Structural and functional investigation of the SRSF1-mediated nuclear export of mRNAs

细胞构成了人体的基本生命单位，将食物和氧气转化为能量，产生蛋白质，蛋白质作为构建模块和分子机器。含有制造蛋白质的基因的DNA蓝图位于细胞中心，即细胞核，它与周围的细胞质分隔开，细胞质是制造蛋白质的地方。从蓝图复制的信使中间分子（mRNA）从细胞核穿过核开口运输到细胞质中，其中每个mRNA指导一种类型蛋白质的组装。其他RNA也是从核心DNA蓝图产生的，需要进入细胞质-它们不传递组装蛋白质的信息，但允许建立一些基因工作机制并根据细胞的需要调节蛋白质的产生。数以万计的蛋白质的数量和功能总体上解释了细胞的正常功能或死亡。我们和其他人已经证明，SRSF 1蛋白在将mRNA转运到细胞质中具有重要作用，它使mRNA与另一种蛋白NXF 1接触，NXF 1驱动mRNA通过核开口。此外，我们最近报道了SRSF 1与不同形状的C9 ORF 72 mRNA的连接，涉及称为肌萎缩侧索硬化症（ALS）和额颞叶痴呆症（FTD）的致命性脑疾病，也是诱导这些特殊mRNA运输到细胞质中的原因。SRSF 1如何附着于NXF 1和mRNA以运输到细胞质中的精确机制仍有待发现。我们的研究项目现在旨在（i）准确了解SRSF 1如何附着于C9 ORF 72-ALS/FTD RNA和NXF 1，以及（ii）SRSF 1如何诱导这些RNA转运到细胞质中。我们将在人神经细胞和果蝇模型中进行C9 ORF 72-ALS/FTD实验，以及在试管中使用纯SRSF 1、NXF 1和RNA的组合。这将使我们首次了解这种动态过程如何在原子尺度上发生。我们的研究计划有三个互补的目标：1。了解SRSF 1如何在原子级别连接到NXF 1。2.发现SRSF 1如何附着于两种类型的C9 ORF 72-ALS/FTD RNA，在原子水平上形成特殊的四链或双链结构。3.研究SRSF 1、C9 ORF 72-ALS/FTD RNA和NXF 1如何在微观水平组装形成单一复合转运机器，以及这对于促进RNA转运到人类细胞模型和C9 ORF 72-ALS/FTD神经细胞和果蝇模型的细胞质中的重要性。我们希望，对SRSF 1允许RNA通过核开口转运的机制的详细了解将对我们有很大的帮助。这对理解新的生物学机制和未来开发用于治疗某些神经退行性疾病如C9 ORF 72-ALS/FTD的药物抑制剂具有重要意义。包括学生和科学家在内的几个学术研究人员社区将直接参与研究。此外，这项工作还将产生鼓舞人心的交流、介绍和出版物，使学术界、公众、当地学校、第三产业受益，并可能在较长时期内使生物技术部门和制药业受益。

Cells form the basic living units of the body, converting food and oxygen into energy to produce proteins that serve as building blocks and molecular machines. The DNA blueprint that contain genes for making up proteins is housed in a cell centre, the nucleus, which is separated from the surrounding compartment, the cytoplasm, where proteins are manufactured. Messenger intermediate molecules (mRNAs) copied from the blueprint are transported from the nucleus into the cytoplasm across nuclear openings where each mRNA guides the assembly of one type of protein. Other RNAs are also produced from the core DNA blueprint and require passage into the cytoplasm - they do not convey information for assembling the proteins but allow building some of the gene-working machineries and modulating the production of proteins depending on the needs of the cells. The quantity and functionality of tens of thousands of proteins account overall for the normal functioning or the death of cells. We and others have shown that the protein with the name SRSF1 has an important role in transporting mRNAs into the cytoplasm by bringing mRNAs into contact with another protein, NXF1, which drives mRNAs through the nuclear openings. In addition, we recently reported that the attachment of SRSF1 to differently shaped C9ORF72 mRNAs, involved in lethal diseases of the brain called amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), is also responsible for inducing transportation of these peculiar mRNAs into the cytoplasm. The precise mechanisms of how SRSF1 attaches to NXF1 and mRNAs for transport into the cytoplasm remain to be discovered. Our research project now aims to (i) understand precisely how SRSF1 attaches to the C9ORF72-ALS/FTD RNAs and NXF1 and (ii) how SRSF1 induces transportation of these RNAs into the cytoplasm. We will carry out experiments in human nerve cells and fruit fly models of C9ORF72-ALS/FTD as well as with combinations of pure SRSF1, NXF1 and RNA in test tubes. This will allow understanding for the first time how this dynamic process occurs at the scale of atoms. Our programme of research has three complementary objectives:1. Discover how SRSF1 attaches to NXF1 at the atomic level.2. Discover how SRSF1 attaches to two types of shaped C9ORF72-ALS/FTD RNAs forming special four-stranded or double-stranded structures at the atomic level.3. Examine how SRSF1, C9ORF72-ALS/FTD RNAs and NXF1 assemble at the microscopic level to form a single composite transport machine and how important this is for promoting the transport of RNAs into the cytoplasm of human cell models and C9ORF72-ALS/FTD nerve cells and fruit fly models.In the long term, we expect that a detailed understanding of the mechanisms by which SRSF1 allow transport of RNA though nuclear openings would have far-reaching implications for the understanding of novel biological mechanisms and the potential future development of drug inhibitors for the treatment of some neurodegenerative diseases such as C9ORF72-ALS/FTD. Several communities of academic researchers including students and scientists will directly be involved in conducting the research. Furthermore, this work will lead to inspirational communications, presentations and publications that will benefit the academic community, the general public, local schools, the tertiary sector and potentially in the longer term the biotechnology sector and the pharmaceutical industry.