Paris Brain Institute, ICM, Inserm U 1127, CNRS UMR 7225, Sorbonne Université, Paris, France.
Molecular Physiology and Adaptation (PhyMA - UMR 7221), Muséum National d'Histoire Naturelle, CNRS, Paris, France.
Elife. 2020 Oct 13;9:e59469. doi: 10.7554/eLife.59469.
The cerebrospinal fluid (CSF) contains an extracellular thread conserved in vertebrates, the Reissner fiber, which controls body axis morphogenesis in the zebrafish embryo. Yet, the signaling cascade originating from this fiber to ensure body axis straightening is not understood. Here, we explore the functional link between the Reissner fiber and undifferentiated spinal neurons contacting the CSF (CSF-cNs). First, we show that the Reissner fiber is required in vivo for the expression of urp2, a neuropeptide expressed in CSF-cNs. We show that the Reissner fiber is also required for embryonic calcium transients in these spinal neurons. Finally, we study how local adrenergic activation can substitute for the Reissner fiber-signaling pathway to CSF-cNs and rescue body axis morphogenesis. Our results show that the Reissner fiber acts on CSF-cNs and thereby contributes to establish body axis morphogenesis, and suggest it does so by controlling the availability of a chemical signal in the CSF.
脑脊液（CSF）中含有一种在脊椎动物中保守的细胞外线程，即 Reissner 纤维，它控制斑马鱼胚胎的体轴形态发生。然而，从这条纤维出发的信号级联，以确保体轴变直，还没有被理解。在这里，我们探索了 Reissner 纤维与接触脑脊液的未分化脊髓神经元（CSF-cNs）之间的功能联系。首先，我们表明，Reissner 纤维在体内对于 urp2 的表达是必需的，urp2 是一种在 CSF-cNs 中表达的神经肽。我们表明，Reissner 纤维对于这些脊髓神经元中的胚胎钙瞬变也是必需的。最后，我们研究了局部肾上腺素能激活如何替代 Reissner 纤维信号通路到 CSF-cNs，并拯救体轴形态发生。我们的结果表明，Reissner 纤维作用于 CSF-cNs，从而有助于建立体轴形态发生，并表明它是通过控制 CSF 中化学信号的可用性来实现的。
