Fig. 1.

Metabolic flexibility of osteoblasts. Much remains to be learned about the metabolic requirements of bone-forming osteoblast. Firstly (A), insulin and insulin receptor (IR) signaling stimulates the glucose transporter (Glut)4-mediated uptake of glucose, which can be utilized via oxidative phosphorylation (Ox.Phos) or aerobic glycolysis. Secondly (B), the Low-density lipoprotein receptor (LDLR) facilitates the uptake of a significant fraction of postprandial lipoproteins (LDL) by bone. Free fatty acids and triglycerides that can then be oxidized to generate ATP. Our recent findings suggest that activation of the Frizzled (Fz)-Lrp5 signaling complex by Wnt-ligands favors lipid oxidation in the osteoblast.