The Binding Between Sclerostin and LRP5 is Altered by DKK1 and by High-Bone Mass LRP5 Mutations
- First Online:
- Cite this article as:
- Balemans, W., Piters, E., Cleiren, E. et al. Calcif Tissue Int (2008) 82: 445. doi:10.1007/s00223-008-9130-9
- 341 Downloads
Low-density lipoprotein receptor–related protein 5 (LRP5), a Wnt coreceptor, plays an important role in bone metabolism as loss-of-function and gain-of-function mutations in LRP5 result in the autosomal recessive osteoporosis-pseudoglioma syndrome and autosomal dominant high–bone mass (HBM) phenotypes, respectively. Prior studies suggested that the presence of HBM-associated LRP5 mutations results in decreased antagonism of LRP5-mediated Wnt signaling. In the present study, we investigated six different HBM-LRP5 mutations and confirm that neither Dickkopf1 (DKK1) nor sclerostin efficiently inhibits HBM-LRP5 signaling. In addition, when coexpressed, DKK1 and sclerostin do not inhibit HBM-LRP5 mutants better than either inhibitor by itself. Also, DKK1 and sclerostin do not simultaneously bind to wild-type LRP5, and DKK1 is able to displace sclerostin from previously formed sclerostin–LRP5 complexes. In conclusion, our results indicate that DKK1 and sclerostin are independent, and not synergistic, regulators of LRP5 signaling and that the function of each is impaired by HBM-LRP5 mutations.