[Pathways regulating bone formation: a complex network]

Bone tissue undergoes permanent remodeling based on the coupled activity of osteoclasts resorbing old bone and osteoblasts forming a new matrix. The latter are considered as the main target of remodeling control pathways. Indeed, they have the full control of osteoclastogenesis through RANK-L / osteoprotegerin, the most critical pathway in the balance between bone formation and resorption. They also are under the effects of numerous transcription factors, especially members of the AP1 complex as well as the canonic Wnt - betacatenin pathway. Most bone tissue pathologies are mediated by alterations of these remodeling control pathways. Therefore, lots of efforts are made to modulate these factors which are very interesting potential therapeutic targets.