(PQ1) Molecular circuit of multi-ciliogenesis regulates choroid plexus differentiation and tumor development

项目摘要 摘要脉络丛新生物是一种罕见的原发性脑肿瘤，主要发生于儿童时期。CP 肿瘤的范围从更常见的和良性的 CP乳头状瘤（CPP）， 的稀有 CP癌（CPC）， 我们对此知之甚少但却极具杀伤力CPC的治疗方法包括手术、放疗和化疗， 会对幸存者造成严重的长期副作用开发更有效和更少衰弱的疗法 由于对特定分子缺陷的作用的认识有限， NOTCH信号传导和CPC中的复发性基因组改变。深入了解这些基因和途径 影响CPC的增殖和生长将为特异性抑制肿瘤的新疗法提供靶点 生长而不会对发育中的大脑产生有害影响。通过诱导持续的NOTCH 1表达， 开发了再现人类CPP的CP肿瘤小鼠模型。血统研究显示， NOTCH诱导的CPP起源于顶板祖细胞，这两者都表现出活跃的NOTCH信号传导， 经历由来自CP上皮的Sonic Hedgehog（SHH）驱动的增殖。相比之下，CP上皮细胞 顶端表面聚集的多个初级纤毛对SHH没有反应，这表明NOTCH 途径抑制多纤毛发生，以保护SHH信号传导关键的单一初级纤毛。 虽然Geminin-coiled-coil domain containing protein 1驱动的多纤毛网络的关键基因 当GEMC 1在CP上皮中表达时，转录程序在NOTCH激活的CPP中被抑制， 缺少多纤毛细胞的细胞。相反，GEMC 1的缺失导致CP中缺乏多纤毛。在目标1中， 我们将研究在CP发展和肿瘤发生过程中GEMC 1指导的多纤毛细胞分化。我们 将确定GEMC 1转录级联的激活是否足以克服组成性 NOTCH信号传导诱导多纤毛发生，并减弱CP肿瘤中的SHH信号传导。的功能研究 GEMC 1及其转录靶点的确定将有助于阐明多纤毛形成的分子机制 并揭示CP肿瘤的潜在治疗途径。与异常SHH和NOTCH一致 在人类CP肿瘤中，两种途径的同时激活导致恶性CP 肿瘤表现出孤立的初级纤毛。类似地，人类的CPC的特征是单一的原发性 纤毛和经常性的基因组改变影响多纤毛分化的关键调节因子。在目标2中， 将利用新的小鼠模型来研究基因间相互作用的分子机制。 NOTCH和SHH通路，并评估潜在的靶向治疗。我们将确定损失是否 GEMC 1的基因与组成型SHH信号传导协作驱动CPC。拟议的研究将大大 提高我们对CPC的认识，并确定潜在的治疗靶点。

Project Abstract Neoplasms of the choroid plexus (CP) are rare primary brain tumors predominantly found in childhood. CP tumors range from the more common and benign CP papilloma (CPP), to the rare CP carcinoma (CPC) that is poorly understood but highly lethal. Treatments for CPC include surgery, radiation, and chemotherapy that cause severe long term side effects in survivors. Development of more effective and less debilitating therapies for CPC has been hampered by limited knowledge of the role of specific molecular defects, including abnormal NOTCH signaling and recurrent genomic alterations, in CPC. Insights into how these genes and pathways affect proliferation and growth of CPC will lead to targets for new therapies that can specifically suppress tumor growth without deleterious effects on the developing brain. By inducing sustained NOTCH1 expression, we developed mouse models of CP tumor that recapitulate CPP in humans. Lineage studies revealed that NOTCH-induced CPP originates from roof plate progenitors, both of which exhibit active NOTCH signaling and undergo proliferation driven by Sonic Hedgehog (SHH) from CP epithelium. In contrast, CP epithelial cells with clustered multiple primary cilia on the apical surface fail to respond to SHH, suggesting that the NOTCH pathway suppresses multi-ciliogenesis to preserve the singular primary cilium critical for the SHH signaling. Though key genes of the multi-ciliation network driven by Geminin coiled-coil domain-containing protein 1 (GEMC1) are expressed in CP epithelium, the transcriptional program is suppressed in NOTCH-activated CPP that lacks multi-ciliated cells. Conversely, GEMC1 loss results in the lack of multi-ciliation in the CP. In Aim 1, we will investigate GEMC1-directed multi-ciliate differentiation during CP development and tumorigenesis. We will determine whether activation of GEMC1 transcriptional cascade is sufficient to overcome constitutive NOTCH signaling to induce multi-ciliogenesis, and attenuate SHH signaling in CP tumor. Functional studies of GEMC1 and identification of its transcriptional targets will establish the molecular mechanisms of multi-ciliation in the CP, and uncover potential therapeutic venues for CP tumor. Consistent with abnormal SHH and NOTCH signaling in CP tumor in humans, simultaneous activation of both pathways in mice leads to malignant CP tumors that exhibit solitary primary cilium. Similarly, CPCs in humans are characterized by singular primary cilium and recurrent genomic alterations affecting crucial regulators of multi-ciliate differentiation. In Aim 2, we will utilize novel mouse models to investigate the molecular mechanisms of the genetic interaction between the NOTCH and SHH pathways and evaluate potential targeted therapeutics. We will determine whether the loss of GEMC1 drives CPC in collaboration with constitutive SHH signaling. The proposed studies will significantly advance our understanding of CPC and identify potential therapeutic targets.