Hedgehog Signal Transduction Across the Cell Membrane

Hedgehog(HH)蛋白家族协调细胞生长和分化，在许多 通过在HH产生细胞周围的细胞中引发分级反应来促进发育。反常的 HH通路活性与面部和前脑发育畸形有关，并普遍存在 前列腺癌和基底细胞癌等癌症。了解HH信号是如何 因此，从细胞外环境传递到细胞内效应器是成功的关键 预防、检测和治疗这些和其他与HH信号有关的疾病。这项建议 重点介绍了允许细胞在血浆中识别分泌的HH蛋白的机制 膜和随后跨膜的信号转导以诱导特定的细胞内 回应。 需要HH与十二个跨膜蛋白补丁(PTC)的直接相互作用 放弃PTC介导的靶向抑制七种跨膜蛋白(Smo) 细胞。这种相互作用是由Dally-like Protein(Dip)和CG9211(A)促进的。 免疫球蛋白(Ig)受体超家族的成员。激活的SMO将信号传递到 在细胞质尾部招募一个大的调节复合体的过程中，膜包括 转录因子Cubitus interruptus(Ci)。DIP、CG9211和这些 胞质蛋白-蛋白相互作用对HH途径反应的贡献尚不清楚。 为了研究HH信号在细胞膜上的接收和传输，我们有 开发了新的工具，包括基于培养细胞的途径响应性分析，试剂 分离和检测抑制特定基因的HH信号复合体和双链RNA文库 通过RNA介导的干扰(RNAi)在果蝇和小鼠中发挥作用。通过将这些工具整合到 基于生物化学和遗传的策略，我们建议：1)确定HH信号是如何在 细胞膜，2)确定Smo如何将HH信号转导到细胞质成分，以及3)识别 通过使用基于RNAi的技术系统地测试基因功能来研究HH途径组件。

The Hedgehog (Hh) family of proteins coordinates cellular growth and differentiation in a number of developmental contexts by eliciting graded responses in the cells surrounding Hh-producing cells. Aberrant Hh pathway activity is associated with developmental deformities of the face and forebrain, and prevalent cancers such as prostate cancer and basal cell carcinoma (BCC). Understanding how the Hh signal is conveyed from the extracellular milieu to intracellular effectors is therefore pivotal to the successful prevention, detection, and treatment of these and other diseases associated with Hh signaling. This proposal focuses on the mechanisms that allow cellular recognition of the secreted Hh protein at the plasma membrane and subsequent transduction of a signal across the membrane to induce specific intracellular responses. Direct interaction of Hh with the twelve transmembrane protein Patched (Ptc) is required for relinquishing Ptc-mediated suppression of the seven transmembrane protein Smoothened (Smo) in target cells. This interaction is facilitated by Dally-like protein (Dip), a heparan sulfate proteoglycan, and CG9211, a member of the immunoglobulin (Ig) superfamily of receptors. Activated Smo transduces a signal across the membrane in a process that involves recruiting to its cytoplasmic tail a large regulatory complex that includes the transcription factor Cubitus interruptus (Ci). The mechanisms by which Dip, CG9211, and these cytoplasmic protein-protein interactions contribute to Hh pathway response are unclear. In order to study reception and transmission of the Hh signal at the cell membrane, we have developed novel tools that include cultured cell-based assays for pathway responsiveness, reagents for isolating and detecting Hh signaling complexes, and double-stranded RNA libraries that inhibit specific gene function in Drosophila and mouse by RNA-mediated interference (RNAi). By incorporating these tools in a biochemically- and genetically-based strategy, we propose to: 1) determine how Hh signal is sensed at the cell membrane, 2) determine how Smo transduces the Hh signal to cytoplasmic components, and 3) identify Hh pathway components by systematically testing gene function using RNAi-based technology.