Determining the molecular mechanisms of ribosomal export through the nuclear pore.

确定核糖体通过核孔输出的分子机制。

• 批准号: RGPIN-2015-06586
• 负责人: Oeffinger, Marlene
• 金额: $ 2.19万
• 依托单位: Université de Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=661138
• 关键词: Determining; molecular; mechanisms; ribosomal; export

The long-term objective of our research program is to study the maturation pathways of essential RNA-protein complexes in different organisms. Ribosomes are the cellular protein production machinery and as such vital to every cell and organism. Ribosome biogenesis is a complex process that involves more than 200 proteins. In cells, ribosomes are processed and assembled within the nucleolus, a specialized compartment of the nucleus, and, once mature, they are exported to the cytoplasm to function during translation. Molecules transporting from the nucleus to the cytoplasm pass through the nuclear pore, a macromolecular complex embedded in the nuclear membrane. Specified proteins, export factors, that are particular to different transporting complexes, mediate transport through the pores. While transport factors have been identified for ribosomes, very little is known about the actual mechanisms of ribosome export. In particular, it is still unclear how a macromolecule as big as the ribosome (~35nm diameter) can pass through the top (~25nm diameter) or spokes (~12.5nm diameter) of the nuclear basket, a nuclear structure of the nuclear pore controlling access to the transport channel, which is believed to be universal to all nuclear pores in all organisms. We want to understand the molecular mechanisms of ribosome export through the nuclear pore complex, and the role of the nuclear basket as well as the function of specific nucleoporins during the targeting, translocation and finally release of ribosomes into the cytoplasm. In the baker's yeast S.cerevisiae, basket-less pores have been identified in an area adjacent to the nucleolus. This suggests the possibility that these basket-less pores could be dedicated to ribosome export. However, basket-less pores have not yet been observed in human cells, which raises the question of how evolutionary conserved ribosome maturation pathways are. Due to their vital function, ribosomes are highly conserved between species, even organisms as distant as Archeabacteria and humans, and so are most aspects of their maturation. However, there may be significant differences due to the complexity of the organism, and the potential consequences of dysfunctional ribosomes, such as malignant cell proliferation and disease development in humans. We will establish the role of the nuclear basket in ribosome export and the function of basket-less nuclear pores, which is as yet unclear. Furthermore, we will determine the existence of basket-less pores in human cells, and examine the differences in ribosome export between lower and higher eukaryotes, namely yeast and humans.**

我们研究计划的长期目标是研究不同生物体中必要的RNA-蛋白质复合体的成熟途径。核糖体是细胞蛋白质的生产机器，因此对每个细胞和有机体都至关重要。核糖体的生物发生是一个复杂的过程，涉及200多种蛋白质。在细胞中，核糖体在核仁内加工和组装，核仁是核的一个特殊的隔间，一旦成熟，核糖体就被输出到细胞质中，在翻译过程中发挥作用。从细胞核到细胞质的分子通过核孔，这是一个嵌入核膜的大分子复合体。特定的蛋白质，即出口因子，是不同运输复合体特有的，通过毛孔调节运输。虽然已经确定了核糖体的运输因素，但对核糖体输出的实际机制知之甚少。特别是，像核糖体(直径~35 nm)这样大的大分子如何穿过核篮子的顶部(直径~25 nm)或辐条(直径~12.5 nm)，目前还不清楚。核篮子是核孔的核结构，控制着运输通道的进入，据信这对所有生物体的所有核孔都是通用的。我们想要了解核糖体通过核孔复合体输出的分子机制，以及核篮子的作用以及特定的核孔蛋白在核糖体的靶向、转位和最终释放到细胞质中的功能。在面包师的酵母中，在靠近核仁的区域发现了无篮子的毛孔。这表明，这些无篮子的毛孔可能专门用于核糖体输出。然而，在人类细胞中还没有观察到无篮子的毛孔，这就提出了一个问题，即核糖体成熟途径在进化上是如何保守的。由于核糖体的重要功能，核糖体在物种之间高度保守，甚至在远古细菌和人类之间也是如此，它们成熟的大部分方面也是如此。然而，由于生物体的复杂性以及功能失调的核糖体的潜在后果，如人类恶性细胞增殖和疾病发展，可能会有显著的差异。我们将确定核篮子在核糖体出口中的作用以及无篮子核孔的功能，这一点尚不清楚。此外，我们将确定人类细胞中是否存在无篮毛孔，并检查低等和高等真核生物，即酵母和人类在核糖体输出方面的差异。