Quantitative analysis of signaling dynamics across the BMP morphogen gradient

摘要 我们目前对BMP信号通路特异性的认识是基于基础遗传学和体外实验。 实验，但我们对细胞如何产生不同但特定的反应的理解有限， 体内类似的信号输入。在果蝇胚胎中，BMP信号的陡梯度动态地被激活。 在原肠胚形成之前建立。这种梯度由不同的细胞群解释，以建立 胚胎的背腹轴，背中线的细胞开启一套独特的转录本 与更多的侧细胞相比。我们不知道梯度形成的动力学和最终的 梯度模式由胚胎中的细胞群解释，以产生正确的时空 转录反应使用新的成像工具和定量系统级方法，我将能够 询问BMP信号通路的上游输入如何在细胞核中被解码， 时空转录反应。 在这项研究中，我将探讨两个潜在的机制，BMP信号编码。第一，新方法 将使我能够分析沿着BMP梯度的信号传导动力学。有了这些数据， 将建立一个输入-输出关系模型来预测驱动BMP响应的机制， 转录动力学其次，我将确定不同的配体和受体对的组合是否起作用。 在BMP梯度的规范和解释中的作用。我将研究动态和组合 信号传导用于在胚胎中产生野生型模式的BMP信号传导应答。然后利用 遗传扰动的关键途径组成部分，传播和形状的形态梯度，我将 测试这些动态和组合信号的输入-输出关系是否在不同的BMP中成立 信令上下文。成功完成这项研究将提供一个量化的观点，如何保护 信号传导途径由体内细胞跨时间和空间解释。

ABSTRACT Our current knowledge of BMP signaling pathway specificity is based upon foundational genetic and in vitro experiments, but we have limited understanding as to how cells produce diverse but specific responses to similar signaling inputs in vivo. In the Drosophila embryo, a steep gradient of BMP signaling is dynamically established prior to gastrulation. This gradient is interpreted by different populations of cells to establish the dorsal-ventral axis of the embryo, with cells at the dorsal midline turning on a unique set of transcripts compared to more lateral cells. We do not know how the dynamics of gradient formation and the final gradient pattern are interpreted by cohorts of cells in the embryo to produce the correct spatiotemporal transcriptional response. Using new imaging tools and a quantitative systems level approach, I will be able to interrogate how upstream inputs to the BMP signaling pathway are decoded in the nucleus to elicit correct spatiotemporal transcriptional responses. In this study I will explore two potential mechanisms by which BMP signaling is encoded. First, new methods will allow me to assay the signaling dynamics of pathway activity along the BMP gradient. With these data I will build an input-output relationship model to predict the mechanisms that drive BMP-responsive transcriptional dynamics. Second, I will determine if different combinations of ligand and receptor pairs play a role in specification and interpretation of the BMP gradient. I will study how both dynamic and combinatorial signaling are used to produce the wild type pattern of BMP signaling responses in the embryo. Then, using genetic perturbations in key pathway components that propagate and shape the morphogen gradient, I will test if these input-output relationships in dynamics and combinatorial signaling hold true across different BMP signaling contexts. Successful completion of this study will provide a quantitative view for how a conserved signaling pathway is interpreted by cells in vivo across time and space.