Kimura J, Sato-Maeda M, Noji S, Ide H
Biological Institute, Graduate School of Science, Tohoku University, Aoba, Sendai, Japan.
Dev Growth Differ. 2000 Jun;42(3):219-27. doi: 10.1046/j.1440-169x.2000.00512.x.
Skeletal patterning of the vertebrate limb is controlled by the zone of polarizing activity (ZPA), apical ectodermal ridge (AER) and dorsal ectoderm. In the present study, to understand the involvement of fibroblast growth factor (FGF) and non-ridge ectoderm in anteroposterior (AP) axis formation, gene expression in chick limb bud mesenchymal cells in culture was investigated by reverse transcription-polymerase chain reaction and in situ hybridization. It was found that Shh expression was locally maintained in the mesenchymal cells underneath and near non-ridge ectoderm in coculture with the posterior mesenchymal cells and non-ridge ectoderm in the presence of FGF-4 by in situ hybridization. In Shh-expressing anterior limb bud mesenchymal cells cultured with non-ridge ectoderm, it was also discovered that Bmp-2 was activated in the presence of FGF-2, -4 and -8, while Hoxd-13 was activated in the presence of FGF-4 and that FGF-2 had a similar effect but FGF-8 did not. This result indicates that Hoxd-13 activation by SHH depends on non-ridge ectoderm and FGF-2 or FGF-4, and that there may be a difference in the effect on AP axis formation of the limb bud between FGF-2, -4 and -8. Possible roles of these genes and signal molecules in AP pattern formation are discussed.
脊椎动物肢体的骨骼模式由极化活性区（ZPA）、顶端外胚层嵴（AER）和背侧外胚层控制。在本研究中，为了解成纤维细胞生长因子（FGF）和非嵴外胚层在前后（AP）轴形成中的作用，通过逆转录-聚合酶链反应和原位杂交研究了培养的鸡肢体芽间充质细胞中的基因表达。通过原位杂交发现，在FGF-4存在的情况下，与后间充质细胞和非嵴外胚层共培养时，Shh表达在非嵴外胚层下方和附近的间充质细胞中局部维持。在用非嵴外胚层培养的表达Shh的前肢芽间充质细胞中，还发现Bmp-2在FGF-2、-4和-8存在时被激活，而Hoxd-13在FGF-4存在时被激活，FGF-2有类似作用但FGF-8没有。这一结果表明，SHH对Hoxd-13的激活依赖于非嵴外胚层和FGF-2或FGF-4，并且FGF-2、-4和-8对肢体芽AP轴形成的影响可能存在差异。讨论了这些基因和信号分子在AP模式形成中的可能作用。
