Warner Jacob F, McCarthy Ali M, Morris Robert L, McClay David R
Duke University, University Program in Genetics and Genomics.
Mol Biol Evol. 2014 Jan;31(1):18-22. doi: 10.1093/molbev/mst176. Epub 2013 Oct 11.
A relatively small number of signaling pathways govern the early patterning processes of metazoan development. The architectural changes over time to these signaling pathways offer unique insights into their evolution. In the case of Hedgehog (Hh) signaling, two very divergent mechanisms of pathway transduction have evolved. In vertebrates, signaling relies on trafficking of Hh pathway components to nonmotile specialized primary cilia. In contrast, protostomes do not use cilia of any kind for Hh signal transduction. How these divergent lineages adapted such dramatically different ways of activating the signaling pathway is an unanswered question. Here, we present evidence that in the sea urchin, a basal deuterostome, motile cilia are required for embryonic Hh signal transduction, and the Hh receptor Smoothened (Smo) localizes to cilia during active Hh signaling. This is the first evidence that Hh signaling requires motile cilia and the first case of an organism requiring cilia outside of the vertebrate lineage.
相对少数的信号通路控制着后生动物发育的早期模式形成过程。随着时间推移，这些信号通路的结构变化为其进化提供了独特的见解。就刺猬索尼克（Hh）信号通路而言，已经进化出两种截然不同的信号转导机制。在脊椎动物中，信号传导依赖于Hh信号通路成分向非运动性特化初级纤毛的运输。相比之下，原口动物在Hh信号转导中不使用任何类型的纤毛。这些不同的谱系如何适应如此截然不同的激活信号通路的方式仍是一个未解之谜。在这里，我们提供证据表明，在基础后口动物海胆中，胚胎Hh信号转导需要运动性纤毛，并且在活跃的Hh信号传导过程中，Hh受体平滑蛋白（Smo）定位于纤毛上。这是Hh信号传导需要运动性纤毛的首个证据，也是脊椎动物谱系之外的生物体需要纤毛的首个案例。
