Receptor activator of nuclear factor κ B (RANK) signaling pathway (RANK signaling pathway)

The **RANK signaling pathway** centers on the interaction between *receptor activator of nuclear factor κ B* (**RANK**, also known as TNFRSF11A) expressed on osteoclast precursors/mature osteoclasts and its ligand *receptor activator for nuclear factor κ B ligand* (**RANKL**) produced by osteoblasts/stromal cells/T cells. Binding triggers trimerization and recruitment of adaptor proteins such as TRAFs 2/3/5/6—which activate downstream cascades including NFκB, MAPK/JNK/AP1/NFATc1 pathways—leading to gene transcription that drives differentiation/survival/activity of osteoclasts essential for normal bone remodeling. The decoy receptor *osteoprotegerin* (**OPG**) regulates this process by sequestering excess RANKL. Beyond skeletal homeostasis, this axis plays roles in immune cell function/regulation—including lymph node organogenesis—and mammary gland development. Dysregulation contributes to diseases such as osteoporosis (excessive activity) or osteopetrosis/malignant infantile forms when defective. Therapeutically targeting this axis—most notably via anti-RANKL antibody denosumab—has proven effective at reducing pathological bone loss in osteoporosis/metastatic cancers but carries risks related to impaired physiological remodeling/immunity.

Other names

RANK/RANKL/OPG signaling pathwayRANKL–RANK–OPG systemTRANCE-R/TRANCE receptorOsteoclast differentiation and activation receptor (ODAR)TNFRSF11A signaling

Drugs like denosumab act as monoclonal antibodies against RANKL, preventing it from binding to RANK on osteoclast precursors. This inhibits osteoclast formation, function, survival—and thus reduces bone resorption.