Caveolin Is Necessary for Wnt-3a-Dependent Internalization of LRP6 and Accumulation of β-Catenin

• Published in: Developmental cell 2006-08, Vol.11 (2), p.213-223
• Main Authors: Yamamoto, Hideki, Komekado, Hideyuki, Kikuchi, Akira
• Format: Article
• Language: English
• Subjects: Axin Protein; beta Catenin - metabolism; Biological and medical sciences; Caveolins - metabolism; Cell differentiation, maturation, development, hematopoiesis; Cell Line; Cell physiology; CELLBIO; Endocytosis - physiology; Frizzled Receptors - metabolism; Fundamental and applied biological sciences. Psychology; HeLa Cells; Humans; Low Density Lipoprotein Receptor-Related Protein-6; Membrane Microdomains - chemistry; Membrane Microdomains - physiology; Molecular and cellular biology; Receptors, G-Protein-Coupled - metabolism; Receptors, LDL - genetics; Receptors, LDL - metabolism; Repressor Proteins - metabolism; Signal Transduction - physiology; SIGNALING; Wnt Proteins - genetics; Wnt Proteins - metabolism; Wnt3 Protein; Wnt3A Protein
• ISSN: 1534-5807; 1878-1551
• DOI: 10.1016/j.devcel.2006.07.003

β-catenin-mediated Wnt signaling is critical in animal development and tumor progression. The single-span transmembrane Wnt receptor, low-density lipoprotein receptor-related protein 6 (LRP6), interacts with Axin to promote the Wnt-dependent accumulation of β-catenin. However, the molecular mechanism of receptor internalization and its impact on signaling are unclear. Here, we present evidence that LRP6 is internalized with caveolin and that the components of this endocytic pathway are required not only for Wnt-3a-induced internalization of LRP6 but also for accumulation of β-catenin. Overall, our data suggest that Wnt-3a triggers the interaction of LRP6 with caveolin and promotes recruitment of Axin to LRP6 phosphorylated by glycogen synthase kinase-3β and that caveolin thereby inhibits the binding of β-catenin to Axin. Thus, caveolin plays critical roles in inducing the internalization of LRP6 and activating the Wnt/β-catenin pathway. We also discuss the idea that distinct endocytic pathways correlate with the specificity of Wnt signaling events.