Hedgehog Signaling Coordinates Stochastic and Stereotyped Patterns in the Drosophila Eye

刺猬信号协调果蝇眼睛中的随机和刻板模式

• 批准号: 10538065
• 负责人: Alison J Ordway
• 金额: $ 6.72万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-01-01 至 2025-12-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10538065
• 关键词: Address; Affect; Binding; Binding Sites; Cells; Chromatin; Clustered Regularly Interspaced Short Palindromic Repeats; Competitive Binding; Congenital Disorders; Coupled; DNA; Defect; Development; Drosophila eye; EMSA; Enhancers; Erinaceidae; Eye; Eye Development; Gene Expression; Generations; Genes; Genetic Models; Genetic Transcription; Human Development; Image; Individual; Light; Mediating; Modeling; Molecular; Morphogenesis; Morphology; Olfactory Pathways; Organ; Organism; Pathway interactions; Pattern; Photoreceptors; Play; Polycomb; Probability; Proteins; Randomized; Regulation; Regulator Genes; Reproducibility; Response Elements; Rhodopsin; Role; Sensory; Signal Transduction; Site; Specific qualifier value; Stereotyping; Structure; Testing; Tissues; Transcriptional Activation; Vision; Visual; Visual system structure; antagonist; cell fate specification; cell type; experimental study; fly; histone modification; in vivo; migration; mutant; precursor cell; smoothened signaling pathway; transcription factor

Project Summary Development of an organism requires both stereotyped and stochastic patterning. Stereotyped patterning robustly generates nearly identical structures across individuals. In contrast, stochastic cell fate specification produces randomized patterns that are unique to each individual. Stochastic fate decisions are required for the development of many sensory organs, including visual and olfactory systems. Despite their importance, how the molecular mechanisms controlling stereotyped and random patterns intersect within the same tissue has not been addressed. This project aims to determine how gene regulatory mechanisms are tuned to generate highly regular patterns and stochastic patterns in the same tissue using the Drosophila eye as a model. The Drosophila eye is composed of ~800 ommatidia in a near perfect array. Each ommatidium comprises eight photoreceptors (R1-8) which develop in a predictable fashion. As photoreceptors are differentiating during larval eye development, a wave of morphogenesis driven by Hedgehog (Hh) signaling drives the highly reproducible structure of the eye. Underlying the uniform morphology of the fly eye is a random pattern of photoreceptor subtypes. Two R7 photoreceptor subtypes are defined by expression of light-detecting Rhodopsin proteins. Random patterning of these two R7 subtypes is controlled by stochastic ON/OFF expression of the transcription factor, Spineless (Ss). SsON R7s express Rhodopsin 4 (Rh4), whereas SsOFF R7s express Rhodopsin 3 (Rh3). ss is regulated by an interplay of transcription and chromatin regulation during larval eye development. I found that Hh signaling plays a second role in eye development to regulate stochastic patterning. hh mutants display a reduction in the percentage of SsON R7s. Cubitus Interruptus (Ci), an effector of Hh signaling, binds at an eye specific enhancer in ss. This site overlaps with a binding site for Klumpfuss (Klu), a repressor of ss, suggesting competitive binding and regulation. I hypothesize that Hh signaling is finely tuned to drive stereotyped eye patterning and induce ss transcription in precursors to generate stochastic R7 subtype patterning. I will test this hypothesis by 1) Determining how the Hh pathway regulates stochastic ss expression, 2) Describing how antagonism between Ci and Klu regulates ss expression, and 3) Determining how Hh signaling and chromatin regulation are integrated at the ss locus. Together, these experiments will provide the first analysis of coordination between stochastic and stereotyped gene expression within a single tissue and will enhance our mechanistic understanding of stochastic cell fate specification.

项目摘要 生物体的发展需要刻板印象和随机图案。定型图案 稳健地生成跨个体的几乎相同的结构。相反，随机细胞命运规范 产生每个人独有的随机模式。需要随机命运决定 开发许多感觉器官，包括视觉和嗅觉系统。尽管它们的重要性，但如何 控制刻板印象的分子机制和在同一组织内相交的随机模式尚未 已解决。该项目旨在确定如何调节基因调节机制以高度生成 使用果蝇眼作为模型，在同一组织中的常规图案和随机模式。 果蝇的眼睛由一个接近完美的阵列中的约800个阳性植物组成。每个膜都包含 以可预测的方式发展的八个光感受器（R1-8）。随着感光体在 幼虫眼发育，刺猬（HH）信号传导驱动的形态发生浪潮驱动高度 眼睛的可再现结构。苍蝇眼的均匀形态的基础是一个随机模式 感光细胞亚型。通过表达光检测视紫红质的表达来定义两个R7光感受器亚型 蛋白质。这两个R7亚型的随机图案由随机开/关表达控制 转录因子，无脊椎（SS）。 SSON R7S Express Rhodopsin 4（RH4），而Ssoff R7S Express Rhodopsin 3（RH3）。 SS受幼体眼中转录和染色质调节的相互作用调节 发展。 我发现HH信号在眼睛发育中起着第二种作用，以调节随机模式。 hh 突变体显示SSON R7的百分比降低。 Cubitus Intruptus（CI），HH信号的效应子， 在SS中的眼睛特异性增强子处结合。该站点与Klumpfuss（Klu）的绑定位点重叠， SS，提示具有竞争性的结合和调节。 我假设HH信号经过精心调整以驱动刻板的眼睛图案并诱导SS 在前体中转录以生成随机R7亚型图案。我将通过1来检验这个假设） 确定HH途径如何调节随机SS表达，2）描述如何在 CI和KLU调节SS表达，3）确定HH信号传导和染色质调节的整合方式 在SS基因座。这些实验将共同提供随机之间的协调性分析 并在单个组织中刻板的基因表达，将增强我们对 随机细胞命运规范。