INTERACTIONS BETWEEN XWNT-8 AND SPEMANN ORGANIZER SIGNALING PATHWAYS GENERATE DORSOVENTRAL PATTERN IN THE EMBRYONIC MESODERM OF XENOPUS
INTERACTIONS BETWEEN XWNT-8 AND SPEMANN ORGANIZER SIGNALING PATHWAYS GENERATE DORSOVENTRAL PATTERN IN THE EMBRYONIC MESODERM OF XENOPUS
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DOI：
10.1101/gad.7.1.13
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发表时间：
1993-01-01
影响因子：
10.5
通讯作者：
MOON, RT
中科院分区：
文献类型：
--
作者：
CHRISTIAN, JL;MOON, RT
本研究分析了层次的信号，空间限制表达非洲爪蟾Xwnt-8的Spemann组织者领域外的中胚层细胞，并探讨了潜在的作用，内源性Xwnt-8可能发挥背腹图案的胚胎中胚层。分析了异位引入Nieuwkoop中心样活性或异位表达goosecoid对内源性Xwnt-8转录物分布的影响。这些研究的结果与以下假设一致：来自Nieuwkoop中心的母体来源的信号起作用以正调节Spemann组织者细胞中同源盒基因goosecoid的表达，导致随后在这些细胞中抑制Xwnt-8的表达。这种排除Xwnt-8的组织者领域的细胞可能是重要的正常的背发育，在异位表达的Xwnt-8的组织者细胞后，囊胚中期阶段，通过注射质粒DNA，ventralizes这些细胞的命运。这与先前观察到的Xwnt-8在囊胚中期之前通过注射RNA表达时的背侧化效应不同。还分析了质粒衍生的Xwnt-8对分离的囊胚动物帽外胚层的影响。在中胚阶段后，Xwnt-8在动物极外胚层中的表达使背侧动物极细胞对激活素的反应腹侧化，并允许幼稚外胚层细胞在没有添加生长因子的情况下分化为腹侧中胚层。总的来说，这些数据与Xwnt-8在正常发育过程中腹侧边缘区细胞的中胚层分化中发挥作用的假设是一致的。此外，内源性Xwnt-8可能ventralize侧中胚层细胞的背侧信号从组织者的反应，从而有助于最终的身体模式的分级性质。
This study analyzes the hierarchy of signals that spatially restrict expression of Xenopus Xwnt-8 to mesodermal cells outside of the Spemann organizer field and examines the potential role that endogenous Xwnt-8 may play in dorsoventral patterning of the embryonic mesoderm. The effects of ectopic introduction of a Nieuwkoop center-like activity or of ectopic expression of goosecoid, on the distribution of endogenous Xwnt-8 transcripts were analyzed. The results of these studies are consistent with the hypothesis that maternally derived signals from the Nieuwkoop center function to positively regulate expression of the homeo box gene goosecoid in Spemann organizer cells, leading to a subsequent repression of Xwnt-8 expression in these cells. This exclusion of Xwnt-8 from cells of the organizer field may be important for normal dorsal development, in that ectopic expression of Xwnt-8 in organizer cells after the midblastula stage, by injection of plasmid DNA, ventralizes the fate of these cells. This is distinct from the previously observed dorsalizing effect of Xwnt-8 when expressed prior to the midblastula stage by injection of RNA. The effects of plasmid-derived Xwnt-8 on isolated blastula animal cap ectoderm were also analyzed. Expression of Xwnt-8 in animal pole ectoderm after the midblastula stage ventralizes the response of dorsal animal pole cells to activin and allows naive ectodermal cells to differentiate as ventral mesoderm in the absence of added growth factors. Collectively, these data are consistent with the hypothesis that Xwnt-8 plays a role in the mesodermal differentiation of ventral marginal zone cells during normal development. Furthermore, endogenous Xwnt-8 may ventralize the response of lateral mesodermal cells to dorsalizing signals from the organizer, thus contributing to the graded nature of the final body pattern.