The role of RNA export factors in tissue specific gene expression

RNA输出因子在组织特异性基因表达中的作用

• 批准号: BB/L001004/1
• 负责人: Helen White-Cooper
• 金额: $ 68.86万
• 依托单位: CARDIFF UNIVERSITY
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2013
• 资助国家: 英国
• 起止时间: 2013 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FL001004%2F1
• 关键词: role; RNA; export; factors; tissue

Individual cells in multicellular organisms are have distinct shapes and characteristics, each specialised for a specific function. A major aim in understanding organism function is to understand how cells become specialised (differentiated). Every cell in a multicellular organism carries the same genes. Cells differentiate by expressing genes for proteins relevant to their final function, and repressing genes whose protein products are not needed (or are even detrimental) for the final function. This project is aimed at increasing understanding of the fundamental biological processes that control gene expression in differentiating cells. We focus on sperm production, since sperm are extremely specialised, and their formation depends on expression of a very large number of genes not used in any other process. We use the fruit fly, Drosophila melanogaster, as a model system as it is highly amenable to a genetic and molecular analysis. Since these processes fundamental to all multi-cellular organisms, we expect our results to have broad implications, eg in understanding human development and disease.Expression of genes requires copying (transcribing) information from DNA, in the cell nucleus, into an RNA molecule that is then transported to the cytoplasm and translated into protein. Gene expression is well known to be regulated at both transcriptional and translational levels. RNA processing in the nucleus, and export from the nucleus, also present control points. The mechanism by which RNAs get exported from the nucleus to the cytoplasm is well characterised, and relies on a set of proteins that are conserved from yeasts to humans.Regulation of gene expression at the transcriptional level relies on the DNA of specific regions near genes "promoters" having sequences that are bound by sequence-specific DNA binding proteins (transcription factors). Binding of these transcription factors to gene promoters then recruits an enzyme complex (RNA polymerase) that actually transcribes the DNA sequence to give an RNA transcript. Usually this contains intervening sequences (introns) that get spliced out to make the final mRNA product. The process of transcription, and particularly splicing, promotes binding of the RNA export proteins to the mRNA. RNAs that are not appropriately processed are degraded.In our recent research we discovered that a component of the RNA export pathway is required for expression of testis-specific transcripts, but not most other transcripts, in sperm development. We have shown that this is because the RNA export factors, which are understood to work downstream of the transcription factors in regulation of gene expression, actually also feed back to promote activity of a specific transcription factor in testes. Without this feedback the genes required specifically to make sperm are not expressed, and the flies are sterile.Our project aim is to understand the mechanism of this feedback. Is the whole export pathway involved, or only specific components? Do the export factors directly bind to the transcription factors? Do the export factors promote binding of the transcription factors to the DNA, or do they promote the transcription factors activity in recruiting the RNA polymerase? Does the transcription factor help protect the testis-specific RNAs from degradation?We also found that reducing activity of the RNA export makes the females sterile, and causes many individual animals to die as pupae. These effects are very specific, and don't appear to be due to a general failure in RNA export, but appear, like the situation in testes, to be caused by defects in specific transcription programmes. We will investigate the generality of our findings on the link between transcription and RNA export by characterising the gene expression defects in these other developmental contexts. We hope to identify the relevant transcription factor, and develop mechanistic insights using our findings from testes as a guide.

