University of Richmond, Richmond, VA 23173, USA.
Evol Dev. 2013 May;15(3):186-96. doi: 10.1111/ede.12032.
Examining the origins of highly conserved gene regulatory networks (GRNs) will inform our understanding of the evolution of animal body plans. Sponges are believed to be the most ancient extant metazoan lineage, and as such, hold clues about the evolution of genetic programs deployed in animal development. We used the emerging freshwater sponge model, Ephydatia muelleri, to study the evolutionary origins of the Pax/Six/Eya/Dac (PSED) GRN. Orthologs to Pax and Six family members are present in E. muelleri and are expressed in endothelial cells lining the canal system as well as cells in the choanoderm. Knockdown of EmPaxB and EmSix1/2 by RNAi resulted in defects to the canal systems. We further show that PaxB may be in a regulatory relationship with Six1/2 in E. muelleri, thus demonstrating that a component of the PSED network was present early in metazoan evolution.
研究高度保守的基因调控网络（GRNs）的起源将有助于我们理解动物体节的进化。海绵被认为是最古老的现存后生动物谱系，因此，它们为动物发育中所使用的遗传程序的进化提供了线索。我们使用新兴的淡水海绵模型 Ephydatia muelleri 来研究 Pax/Six/Eya/Dac（PSED）GRN 的进化起源。 Ephydatia muelleri 中存在与 Pax 和 Six 家族成员同源的基因，并且在沿著腔系统排列的内皮细胞以及领细胞中表达。通过 RNAi 敲低 EmPaxB 和 EmSix1/2 导致腔系统缺陷。我们进一步表明，PaxB 可能与 Ephydatia muelleri 中的 Six1/2 存在调节关系，因此证明了 PSED 网络的一个组成部分在后生动物进化的早期就存在了。
