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  • The EMBO Journal (2007) 26, 2350 - 2360
  • doi:10.1038/sj.emboj.7601684

Published online: 12 April 2007

XTsh3 is an essential enhancing factor of canonical Wnt signaling in Xenopus axial determination

Takayuki Onai1,a, Mami Matsuo-Takasaki1,a, Hidehiko Inomata1, Toshihiro Aramaki1, Michiru Matsumura1, Rieko Yakura1, Noriaki Sasai1 and Yoshiki Sasai1

  1. Organogenesis and Neurogenesis Group, Center for Developmental Biology, RIKEN, Kobe, Japan

Correspondence to:

Yoshiki Sasai, Organogenesis and Neurogenesis Group, Center for Developmental Biology, RIKEN, 2-2-3 Minatojima-minamimachi, Chuo, Kobe 650-0047, Japan. Tel.: +81 78 306 1841; Fax +81 78 306 1854; E-mail: yoshikisasai@cdb.riken.jp

aThese two authors contributed equally to this work

Received 6 August 2006; Accepted 19 March 2007

In Xenopus, an asymmetric distribution of Wnt activity that follows cortical rotation in the fertilized egg leads to the dorsal–ventral (DV) axis establishment. However, how a clear DV polarity develops from the initial difference in Wnt activity still remains elusive. We report here that the Teashirt-class Zn-finger factor XTsh3 plays an essential role in dorsal determination by enhancing canonical Wnt signaling. Knockdown of the XTsh3 function causes ventralization in the Xenopus embryo. Both in vivo and in vitro studies show that XTsh3 substantially enhances Wnt signaling activity in a beta-catenin-dependent manner. XTsh3 cooperatively promotes the formation of a secondary axis on the ventral side when combined with weak Wnt activity, whereas XTsh3 alone has little axis-inducing ability. Furthermore, Wnt1 requires XTsh3 for its dorsalizing activity in vivo. Immunostaining and protein analyses indicate that XTsh3 is a nuclear protein that physically associates with beta-catenin and efficiently increases the level of beta-catenin in the nucleus. We discuss the role of XTsh3 as an essential amplifying factor of canonical Wnt signaling in embryonic dorsal determination.

  • Keywords:

    • beta-catenin,
    • axis development,
    • Tsh3,
    • Wnt,
    • Xenopus