PHOSPHORYLATION IN A DEVELOPMENTAL SIGNALING PATHWAY

这项研究的长期目标是理解一个信号 调节基因表达程序的转导途径，通过 控制调节蛋白的亚细胞定位。在 果蝇、果蝇细胞内信号转导收到 在胚胎表面促进细胞核移位 转录因子背侧，从而建立背腹侧 轴心。在果蝇、植物和哺乳动物中，同源通路直接指向细胞核 作为免疫或免疫过程中关键步骤的相关转录因子的导入 防御性反应。 除了背部，果蝇的背腹信号通路 需要跨膜受体Toll，支架蛋白管， 蛋白激酶Pelle和抑制剂仙人掌。事实上，这些 五个途径的成分已经在遗传和 分子水平和可以通过胚胎微量注射进行检测的技术 该系统特别适合于实验研究。现在是时候了 因此，有可能解决关于 信号转导机制。 这项提案的前两个具体目标将集中在 启动细胞内信号传递。的势函数 肌动蛋白结合蛋白丝素作为Toll和Tube之间的纽带将被 在免疫共沉淀和遗传相互作用研究中进行了研究。 更多的实验将解决的机制和意义 Toll激活后的管子重新定位。第三和 第四个目标将解决信号如何传播的问题。 将探索自动磷酸化作为PEELL的一种潜在机制 体内调节。分子和生化研究也将是 用来确定哪些途径蛋白经历了PEELL介导 胚胎中的磷酸化。第五个也是最后一个具体目标将集中在 论合胞环境中信号的空间调控 胚芽的胚胎。 鉴于信号通路的保守性，研究结果表明 拟议的研究不仅在以下方面应该具有实质性的兴趣 在昆虫胚胎中形成图案，但也发出信号 在广泛的动植物中的转导和免疫。

The long term goal of this research is to understand a signal transduction pathway that regulates programs of gene expression by controlling the subcellular localization of regulatory proteins. In the fruit fly Drosophila, intracellular transduction of a signal received at the surface of the embryo promotes nuclear translocation of the transcription factor Dorsal and thereby establishes the dorsoventral axis. In flies, plants, and mammals, homologous pathways direct nuclear import of related transcription factors as a critical step in immune or defensive responses. In addition to Dorsal, the Drosophila dorsoventral signaling pathway requires the transmembrane receptor Toll, the scaffolding protein Tube, the protein kinase Pelle, and the inhibitor Cactus. The fact that these five pathway components have been characterized at both the genetic and molecular level and can be assayed by embryo microinjection makes this system particularly amenable to experimental investigation. It is now possible, therefore, to address fundamental questions about the mechanism for signal transduction. The first two specific aims of this proposal will focus on the initiation of intracellular signaling. The potential function of the actin-binding protein Filamin as a link between Toll and Tube will be investigated in coimmunoprecipitation and genetic interaction studies. Additional experiments will address the mechanism and significance of Tube relocalization in response to Toll activation. The third and fourth aims will address how the signal is propagated. Autophosphorylation will be explored as a potential mechanism for Pelle regulation in vivo. Molecular and biochemical studies will also be carried out to determine which pathway proteins undergo Pelle-mediated phosphorylation in embryos. The fifth and final specific aim will focus on the spatial regulation of signaling within the syncytial environment of the blastoderm embryo. Given the conserved nature of the signaling pathway, the results of the proposed research should be of substantial interest with regard not only to pattern formation in the insect embryo, but also to signal transduction and immunity in a broad range of plants and animals.