What is the function of OPG?
OPG protects bone from excessive resorption by binding to RANKL and preventing it from binding to RANK. Thus, the relative concentration of RANKL and OPG in bone is a major determinant of bone mass and strength.
What is the role of RANKL?
RANKL, through its ability to stimulate osteoclast formation and activity, is a critical mediator of bone resorption and overall bone density. Overproduction of RANKL is implicated in a variety of degenerative bone diseases, such as rheumatoid arthritis and psoriatic arthritis.
What does bone resorption indicate?
Bone resorption is the destruction of bone tissues that promotes bone loss, that is, a decrease in bone mass and bone density.
What is RANKL in osteoporosis?
The interaction of RANK with its ligand (RANKL) has been identified as the final common pathway through which bone resorption is regulated [29]. By binding to its receptor RANK on osteoclastic precursors, RANKL controls the differentiation, proliferation, and survival of osteoclasts.
Is OPG a cytokine?
Osteoprotegerin (OPG), also known as osteoclastogenesis inhibitory factor (OCIF) or tumour necrosis factor receptor superfamily member 11B (TNFRSF11B), is a cytokine receptor of the tumour necrosis factor (TNF) receptor superfamily encoded by the TNFRSF11B gene.
What is OPG in osteoporosis?
Osteoprotegerin (OPG) is secreted by osteoblasts and osteogenic stromal stem cells and protects the skeleton from excessive bone resorption by binding to RANKL and preventing it from interacting with RANK. The RANKL/OPG ratio in bone marrow is thus an important determinant of bone mass in normal and disease states.
Is RANKL a cytokine?
RANKL is a key cytokine for inducing Aire expression in these epithelial cells, and it is provided by lymphoid tissue inducer (LTi) cells, single positive thymocytes, Vγ5+ γδ T cells, and invariant natural killer T (iNKT) cells (Fig. 2a) [60,61,62,63].
What stimulates OPG?
Estrogen stimulates OPG expression mainly at a transcriptional level through the estrogen receptor (ER), particularly ERα (13–15,18). Furthermore, an estrogen response element has been identified in the OPG promoter (19).
How is bone resorption measured?
Bone diseases occur when formation and resorption are uncoupled. Several assays are available that measure bone turnover markers (BTMs). These assays measure collagen breakdown products and other molecules released from osteoclasts and osteoblasts during the process of bone resorption and formation.
Does OPG inhibit bone resorption?
OPG also inhibits bone resorption in a variety of animal disease models, including ovariectomy-induced osteoporosis, humoral hypercalcemia of malignancy, and experimental bone metastasis. OPG might represent an effective therapeutic option for diseases associated with excessive osteoclast activity.
What is OPG gene?
What cell produces OPG?
Interestingly, human B cells have also been recognized as a significant source of OPG [3] although the significance of this discovery for bone biology was not immediately appreciated.
Does OPG bind to RANK or RANKL?
Osteoprotegerin (OPG) is secreted by osteoblasts and osteogenic stromal stem cells and protects the skeleton from excessive bone resorption by binding to RANKL and preventing it from interacting with RANK.
What is RANKL in rheumatoid arthritis?
RANKL stimulates osteoclast differentiation from monocyte/macrophage-lineage precursor cells, leading to bone erosion in rheumatoid arthritis. Denosumab specifically binds to RANKL and suppresses osteoclast differentiation.
What OPG inhibits?
OPG inhibits osteoclast differentiation and maturation and promotes their apoptosis in endothelial cells and in VSMCs and seems to play a key role in cell survival via its interaction with TNF-related apoptosis inducing ligand [127].
What is CTX test?
Information on the serum CTX Test This test is called the Collagen Type-1 C-Telopeptide (CTX) test. The serum CTX (C-Terminal Cross-Linking Telopeptide) measures the rate of bone turnover and can be affected with patients taking bone-sparing drugs for osteoporosis/osteopenia.
What does CTX measure?
Serum cross-linked C-telopeptide of type I collagen (CTX) is a marker of osteoclast activity and is used to assess the level of bone resorption.