Figure 2

Signaling pathways and key transcription factors in regulating the adipo-osteogenic differentiation of MSCs. The fine balance of adipogenic and osteogenic differentiation of MSCs is achieved by the actions of critical signaling pathways and key transcription factors. MSCs exist in specific microenvironments or niches, which is composed of various extracellular matrix components, growth factors, cytokines, and chemokines. Upon interaction with MSCs, these components activate or inhibit the lineage commitment of MSCs. In addition, the initiated cellular signaling pathways can also interfere each other to form a fine regulatory network. Ultimately, this signaling network maintains a delicate differentiation balance through regulating key transcription factors such as PPARγ and C/EBPs or Runx2 and Osterix for adipogenesis or osteogenesis respectively. OPN, osteopontin; FZD, Frizzled receptor; Hh, Hedgehog; Ptc, Patched; Smo, Smoothened