Understanding the link between splicing and mRNA localization by structural biology

在所有发育过程中，如细胞运动、细胞特化和细胞不对称分裂，信使核糖核酸的定位是必不可少的。在果蝇中，Oskar mRNA定位于卵母细胞的后极，决定了腹部和原始生殖细胞的形成位置。这种转运需要反式作用因子识别Oskar mRNA转录本中的特定序列。然后，这些核糖核蛋白颗粒与运动蛋白马达相互作用，沿着微管运输。唯一的RNA是一种特定的Oskar mRNA序列，它在剪接时形成，距离外显子连接复合体(EJC)沉积位置只有几个核苷酸。单一RNA和EJC对于mRNA的定位都是必不可少的。PYM(Y14-MAGO的伙伴)是一种蛋白质，因为它与EJC Y14和MAGO的核心成分相关。PYM在EJC动态平衡和mRNA定位中具有双重作用。最近我们发现蛋白质直接与单一RNA相互作用，这表明mRNA定位和EJC动态平衡可能是共同调节的。在这项拨款提案中，我们旨在阐明单一RNA和平阳霉素在mRNA定位中的作用，以及它们与EJC的相互作用。我们将采取结构生物学、体内功能分析和生物化学相结合的跨学科方法。这个项目将有助于从分子上理解生物体发育过程中最受调控、最复杂和最基本的过程之一。

mRNA localization is essential to all developmental programmes, such as cell movement, cell specialization and asymmetric cell division. In Drosophila melanogaster, oskar mRNA localization to the posterior pole of the oocyte determines where the abdomen and primordial germ cells form. The transport requires the recognition of specific sequences in the oskar mRNA transcript by trans acting factors. These ribonucleoprotein particles then interact with the kinesin motor for transport along the microtubules. The SOLE RNA is a specific oskar mRNA sequence that forms upon splicing and is located only a few nucleotides away from the Exon Junction Complex (EJC) deposition site. Both the SOLE RNA and the EJC are indispensable for mRNA localization.PYM (Partner of Y14-Mago) is a protein that was identified because of its association with the core components of the EJC Y14 and Mago. PYM has a dual role in both EJC homeostasis and mRNA localization. Recently we discovered that the protein directly interacts with the SOLE RNA, suggesting that mRNA localization and EJC homeostasis might be co-regulated.In this grant proposal we aim at shedding light on the role of the SOLE RNA and PYM in mRNA localization, as well as their interplay with the EJC. We will take an interdisciplinary approach combining structural biology, functional assays in vivo and biochemistry.This project will contribute to the molecular understanding of one of the most regulated, complex and fundamental processes of organism development.