The Extracellular Calcium-Sensing Receptor (CaSR) Is a Critical Modulator of Skeletal Development

The extracellular Ca2+-sensing receptor (CaSR) plays a nonredundant role in the functions of the parathyroid gland (PTG) and the kidney. Severe hyperparathyroidism, premature death, and incomplete gene excision in Casr(-/-) mice have precluded the assessment of CaSR function in other tissues. We generated mice with tissue-specific deletion of Casr in the PTG, bone, or cartilage. Deletion of Casr in the PTG or bone resulted in profound bone defects, whereas deletion of Casr in chondrocytes (cartilage-producing cells) resulted in death before embryonic day 13 (E13). Mice in which chondrocyte-specific deletion of Casr was induced between E16 and E18 were viable but showed delayed growth plate development. Our data show a critical role for the CaSR in early embryogenesis and skeletal development.