Yaguchi Junko, Yamazaki Atsuko, Yaguchi Shunsuke
Shimoda Marine Research Center, University of Tsukuba, 5-10-1, Shimoda, Shizuoka 415-0025, Japan.
Shimoda Marine Research Center, University of Tsukuba, 5-10-1, Shimoda, Shizuoka 415-0025, Japan.
Dev Biol. 2018 Dec 1;444(1):1-8. doi: 10.1016/j.ydbio.2018.09.018. Epub 2018 Sep 25.
Precise body axis formation is an essential step in the development of multicellular organisms, for most of which the molecular gradient and/or specifically biased localization of cell-fate determinants in eggs play important roles. In sea urchins, however, any biased proteins and mRNAs have not yet been identified in the egg except for vegetal cortex molecules, suggesting that sea urchin development is mostly regulated by uniformly distributed maternal molecules with contributions to axis formation that are not well characterized. Here, we describe that the maternal Meis transcription factor regulates anterior-posterior axis formation through maintenance of the most anterior territory in embryos of a sea urchin, Hemicentrotus pulcherrimus. Loss-of-function experiments revealed that Meis is intrinsically required for maintenance of the anterior neuroectoderm specifier foxQ2 after hatching and, consequently, the morphant lost anterior neuroectoderm characteristics. In addition, the expression patterns of univin and VEGF, the lateral ectoderm markers, and the mesenchyme-cell pattern shifted toward the anterior side in Meis morphants more than they did in control embryos, indicating that Meis contributes to the precise anteroposterior patterning by regulating the anterior neuroectodermal fate.
精确的体轴形成是多细胞生物体发育过程中的一个关键步骤，对于大多数多细胞生物体而言，卵中细胞命运决定因子的分子梯度和/或特定的偏向性定位起着重要作用。然而，在海胆中，除了植物皮质分子外，尚未在卵中鉴定出任何有偏向性的蛋白质和mRNA，这表明海胆的发育主要由均匀分布的母体分子调控，这些分子对轴形成的贡献尚未得到充分表征。在此，我们描述了母体Meis转录因子通过维持海胆胚胎（光棘球海胆）最前端区域来调节前后轴的形成。功能丧失实验表明，Meis对于孵化后维持前神经外胚层特异性因子foxQ2是内在必需的，因此，形态发生突变体失去了前神经外胚层特征。此外，在Meis形态发生突变体中，侧外胚层标记物univin和VEGF的表达模式以及间充质细胞模式比对照胚胎更向身体前部偏移，这表明Meis通过调节前神经外胚层命运来促进精确的前后模式形成。
