miR-34/449 miRNAs regulate ciliogenesis and cerebrospinal fluid production in choroid plexus

项目摘要 脉络丛是一个高度血管化的分泌组织，突出到大脑 脑室，其主要功能是产生脑脊液（CSF）。CSF提供 营养和代谢支持大脑发育，并介导有效的废物清除。 脉络丛由纤毛上皮细胞的顶端单层组成， 毛细血管和结缔组织的核心。脉络丛上皮细胞（CPECs）每种形式 一至二十几根纤毛，这些纤毛是从顶端伸出的微管细胞器 膜的新出现的证据表明纤毛在脉络丛中的重要性 发展和功能，作为一个连接已经建立了一个有缺陷的纤毛发生之间 在脉络丛和过量的CSF产生的小鼠。我们的初步研究发现 高度冗余的miRNA家族，miR-34/449 miRNA，作为CPEC纤毛发生的关键调节因子。 miR-34/449家族包括六种进化上保守的同源miRNA， 在纤毛CPECs中高度富集。miR-34/449缺陷型小鼠的特征在于降低的 脑室大小，异常CPEC形态和脑发育受损，表明 由于脉络丛功能缺陷导致CSF产生减少。有趣的是， 我们可以在miR-34/449缺陷脉络丛中检测到的缺陷是CPEC中的异常纤毛发生， 其特征是每个细胞的纤毛数量显著增加， 轴丝鉴于CPEC纤毛在负调节CSF产生中的功能重要性， 我们假设miR-34/449缺陷导致过度的CPEC纤毛生成， 抑制CSF的产生并损害大脑发育。在这里，我们建议在功能上 表征miR-34/449 miRNA在CPEC纤毛发生和CSF产生中的作用，并阐明 潜在的细胞和分子机制。使用遗传小鼠模型， 体外培养，细胞生物学和分子生物学方法，我们将表征细胞和 miR-34/449-TKO脉络丛中的分子缺陷，并研究功能连接 CPEC纤毛与脉络丛功能之间的关系。我们还将确定关键的miR-34/449靶点 介导CPEC纤毛发生和CSF产生。我们的研究不仅会揭示出 CPEC纤毛发生的强大调控机制，但也提供了重要的见解， CPEC纤毛在脉络丛功能中的功能重要性。

Project summary The choroid plexus is a highly vascularized, secretory tissue that protrudes into the brain ventricles, whose primary function is to produce cerebrospinal fluid (CSF). CSF provides nutritional and metabolic support for brain development and mediates efficient waste removal. Choroid plexus consists of an apical monolayer of ciliated epithelial cells that surround a stromal core of capillaries and connective tissues. Choroid plexus epithelial cells (CPECs) each forms one to two dozen cilia, which are microtubule-based organelles that project from the apical membrane. Emerging evidence has suggested the importance of cilia in choroid plexus development and function, as a connection has been established between a defective ciliogenesis in choroid plexus and the excessive CSF production in mice. Our preliminary studies identified a highly redundant miRNA family, miR-34/449 miRNAs, as the key regulators for CPEC ciliogenesis. The miR-34/449 family comprises six evolutionarily conserved, homologous miRNAs that are highly enriched in the ciliated CPECs. miR-34/449-deficient mice are characterized by reduced brain ventricle size, aberrant CPEC morphology and impaired brain development, suggesting a reduced CSF production due to defective choroid plexus functions. Interestingly, the earliest defect we can detect in miR-34/449-deficient choroid plexus is the aberrant ciliogenesis in CPECs, characterized by a significant increase of the cilium number per cell and a greater length of the axonemes. Given the functional importance of CPEC cilia in negatively regulating CSF production, we hypothesize that the miR-34/449 deficiency leads to excessive CPEC ciliogenesis, which represses CSF production and impairs brain development. Here, we propose to functionally characterize miR-34/449 miRNAs in CPEC ciliogenesis and CSF production, and to elucidate the underlying cellular and molecular mechanisms. Using genetic mouse models, choroid plexus in vitro culture, cell biology and molecular biology approaches, we will characterize the cellular and molecular defects in miR-34/449-TKO choroid plexus, and investigate the functional connection between CPEC cilia and choroid plexus function. We will also identify the key miR-34/449 targets that mediate CPEC ciliogenesis and CSF production. Our studies will not only reveal a highly robust regulatory mechanism for CPEC ciliogenesis, but also provide important insights into the functional importance of CPEC cilia in choroid plexus function.