J0270101 Interaction measurement of Wnt signal receptor and its regulators using AFM

Bone remodeling, which plays an important role in maintaining bone homeostasis and its structural adaptation to mechanical environment, is regulated by various kinds of molecular signals. Wnt signaling is one of the most important factors in bone remodeling, particularly in bone formation. To reveal the Wnt signaling and its inhibition mechanisms, we measured the interaction between Wnt signal receptor, LRP5, and its signaling molecules, Wnt3a, Dkk1, and Sclerostin, by using Atomic Force Microscope (AFM). In this study, we calculated the dissociation constants of Wnt3a/LRP5, sclerostin/LRP5, and Dkk1/LRP5, and it was proved that the dissociation constant of Dkk1/LRP5 is about 10-times smaller than that of sclerostin/LRP5, that is, the bond life time of Dkk1/LRP5 was about 10-times longer than that of sclerostin/LRP5. As the results, we quantitatively verified a previous suggestion that Dkk1 may function as a main regulator of Wnt signaling, and that sclerostin, which is more selective in its activity and restricted in its expression, may function as a more refined regulator of Wnt signaling.