Osteoprotegerin disrupts peripheral adhesive structures of osteoclasts by modulating Pyk2 and Src activities

Osteoprotegerin has previously been shown to modulate bone mass by blocking osteoclast maturation and function.The detailed mechanisms of osteoprotegerin-induced disassembly of podosomes,disruption of adhesive structures and modulation of adhesion-related proteins in osteoclasts,however,are not well characterized.In this study,tartrate-resistant acidic phosphatase staining demonstrated that osteoprotegerin inhibited differentiation of osteoclasts.The use of scanning electron microscopy,real-time cell monitoring and confocal microscopy indicated that osteoclasts responded in a time and dose-dependent manner to osteoprotegerin treatments with retraction of peripheral adhesive structures and detachment from the extracellular substrate.Combined imaging and Western blot studies showed that osteoprotegerin induced dephosphorylation of Tyr 402 in Pyk2 and decreased its labeling in peripheral adhesion regions.Osteoprotegerin induced increased intracellular labeling of Tyr 402 in Pyk2,Tyr416 in Src,increased dephospho