Abstract
Wnt/β-catenin signaling is activated when extracellular Wnt ligands bind Frizzled (FZD) receptors at the cell membrane. Wnts bind FZD cysteine-rich domains (CRDs) with high affinity through a palmitoylated N-terminal “thumb” and a disulfide-stabilized C-terminal “index finger,” yet how these binding events trigger receptor activation and intracellular signaling remains unclear. Here we report the crystal structure of the Frizzled-4 (FZD4) CRD in complex with palmitoleic acid, which reveals a CRD tetramer consisting of two cross-braced CRD dimers. Each dimer is stabilized by interactions of one hydrophobic palmitoleic acid tail with two CRD palmitoleoyl-binding grooves oriented end to end, suggesting that the Wnt palmitoleoyl group stimulates CRD–CRD interaction. Using bioluminescence resonance energy transfer (BRET) in live cells, we show that WNT5A stimulates dimerization of membrane-anchored FZD4 CRDs and oligomerization of full-length FZD4, which requires the integrity of CRD palmitoleoyl-binding residues. These results suggest that FZD receptors may form signalosomes in response to Wnt binding through the CRDs and that the Wnt palmitoleoyl group is important in promoting these interactions. These results complement our understanding of lipoprotein receptor-related proteins 5 and 6 (LRP5/6), Dishevelled, and Axin signalosome assembly and provide a more complete model for Wnt signalosome assembly both intracellularly and at the membrane.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 916-926 |
| Number of pages | 11 |
| Journal | Genes and Development |
| Volume | 31 |
| Issue number | 9 |
| DOIs | |
| State | Published - 2017 |
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Keywords
- Cysteine-rich domain
- Frizzled
- Frizzled-4
- Signalosome
- Wnt
- WNT5A
ASJC Scopus subject areas
- Genetics
- Developmental Biology
Cite this
Wnt5a promotes Frizzled-4 signalosome assembly by stabilizing cysteine-rich domain dimerization. / DeBruine, Zachary J.; Ke, Jiyuan; Harikumar, Kaleeckal G.; Gu, Xin; Borowsky, Peter; Williams, Bart O.; Xu, Wenqing; Miller, Laurence J; Xu, H. Eric; Melcher, Karsten.
In: Genes and Development, Vol. 31, No. 9, 2017, p. 916-926.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Wnt5a promotes Frizzled-4 signalosome assembly by stabilizing cysteine-rich domain dimerization
AU - DeBruine, Zachary J.
AU - Ke, Jiyuan
AU - Harikumar, Kaleeckal G.
AU - Gu, Xin
AU - Borowsky, Peter
AU - Williams, Bart O.
AU - Xu, Wenqing
AU - Miller, Laurence J
AU - Xu, H. Eric
AU - Melcher, Karsten
PY - 2017
Y1 - 2017
N2 - Wnt/β-catenin signaling is activated when extracellular Wnt ligands bind Frizzled (FZD) receptors at the cell membrane. Wnts bind FZD cysteine-rich domains (CRDs) with high affinity through a palmitoylated N-terminal “thumb” and a disulfide-stabilized C-terminal “index finger,” yet how these binding events trigger receptor activation and intracellular signaling remains unclear. Here we report the crystal structure of the Frizzled-4 (FZD4) CRD in complex with palmitoleic acid, which reveals a CRD tetramer consisting of two cross-braced CRD dimers. Each dimer is stabilized by interactions of one hydrophobic palmitoleic acid tail with two CRD palmitoleoyl-binding grooves oriented end to end, suggesting that the Wnt palmitoleoyl group stimulates CRD–CRD interaction. Using bioluminescence resonance energy transfer (BRET) in live cells, we show that WNT5A stimulates dimerization of membrane-anchored FZD4 CRDs and oligomerization of full-length FZD4, which requires the integrity of CRD palmitoleoyl-binding residues. These results suggest that FZD receptors may form signalosomes in response to Wnt binding through the CRDs and that the Wnt palmitoleoyl group is important in promoting these interactions. These results complement our understanding of lipoprotein receptor-related proteins 5 and 6 (LRP5/6), Dishevelled, and Axin signalosome assembly and provide a more complete model for Wnt signalosome assembly both intracellularly and at the membrane.
AB - Wnt/β-catenin signaling is activated when extracellular Wnt ligands bind Frizzled (FZD) receptors at the cell membrane. Wnts bind FZD cysteine-rich domains (CRDs) with high affinity through a palmitoylated N-terminal “thumb” and a disulfide-stabilized C-terminal “index finger,” yet how these binding events trigger receptor activation and intracellular signaling remains unclear. Here we report the crystal structure of the Frizzled-4 (FZD4) CRD in complex with palmitoleic acid, which reveals a CRD tetramer consisting of two cross-braced CRD dimers. Each dimer is stabilized by interactions of one hydrophobic palmitoleic acid tail with two CRD palmitoleoyl-binding grooves oriented end to end, suggesting that the Wnt palmitoleoyl group stimulates CRD–CRD interaction. Using bioluminescence resonance energy transfer (BRET) in live cells, we show that WNT5A stimulates dimerization of membrane-anchored FZD4 CRDs and oligomerization of full-length FZD4, which requires the integrity of CRD palmitoleoyl-binding residues. These results suggest that FZD receptors may form signalosomes in response to Wnt binding through the CRDs and that the Wnt palmitoleoyl group is important in promoting these interactions. These results complement our understanding of lipoprotein receptor-related proteins 5 and 6 (LRP5/6), Dishevelled, and Axin signalosome assembly and provide a more complete model for Wnt signalosome assembly both intracellularly and at the membrane.
KW - Cysteine-rich domain
KW - Frizzled
KW - Frizzled-4
KW - Signalosome
KW - Wnt
KW - WNT5A
UR - http://www.scopus.com/inward/record.url?scp=85020191672&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85020191672&partnerID=8YFLogxK
U2 - 10.1101/gad.298331.117
DO - 10.1101/gad.298331.117
M3 - Article
C2 - 28546512
AN - SCOPUS:85020191672
VL - 31
SP - 916
EP - 926
JO - Genes and Development
JF - Genes and Development
SN - 0890-9369
IS - 9
ER -