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.

核孔介导细胞核和细胞质之间的蛋白质和RNA的转运。成熟的mRNA通过与蛋白作为RNP颗粒结合的核孔导出。人们认为，一种或多种结合蛋白充当靶向mRNA到孔的载体，并介导其与各种孔蛋白的相互作用。一旦mRNA到达细胞质，载体就会解散并重新进入细胞核，从而在细胞核和细胞质之间穿梭。酵母，哺乳动物和病毒系统中的遗传和生化研究已导致鉴定出几种可以被认为是mRNA潜在载体的蛋白质。为了使蛋白质被认为是mRNA的导出载体，必须在功能上与mRNA输出，结合mRNA，梭子之间的梭子和细胞质之间的班车并以NES依赖性方式退出细胞核。 我们已经使用了裂变酵母菌型糖果糖作为模型系统，用于研究真核细胞如何将其mRNA从细胞核中导出。通过遗传方法，我们发现了其产物会影响mRNA从细胞核出口到细胞质的基因。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在遗传和功能上都与核孔蛋白，NPP106P和NUP184P相互作用，以将mRNA从细胞核中输出。我们的结果表明了一个模型，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导出中起作用。此外，我们证明SPMEX67P通过参与RAE1P的mRNA导出中的各种常见步骤，作为RAE1P依赖性mRNA导出的辅助因子。 在S. pombe中，我们已经鉴定出一种RNA结合蛋白CRP79P，该蛋白完整地填充了mRNA输出载体的要求。它结合mRNA，补充了与RAE1-167 NUP184-1双重突变体相关的mRNA输出缺陷，核和细胞质之间的班车，并包含C-terminus的核输出效率，这对于CRP79P来说至关重要，以使其在mRNA导出中的作用。 CRP79P的核进口需要RAN-GTPase开关系统的功能。我们发现，在pombe S. pombe中，mRNA导出的CRP79P在功能上是多余的，并且它在RAE1P mRNA输出途径的mRNA导出率中起作用。