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 生物体的发展既需要刻板印象，也需要随机模式。定型图案 强健地在个体之间产生几乎相同的结构。相反，随机细胞命运规范 产生每个个体唯一的随机化图案。随机的命运决定是需要的 许多感觉器官的发育，包括视觉和嗅觉系统。尽管它们很重要，但如何 控制定型图案和随机图案的分子机制在同一组织中没有相交 已经解决了。这个项目旨在确定基因调控机制是如何调整以产生高度 以果蝇眼为模型，研究了同一组织中的规律性图案和随机图案。 果蝇的眼睛由大约800个小眼组成，排列得近乎完美。每个小眼包括 八个光感受器(R1-8)，它们以可预测的方式发育。因为光感受器在 幼虫眼睛发育，由Hedgehog(HH)信号驱动的一波形态发生驱动高度 眼睛的可复制结构。苍蝇眼的均匀形态下是一种随机的图案 光感受器亚型。光检测视紫红质的表达决定了两种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，无刺(SS)。SSON R7表达视紫红质4(Rh4)，而SsOFF R7表达 视紫红质3(Rh3)。幼虫眼部SS受转录和染色质调节的相互作用 发展。 我发现，HH信号在眼睛发育中扮演着第二个角色，以调节随机图案。HH 突变体表现出sson R7s百分比的降低。手肘中断(Ci)，HH信号的效应者， 结合在SS中的眼睛特异性增强剂上。这个位点与Klumpfuss(Klu)的结合位点重叠，Klu是一种 SS，暗示竞争结合和调节。 我假设HH信号是微调的，以驱动刻板印象的眼睛模式和诱导SS 在前体中转录以产生随机的R7亚型图案。我将通过1)来检验这一假设 确定HH途径如何调节随机SS表达，2)描述 Ci和Klu调节ss的表达，3)决定HH信号和染色质调节的整合方式 在党卫军的轨迹上。总而言之，这些实验将提供第一次分析随机之间的协调 和刻板印象基因在单个组织中的表达，将增强我们对 随机细胞命运规范。