Post-transcriptional gene regulation during early Drosophila development

项目总结/摘要 基因调控的转录和转录后机制共同作用， 每个基因在所有动物的早期发育过程中，基因表达的转录后控制是唯一的。 重要的是，没有转录发生，相反，母体沉积的基因产物控制着最早的事件， 卵子受精后的胚胎发育。母体基因产物控制着发育，直到母体- 向合子转换（MZT），当母体沉积的mRNA被降解，合子基因组被 激活在黑腹果蝇中，近60%的母体沉积的mRNA在一个不稳定的环境中被破坏。 广泛的，基因特异性的mRNA降解波，由母系编码和合子控制 转录调节子。成功地从母体到合子控制的交接需要这一波母体控制。 mRNA不稳定，但我们对这一基本过程的理解存在重大差距，因为 导致不稳定的分子调节剂在很大程度上是未知的。我提议的目的是为了更好地 了解在早期果蝇胚胎中起作用的转录后控制。的主要障碍 了解母体沉积的mRNA是如何不稳定的是，近三分之二的母体沉积的mRNA是不稳定的。 一旦合子基因组有活性，不稳定的沉积mRNA就开始转录。这防止 准确鉴定不稳定的mRNA，因为合子表达的转录本无法区分 来自于同一基因的母体沉积形式。首先，我的目标是确定母性的动力学 在母体到合子的转变过程中沉积和合子转录的mRNA， 准确区分母体沉积和合子转录的转录本。这些定量 测量将是发育生物学和苍蝇社区的宝贵资源，因为它们 提供了一个mRNA动态的角度与时间分辨率是无与伦比的其他研究。二我 目的是鉴定调节母体沉积mRNA稳定性的蛋白质。初步分析，我 注释了果蝇胚胎发育过程中表达的基因的3′端，发现大多数基因 表达多种交替的3′串联异构体。我建议利用自然产生的差异 在串联同种型序列之间鉴定调节mRNA稳定性和RBP的RNA序列 能够识别这些序列。这些数据将从根本上有助于我们的mRNA降解模型 在MZT期间，通过探索这一过程的新调节剂，我将能够确定为什么 母体mRNA降解对胚胎发育至关重要。任何被确定为在 MZT也可能影响非发育环境中的mRNA稳定性，提供以下信息： 在其他细胞环境中mRNA半衰期的决定因素。

PROJECT SUMMARY/ABSTRACT Transcriptional and post-transcriptional mechanisms of gene regulation collaborate to shape the expression of every gene. During early development in all animals, post-transcriptional control of gene expression is uniquely important as no transcription occurs, instead, maternally deposited gene products control the earliest events of embryonic development after egg fertilization. Maternal gene products control development until the maternal- to-zygotic transition (MZT), when maternally deposited mRNAs are degraded and the zygotic genome is activated. In Drosophila melanogaster, nearly 60% of maternally deposited mRNAs are destabilized in a widespread, gene-specific wave of mRNA degradation that is controlled by maternally encoded and zygotically transcribed regulators. Successful handoff from maternal to zygotic control requires this wave of maternal mRNA destabilization, but there is a major gap in our understanding of this fundamental process because the molecular regulators underlying the destabilization are largely unknown. The goal of my proposal is to better understand the post-transcriptional control that operates in the early Drosophila embryo. A major barrier to understanding how maternally deposited mRNAs are destabilized is the fact that nearly two-thirds of maternally deposited mRNAs that are destabilized become transcribed once the zygotic genome is active. This prevents accurate identification of destabilized mRNAs, as the zygotically expressed transcript cannot be distinguished from the maternally deposited form of the same gene. First, I aim to determine the dynamics of maternally deposited and zygotically transcribed mRNAs during the maternal-to-zygotic transition using a method that can accurately distinguish between maternally deposited and zygotically transcribed transcripts. These quantitative measurements will be a valuable resource for the developmental biology and fly communities because they offer a perspective on mRNA dynamics with temporal resolution that is unparalleled by other studies. Second, I aim to identify proteins that regulate the stability of maternally deposited mRNAs. In a preliminary analysis, I annotated the 3′ ends of genes expressed during Drosophila embryogenesis and I found that most genes express multiple alternative 3′ tandem isoforms. I propose to leverage the naturally occurring differences between the sequence of tandem isoforms to identify RNA sequences that modulate mRNA stability and RBPs that recognize these sequences. These data will fundamentally contribute to our models of mRNA degradation during MZT and through exploring novel regulators of this process I will be in a position to determine why maternal mRNA degradation is essential for embryonic development. Any regulators identified as acting during MZT are also likely to influence mRNA stability in non-developmental contexts, providing information on determinants of mRNA half-life in other cellular contexts.