Hematopoietic Stem Cell Development, Niches, and Signaling Pathways
Figure 6
A canonical Wnt signaling pathway. In the presence of Wnt, the signals are transduced through Frizzled family receptors and LRP5/LRP6 coreceptor to the -catenin signaling cascade which then stabilize hypophosphorylated -catenin and interact with TCF/LEF, Legless and PYGO for target gene activations. MARK and CKI are the positive regulators of canonical Wnt pathway, while APC, AXIN1, AXIN2, CKI, NKD1, NKD2, TRCP1, TRCP2, and ANKRD6 are negative regulators. In the absence of Wnt, -catenin-forming complex with AXIN and APC is phosphorylates, leading to be a target for ubiquitination and degradation by proteasome (adapted from [16]).