Myristoylated Naked2 Antagonizes Wnt-β-Catenin Activity by Degrading Dishevelled-1 at the Plasma Membrane

Abstract

In Drosophila, naked cuticle is an inducible antagonist of the Wnt-␤-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-␤-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.

NKD2, a negative regulator of Wnt signaling, suppresses tumor growth and metastasis in osteosarcoma

“…25–27 The NKD family (including NKD1 and NKD2) were predicted to be candidate tumor suppressors 28 and hypermethylated in astrocytic gliomas. 29 Analysis of NKD1 expression in metastatic mouse and human OS tumors did not reveal any significant differences in expression compared with localized tumors (Supplementary Figures S5a and b).…”

Rac1 acts in conjunction with Nedd4 and Dishevelled-1 to promote maturation of cell-cell contacts

“…Nedd4 is not the only ubiquitin ligase for Dvl1 as the HECT ligase NEDL1 can ubiquitylate Dvl1 as well (Miyazaki et al, 2004), comparable to inversin and KLHL12 . Dvl1 degradation at the plasma membrane is promoted by the adapter protein NKD2 (Hu et al, 2010), an antagonist of Wnt signalling. It is currently unclear whether NKD2 is involved in the Nedd4-mediated Dvl1 degradation.…”

From wavy hair to naked proteins: The role of transforming growth factor alpha in health and disease

“…Thus, TGFA interaction stabilizes NKD2. Finally, in addition to regulating EGFR activity, NKD2 also antagonizes Wnt signaling by interacting with DVL1 and forming a co-degradation complex at the plasma membrane that is myristoylation-dependent [105]. …”