Regulation of Hedgehog-dependent proliferation by dynamic primary cilia

项目总结 初级纤毛是一种以微管为基础的信号细胞器，在许多脊椎动物中具有重要作用。 纸巾。纤毛结构或功能的破坏会导致广泛的发育障碍，包括 一些癌症，揭示了纤毛的关键功能。纤毛是动态的结构，正在进行组装和 在每个循环中进行拆卸。虽然纤毛信号可以直接调节细胞周期，但纤毛 对其在细胞增殖中的作用研究甚少。因此，暂时的细胞器是如何 可以调节一个持续的过程，如扩散。这项提案的目标是在#年解决这一问题。 刺猬(Hedgehog，HH)信号的背景，这是一个需要 纤毛用于信号转导。 我建议研究髓母细胞瘤(MB)中HH依赖的增殖机制， 最常见的儿童脑癌。MB细胞需要纤毛和HH信号才能增殖，而我的 在已建立的MB细胞培养模型中的初步工作提供了纤毛周期的证据。鉴于该MB 即使纤毛是短暂的，细胞也会增殖，我的中心假设是，未描述的下游 机制是必需的，以缓冲依赖于HH的增殖，防止纤毛变化。我要测试一下这个 假设的目的如下：1)我将建立HH信号与纤毛周期之间的关系。 使用荧光实时成像和HH信号分析，我将确定纤毛和HH信号如何变化 在整个细胞周期中。2)我将决定什么时候纤毛信号对细胞周期是必要的和充分的 进展，使用细胞周期的实时成像和HH信号的小分子抑制物。3)我将使用 来自大规模基因筛查的候选人，以确定HH依赖的增殖的新调控因子 构成HH信号与增殖之间联系的新组件以及HH的调节器 MB细胞生理学特有的信号通路。结果将揭示HH信号、纤毛和 细胞周期协同驱动MB生长，提高了我们对基于纤毛的信号的理解 和疾病状态。

PROJECT SUMMARY The primary cilium is a microtubule-based signaling organelle with essential roles in many vertebrate tissues. Disruptions in cilium structure or function lead to a broad range of developmental disorders, including some cancers, revealing the critical function of cilia. Cilia are dynamic structures, undergoing assembly and disassembly during each cycle. Although cilium-based signaling can directly regulate the cell cycle, cilia function has been poorly studied in proliferating cells. Therefore, it is not understood how a transient organelle can regulate a sustained process such as proliferation. The goal of this proposal is to address this question in the context of Hedgehog (Hh) signaling, the classic example of a developmental pathway that requires the cilium for signal transduction. I propose to investigate the mechanisms of Hh-dependent proliferation in medulloblastoma (MB), the most frequent childhood brain cancer. MB cells require both cilia and Hh signaling for proliferation, and my preliminary work in an established cell culture model of MB provides evidence of a cilium cycle. Given that MB cells proliferate even though cilia are transient, my central hypothesis is that uncharacterized downstream mechanisms are necessary to buffer Hh-dependent proliferation against changing cilia. I will test this hypothesis with the following aims: 1) I will establish the relationship between Hh signaling and the cilium cycle. Using fluorescent live imaging and Hh signaling assays, I will determine how cilia and Hh signaling change throughout the cell cycle. 2) I will determine when signaling at cilia is necessary and sufficient for cell cycle progression, using live imaging of the cell cycle and small molecule inhibitors of Hh signaling. 3) I will use candidates from a large-scale genetic screen to identify new regulators of Hh-dependent proliferation that constitute novel components of the link between Hh signaling and proliferation as well as modulators of the Hh signaling pathway specific to the physiology of MB cells. The results will reveal how Hh signaling, cilia, and the cell cycle cooperate to drive MB growth, improving our understanding of cilium-based signaling in both normal and disease states.