Department of Biology, University of Richmond, Richmond, Virginia, United States of America.
Department of Biological Sciences, University of the Pacific, Stockton, California, United States of America.
PLoS One. 2019 Feb 22;14(2):e0212005. doi: 10.1371/journal.pone.0212005. eCollection 2019.
Canonical and non-canonical Wnt signaling, as well as the Pax/Six gene network, are involved in patterning the freshwater sponge aquiferous system. Using computational approaches to identify transcription factor binding motifs in a freshwater sponge genome, we located putative PaxB binding sites near a Secreted Frizzled Related Protein (SFRP) gene in Ephydatia muelleri. EmSFRP is expressed throughout development, but with highest levels in juvenile sponges. In situ hybridization and antibody staining show EmSFRP expression throughout the pinacoderm and choanoderm in a subpopulation of amoeboid cells that may be differentiating archeocytes. Knockdown of EmSFRP leads to ectopic oscula formation during development, suggesting that EmSFRP acts as an antagonist of Wnt signaling in E. muelleri. Our findings support a hypothesis that regulation of the Wnt pathway by the Pax/Six network as well as the role of Wnt signaling in body plan morphogenesis was established before sponges diverged from the rest of the metazoans.
经典和非经典 Wnt 信号通路，以及 Pax/Six 基因网络，参与淡水海绵输水系统的模式形成。我们使用计算方法在淡水海绵基因组中识别转录因子结合基序，在 Ephydatia muelleri 中发现了一个 Secreted Frizzled Related Protein (SFRP) 基因附近的假定 PaxB 结合位点。EmSFRP 在整个发育过程中表达，但在幼年海绵中表达水平最高。原位杂交和抗体染色显示，EmSFRP 在变形细胞层和领细胞层中广泛表达，可能是正在分化的原细胞。EmSFRP 的敲低导致发育过程中出现异位口器形成，表明 EmSFRP 作为 Ephydatia muelleri 中 Wnt 信号的拮抗剂发挥作用。我们的发现支持这样一个假设，即 Pax/Six 网络对 Wnt 途径的调控以及 Wnt 信号在体型形态发生中的作用，是在海绵与后生动物的其他分支分化之前就建立起来的。
