Molecular Mechanisms of Mammalian Hedgehog Signal Transduction

描述（由申请人提供）：本研究的长期目标是了解哺乳动物Hedgehog（Hh）信号转导的分子机制。异常的Hh信号传导与各种人类癌症和出生缺陷有关。最近的证据表明，Hh信号转导的几个方面在无脊椎动物和脊椎动物之间并不保守。不仅脊椎动物中一些主要参与者的角色发生了变化，而且它们的遗传相互作用和信号转导模式也发生了变化。此外，初级纤毛似乎在哺乳动物而不是果蝇Hh信号传导中起主要作用。这些发现突出了阐明哺乳动物Hh通路组分的功能的重要性，以进一步了解脊椎动物Hh信号转导。本研究的重点是哺乳动物Hh信号转导中的一个关键参与者--融合抑制因子（Suppressor of Fused，Sufu），并将阐明Sufu调控Gli转录因子功能的机制。Gli转录因子是哺乳动物发育过程中Hh信号转导的唯一介质。我们提出了以下具体目标：1）确定Sufu在控制Gli 2纤毛定位中的作用。2)阐明Sufu介导Gli 3蛋白稳定的分子机制。3)描述初级纤毛在Sufu或SPOP介导的Gli蛋白功能中的需求。4)验证腐乳与Kif 7（驱动蛋白家族成员）相互作用调节哺乳动物Hh信号传导的假设。将采用基于细胞的测定、使用基因敲除小鼠的遗传研究和蛋白质生物化学的组合来解决这些核心问题。这些研究将为哺乳动物Hh信号如何在应答细胞中转导提供新的机制见解7。公共卫生相关性：Hedgehog（Hh）信号异常与癌症和出生缺陷有关。阐明Hh信号是如何转导的对于理解Hh相关疾病的潜在机制以及确定诊断和合理治疗的潜在靶点至关重要。

DESCRIPTION (provided by applicant): The long-term goal of this study is to understand the molecular mechanism of mammalian Hedgehog (Hh) signal transduction. Aberrant Hh signaling has been associated with various human cancers and birth defects. Recent evidence indicates that several aspects of Hh signaling are not conserved between invertebrates and vertebrates. Not only have the roles of some of the main players changed in vertebrates, but also their genetic interactions and the mode of signal transduction have been modified. Further, primary cilia appear to play a major role in mammalian and not Drosophila Hh signaling. These findings highlight the importance of elucidating the functions of mammalian Hh pathway components directly in order to further understand vertebrate Hh signal transduction. This proposal focuses on one critical player in mammalian Hh signal transduction, Suppressor of Fused (Sufu), and will define the mechanism of Sufu in regulating the functions of Gli transcription factors, the sole mediators of Hh signaling during mammalian development. We propose the following specific aims: 1) Define the role of Sufu in controlling ciliary localization of Gli2. 2) Elucidate the molecular mechanism of Sufu-mediated Gli3 protein stabilization. 3) Delineate the requirement of primary cilia in Sufu- or SPOP-mediated Gli protein function. 4) Test the hypothesis that Sufu interacts with Kif7, a kinesin family member, in modulating mammalian Hh signaling. A combination of cell-based assays, genetic studies using knockout mice and protein biochemistry will be employed to address these central issues. These studies will provide new mechanistic insights into how the mammalian Hh signal is transduced in responsive cells 7. PUBLIC HEALTH RELEVANCE: Aberrant Hedgehog (Hh) signaling is associated with cancers and birth defects. Elucidating how the Hh signal is transduced is critical to understanding the underlying mechanisms of Hh-related diseases as well as identifying potential targets for diagnosis and rational therapies.