Fresques Tara M, Wessel Gary M
Department of Molecular and Cell Biology and Biochemistry, Brown University, 185 Meeting St., Providence, RI 02912, USA.
Department of Molecular and Cell Biology and Biochemistry, Brown University, 185 Meeting St., Providence, RI 02912, USA
Development. 2018 Jan 22;145(2):dev155663. doi: 10.1242/dev.155663.
Specification of the germ cell lineage is required for sexual reproduction in animals. The mechanism of germ cell specification varies among animals but roughly clusters into either inherited or inductive mechanisms. The inductive mechanism, the use of cell-cell interactions for germ cell specification, appears to be the ancestral mechanism in animal phylogeny, yet the pathways responsible for this process are only recently surfacing. Here, we show that germ cell factors in the sea star initially are present broadly, then become restricted dorsally and then in the left side of the embryo where the germ cells form a posterior enterocoel. We find that Nodal signaling is required for the restriction of two germ cell factors, Nanos and Vasa, during the early development of this animal. We learned that Nodal inhibits germ cell factor accumulation in three ways including: inhibition of specific transcription, degradation of specific mRNAs and inhibition of tissue morphogenesis. These results document a signaling mechanism required for the sequential restriction of germ cell factors, which causes a specific set of embryonic cells to become the primordial germ cells.
生殖细胞谱系的特化是动物有性生殖所必需的。生殖细胞特化的机制在动物之间有所不同，但大致可分为遗传机制或诱导机制。诱导机制，即利用细胞间相互作用进行生殖细胞特化，似乎是动物系统发育中的祖先机制，但负责这一过程的途径直到最近才被揭示出来。在这里，我们表明，海星中的生殖细胞因子最初广泛存在，然后在背侧受到限制，然后在胚胎左侧受到限制，生殖细胞在那里形成后肠体腔。我们发现，在这种动物的早期发育过程中，Nodal信号对于两种生殖细胞因子Nanos和Vasa的限制是必需的。我们了解到，Nodal通过三种方式抑制生殖细胞因子的积累，包括：抑制特定转录、降解特定mRNA和抑制组织形态发生。这些结果记录了一种信号机制，该机制是生殖细胞因子顺序限制所必需的，它导致一组特定的胚胎细胞成为原始生殖细胞。
