Yang Y, Niswander L
Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021.
Cell. 1995 Mar 24;80(6):939-47. doi: 10.1016/0092-8674(95)90297-x.
Growth and patterning of the vertebrate limb are controlled by the ridge, posterior mesenchyme, and non-ridge ectoderm. Fibroblast growth factor 4 (FGF4) and Sonic hedgehog (SHH) can mediate signaling from the ridge and posterior mesenchyme, respectively. Here we show that dorsal ectoderm is required together with FGF4 to maintain Shh expression. Removal of dorsal ectoderm results in loss of posterior skeletal elements, which can be rescued by exogenous SHH. Wnt7a, which is expressed in dorsal ectoderm, provides the signal required for Shh expression and formation of posterior structures. These results provide evidence that all three axes (dorsoventral, proximodistal, and anteroposterior) are intimately linked by the respective signals WNT7a, FGF4, and SHH during limb out-growth and patterning.
脊椎动物肢体的生长和模式形成由嵴、后间充质和非嵴外胚层控制。成纤维细胞生长因子4（FGF4）和音猬因子（SHH）可分别介导来自嵴和后间充质的信号传导。在此我们表明，背侧外胚层与FGF4共同作用以维持Shh表达。去除背侧外胚层会导致后部骨骼元件缺失，而外源性SHH可挽救这一情况。在背侧外胚层中表达的Wnt7a提供了Shh表达和后部结构形成所需的信号。这些结果证明，在肢体生长和模式形成过程中，所有三个轴（背腹、近远和前后）通过各自的信号WNT7a、FGF4和SHH紧密相连。
