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

项目摘要 脉络丛肿瘤(CP)是一种罕见的原发脑肿瘤，主要见于儿童。CP 肿瘤的范围从更常见的和良性的 CP乳头状瘤(CPP)， 对稀有的 CP癌(CPC)，即 人们对此知之甚少，但杀伤力极强。CPC的治疗方法包括手术、放疗和化疗 对幸存者造成严重的长期副作用。开发更有效和更少虚弱的治疗方法 对于CPC来说，由于对特定分子缺陷的作用了解有限，包括异常 在CPC中，缺口信号和反复发生的基因组改变。洞察这些基因和途径是如何 影响CPC的增殖和生长将导致特异性抑制肿瘤的新疗法的靶点 对发育中的大脑没有有害影响的生长。通过诱导NOTCH1的持续表达，我们 开发了重现人类CPP的CP肿瘤小鼠模型。世系研究表明， 缺口诱导的CPP起源于屋顶板祖细胞，两者都表现出活跃的缺口信号和 在Sonic Hedgehog(SHH)的推动下，从CP上皮进行增殖。相比之下，CP上皮细胞与 根尖表面丛生的多根初级纤毛对SHH无反应，提示切迹 通路抑制多纤毛的发生，以保护对SHH信号至关重要的单一初级纤毛。 通过双生螺旋卷曲结构域蛋白1驱动的多中介网络的关键基因 (GEMC1)在CP上皮细胞中表达，在缺口激活的CPP中转录程序被抑制 缺乏多纤毛细胞。相反，GEMC1的缺失导致了CP中缺乏多重调解。在目标1中， 我们将研究GEMC1在CP发展和肿瘤发生过程中引导的多纤毛虫分化。我们 将决定GEMC1转录级联的激活是否足以克服结构性 Notch信号在CP肿瘤中诱导多纤毛发生和减弱SHH信号。神经细胞的功能研究 GEMc1及其转录靶点的确定将建立多种调节的分子机制 在CP中，发现CP肿瘤的潜在治疗场所。与SHH和凹槽异常一致 在人类CP肿瘤中的信号转导，在小鼠中两条通路的同时激活导致恶性CP 表现为孤立的原发纤毛的肿瘤。类似地，人类中的CPC的特征是单一的初级 纤毛和影响多纤毛虫分化的关键调节因子的周期性基因组变化。在目标2中，我们 将利用新的小鼠模型来研究基因相互作用的分子机制 切开和SHH途径，并评估潜在的靶向治疗。我们将确定损失是否 GEMC1的作用与构成SHH信号协同驱动CPC。拟议的研究将极大地 增进我们对CPC的认识，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.