A Second Canon

Abstract

More is becoming known about so-called noncanonical Wnt pathways that signal independently of beta-catenin. Here we review recent developments in both the functions and mechanisms of noncanonical Wnt signaling. We also discuss some unresolved and vexing questions. How many noncanonical Wnt pathways are there? How extensive are the parallels between Drosophila planar polarization and vertebrate convergence and extension? Last, we will outline some challenges and difficulties we foresee for this exciting but still very young field.

Atherosclerotic Calcification: Wnt Is the Hint

“…At rest, under unstimulated conditions, a protein scaffold of Axin, adenomatous polyposis coli,74 and glycogen synthase kinase‐3β (GSK3) mediate the phosphorylation of β‐catenin. This results in the polyubiquitination and proteasomal degradation of β‐catenin 75, 76.…”

Wnt signaling and skeletal development

“…However, an increasing body of research concerns non-canonical, β-catenin independent Wnt pathways. Potential mechanisms of the non-canonical Wnt signal transduction are very diverse, including signaling through calcium flux, JNK, and both small and heterotrimeric G proteins [14]. The pathway of β-catenin independent Wnt signaling is an unresolved issue.…”

Blockade of Wnt-1 signaling induces apoptosis in human colorectal cancer cells containing downstream mutations

“…In contrast, noncanonical signaling pathways do not require b-catenin, and they signal through other mediators, such as JNK, G proteins, or calcium flux (Veeman et al, 2003). A number of Wnt antagonists have been reported to interfere with ligand-receptor interactions (Kawano and Kypta, 2003).…”