Departament de Genètica, Facultat de Biologia, Universitat de Barcelona and Institut de Biomedicina de Universitat de Barcelona, Avinguda Diagonal 645, Edifici Annex, Planta 1, 08028 Barcelona, Catalunya, Spain.
Curr Biol. 2011 Feb 22;21(4):300-5. doi: 10.1016/j.cub.2011.01.016. Epub 2011 Feb 3.
Planarians regenerate a whole animal from a small body piece within a few days. Recent studies have shown that the bone morphogenetic protein (BMP) pathway is required to reestablish the dorsoventral (DV) axis. In vertebrates, the specification of the DV axis depends on the coordinated action of a dual organizer defined by BMP and antidorsalizing morphogenetic protein (ADMP) under the control of several factors, including the inhibitors chordin and noggin. Planarians have an expanded noggin family (up to ten members), which have been classified as canonical noggin (nog) and noggin-like (nlg) genes, the latter carrying an insertion within the noggin domain. Here we show that a BMP/ADMP organizer governs DV axis reestablishment during planarian regeneration, highlighting a greater-than-thought conservation of the mechanisms that establish this axis in protostomes and deuterostomes. Also, we report that whereas noggin genes function as canonical BMP inhibitors, the silencing of planarian nlg8 induces ectopic neurogenesis and enhances ventralizing bmp(RNAi) phenotypes. Finally, we show that noggin-like genes are conserved from cnidarian to vertebrates and that both planarian nlg8 and Xenopus nlg ventralize Xenopus embryos when overexpressed. Remarkably, this ventralization is not associated with an increase in SMAD1/5/8 phosphorylation.
涡虫可以在几天内从一小段身体组织中再生出一个完整的动物。最近的研究表明，骨形态发生蛋白（BMP）途径是重新建立背腹（DV）轴所必需的。在脊椎动物中，DV 轴的特化取决于由 BMP 和反背化形态发生蛋白（ADMP）协调作用的双重组织者的定义，这是在包括抑制素 chordin 和 noggin 在内的几个因素的控制下完成的。涡虫具有扩展的 noggin 家族（多达十个成员），它们被分类为经典 noggin（nog）和 noggin 样（nlg）基因，后者在 noggin 结构域内带有插入。在这里，我们表明 BMP/ADMP 组织者控制着涡虫再生过程中 DV 轴的重建，突出了在原口动物和后口动物中建立这个轴的机制的保存程度超过了人们的想象。此外，我们报告说，尽管 noggin 基因作为经典的 BMP 抑制剂发挥作用，但沉默涡虫 nlg8 会诱导异位神经发生，并增强 BMP（RNAi）表型的腹侧化。最后，我们表明，从刺胞动物到脊椎动物，noggin 样基因是保守的，并且当过表达时，两种涡虫 nlg8 和非洲爪蟾 nlg 都会使非洲爪蟾胚胎腹侧化。值得注意的是，这种腹侧化与 SMAD1/5/8 磷酸化的增加无关。
