University of Rostock, Institute of Biological Sciences, Department of Genetics, Albert-Einstein Str. 3, 18059 Rostock, Germany.
Dev Biol. 2013 Sep 1;381(1):121-33. doi: 10.1016/j.ydbio.2013.05.031. Epub 2013 Jun 12.
Fibroblast growth factor (FGF) signalling plays a key role in early embryonic development and cell migration in vertebrates and in invertebrates. To gain novel insights into FGF signalling in an arthropod, we characterized the fgf1b ortholog in the beetle Tribolium that is not represented in the Drosophila genome. We found that FGF1b dependent signalling organizes the anterior to posterior axis of the early embryo. The loss of Tc-fgf1b function in Tribolium by RNA interference resulted in the reduction of the anteriormost extraembryonic fate, in an anterior shift of embryonic fate and in the loss or malformation of anterior embryonic structures. Without intact extraembryonic membranes the serosa and the amnion, Tc-fgf1b(RNAi) embryos did not undergo morphogenetic movements and remained posteriorly localized throughout embryogenesis. Only weakly affected embryos developed into a cuticle that show dorsally curved bodies with head defects and a dorsal opening. Except for the posterior dorsal amnion, the overall topology of the dorsal-ventral axis seemed unaffected. Moreover, FGF signalling was not required for the onset of mesoderm formation but for fine-tuning this tissue during later development. We also show that in affected embryos the dorsal epidermis was expanded and expressed Tc-dpp at a higher level. We conclude that in the Tribolium blastoderm embryo, FGF1-signalling organizes patterning along the AP-axis and also balances the expression level of Dpp in the dorsal epidermis, a tissue critically involved in dorsal closure.
成纤维细胞生长因子（FGF）信号在脊椎动物和无脊椎动物的早期胚胎发育和细胞迁移中发挥着关键作用。为了深入了解节肢动物中的 FGF 信号，我们鉴定了在果蝇基因组中没有的甲虫 T ribolium 中的 fgf1b 直系同源物。我们发现 FGF1b 依赖性信号组织了早期胚胎的前-后轴。在 T. castaneum 中通过 RNA 干扰丧失 Tc-fgf1b 功能导致最前的胚外命运减少，胚胎命运的前移位以及前胚胎结构的丧失或畸形。由于完整的胚外膜缺失，浆膜和羊膜，Tc-fgf1b（RNAi）胚胎没有进行形态发生运动并且在整个胚胎发生过程中保持后向定位。只有受影响较小的胚胎发育成具有头部缺陷和背部开口的背侧弯曲的身体的表皮。除了后背部羊膜外，背-腹轴的整体拓扑结构似乎不受影响。此外，FGF 信号对于中胚层形成的起始不是必需的，而是在后期发育中对这种组织进行微调。我们还表明，在受影响的胚胎中，背侧表皮扩张并以更高的水平表达 Tc-dpp。我们得出结论，在 T. castaneum 原肠胚胚胎中，FGF1 信号沿 AP 轴组织模式形成，并且还平衡了背部表皮中 Dpp 的表达水平，背部表皮是参与背部闭合的关键组织。
