MIM regulates Shh target gene expression in tumors

描述(由申请人提供)：这个项目的长期目标是了解不受调控的上皮细胞增殖和侵袭如何导致癌症发生。Sonic hedgehog(Shh)信号控制着许多器官的祖细胞的增殖和迁移，不受控制的Shh靶基因诱导促进了25%的人类癌症的生长和侵袭，包括肺癌、乳腺癌、前列腺癌、胰腺癌以及髓母细胞瘤和基底细胞癌。虽然Gli转录因子家族介导Shh的转录效应，但在正常和致癌环境中控制Gli转录输出和Shh依赖的迁移和侵袭的机制仍然知之甚少。ShH信号成分，包括融合抑制因子(Sufu)和Smoothens，已被证明集中在初级纤毛上，初级纤毛是一种基于微管的动态信号细胞器。大多数哺乳动物细胞上都有初级纤毛，Shh信号成分集中在纤毛上，以调节Gli3的裂解和Gli1/2的激活。纤毛的丧失会导致Shh信号的缺陷和各种发育缺陷和疾病，从某些类型的视网膜变性和脱发到多囊肾/肝脏疾病和Bardet-Biedl综合征。我们已经发现了一个新的Shh通路成员，转移中缺失(MIM)，这是一种调控膜动力学的杆状结构域蛋白，其水平在各种上皮性癌症中发生变化，并与乳腺癌的预后负相关。到目前为止，我们已经确定在许多类型的细胞中，MIM是诱导Shh靶基因所必需的，并与肿瘤抑制因子Sufu、Shh信号的主要负调控因子Sufu和癌基因Gli合作，重述Shh介导的上皮细胞的增殖和侵袭。此外，初级纤毛的形成需要MIM。我们的工作假设是，MIM通过促进初级纤毛形成和拮抗Sufu来调节肿瘤中Shh靶基因的表达。这项建议试图利用生化、细胞生物学和遗传学技术的组合来：1)确定MIM在纤毛发生过程中调节膜动力学的机制；2)确定MIM依赖的Sonic Hedgehog信号在初级纤毛上的增强机制。资助这项研究将使我们能够深入了解Shh介导的肿瘤生长和侵袭，以及Shh在纤毛相关疾病中的信号转导。

DESCRIPTION (provided by applicant): The long-term goal of this project is to understand how unregulated epithelial proliferation and invasion leads to carcinogenesis. Sonic hedgehog (Shh) signaling controls the proliferation and migration of progenitor cells of many organs, and uncontrolled Shh target gene induction promotes growth and invasion of 25% of human cancers including lung, breast, prostate, pancreatic, as well as medulloblastoma and basal cell carcinoma. While the Gli family of transcription factors mediates the transcriptional effects of Shh, the mechanism for controlling Gli transcriptional output and Shh-dependent migration and invasion during normal and oncogenic contexts remain poorly understood. Shh signaling components including Suppressor of fused (Sufu) and Smoothened have been shown to concentrate at the primary cilia, a dynamic microtubule-based signaling organelle. Primary cilia are found on most mammalian cells and Shh signaling components concentrate at the cilia in order to regulate Gli3 cleavage and Gli1/2 activation. Loss of cilia leads to defects in Shh signaling and a variety of developmental defects and disorders that range from certain types of retinal degeneration and hair loss to polycystic kidney/liver disease and Bardet-Biedl syndrome. We have identified a novel Shh pathway member, Missing in Metastasis (MIM), a BAR-domain protein that regulates membrane dynamics and whose levels are altered in a variety of epithelial cancers and negatively correlates with outcome in breast cancer. So far, we have established that MIM is required for Shh target gene induction in many cell types and cooperates with the tumor suppressor Sufu, a major negative regulator of Shh signaling, and the Gli oncogene to recapitulate Shh-mediated epithelial proliferation and invasion. In addition, MIM is required for primary cilia formation. Our working hypothesis is that MIM functions to regulate Shh target gene expression in tumors by promoting primary cilia formation and antagonizing Sufu. This proposal seeks to utilize a combination of biochemical, cell biological, and genetic techniques to: 1) Determine the mechanism by which MIM regulates membrane dynamics during ciliogenesis and 2) Determine the mechanism of MIM-dependent potentiation of Sonic hedgehog signaling at the primary cilium. Funding this fellowship will allow us to gain insight into Shh-mediated tumor growth and invasion and Shh signaling in cilia-related disorders.