Bertocchini Federica, Stern Claudio D
Department of Anatomy and Developmental Biology, University College London, Gower Street, WC1E 6BT, London, United Kingdom.
Dev Cell. 2002 Nov;3(5):735-44. doi: 10.1016/s1534-5807(02)00318-0.
The hypoblast (equivalent to the mouse anterior visceral endoderm) of the chick embryo plays a role in regulating embryonic polarity. Surprisingly, hypoblast removal causes multiple embryonic axes to form, suggesting that it emits an inhibitor of axis formation. We show that Cerberus (a multifunctional antagonist of Nodal, Wnt, and BMP signaling) is produced by the hypoblast and inhibits primitive streak formation. This activity is mimicked by Cerberus-Short (CerS), which only inhibits Nodal. Nodal misexpression can initiate an ectopic primitive streak, but only when the hypoblast is removed. We propose that, during normal development, the primitive streak forms only when the hypoblast is displaced away from the posterior margin by the endoblast, which lacks Cerberus.
鸡胚的下胚层（相当于小鼠的前内脏内胚层）在调节胚胎极性方面发挥作用。令人惊讶的是，去除下胚层会导致多个胚胎轴形成，这表明它会发出轴形成的抑制剂。我们发现，塞布罗斯（一种Nodal、Wnt和BMP信号的多功能拮抗剂）由下胚层产生，并抑制原条形成。塞布罗斯-短肽（CerS）也具有这种活性，它只抑制Nodal。Nodal的异位表达可以引发异位原条，但只有在去除下胚层时才会发生。我们提出，在正常发育过程中，只有当内胚层（缺乏塞布罗斯）将下胚层从后缘移开时，原条才会形成。
