Coupling of bone formation and resorption

Abstract

Bone is continually renewed by the “remodeling” process, which occurs asynchronously at multiple sites throughout the skeleton. During remodeling, osteoclasts resorb a portion of bone, which, after the reversal phase, is replaced by osteoblast-mediated bone formation. The unidirectional process mediating the progression from bone resorption to bone formation is termed “coupling.” For bone mass to be maintained, coupling must be balanced. In this chapter, we review mechanisms of coupling that initiate bone formation on surfaces that have been resorbed. These include: (1) the supply of osteoclast-derived factors (by release from the resorbed matrix or by protein expression by the osteoclast) t..