多细胞生物中的单个细胞具有不同的形状和特征，每个细胞都有特定的功能。了解生物体功能的一个主要目的是了解细胞如何特化（分化）。多细胞生物中的每个细胞都携带相同的基因。细胞通过表达与最终功能相关的蛋白质基因和抑制最终功能不需要（甚至有害）蛋白质产物的基因来分化。该项目旨在增加对细胞分化过程中控制基因表达的基本生物学过程的理解。我们关注的是精子的产生，因为精子是非常专门化的，它们的形成依赖于大量基因的表达，而这些基因在任何其他过程中都不会用到。我们使用果蝇（Drosophila melanogaster）作为模型系统，因为它非常适合进行遗传和分子分析。由于这些过程是所有多细胞生物的基础，我们希望我们的结果具有广泛的意义，例如在理解人类发育和疾病方面。基因的表达需要将细胞核中的DNA信息复制（转录）到RNA分子中，然后将RNA分子运送到细胞质中并翻译成蛋白质。众所周知，基因表达在转录和翻译水平上都受到调控。RNA在细胞核中的加工和从细胞核中输出，也存在控制点。rna从细胞核输出到细胞质的机制已经被很好地描述了，它依赖于一组从酵母到人类保存下来的蛋白质。在转录水平上，基因表达的调控依赖于基因“启动子”附近特定区域的DNA，这些区域的序列由序列特异性DNA结合蛋白（转录因子）结合。这些转录因子与基因启动子结合，然后招募一种酶复合体（RNA聚合酶），这种酶复合体实际上将DNA序列转录成RNA转录物。通常这包含中间序列（内含子），它们被剪接出来形成最终的mRNA产物。转录过程，特别是剪接，促进了RNA输出蛋白与mRNA的结合。没有被适当处理的rna会被降解。在我们最近的研究中，我们发现在精子发育过程中，睾丸特异性转录物的表达需要RNA输出途径的一个组成部分，而不是大多数其他转录物的表达。我们已经证明，这是因为RNA输出因子，被理解为在调节基因表达的转录因子下游工作，实际上也反馈促进睾丸中特定转录因子的活性。没有这种反馈，制造精子所需的基因就不会表达，果蝇就会不育。我们的项目目标是了解这种反馈的机制。是涉及整个出口路径，还是仅涉及特定组件？输出因子是否直接与转录因子结合？输出因子是促进转录因子与DNA结合，还是促进转录因子招募RNA聚合酶的活性？转录因子是否有助于保护睾丸特异性rna免受降解？我们还发现，RNA输出活性的降低使雌性不育，并导致许多个体动物作为蛹死亡。这些影响是非常特异性的，似乎不是由于RNA输出的一般失败，而是像睾丸中的情况一样，是由特定转录程序的缺陷引起的。我们将通过描述这些其他发育背景下的基因表达缺陷来研究我们关于转录和RNA输出之间联系的发现的普遍性。我们希望确定相关的转录因子，并利用我们在睾丸中的发现作为指导，开发机制见解。

项目成果

Understanding the importance of RNA export factor, Nxt1, during the metamorphosis and in ovaries in Drosophila melanogaster

了解 RNA 输出因子 Nxt1 在果蝇变态过程中和卵巢中的重要性

• 发表时间: 2018
• 作者: Van Der Graaf Kevin

Genome-wide analysis of gene regulation mechanisms during Drosophila spermatogenesis.

• DOI: 10.1186/s13072-018-0183-3
• 发表时间: 2018-04-02
• 期刊: Epigenetics & chromatin
• 影响因子: 3.9
• 作者: Laktionov PP;Maksimov DA;Romanov SE;Antoshina PA;Posukh OV;White-Cooper H;Koryakov DE;Belyakin SN
• 通讯作者: Belyakin SN

Roles for RNA export factor, Nxt1, in ensuring muscle integrity and normal RNA expression in Drosophila.

• DOI: 10.1093/g3journal/jkaa046
• 发表时间: 2021-01-18
• 期刊: G3 (Bethesda, Md.)
• 作者: van der Graaf K;Jindrich K;Mitchell R;White-Cooper H
• 通讯作者: White-Cooper H

Analysis of the expression patterns, subcellular localisations and interaction partners of Drosophila proteins using a pigP protein trap library.

• DOI: 10.1242/dev.111054
• 发表时间: 2014-10
• 期刊: Development (Cambridge, England)
• 作者: Lowe N;Rees JS;Roote J;Ryder E;Armean IM;Johnson G;Drummond E;Spriggs H;Drummond J;Magbanua JP;Naylor H;Sanson B;Bastock R;Huelsmann S;Trovisco V;Landgraf M;Knowles-Barley S;Armstrong JD;White-Cooper H;Hansen C;Phillips RG;UK Drosophila Protein Trap Screening Consortium;Lilley KS;Russell S;St Johnston D
• 通讯作者: St Johnston D