Osteoprotegerin (ORG) is a secreted protein that affects bone turnover and is implicated in heart and kidney disease. It is a glycoprotein of the TNF receptor superfamily 11b (gene name TNFRSF11B). OPG is synthesized as a monomer of 380 amino acids and is assembled as a homodimer within the cell and then secreted mainly as a disulfide-linked homodimer into the extracellular compartment. OPG is produced by many different tissues and cell types including osteoblasts. OPG is a negative regulator of bone resorption by acting as decoy receptor for RANKL, thus neutralizing its function in osteoclastogenesis. This glycoprotein is also involved in the regulation of vascular calcification. A recent study identifies OPG as an independent risk factor for all-cause mortality in patients after kidney transplantation. 982 prevalent kidney transplant (KT) recipients were followed up for all-cause mortality for 6 years. The researchers observed that each 1 pmol/L higher-serum OPG level was associated with a 49% higher risk of mortality.
Association between serum osteoprotegerin level and mortality in kidney transplant recipients. Gupta V et al., 2021. Transpl Int 19. doi: 10.1111/tri.13847. Epub ahead of print. PMID: 33606319.