Title: The cysteine-rich frizzled domain of Frzb-1 is required and sufficient for modulation of Wnt signaling
Authors: Linsen, Koen ×
Wang, Sharon (Shuang)
Julius, M A
Kitajewski, J
Moos, M
Luyten, F P #
Issue Date: 12-Nov-1997
Series Title: Proceedings of the National Academy of Sciences of the United States of America vol:94 issue:21 pages:11196-200
Abstract: Convincing evidence has accumulated to identify the Frizzled proteins as receptors for the Wnt growth factors. In parallel, a number of secreted frizzled-like proteins with a conserved N-terminal frizzled motif have been identified. One of these proteins, Frzb-1, binds Wnt-1 and Xwnt-8 proteins and antagonizes Xwnt-8 signaling in Xenopus embryos. Here we report that Frzb-1 blocks Wnt-1 induced cytosolic accumulation of beta-catenin, a key component of the Wnt signaling pathway, in human embryonic kidney cells. Structure/function analysis reveals that complete removal of the frizzled domain of Frzb-1 abolishes the Wnt-1/Frzb-1 protein interaction and the inhibition of Wnt-1 mediated axis duplication in Xenopus embryos. In contrast, removal of the C-terminal portion of the molecule preserves both Frzb-Wnt binding and functional inhibition of Wnt signaling. Partial deletions of the Frzb-1 cysteine-rich domain maintain Wnt-1 interaction, but functional inhibition is lost. Taken together, these findings support the conclusion that the frizzled domain is necessary and sufficient for both activities. Interestingly, Frzb-1 does not block Wnt-5A signaling in a Xenopus functional assay, even though Wnt-5A coimmunoprecipitates with Frzb-1, suggesting that coimmunoprecipitation does not necessarily imply inhibition of Wnt function.
ISSN: 0027-8424
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Rheumatology Section (-)
Electrical Engineering - miscellaneous
× corresponding author
# (joint) last author

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