鉴定了Los1p。Los1p及其同系物(XPO-t)在tRNA核出口中发挥作用。然而，LOS1/XPO-t在所有生物体中都是一个非必需的基因，它的功能已经有可能被去除，这需要细胞拥有Los1p非依赖的tRNA核输出途径(S)。拟议工作的目标1采用候选和全基因组技术来揭示Los1p非依赖性tRNA核输出途径(S)。直到最近，tRNA的运动被认为是从合成的核部位到功能的胞浆部位的单向运动。然而，我们发现，相反的情况也会发生。事实上，在特定的生理条件下，尤其是酵母突变体，从细胞质输入的大量tRNA迅速且可逆地驻留在细胞核中。这种“逆行tRNA核输入途径”很可能是所有真核生物新发现的基因表达水平。目的2试图了解控制逆行途径的机制及其与细胞代谢的协调。在目标3中，我们使用全基因组的方法来了解复杂和动态的核是如何被组织成不被膜彼此分开的区域的。到目前为止，我们发现了N-乙酰化的必要作用和一个完整的膜蛋白来适当地将我们的记者拴在内核膜上。我们试图鉴定其他这样的基因产物，并了解那些已经鉴定的基因产物是否在亚核组织中发挥普遍作用。我们预计收集到的信息将在人类疾病中有重要的应用，如癌症、Emery-Dreifuss肌营养不良症和Hutchison-Gilford Progeria综合征，这些疾病是由不适当的核/胞浆动力学和核组织引起的。

DESCRIPTION (provided by applicant): 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 Los1p. Los1p and its homologues (Xpo-t) function in tRNA nuclear egress. However, LOS1/Xpo-t is an unessential gene in all organisms that it has been possible to ablate its function, requiring that cells possess Los1p-independent tRNA nuclear export pathway(s). Aim 1 of the proposed work employs both candidate and genome-wide technologies to uncover the Los1p-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.