Yeast Model to Study nucleocytoplasmic trafficking

研究核细胞质运输的酵母模型

• 批准号: 6558940
• 负责人: RAVI DHAR
• 金额: --
• 依托单位: DIVISION OF BASIC SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6558940
• 关键词: Schizosaccharomyces pombe; biological models; cell cycle; cell growth regulation; cyclins; eukaryote; fungal genetics; genetic strain; intracellular transport; messenger RNA; mutant; nuclear membrane; pore forming protein; protein kinase; protein transport; transport proteins

Nuclear pores mediate the transport of proteins and RNA between the nucleus and cytoplasm. Mature mRNA is exported through the nuclear pores bound to proteins as an RNP particle. It is thought one or more of the bound proteins act as a carrier to target the mRNA to the pore and mediate its interaction with various pore proteins. Once the mRNA reaches the cytoplasm, the carrier dissociates and reenters the nucleus, thereby shuttling between the nucleus and the cytoplasm. Genetic and biochemical studies in yeast, mammalian and viral systems have led to identification of several proteins that could be considered as potential carriers of mRNA. For a protein to be considered an export carrier of mRNA it must be functionally linked to mRNA export, bind mRNA, shuttle between the nucleus and cytoplasm and exit the nucleus in an NES dependent manner. We have used fission yeast Schizosaccharomyces pombe as a model system to study how eukaryotic cells export their mRNA out of the nucleus. Through genetic approaches we have identified genes whose products influence the export of mRNA from the nucleus into the cytoplasm. We identified mRNA export factor spmex67 through its genetic interaction with rae1. Both spMex67p and Rae1p genetically and functionally interact with nucleoporins, Npp106p and Nup184p to export mRNA out of the nucleus. Our results suggest a model in which both Rae1p and spMex67p can function in mRNA export by interacting with common mRNA export complexes. Furthermore, we demonstrate that spMex67p acts as an accessory factor in Rae1p-dependent mRNA export by participating at various common steps in mRNA export with Rae1p. In S. pombe we have identified an RNA binding protein, Crp79p that fullfills the requirements of an mRNA export carrier. It binds mRNA, complements the mRNA export defects associated with rae1-167 nup184-1 double mutant, shuttles between the nucleus and cytoplasm, and contains a nuclear export acitivity at the C-terminus that is essential for Crp79p to fullfill its role in mRNA export. The nuclear import of Crp79p requires the functioning of the Ran-GTPase switch system. We have found that in S. pombe, Crp79p is functionally redundant in mRNA export and that it functions in mRNA export idependent of the Rae1p mRNA export pathway.

核孔介导蛋白质和RNA在细胞核和细胞质之间的运输。成熟的 mRNA 通过与蛋白质结合的核孔作为 RNP 颗粒输出。人们认为一种或多种结合蛋白充当载体，将 mRNA 靶向孔并介导其与各种孔蛋白的相互作用。一旦mRNA到达细胞质，载体就会解离并重新进入细胞核，从而在细胞核和细胞质之间穿梭。对酵母、哺乳动物和病毒系统的遗传和生化研究已经鉴定出几种可被视为 mRNA 潜在载体的蛋白质。对于被认为是 mRNA 输出载体的蛋白质，它必须在功能上与 mRNA 输出相关，结合 mRNA，在细胞核和细胞质之间穿梭，并以 NES 依赖性方式离开细胞核。 我们使用裂殖酵母粟酒裂殖酵母作为模型系统来研究真核细胞如何将其 mRNA 从细胞核中输出。通过遗传方法，我们已经鉴定出其产物影响 mRNA 从细胞核到细胞质的输出的基因。我们通过与 rae1 的遗传相互作用鉴定了 mRNA 输出因子 spmex67。 spMex67p 和 Rae1p 都在遗传和功能上与核孔蛋白、Npp106p 和 Nup184p 相互作用，将 mRNA 输出到细胞核外。我们的结果提出了一个模型，其中 Rae1p 和 spMex67p 都可以通过与常见 mRNA 输出复合物相互作用来在 mRNA 输出中发挥作用。此外，我们证明 spMex67p 通过参与 Rae1p mRNA 输出的各种常见步骤，在 Rae1p 依赖性 mRNA 输出中充当辅助因子。 在粟酒裂殖酵母中，我们鉴定了一种 RNA 结合蛋白 Crp79p，它满足 mRNA 输出载体的要求。它结合 mRNA，补充与 rae1-167 nup184-1 双突变体相关的 mRNA 输出缺陷，在细胞核和细胞质之间穿梭，并在 C 末端包含核输出活性，这对于 Crp79p 发挥其在 mRNA 输出中的作用至关重要。 Crp79p 的核输入需要 Ran-GTPase 开关系统的功能。我们发现，在粟酒裂殖酵母中，Crp79p 在 mRNA 输出中功能冗余，并且其在 mRNA 输出中的功能独立于 Rae1p mRNA 输出途径。