TOPGAL Mice Show That the Canonical Wnt Signaling Pathway Is Active During Bone Development and Growth and Is Activated by Mechanical Loading In Vitro

Abstract

Canonical Wnt signaling was active in several cell types in the fetal and neonatal skeleton, including chondrocytes, osteoblasts, and osteocytes. With age, activation of Wnt signaling became less prominent but persisted in chondrocytes and osteocytes. Although osteoblasts in culture expressed many different individual Wnt's and Wnt receptors, the TOPGAL transgene was not active in these cells at baseline. However, Wnt signaling was activated in these cells by physical deformation. Together with the activation of canonical Wnt signaling in osteocytes seen in vivo, these data suggest that Wnt signaling may be involved in the coupling of mechanical force to anabolic activity in the skeleton.