T (Brachyury) is a direct target of Wnt3a during paraxial mesoderm specification

  1. Terry P. Yamaguchi,
  2. Shinji Takada,
  3. Yoshiaki Yoshikawa,
  4. Nongying Wu, and
  5. Andrew P. McMahon
  1. Department of Molecular and Cellular Biology, Biological Laboratories, Harvard University, Cambridge, Massachusetts 02138 USA; Center for Molecular and Developmental Biology, Graduate School of Science, Kyoto University, Kitashirakawa, Sakyo-ku, Kyoto 606-8502, Japan; Kondoh Differentiation Signaling Project, Exploratory Research for Advanced Technology (ERATO), Japan Science and Technology Corporation (JST), Sakyo-ku, Kyoto 606-8305, Japan; Department of Dermatology, Graduate School of Medicine, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan

Abstract

Wnt3a encodes a signal that is expressed in the primitive streak of the gastrulating mouse embryo and is required for paraxial mesoderm development. In its absence cells adopt ectopic neural fates. Embryos lacking the T-box-containing transcription factors, Brachyury or Tbx6, also lack paraxial mesoderm. Here we show that Brachyury is specifically down-regulated in Wnt3a mutants in cells fated to form paraxial mesoderm. Transgenic analysis of the T promoter identifies T (Brachyury) as a direct transcriptional target of the Wnt signaling pathway. Our results suggest that Wnt3a, signaling via Brachyury, modulates a balance between mesodermal and neural cell fates during gastrulation.

Keywords

Footnotes

  • Present address as of 1/1/2000: Cancer and Developmental Biology Laboratory, National Cancer Institute–Frederick Cancer Research and Development Center, Frederick, Maryland 27102 USA.

  • These authors contributed equally.

  • Corresponding author.

  • E-MAIL amcmahon{at}biosun.harvard.edu; FAX (617) 496-3763.

    • Received September 13, 1999.
    • Accepted October 13, 1999.
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