Review of Signaling Pathways Governing MSC Osteogenic and Adipogenic Differentiation

Figure 3

Schematic of β-catenin dependent and independent Wnt signaling pathways. Wnt signaling transduction occurs via β-catenin dependent or β-catenin independent signaling pathways. In β-catenin dependent signaling, extracellular Wnt ligands bind to the LRP5-Frizzled (Frz) complex to activate intracellular disheveled (DSH). This subsequently inhibits the intracellular complex comprised of axin, glycogen synthase kinase 3 (GSK3), and adenomatosis polyposis coli (APC) protein. This inhibits the cytosolic degradation of β-catenin, which accumulates and is free to enter the nucleus to heterodimerize with lymphoid enhancer-binding factor/T cell factor (LEF/TCF1) and mediate effects of gene transcription. Under the β-catenin independent signaling pathway, a similar transmembrane complex forms between Wnt, Frz, DSH, and Ror2 and activates secondary messengers.