Across the Bilateria, FGF/FGFR signaling is critical for normal development, and in both Drosophila and vertebrates, docking proteins are required to connect activated FGFRs with downstream pathways. While vertebrates use Frs2 to dock FGFR to the RAS/MAPK or PI3K pathways, the unrelated protein, downstream of FGFR (Dof/stumps/heartbroken), fulfills the corresponding function in Drosophila. To better understand the evolution of the signaling pathway downstream of FGFR, the available sequence databases were screened to identify Frs2, Dof, and other key pathway components in phyla that diverged early in animal evolution. While Frs2 homologues were detected only in members of the Bilateria, canonical Dof sequences (containing Dof, ankyrin, and SH2/SH3 domains) were present in cnidarians as well as bilaterians (but not in other animals or holozoans), correlating with the appearance of FGFR. Although these data suggested that Dof coupling might be ancestral, gene expression analysis in the cnidarian Hydra revealed that Dof is not upregulated in the zone of strong FGFRa and FGFRb expression at the bud base, where FGFR signaling controls detachment. In contrast, transcripts encoding other, known elements of FGFR signaling in Bilateria, namely the FGFR adaptors Grb2 and Crkl, which are acting downstream of Dof (and Frs2), as well as the guanyl nucleotide exchange factor Sos, and the tyrosine phosphatase Csw/Shp2, were strongly upregulated at the bud base. Our expression analysis, thus, identified transcriptional upregulation of known elements of FGFR signaling at the Hydra bud base indicating a highly conserved toolkit. Lack of transcriptional Dof upregulation raises the interesting question, whether Hydra FGFR signaling requires either of the docking proteins known from Bilateria.

中文翻译：

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背后的内容：Hydra为FGFR对接蛋白的进化提供了CNIDIAN观点。

在整个Bilateria中，FGF / FGFR信号传导对于正常发育至关重要，在果蝇和脊椎动物中，都需要对接蛋白来将活化的FGFR与下游途径相连。脊椎动物使用Frs2将FGFR停靠到RAS / MAPK或PI3K途径时，FGFR下游（Dof /残基/断肠）的无关蛋白在果蝇中发挥相应的功能。。为了更好地了解FGFR下游信号通路的进化，筛选了可用的序列数据库，以鉴定在动物进化早期发散的门上的Frs2，Dof和其他关键通路成分。虽然仅在Bilateria的成员中检测到Frs2同源物，但在下颚动物和双侧动物（但在其他动物或整体动物中）中却都存在规范的Dof序列（包含Dof，锚蛋白和SH2 / SH3域）。 FGFR。尽管这些数据表明Dof偶联可能是祖先的，但在刺id蛇中的基因表达分析表明，在强FGFRa和FGFRb区域中Dof没有上调。在芽基表达，FGFR信号控制分离。相反，在Bilateria中编码其他已知FGFR信号传导元件的转录物，即在Dof（和Frs2）下游起作用的FGFR衔接子Grb2和Crkl，以及鸟嘌呤核苷酸交换因子Sos和酪氨酸磷酸酶Csw / Shp2，在芽基部强烈上调。因此，我们的表达分析确定了Hydra芽基处FGFR信号传导已知元素的转录上调，表明该工具包非常保守。缺乏转录自由度上调引起了一个有趣的问题，即Hydra FGFR信号传导是否需要从Bilateria已知的两种对接蛋白。