Hedgehog signaling at the cell's antenna: Smoothened and the primary cilium

 描述(申请人提供)：Hedgehog信号是一种细胞间通讯手段，依赖于Smoothens突变，在这种突变中会导致癌症，如基底细胞癌。我们发现，脊椎动物刺猬的信号被平滑到初级纤毛，并且这种移动是平滑活动所必需的。尽管有这些关于Smoothed功能的细胞生物学见解，但纤毛和Smoothed如何合作激活下游转录效应器Gli2仍不清楚。在这个修订的更新应用中，我们研究了纤毛激活Smo和Gli2的分子机制。我们发现睫状膜由独特的脂类组成，不同的睫状脂是激活哺乳动物Hedgehog信号的必要条件和充分条件。因此，我们将测试睫状脂如何参与平滑激活和Hedgehog信号。Smoothed如何与Gli2通信仍是个未知数。我们已经创造了一种生化上易于处理的敲入Gli2等位基因，这将使我们能够揭示Gli2在胚胎发生和肿瘤发生中激活的机制。此外，我们将评估干扰睫状脂成分是否是阻止HH途径相关癌症形成的一种新方法。拟议的实验结合了脊椎动物的遗传学、细胞生物学、成像和生化方法，以揭示刺猬信号转导途径如何利用纤毛传递信息，无论是在发育过程中还是疾病过程中。

 DESCRIPTION (provided by applicant): Hedgehog signaling is a means of intercellular communication that relies on Smoothened, mutations in which cause cancers such as basal cell carcinoma. We discovered that vertebrate Hedgehog signals move Smoothened to primary cilia, and that this movement is necessary for Smoothened activity. Despite these cell biological insights into Smoothened function, how cilia and Smoothened collaborate to activate the downstream transcriptional effector, Gli2, remains unclear. In this revised renewal application, we examine the molecular mechanisms by which the cilium activates Smo and Gli2. We have discovered that the ciliary membrane is comprised of unique lipids, and that different ciliary lipids are necessary and sufficient to activate mammalian Hedgehog signaling. Therefore, we will test how ciliary lipids participate in Smoothened activation and Hedgehog signaling. How Smoothened communicates to Gli2 remains unknown. We have created a biochemically tractable knock-in Gli2 allele that will allow us to uncover mechanisms of Gli2 activation in embryogenesis and oncogenesis. Additionally, we will assess whether perturbing ciliary lipid composition is a novel means of blocking Hh pathway-related cancer formation. The proposed experiments use a combination of vertebrate genetic, cell biological, imaging and biochemical approaches to reveal how the Hedgehog signal transduction pathway uses cilia to transmit information, both in development and disease.