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

 描述（由申请人提供）：Hedgehog信号传导是一种依赖于Smoothened的细胞间通讯方式，Smoothened突变会导致基底细胞癌等癌症。我们发现脊椎动物的刺猬信号将Smoothened移动到初级纤毛，并且这种移动是Smoothened活动所必需的。尽管Smoothened功能有这些细胞生物学见解，但纤毛和Smoothened如何合作激活下游转录效应子Gli2仍不清楚。在这个修订后的更新申请中，我们研究了纤毛激活Smo和Gli2的分子机制。我们已经发现，睫状膜是由独特的脂质，不同的睫状脂质是必要的，足以激活哺乳动物刺猬信号。因此，我们将测试纤毛脂质如何参与Smoothened激活和Hedgehog信号传导。Smoothened如何与Gli2通信仍然未知。我们已经创建了一个生物化学上易于处理的Gli2等位基因敲入，这将使我们能够揭示胚胎发生和肿瘤发生中Gli2激活的机制。此外，我们将评估是否扰乱睫状体脂质组成是一种新的手段，阻止Hh通路相关的癌症形成。拟议的实验使用脊椎动物遗传学，细胞生物学，成像和生物化学方法的组合来揭示Hedgehog信号转导途径如何使用纤毛来传递信息，无论是在发育还是疾病中。

 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.