PTH and PTHR1 in osteocytes. New insights into old partners.

Parathyroid hormone receptors are present in bone cells and play a crucial role in the maintenance of skeletal integrity, bone homeostasis and regulation of calcium and phosphate metabolism. Although the function of these receptors has long being recognized in the cells of the osteoblastic lineage regulating directly osteoblast differentiation and function and indirectly osteoclastogenesis, recent findings demonstrate their functional presence in osteocytes participating in the co-ordination of bone remodelling. In this review we focus on the key roles of these receptors in osteoblasts and osteocytes, combining what is known and what is new regarding these interesting pleiotropic hormone receptors.