[Regulatory mechanism of calcium metabolism.]
It is often difficult for terrestrial animals to take enough calcium. To maintain serum or extracellular calcium levels is very important for muscle and nerve function. Two major regulators to increase the serum calcium levels are parathyroid hormone(PTH)and vitamin D. PTH binds to the G protein coupling receptor, PTH1R, and increases intracellular cAMP levels. Impirement in the PTH signalling causes many diseases such as pseudohypoparathyroidism and acrodysostosis with hormone resistance. Vitamin D is activated to 1,25-dihydroxyvitamin D[1,25(OH)2D]by two steps of hydroxylation which occurs in the Liver and Kidney. Then, 1,25(OH)2D binds to vitamin D receptor(VDR), which works as a ligand-dependent transcription factor. Hypocalcemia and hypercalcemia are caused by various disorders including abnormal regulation of PTH and vitamin D production and their signal transduction.
Department of Pediatrics Osaka University Graduate School of Medicine, Japan.
Keiichi
K
Ozono
D000818:Animals; D002117:Calcitriol / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D006801:Humans; D010281:Parathyroid Hormone / Q000378:metabolism; D010766:Phosphorylation; D044169:Receptors, Calcium-Sensing / Q000378:metabolism; D015398:Signal Transduction
D010281:Parathyroid Hormone; D044169:Receptors, Calcium-Sensing; D002117:Calcitriol; D002118:Calcium