title: Role of the calcium-sensing receptor in extracellular calcium homeostasis.
abstract: Maintaining a constant level of blood Ca(2+) is essential because of calcium's myriad intracellular and extracellular roles. The CaSR plays key roles in maintaining [Formula: see text] homeostasis by detecting small changes in blood Ca(2+) and modulating the production/secretion of the Ca(2+)-regulating hormones, PTH, CT, FGF23 and 1,25(OH)2D3, so as to appropriately regulate Ca(2+) transport into or out of blood via kidney, intestine, and/or bone. When Ca(2+) is high, the CaSR suppresses PTH synthesis and secretion, promotes its degradation, and inhibits parathyroid cellular proliferation. It has just the opposite effects on the C-cell, stimulating CT when [Formula: see text] is high. In bone, Ca(2+), acting via the CaSR, stimulates recruitment and proliferation of preosteoblasts, their differentiation to mature osteoblasts, and synthesis and mineralization of bone proteins. Conversely, [Formula: see text] inhibits the formation and activity and promotes apoptosis of osteoclasts, likely via the CaSR. These actions tend to mobilize skeletal Ca(2+) during [Formula: see text] deficiency and retain it when Ca(2+) is plentiful.
authors.affiliation: Division of Endocrinology, Diabetes and Hypertension, EBRC 223A, Brigham and Women's Hospital, 221 Longwood Ave., Boston, MA 02115, USA. embrown@partners.org
authors.forename: Edward M
authors.initials: EM
authors.lastname: Brown
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000378:metabolism*; D002116:Calcitonin / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology*; D000089703:Fibroblast Growth Factor-23; D006706:Homeostasis / Q000502:physiology*; D006801:Humans; D010006:Osteoblasts / Q000378:metabolism; D010010:Osteoclasts / Q000378:metabolism; D044169:Receptors, Calcium-Sensing / Q000502:physiology*
chemical_list: C000717427:FGF23 protein, human; D044169:Receptors, Calcium-Sensing; D000089703:Fibroblast Growth Factor-23; D002116:Calcitonin; D002118:Calcium
keywords: 1,25(OH)(2)D(3); PTH; calcitonin; calcium; calcium-sensing receptor; extracellular; osteoblast; osteoclast