Parathyroid hormone receptor 1 (PTH1R) (PTH1R)

The term "Osteoclast functional response to parathyroid hormone" refers to a physiological outcome rather than a specific protein; however, the primary molecular target mediating this effect is the Parathyroid hormone receptor 1 (PTH1R). PTH1R is a Class B G protein-coupled receptor primarily expressed on osteoblasts and osteocytes, where it regulates bone metabolism and systemic calcium levels (UniProt: Q03431). Although the input name focuses on osteoclasts, PTH does not typically act directly on mature osteoclasts; instead, it stimulates osteoblasts to increase the RANKL/OPG ratio, which indirectly promotes osteoclastogenesis and bone resorption (PubMed: 17002574). Intermittent administration of PTH1R agonists, such as teriparatide, promotes bone formation and is a standard treatment for severe osteoporosis (StatPearls: NBK499940). Conversely, continuous exposure to high PTH levels, as seen in hyperparathyroidism, leads to excessive osteoclast activity and bone loss. Monitoring of bone turnover markers like CTX and P1NP is often used to assess the efficacy of drugs targeting this pathway.

Other names

Parathyroid hormone 1 receptorPTH/PTHrP receptorPTHR1PTHR

Agonism of the Parathyroid hormone receptor 1 (PTH1R) activates the Gs/adenylyl cyclase/cAMP and Gq/phospholipase C/calcium signaling pathways, which indirectly stimulates osteoclast activity through the upregulation of RANKL in osteoblasts (PubMed: 17002574).