Temporal control of cell patterning, signaling, and movement in early embryos

早期胚胎细胞模式、信号传导和运动的时间控制

• 批准号: 10445335
• 负责人: Angelike Stathopoulos
• 金额: $ 62.31万
• 依托单位: CALIFORNIA INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-08-11 至 2026-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10445335
• 关键词: Actins; Adherens Junction; Animals; Blastoderm; Cell physiology; Cells; Cellular Morphology; Chromatin; Comparative Study; Cytoskeleton; Data; Development; Dominant-Negative Mutation; Dorsal; Drosophila genus; Embryo; Embryonic Development; Enhancers; Fibroblast Growth Factor; Funding; Gene Expression; Gene Expression Regulation; Genes; Genetic Transcription; Goals; Homologous Gene; Hour; Image; Ligands; Movement; NF-kappa B; Output; Pattern; Process; Regulatory Element; Research; Series; Signal Pathway; Signal Transduction; Signaling Molecule; Supporting Cell; System; Time; Tissues; Transcript; Variant; Work; cell motility; combinatorial; epithelial to mesenchymal transition; experimental study; gastrulation; in vivo imaging; insight; morphogens; preimplantation; programs; transcription factor

Regulation of gene expression along the dorsal-ventral (DV) axis of Drosophila embryos serves as a paradigm of developmental patterning. Comparative studies of cis-regulatory elements that support expression along the DV axis from many research groups have made it clear that combinatorial input into enhancers by multiple transcription factors drives distinct spatial-outputs of gene expression. A pivotal regulator of this patterning process is the maternally-provided transcription factor Dorsal (Dl), homolog of NFKB. Dl functions as a morphogen to activate target gene expression in a concentration-dependent manner along the DV axis, contributing to the initiation of zygotic gene expression at the maternal-to-zygotic transition (MZT). Using live imaging, we quantified the Dl gradient in embryos and found, surprisingly, that levels change not only in space but also build in time. Our focus during the previous funding period was to study the impact of these Dl dynamics on target gene expression using quantitative approaches involving analysis of live imaging or fixed embryo time-series data to provide insight. In the current proposal, we follow three new and exciting directions, which relate to the timing of cell actions in early embryos and arose as a result of the previous work. Project 1 involves studying how broadly-expressed activators and repressors cooperate to control the onset of zygotic gene expression during the MZT. We hypothesize that broadly-expressed repressors are equally important to pioneer activators in the control of chromatin accessibility and thereby also regulate initiation of zygotic gene expression. Project 2 focuses on dissecting the function of short-transcripts for long genes that are expressed specifically in the early syncytial embryo. We hypothesize that these short transcripts act to regulate timing of cell signaling pathway activation by functioning as dominant-negative variants of signaling molecules. Project 3 focuses on identifying the mechanism by which FGF signaling regulates adherens junctions (AJs) and their interaction with the actin cytoskeleton to contribute to the first epithelial-to-mesenchymal transition (EMT) in embryos; in particular, to understand how a degron associated with one FGF ligand, Pyramus, limits signaling time. The overarching goal of the proposed research program is to understand how the timing of these cell activities - patterning, signaling, and movement - are controlled in developing Drosophila embryos and to provide general insights applicable to higher animals. While many studies have focused on spatial outputs of gene expression, less is known about the temporal dynamics of patterning. Drosophila embryos are a tractable system to study MZT as it occurs in 3-4 hours, in contrast to taking days in preimplantation mammalian embryos. The Drosophila embryo is also amenable to live in vivo imaging and tracking analyses making it well-suited to the study of nascent transcription and cell morphology. Lastly, our proposed studies will provide general insight into early embryo development of higher animals as many regulatory mechanisms are likely conserved.

果蝇胚胎背腹（DV）轴基因表达的调控 发展模式的范式。顺式调控元件的比较研究 许多研究小组沿 DV 轴的支持表达已经明确表示 多个转录因子对增强子的组合输入驱动不同的 基因表达的空间输出。该图案化过程的关键调节器是 母体提供的转录因子 Dorsal (Dl)，NFKB 的同源物。 Dl 的功能为 形态发生素以浓度依赖性方式激活靶基因表达 DV 轴，有助于合子基因表达的启动 母体向合子转变（MZT）。使用实时成像，我们量化了胚胎中的 Dl 梯度 令人惊讶的是，我们发现水平不仅在空间上变化，而且还在时间上变化。我们的 上一个资助期间的重点是研究这些 Dl 动态对目标的影响 使用涉及实时成像或固定胚胎分析的定量方法进行基因表达 时间序列数据提供洞察力。在当前的提案中，我们遵循三个令人兴奋的新内容 方向，与早期胚胎中细胞活动的时间有关，并且是由于 之前的工作。项目 1 涉及研究广泛表达的激活子和阻遏子 合作控制 MZT 期间合子基因表达的开始。我们假设 广泛表达的阻遏蛋白与先锋激活蛋白在控制中同样重要 染色质可及性，从而也调节合子基因表达的起始。项目2 专注于剖析所表达的长基因的短转录本的功能 特别是在早期合胞体胚胎中。我们假设这些简短的转录本的作用是 通过作为显性失活变体调节细胞信号通路激活的时间 信号分子。项目 3 侧重于确定 FGF 信号传导的机制 调节粘附连接 (AJ) 及其与肌动蛋白细胞骨架的相互作用，以促进 胚胎中第一次上皮-间质转化（EMT）；特别是要了解 与一种 FGF 配体 Pyramus 相关的降解决定子如何限制信号传导时间。总体目标 拟议的研究计划的目的是了解这些细胞活动的时间安排 - 模式、信号传导和运动——在发育中的果蝇胚胎中受到控制 并提供适用于高等动物的一般见解。虽然许多研究都集中在 基因表达的空间输出，但对于模式的时间动态知之甚少。 果蝇胚胎是研究 MZT 的易处理系统，因为它在 3-4 小时内发生，在 与植入前哺乳动物胚胎需要数天的时间形成鲜明对比。果蝇胚胎是 还适合活体成像和跟踪分析，使其非常适合研究 新生转录和细胞形态。最后，我们提出的研究将提供一般性的 深入了解高等动物的早期胚胎发育，因为许多调控机制可能 保守的。