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Purified Wnt 5a protein activates or inhibits β-catenin-TCF signaling depending on receptor context Mikels et al., 2006, PLOS Biology
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Mouse limb bud Over-expression of Wnt 5 blocks the ability of Wnt 8 to promote dorsal cell fate in Xenopus. - Torres et al., 2003, J. Cell Biol. In the distal tip of mouse limb buds, Wnt 5a antagonizes b-catenin signaling, since in Wnt 5a -/- limbs higher levels of b-catenin can be detected in the distal tip. - Topol et al., 2003, J. Cell Biol. Removal of maternal and zygotic functions of zebrafish Wnt 5 result in variable degrees of dorsalization, including formation of secondary axis. - Westfall et al., 2003, Dev. Biol. Wnts antagonize Wnts
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Dominant negative Wnt 11 and CaMK II promotes dorsal cell fates. - Kuhl et al., 2000, J. Biol. Chem. Over-expression of Wnt 5 can activate Nemo-like kinase, which in C. elegans and mammalian cells Inhibit Tcf transcription factors to which b-catenin binds to regulate gene expression. - Ishitani et al., 2003, Mol. Cell. Biol. Siah 2 (b-catenin destruction complex) is transcriptionally activated by Wnt 5a. - Topol et al., 2003, J. Cell Biol. How to inhibit the canonical signaling…?
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SuperTopflash in 293 cells Purified Wnt 5a protein inhibits canonical Wnt signaling wnt 3a wnt 5a (after 1, 3hr) wnt 5a 6hr after washing wnt 3a
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Wnt 5a does not affect b-catenin protein stabilization Wnt 5a protein competes with Wnt 3a for Fz receptor context. Siah 2, which targets b-catenin for b-TrCP independent proteasomal degradation, is transcriptionally activated by Wnt 5a. - Topol et al., 2003, J. Cell Biol. 293 cells Cytosolic fraction of 293 cells
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Wnt 5a - mediated inhibition of canonical signaling is not associated with Wnt- stimulated Ca ++ flux * PTX (pertussis toxin) : inhibition of G protein binding with membrane receptor * LPA (lysophosphatidic acid) : agonist of G protein signaling wnt 5a Ca ++ CaMKII TAK/NLK mitogen activated Signaling cascade TCF/LEF - phosphorylation DNA b-cat G-protein * Ionomycin :raises the intracellular level of Ca 2+ Wnt stimulated calcium flux
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Wnt 5a protein activates b-catenin signaling depending on receptor context XWnt 5a RNA with Xfz4 RNA leads to the synergistic activation of Wnt/b-cat target genes in Xenopus animal caps. - Umbhauer et al., 2000, EMBO J
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An alternative Wnt receptor, mRor2, mediates Wnt 5a’s inhibitory activity
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Expression of mRor2 is required for Wnt 5a- mediated inhibition of canonical Wnt signaling SuperTopflash LRP cotransfection
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Membrane tethered form (no transmembrane & cytoplasmic domain) 293 Transmembrane domain : O Cytoplasmic domain : X
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A member of the Fz protein family (hFz5) mediating axis induction by Wnt 5a. - He et al., 1997, Scinece.
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