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Wnt11/β-catenin signaling in both oocytes and early embryos acts through LRP6-mediated regulation of axin
Journal article   Open access   Peer reviewed

Wnt11/β-catenin signaling in both oocytes and early embryos acts through LRP6-mediated regulation of axin

Matt Kofron, Bilge Birsoy, Douglas Houston, Qinghua Tao, Christopher Wylie and Janet Heasman
Development (Cambridge), Vol.134(3), pp.503-513
02/2007
DOI: 10.1242/dev.02739
PMID: 17202189
url
https://doi.org/10.1242/dev.02739View
Published (Version of record) Open Access

Abstract

Current models of canonical Wnt signaling assume that a pathway is active if beta-catenin becomes nuclearly localized and Wnt target genes are transcribed. We show that, in Xenopus, maternal LRP6 is essential in such a pathway, playing a pivotal role in causing expression of the organizer genes siamois and Xnr3, and in establishing the dorsal axis. We provide evidence that LRP6 acts by degrading axin protein during the early cleavage stage of development. In the full-grown oocyte, before maturation, we find that axin levels are also regulated by Wnt11 and LRP6. In the oocyte, Wnt11 and/or LRP6 regulates axin to maintain beta-catenin at a low level, while in the embryo, asymmetrical Wnt11/LRP6 signaling stabilizes beta-catenin and enriches it on the dorsal side. This suggests that canonical Wnt signaling may not exist in simple off or on states, but may also include a third, steady-state, modality.
Signal Transduction Receptors, LDL - genetics Oocytes - growth & development Low Density Lipoprotein Receptor-Related Protein-6 Oocytes - metabolism Xenopus - genetics RNA, Messenger - genetics Receptors, LDL - metabolism RNA, Messenger - metabolism Wnt Proteins - metabolism Xenopus - embryology beta Catenin - metabolism Body Patterning - physiology Animals Xenopus - metabolism Models, Biological Base Sequence Axin Protein Female Xenopus Proteins - metabolism Body Patterning - genetics Repressor Proteins - metabolism

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