Modeling and analysis of BMP-mediated Dorsal/Ventral patterning in zebrafish embryos

项目摘要 骨形态发生蛋白（BMP）在发育过程中起形态发生剂的作用， 胚胎轴和器官结构的组织。许多细胞外拮抗剂和辅助因子的工作 与动态控制BMP信号沿着背腹（DV）胚胎轴的分布一致， 脊椎动物诱导基因表达的空间和时间依赖性模式。随着胚胎从 从囊胚期到原肠胚期，响应BMP信号的合子反馈开始，细胞开始 通过同时响应BMP和调节拮抗剂的分泌而发挥积极作用， 影响BMP梯度形状的其他因素。然而，还没有很好地理解系统如何动态地 调节模式形成。对原肠胚阶段BMP模式形成的研究为研究BMP在胚胎发育中的作用提供了理想的背景。 阐明反馈调节如何在脊椎动物系统中形成BMP信号梯度。我们 假设由admp、sizzled、tld和bambi引起BMP介导的反馈动态地塑造了 原肠胚我们的目标是描绘如何耦合图案和反馈形状梯度， 发现斑马鱼原肠胚中BMP的调控机制。在目标1中，我们将量化时空BMP 野生型和突变型斑马鱼原肠胚中的信号和反馈靶基因表达。 此外，我们将测量野生型（wt）原肠胚胚胎中磷酸化Smad 1/5（PSmad）的水平， 并开发我们新的基于小波的分割和图像分析软件WaveSeg （https：//www.example.com）来量化、分段和登记数据。这项工作将提供第一个- 确定形成PSmad梯度的反馈关系所需的任何定量数据。定量 在原肠胚阶段胚胎中BMP模式的研究将提供对梯度细化中反馈作用的深入了解 在快速变化的空间中。在目标2中，我们将开发一个三维增长网格有限元 原肠期胚胎中BMP模式形成的模型。对模型进行定量评估 成像数据为辨别原肠胚胚胎模式形成的机制提供了严格的基础， 生成新的测试来验证或反驳一致的机制。无缝集成和后台- 第四，成像，遗传学和建模之间的关系将阐明细胞外BMP通路因子 调节BMP信号梯度。最后，在目标3中，我们将研究BMP信号传导中的反馈回路 已经提出了提供胚胎尺度不变性、相对于部分损失的鲁棒性， 网络组件，并增加信号解释的动态范围。了解这些网络 BMP调控的研究将为我们深入了解BMP在其他环境中的功能，包括器官发生、癌症 转移、血管生成和发育。

Project summary Bone Morphogenetic Proteins (BMPs) function as morphogens during development to specify spatial organization of embryonic axes and organ structures. Numerous extracellular antagonists and co-factors work in concert to dynamically control BMP signaling distributions along the dorsal-ventral (DV) embryonic axis in vertebrates to induce space and time-dependent patterns of gene expression. As the embryo progresses from the blastula stage into the gastrula stage, zygotic feedback in response to BMP signaling begins and cells start to play an active role by simultaneously responding to BMPs and regulating the secretion of antagonists and other factors that shape the BMP gradient. However it is not well understood how the system dynamically regulates pattern formation. Studies of gastrula stage BMP pattern formation provide an ideal context to unravel how feedback regulation shapes the gradients of BMP signaling in a vertebrate system. We hypothesize that BMP-mediated feedback by admp, sizzled, tld, and bambi dynamically shape the gradient in gastrula embryos. Our objective is to delineate how coupled patterning and feedback shape gradients and discover mechanisms of BMP regulation in zebrafish gastrula. In Aim 1 we will quantify spatiotemporal BMP signaling and feedback target gene expression in wild-type and mutant zebrafish gastrula embryos. Furthermore, we will measure phospho-Smad 1/5 (PSmad) levels in toto in wild-type (wt) gastrula embryos, and develop our new wavelet-based segmentation and image analysis software WaveSeg (https://waveletseg.weebly.com) to quantify, segment, and register the data. This work will provide the first- ever quantitative data needed to identify feedback relationships that shape the PSmad gradient. Quantification of BMP patterning in gastrula stage embryos will provide insight into the role of feedback in gradient refinement in a rapidly changing spatial domain. In Aim 2 we will develop a 3-dimensional growing mesh finite element model of BMP pattern formation in gastrula stage embryos. Evaluation of the models against quantitative imaging data provides a rigorous basis to discern the mechanisms of gastrula embryo pattern formation and generate new tests to validate or refute the consistent mechanisms. The seamless integration and back-and- forth between imaging, genetics, and modeling will elucidate how the extracellular BMP pathway factors modulate the BMP signaling gradient. Lastly, in Aim 3 we will investigate the feedback loops in BMP signaling that have been proposed to provide embryonic scale invariance, robustness with respect to partial loss of network components, and increase the dynamic range of signal interpretation. Understanding these networks of BMP regulation will provide insight into BMP function in other contexts including organogenesis, cancer metastasis, angiogenesis and development.