Atypical Protein Kinase Cι Is Required for Wnt3a-dependent Neurite Outgrowth and Binds to Phosphorylated Dishevelled 2

Abstract

Background: Wnt3a-dependent neurite outgrowth is associated with Dishevelled phosphorylation. Results: PKC is required for Wnt3a-induced neurite extension. PKC binds wild-type Dishevelled, but not an inactive phosphorylation-deficient Dishevelled mutant. Conclusion: PKC mediates Wnt3a-dependent neurite outgrowth; Dishevelled phosphorylation is required for PKC interaction. Significance: PKC has key role in Wnt3a-induced neurite outgrowth; Dvl phosphorylation at defined sites is critical for PKC association.

Functional Consequences of Wnt-induced Dishevelled 2 Phosphorylation in Canonical and Noncanonical Wnt Signaling

“…More strikingly, and in contrast, Dvl2 P4m was unable to rescue Wnt3a-induced neurite outgrowth in TC-32 cells. We have previously reported that Wnt-mediated neurite extension in these cells does not require the canonical Wnt/␤-catenin pathway receptor LRP5/6 and instead is mediated by noncanonical Wnt pathways that rely on JNK and atypical PKC (10,54). In the accompanying manuscript (54), we further show that Dvl2 P4m, in contrast to Dvl2 WT, fails to co-immunoprecipitate with PKC, and this may account for its inability to mediate neurite outgrowth.…”

Targeting protein kinase C in sarcoma

“…Wnt and its downstream effectors regulate various processes important for cancer progression [92], and neurite outgrowth in TC-32 cells, has been successfully used as a cancer model to interrogate Wnt signalling pathways [93]. Greer et al demonstrated in TC-32 cells that Wnt3a ligand treatment leads to neurite extension which can be abrogated by siRNA or chemical inhibition of either PKCι or casein kinase 1 delta (CK1δ) [91,94]. Interrogation of this pathway demonstrated that Wnt3a leads to casein kinase 1 delta (CK1δ) dependent phosphorylation of Dishevelled 2 (Dvl2) and in this phosphorylated form, Dvl2 forms an immunocomplex with PKCι extracted from cells [91].…”

“…Greer et al demonstrated in TC-32 cells that Wnt3a ligand treatment leads to neurite extension which can be abrogated by siRNA or chemical inhibition of either PKCι or casein kinase 1 delta (CK1δ) [91,94]. Interrogation of this pathway demonstrated that Wnt3a leads to casein kinase 1 delta (CK1δ) dependent phosphorylation of Dishevelled 2 (Dvl2) and in this phosphorylated form, Dvl2 forms an immunocomplex with PKCι extracted from cells [91]. This Wnt3a N CK1δ N Dvl2 N PKCι axis is further supported by the finding that Wnt3a leads to pericentrosomal distribution of PKCι and co-localisation with CK1δ.…”

“…Recently, PKCι was shown to be necessary for non-canonical Wnt signalling in an Ewing sarcoma cell line, TC-32 [91]. Wnt and its downstream effectors regulate various processes important for cancer progression [92], and neurite outgrowth in TC-32 cells, has been successfully used as a cancer model to interrogate Wnt signalling pathways [93].…”

aPKC in neuronal differentiation, maturation and function

“…Agonist-dependent activation of aPKC may occur through the displacement of the pseudosubstrate. Agonist-dependent activation of full-length aPKC in the nervous system remains mostly undescribed, although a few studies have described WNT (portmanteau from Wingless and Int)-or IGF-1 (insulin-like growth factor 1)-dependent full-length aPKC activation during neuronal polarization [28][29][30] (reviewed in [31]). As described earlier, PKMζ lacks PS and is constitutively active [32,33].…”