Division of Cyclotron Nuclear Medicine, Cyclotron and Radioisotope Center, Tohoku University.
Department of Developmental Neuroscience, United Centers for Advanced Research and Translational Medicine, Tohoku University Graduate School of Medicine.
Tohoku J Exp Med. 2020 Nov;252(3):199-208. doi: 10.1620/tjem.252.199.
Ependymal cells have an essential role in regulating the dynamics of the cerebrospinal fluid flow by the movement of their multiple cilia. Impaired generation or function of cilia could cause hydrocephalus due to the disordered dynamics of the cerebrospinal fluid flow. However, molecular bases regulating differentiation of the ependymal cells and their ciliogenesis have not been fully elucidated. We report here that bone morphogenetic proteins (BMPs), growth factors orchestrating tissue architecture throughout the body, inhibit ciliogenesis during ependymal cell differentiation in primary cell culture. Previous in vitro study has reported that ectopic expression of Smad6 and Smad7 promotes differentiation of embryonic stem cells into multi-ciliated ependymal-like cells. Since Smad6 and Smad7 have been known as the intracellular inhibitory factors of the BMP signaling pathway, the activation of the pathway could cause a deficit in ciliogenesis of ependymal cells. To examine whether activation of the pathway affects ciliogenesis, we investigated the effects of two BMPs, BMP2 and BMP4, on the ependymal differentiation of the primary cultured cells prepared from the neonatal mouse brain. Supplementation of BMP2 or BMP4 in culture media significantly reduced the number of cells with multiple cilia among the total cells, while most of the cells expressed FoxJ1, a master regulator of ciliogenesis. Activation of the pathway was confirmed by the phosphorylation of intracellular Smad1/5/8, downstream factors of the BMP receptors. These in vitro results suggest that inhibition of the BMP signaling pathway might be essential for ciliogenesis during the ependymal cell differentiation in vivo.
室管膜细胞通过其多个纤毛的运动在调节脑脊液流动动力学方面起着至关重要的作用。纤毛的生成或功能受损可能会导致脑积水，因为脑脊液流动动力学紊乱。然而，调节室管膜细胞分化及其纤毛发生的分子基础尚未完全阐明。我们在这里报告，骨形态发生蛋白（BMPs），协调全身组织结构的生长因子，在原代细胞培养中抑制室管膜细胞分化过程中的纤毛发生。以前的体外研究报告称，Smad6 和 Smad7 的异位表达促进胚胎干细胞分化为多纤毛室管膜样细胞。由于 Smad6 和 Smad7 已被认为是 BMP 信号通路的细胞内抑制因子，因此该通路的激活可能导致室管膜细胞纤毛发生缺陷。为了研究该通路的激活是否影响纤毛发生，我们研究了两种 BMPs（BMP2 和 BMP4）对来自新生小鼠大脑的原代培养细胞的室管膜分化的影响。在培养物中补充 BMP2 或 BMP4 可显著减少总细胞中具有多个纤毛的细胞数量，而大多数细胞表达 FoxJ1，这是纤毛发生的主要调节因子。该通路的激活通过 BMP 受体的下游因子 Smad1/5/8 的细胞内磷酸化来确认。这些体外结果表明，BMP 信号通路的抑制可能是体内室管膜细胞分化过程中纤毛发生所必需的。
