Schaefer J J, Oliver G, Henry J J
Department of Cell and Structural Biology, University of Illinois, Urbana, Illinois 61801, USA.
Dev Dyn. 1999 Aug;215(4):308-18. doi: 10.1002/(SICI)1097-0177(199908)215:4<308::AID-AJA3>3.0.CO;2-I.
Few molecular comparisons have been made between the processes of embryogenesis and regeneration or transdifferentiation that lead to the formation of the same structures. In the amphibian, Xenopus laevis, the cornea can undergo transdifferentiation to form a lens when the original lens is removed during tadpole larval stages. Unlike the process of embryonic lens induction, cornea-lens transdifferentiation is elicited via a single inductive interaction involving factors produced by the neural retina. In this study, we compared the expression of a number of genes known to be activated during various phases of embryonic lens formation, during the process of cornea-lens transdifferentiation. mRNA expression was monitored via in situ hybridization using digoxigenin-labeled riboprobes of pax-6, Xotx2, xSOX3, XProx1, and gamma6-cry. We found that all of the genes studied are expressed during both embryogenesis and cornea-lens transdifferentiation, though in some cases their relative temporal sequences are not maintained. The reiterated expression of these genes suggests that a large suite of genes activated during embryonic lens formation are also involved in cornea-lens transdifferentiation. Ultimately functional tests will be required to determine whether they actually play similar roles in these processes. It is significant that the single inductive event responsible for initiating cornea-lens transdifferentiation triggers the expression of genes activated during both the early and late phases of embryonic lens induction. These findings have significant implications in terms of our current understanding of the "multistep" process of lens induction. Dev Dyn 1999;215:308-318.
在胚胎发生过程与再生或转分化过程（这些过程会形成相同结构）之间，很少有分子层面的比较。在两栖动物非洲爪蟾中，当蝌蚪幼体阶段的原始晶状体被移除时，角膜可以进行转分化形成晶状体。与胚胎晶状体诱导过程不同，角膜 - 晶状体转分化是通过涉及神经视网膜产生的因子的单一诱导相互作用引发的。在本研究中，我们比较了许多已知在胚胎晶状体形成的各个阶段以及角膜 - 晶状体转分化过程中被激活的基因的表达情况。使用地高辛标记的pax - 6、Xotx2、xSOX3、XProx1和gamma6 - cry核糖探针，通过原位杂交监测mRNA表达。我们发现所有研究的基因在胚胎发生和角膜 - 晶状体转分化过程中均有表达，尽管在某些情况下它们的相对时间顺序并不保持一致。这些基因的重复表达表明，在胚胎晶状体形成过程中被激活的一大组基因也参与了角膜 - 晶状体转分化。最终需要进行功能测试来确定它们在这些过程中是否实际发挥相似的作用。重要的是，负责启动角膜 - 晶状体转分化的单一诱导事件触发了在胚胎晶状体诱导的早期和晚期阶段均被激活的基因的表达。这些发现对于我们目前对晶状体诱导的“多步骤”过程的理解具有重要意义。《发育动力学》1999年；215:308 - 318。
