Extracellular Regulation of BMP signaling in Development and Disease

骨形态发生蛋白（BMP）信号传导是脊椎动物和无脊椎动物发育以及进入成年期的关键途径。因此，BMP信号传导的失调可导致多种疾病，包括骨骼缺陷和各种癌症。调节BMP信号传导的关键方式是在细胞外环境中通过在许多发育阶段使用的关键蛋白Sog。Sog对BMP的调节受一组蛋白质的调节，包括扭曲胃形成（Tsg）。Tsg可以通过促进三元Sog-Tsg-BMP复合物的形成来增强Sog对BMP的抑制，所述三元Sog-Tsg-BMP复合物阻断BMP结合其靶受体并因此阻断信号传导。然而，Tsg在不同的情况下也显示出pro-BMP信号传导活性。本项目的目的是进一步研究Sog和Tsg如何能够在细胞外环境中调节BMP信号传导。鉴于该途径的保守性，将在模式生物果蝇中研究BMP调控。Sog-BMP和Sog-BMP-Tsg复合物的结构表征将使用小角X射线散射和冷冻电子显微镜来实现。此外，实时成像将用于可视化和跟踪胚胎发育过程中Sog和Tsg复合物的形成和命运。最后，CRISPR介导的基因组编辑将允许对关键残基进行靶向诱变，以干扰通过复合物的结构表征鉴定的相互作用，并且将确定这种干扰对蛋白质定位、功能和胚胎模式的影响。通过这个项目，更好地了解BMP信号传导的分子水平调控不仅有助于早期发育调控的学术理解，而且有助于设计新的试剂来抑制或增强BMP信号传导。这是一个主要的治疗目标。

Bone Morphogenic Protein (BMP) signaling is a key pathway in the development of vertebrates and invertebrates, as well as into adulthood. As such, misregulation of BMP signaling can lead to a wide variety of diseases, including skeletal defects and various cancers. A key way in which BMP signaling is regulated is in the extracellular environment via a key protein, Sog, employed at many developmental stages. The regulation of BMP by Sog is modulated by a set of proteins, including Twisted Gastrulation (Tsg). Tsg can enhance Sog inhibition of BMP by promoting formation of a ternary Sog-Tsg-BMP complex which blocks BMP binding its target receptor and therefore signaling. However, Tsg also displays pro-BMP signaling activity in different contexts. The aim of this project is to further investigate how Sog and Tsg are able to regulate BMP signaling in the extracellular environment. Given the conserved nature of the pathway, BMP regulation will be investigated in the model organism Drosophila melanogaster. Structural characterization of the Sog-BMP and Sog-BMP-Tsg complexes will be achieved using Small Angle Xray Scattering and Cryo-Electron Microscopy. Moreover, live imaging will be used to visualize and follow the formation and fate of Sog and Tsg complexes during embryonic development. Finally, CRISPR-mediated genome editing will allow targeted mutagenesis to key residues to disturb interactions identified by the structural characterization of the complexes and the effect of such disturbances on the protein localization, function and embryonic patterning will be determined. Through this project, a better understanding of the molecular level regulation BMP signaling will aid not just in the academic understanding of early developmental regulation, but also in the design of novel reagents to inhibit or enhance BMP signaling. This represents a major therapeutic goal.