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Molecular dissection of Wnt3a-Frizzled8 interaction reveals essential and modulatory determinants of Wnt signaling activity.
- Source :
-
BMC biology [BMC Biol] 2014 May 30; Vol. 12, pp. 44. Date of Electronic Publication: 2014 May 30. - Publication Year :
- 2014
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Abstract
- Background: Wnt proteins are a family of secreted signaling molecules that regulate key developmental processes in metazoans. The molecular basis of Wnt binding to Frizzled and LRP5/6 co-receptors has long been unknown due to the lack of structural data on Wnt ligands. Only recently, the crystal structure of the Wnt8-Frizzled8-cysteine-rich-domain (CRD) complex was solved, but the significance of interaction sites that influence Wnt signaling has not been assessed.<br />Results: Here, we present an extensive structure-function analysis of mouse Wnt3a in vitro and in vivo. We provide evidence for the essential role of serine 209, glycine 210 (site 1) and tryptophan 333 (site 2) in Fz binding. Importantly, we discovered that valine 337 in the site 2 binding loop is critical for signaling without contributing to binding. Mutations in the presumptive second CRD binding site (site 3) partly abolished Wnt binding. Intriguingly, most site 3 mutations increased Wnt signaling, probably by inhibiting Wnt-CRD oligomerization. In accordance, increasing amounts of soluble Frizzled8-CRD protein modulated Wnt3a signaling in a biphasic manner.<br />Conclusions: We propose a concentration-dependent switch in Wnt-CRD complex formation from an inactive aggregation state to an activated high mobility state as a possible modulatory mechanism in Wnt signaling gradients.
- Subjects :
- Amino Acid Sequence
Animals
Embryo, Nonmammalian metabolism
HEK293 Cells
Humans
Mice
Models, Biological
Models, Molecular
Molecular Sequence Data
Mutant Proteins metabolism
Point Mutation genetics
Protein Binding
Protein Structure, Tertiary
Solubility
Structure-Activity Relationship
Zebrafish embryology
Receptors, G-Protein-Coupled chemistry
Receptors, G-Protein-Coupled metabolism
Wnt Signaling Pathway
Wnt3A Protein chemistry
Wnt3A Protein metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1741-7007
- Volume :
- 12
- Database :
- MEDLINE
- Journal :
- BMC biology
- Publication Type :
- Academic Journal
- Accession number :
- 24885675
- Full Text :
- https://doi.org/10.1186/1741-7007-12-44