Structure and function of a novel population of regenerating ependymal cells

项目摘要 实验室已经鉴定出一种新型的室管膜细胞（E2），它有两条长纤毛， 比其他细胞中的体大30-100倍（Mirzadeh等人，2008，2017）。E2细胞存在于 脑室系统的战略位置，旁边的神经干细胞（NSC）在侧壁 在第三脑室和第四脑室的区域中，对于进食和葡萄糖调节至关重要，昼夜节律 节律、意识、警觉性和睡眠（Mirzadeh et al. 2017）。有趣的是，E2样细胞也被 在室管膜瘤中观察到，表明与增殖祖细胞和癌症有关（Alfaro-Cervelló et al. 2015; Ho，Caccamo和Garcia 1994）。E2细胞的遗传特征，其组成和组织 独特的纤毛和基体，它们的发育起源，它们的再生能力和它们的功能， 知道的室管膜（E）细胞仍然是大脑中最不了解的神经胶质细胞类型之一，然而这些细胞是 参与了正常大脑功能所必需的功能。多纤毛室管膜（E1）细胞，通过 它们的~50根运动纤毛的协调跳动，有助于脑脊液（CSF）流动，并需要 预防脑积水（Jiménez et al. 2014; Ohata and Alvarez-Buylla 2016; Banizs et al. 2005）。在横向 在脑室，E细胞有助于调节成体神经干细胞（NSC）和脑室中的神经元迁移。 成年人大脑中最大的动脑区：脑室-脑室下区（V-SVZ）。E细胞如何感知和 将CSF信号传递到这个生殖器小生境仍然未知。E2细胞不太可能通过它们的两条纤毛 对脑脊液流动有很大的影响。相反，我们认为E2纤毛和基底体可能在 CSF信号的检测。它们位于CSF和重要脑区之间的界面 这强烈表明它们在大脑功能中具有关键的，尚未确定的作用。令人惊讶的是，初步数据 表明侧脑室E2细胞相对较短，数量随年龄而减少， 在成年小鼠体内不断再生我们建议：1）表征E2细胞及其纤毛和基体 使用单细胞基因表达分析，电子和超高分辨率显微镜; 2）确定 E2细胞的发育和成年群体动力学，并鉴定产生新E2的祖细胞 成体中的E2细胞（初步证据表明E2细胞来源于成体NSC）;和3）研究 E2细胞纤毛信号传导是否调节成体干细胞小生境功能，使用关键纤毛的条件性缺失 E2细胞中富集的信号分子。这些新知识对于解读E2的功能至关重要。 成人V-SVZ中的细胞。此外，在E2细胞中发现的分子标记和信号通路可能有助于 了解室管膜瘤的细胞来源和生长控制。考虑到E2细胞在 第三和第四脑室，中央管，旁边的区域非常重要的功能，这个新的 了解这一点也将有助于对整个大脑中E细胞功能的研究。

PROJECT SUMMARY The laboratory has identified a novel type of ependymal cell (E2) that has two long cilia anchored by two basal bodies that are 30-100 fold larger than those in other cells (Mirzadeh et al. 2008, 2017). E2 cells are found in strategic locations of the ventricular system, next to Neural Stem Cells (NSCs) in the walls of the lateral ventricle and in regions of the third and fourth ventricle critical to feeding and glucose regulation, circadian rhythms, consciousness, alertness and sleep (Mirzadeh et al. 2017). Interestingly, E2-like cells have been also observed in ependymomas, suggesting a link to proliferating progenitors and cancer (Alfaro-Cervelló et al. 2015; Ho, Caccamo, and Garcia 1994). E2 cells' genetic profile, the composition and organization of their unique cilia and basal bodies, their developmental origin, their regenerative capacity, and their function are not known. Ependymal (E) cells remain one of the least understood glial cell types in the brain, yet these cells are involved in functions that are essential for proper brain function. Multiciliated ependymal (E1) cells, through the coordinated beating of their ~50 motile cilia, contribute to cerebrospinal fluid (CSF) flow, and are required to prevent hydrocephalus (Jiménez et al. 2014; Ohata and Alvarez-Buylla 2016; Banizs et al. 2005). In the lateral ventricles, E cells contribute to the regulation of adult neural stem cells (NSCs) and neuronal migration in the largest germinal zone of the adult brain: the ventricular-subventricular zone (V-SVZ). How E cells sense and transmit CSF signals to this germinal niche remains unknown. It is unlikely that E2 cells through their two cilia contribute significantly to CSF flow. Instead, we propose that E2 cilia and basal body could play a key role in the detection of CSF signals. Their location at the interface between the CSF and important brain regions strongly suggests they have pivotal, as-yet unidentified, roles in brain function. Surprisingly, preliminary data indicate that the lateral ventricle E2 cells are relatively short-lived, decrease in number with age, and are constantly regenerated in adult mice. We propose to: 1) characterize E2 cells and their cilia and basal bodies using single cell gene expression analysis, electron and ultra-high resolution microscopy; 2) determine the development and adult population dynamics of E2 cells, and identify the progenitor cells giving rise to new E2 cells in the adult (preliminary evidence suggests that E2 cells are derived from adult NSCs); and 3) investigate whether E2 cell cilia signaling modulates adult stem cell niche function, using conditional deletion of a key cilia signaling molecule enriched in E2 cells. This new knowledge will be essential to decipher the function of E2 cells in the adult V-SVZ. In addition, molecular markers and signaling pathways identified in E2 cells could help understand the cell of origin and growth control of some ependymomas. Given the presence of E2 cells in the third and fourth ventricles, and central canal, next to regions of great functional importance, this new understanding will also help studies of E cell function throughout the brain.