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OPG/RANK/RANKL System

Meaning

The OPG/RANK/RANKL System is a critical, tripartite molecular signaling pathway that functions as the master regulator of bone remodeling, balancing the activity of bone-resorbing osteoclasts and bone-forming osteoblasts. OPG (Osteoprotegerin) is a soluble decoy receptor that blocks the binding of RANKL (Receptor Activator of Nuclear factor Kappa-B Ligand) to its receptor, RANK, on pre-osteoclast cells. The ratio of OPG to RANKL is a key determinant of bone density; a higher OPG/RANKL ratio promotes bone preservation, while a lower ratio drives bone loss. This system is significantly influenced by sex hormones, particularly estrogen.