Myristoylated Naked2 antagonizes Wnt-beta-catenin activity by degrading Dishevelled-1 at the plasma membrane.
In Drosophila, naked cuticle is an inducible antagonist of the Wnt-beta-catenin pathway, likely acting at the level of Dishevelled (Dsh/Dvl), an essential component of this pathway. The mechanism by which naked cuticle and its two vertebrate orthologs, Naked1 (NKD1) and Naked2 (NKD2), inhibit Dvl function is unknown. NKD2 is myristoylated, a co-translational modification that leads to its plasma membrane localization. In contrast, myristoylation-deficient G2A NKD2 is cytoplasmic. Herein we show that the ability of Nkd2/NKD2 to antagonize Wnt-beta-catenin activity during zebrafish embryonic development and in mammalian HEK293 cells is myristoylation-dependent. NKD2 and Dvl-1 interact and co-localize at the lateral membrane of polarized epithelial cells. In reciprocal overexpression and siRNA knockdown experiments, NKD2 and Dvl-1 destabilize each other via enhanced polyubiquitylation; this effect is also dependent upon Naked2 myristoylation. Cell fractionation and ubiquitylation assays indicate that endogenous NKD2 interacts with a slower migrating, ubiquitylated form of Dvl-1 in plasma membrane fractions. These results provide a mechanism by which NKD2 antagonizes Wnt signaling: myristoylated NKD2 interacts with Dvl-1 at the plasma membrane, and this interaction leads to their mutual ubiquitin-mediated proteasomal degradation.
Hu
Tianhui
T
Cancer Research Center, Xiamen University Medical College, Xiamen, 361005 Fujian, China.
Li
Cunxi
C
Cao
Zheng
Z
Van Raay
Terence J
TJ
Smith
Jason G
JG
Willert
Karl
K
Solnica-Krezel
Lila
L
Coffey
Robert J
RJ
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D018938:Caco-2 Cells; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism*; D016764:Cell Polarity / Q000502:physiology; D000072261:Dishevelled Proteins; D004285:Dogs; D004330:Drosophila; D029721:Drosophila Proteins; D004847:Epithelial Cells / Q000378:metabolism*; D006801:Humans; D019814:Myristic Acid / Q000378:metabolism*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000235:genetics / Q000378:metabolism; D046188:Protein Modification, Translational / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology; D054875:Ubiquitination / Q000502:physiology; D051153:Wnt Proteins / Q000235:genetics / Q000378:metabolism*; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; C000606578:DVL1 protein, human; D000072261:Dishevelled Proteins; D029721:Drosophila Proteins; C449091:NKD1 protein, human; C449092:NKD2 protein, human; D010750:Phosphoproteins; D051153:Wnt Proteins; D051176:beta Catenin; C000606588:dsh protein, Drosophila; D019814:Myristic Acid; D046988:Proteasome Endopeptidase Complex