Distinct WNT Pathways Regulating AER Formation and Dorsoventral Polarity in the Chick Limb Bud

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Science  22 May 1998:
Vol. 280, Issue 5367, pp. 1274-1277
DOI: 10.1126/science.280.5367.1274


The apical ectodermal ridge (AER) is an essential structure for vertebrate limb development. Wnt3a is expressed during the induction of the chick AER, and misexpression of Wnt3ainduces ectopic expression of AER-specific genes in the limb ectoderm. The genes β-catenin and Lef1 can mimic the effect of Wnt3a, and blocking the intrinsic Lef1activity disrupts AER formation. Hence, Wnt3a functions in AER formation through the β-catenin/LEF1 pathway. In contrast, neither β-catenin nor Lef1 affects theWnt7a-regulated dorsoventral polarity of the limb. Thus, two related Wnt genes elicit distinct responses in the same tissues by using different intracellular pathways.

  • * These authors contributed equally to this work.

  • Present address: Department of Biophysics, Kyoto University, Sakyo-ku, Kyoto 606, Japan.

  • To whom correspondence should be addressed. E-mail: belmonte{at}

  • § The laboratories of these authors contributed equally to this study.

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