Systematic Mapping of WNT-FZD Protein Interactions Reveals Functional Selectivity by Distinct WNT-FZD Pairs


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Dijksterhuis J. P., Baljinnyam B., Stanger K., Sercan H. O., Ji Y., Andres O., ...More

JOURNAL OF BIOLOGICAL CHEMISTRY, vol.290, no.11, pp.6789-6798, 2015 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 290 Issue: 11
  • Publication Date: 2015
  • Doi Number: 10.1074/jbc.m114.612648
  • Journal Name: JOURNAL OF BIOLOGICAL CHEMISTRY
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.6789-6798
  • Dokuz Eylül University Affiliated: Yes

Abstract

The seven-transmembrane-spanning receptors of the FZD1-10 class are bound and activated by the WNT family of lipoglycoproteins, thereby inducing a complex network of signaling pathways. However, the specificity of the interaction between mammalian WNT and FZD proteins and the subsequent signaling cascade downstream of the different WNT-FZD pairs have not been systematically addressed to date. In this study, we determined the binding affinities of various WNTs for different members of the FZD family by using bio-layer interferometry and characterized their functional selectivity in a cell system. Using purified WNTs, we show that different FZD cysteine-rich domains prefer to bind to distinct WNTs with fast on-rates and slow off-rates. In a 32D cell-based system engineered to overexpress FZD(2), FZD(4), or FZD(5), we found that WNT-3A (but not WNT-4, -5A, or -9B) activated the WNT-beta-catenin pathway through FZD(2/4/5) as measured by phosphorylation of LRP6 and beta-catenin stabilization. Surprisingly, different WNT-FZD pairs showed differential effects on phosphorylation of DVL2 and DVL3, revealing a previously unappreciated DVL isoform selectivity by different WNT-FZD pairs in 32D cells. In summary, we present extensive mapping of WNT-FZD cysteine-rich domain interactions complemented by analysis of WNT-FZD pair functionality in a unique cell system expressing individual FZD isoforms. Differential WNT-FZD binding and selective functional readouts suggest that endogenous WNT ligands evolved with an intrinsic natural bias toward different downstream signaling pathways, a phenomenon that could be of great importance in the design of FZD-targeting drugs.