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Abstract：
AQP4 is expressed in the endfeet membranes of subpial and perivascular astrocytes and in the ependymal cells that line the ventricular system. The sporadic appearance of obstructive congenital hydrocephalus (OCHC) has been observed in the offspring of AQP4-/- mice (KO) due to stenosis of Silvio\'s aqueduct. Here, we explore whether the lack of AQP4 expression leads to abnormal development of ependymal cells in the aqueduct of mice. We compared periaqueductal samples from wild-type and KO mice. The microarray-based transcriptome analysis reflected a large number of genes with differential expression (809). Gene sets (GS) associated with ependymal development, ciliary function and the immune system were specially modified qPCR confirmed reduced expression in the KO mice genes: (i) coding for transcription factors for ependymal differentiation (Rfx4 and FoxJ1), (ii) involved in the constitution of the central apparatus of the axoneme (Spag16 and Hydin), (iii) associated with ciliary assembly (Cfap43, Cfap69 and Ccdc170), and (iv) involved in intercellular junction complexes of the ependyma (Cdhr4). By contrast, genes such as Spp1, Gpnmb, Itgax, and Cd68, associated with a Cd11c-positive microglial population, were overexpressed in the KO mice. Electron microscopy and Immunofluorescence of vimentin and γ-tubulin revealed a disorganized ependyma in the KO mice, with changes in the intercellular complex union, unevenly orientated cilia, and variations in the planar cell polarity of the apical membrane. These structural alterations translate into reduced cilia beat frequency, which might alter cerebrospinal fluid movement. The presence of CD11c + microglia cells in the periaqueductal zone of mice during the first postnatal week is a novel finding. In AQP4-/- mice, these cells remain present around the aqueduct for an extended period, showing peak expression at P11. We propose that these cells play an important role in the normal development of the ependyma and that their overexpression in KO mice is crucial to reduce ependyma abnormalities that could otherwise contribute to the development of obstructive hydrocephalus.
摘要：
AQP4在膜下和血管周围星形胶质细胞的足底膜以及位于心室系统的室管膜中表达。由于Silvio导水管的狭窄，在AQP4-/-小鼠（KO）的后代中观察到了阻塞性先天性脑积水（OCHC）的零星出现。这里,我们探讨AQP4表达缺乏是否会导致小鼠导水管中室管膜细胞发育异常。我们比较了野生型和KO小鼠的导水管周围样品。基于微阵列的转录组分析反映了大量具有差异表达的基因(809)。与室管膜发育相关的基因集（GS），纤毛功能和免疫系统经过特殊修饰的qPCR证实，KO小鼠基因表达降低：（i）编码室管膜分化的转录因子（Rfx4和FoxJ1），（ii）参与轴突的中央器官（Spag16和Hydin）的构成，(iii)与睫状组件相关(Cfap43、Cfap69和Ccdc170)，和（iv）参与室管膜的细胞间连接复合物（Cdhr4）。相比之下,基因如Spp1，Gpnmb，伊加克斯,和Cd68，与Cd11c阳性小胶质细胞群体相关，在KO小鼠中过表达。波形蛋白和γ-微管蛋白的电子显微镜和免疫荧光显示KO小鼠的室管膜紊乱，随着细胞间复杂结合的变化，不均匀的纤毛,以及顶膜平面细胞极性的变化。这些结构改变转化为纤毛搏动频率降低，这可能会改变脑脊液的运动。在出生后的第一周，小鼠导水管周围区域中CD11c小胶质细胞的存在是一个新发现。在AQP4-/-小鼠中，这些细胞长时间存在于渡槽周围，在P11处显示峰值表达。我们建议这些细胞在室管膜的正常发育中起重要作用，并且它们在KO小鼠中的过度表达对于减少室管膜异常至关重要，否则可能导致梗阻性脑积水的发展。
