Putative Membrane Receptor for 1,25(OH) 2 Vitamin D 3 in Human Mineralized Tissues During Prenatal Development

Abstract

The calciotropic hormone, 1,25(OH) 2 vitamin D 3 [1,25(OH) 2 D 3 ], controls the formation of dental and bone mineralized tissues. The role of nuclear 1,25(OH) 2 D 3 receptor has been extensively studied in the diverse secretory cells, i.e., osteoblasts, chondrocytes, ameloblasts, and odontoblasts. A nongenomic pathway also has been characterized and related to the interactions of 1,25(OH) 2 D 3 ligand with a putative cell membrane receptor. This recognition moiety called 1,25(OH) 2 vitamin D 3 membrane-associated, rapid-response steroid-binding [1,25D 3 -MARRS] protein is investigated here in the craniofacial skeleton of human embryos and fetuses. Immunolocalization using a specific Ab099 against chick intestinal basolateral 1,25D 3 -MARRS protein was performed. The data show a complementary expression pattern of the membrane receptor when compared with published data on the nuclear receptor, notably during amelogenesis. In mandible, membrane receptors for 1,25(OH) 2 D 3 were identified in the heterogenous bone cell population, including osteoblasts and osteoclasts. Differential 1,25D 3 -MARRS protein levels were observed in distinct developmental stages and anatomical sites of tooth and bone, suggesting the existence of cross-talk between local factors and 1,25D 3 -MARRS protein expression.