Xenbase Image ID: 132374

FIG. 6. (a) Misexpression of either LEF-1 or b-catenin in Xenopus ectodermal explants leads to accumulation of Xnr3 transcripts. The animal pole of Xenopus embryos was injected with 100 pg LEF-1 (lanes 9 and 10), 100 pg b-catenin (lanes 3 and 4), or 1 ng Xwnt8 mRNA (lanes 11 and 12) or left uninjected. Animal pole tissue was explanted at the blastula stage and allowed to develop in isolation until gastrula stages, and then the amount of Xnr3 transcript was assayed by RT-PCR. Explanted animal pole tissue does not normally express Xnr3 (lanes 1 and 2), but injection of any of these three components of the wnt signaling pathway, LEF-1, b-catenin, or Xwnt8, induced Xnr3 expression. Induction of Xnr3 expression by b-catenin was decreased by coinjection of 333 pg of the HMG box of LEF-1 (lanes 5 and 6) and completely abrogated by 1 ng of HMG LEF-1 (lanes 7 and 8). (b) The differential activation of the Xnr3 promoter on the dorsal side of Xenopus gastrulae is dependent on the LEF-1 binding sites. pXnr3lux was injected into the dorsal or ventral side of a four-cell stage embryo. Expression of the reporter from this construct was between 6- and 15-fold higher after dorsal injection com-pared to ventral injection. This differential activation on the dorsal side of the embryo was not observed when the LEF-1 binding sites in the Xnr3 promoterwere mutated as in the plasmid pXnr3luxmLEF. Image published in: McKendry R et al. (1997) Copyright © 1997. Image reproduced with permission of the Publisher, Elsevier B. V. Larger Image Printer Friendly View

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