title: Calcilytic Ameliorates Abnormalities of Mutant Calcium-Sensing Receptor (CaSR) Knock-In Mice Mimicking Autosomal Dominant Hypocalcemia (ADH).
abstract: Activating mutations of calcium-sensing receptor (CaSR) cause autosomal dominant hypocalcemia (ADH). ADH patients develop hypocalcemia, hyperphosphatemia, and hypercalciuria, similar to the clinical features of hypoparathyroidism. The current treatment of ADH is similar to the other forms of hypoparathyroidism, using active vitamin D3 or parathyroid hormone (PTH). However, these treatments aggravate hypercalciuria and renal calcification. Thus, new therapeutic strategies for ADH are needed. Calcilytics are allosteric antagonists of CaSR, and may be effective for the treatment of ADH caused by activating mutations of CaSR. In order to examine the effect of calcilytic JTT-305/MK-5442 on CaSR harboring activating mutations in the extracellular and transmembrane domains in vitro, we first transfected a mutated CaSR gene into HEK cells. JTT-305/MK-5442 suppressed the hypersensitivity to extracellular Ca(2+) of HEK cells transfected with the CaSR gene with activating mutations in the extracellular and transmembrane domains. We then selected two activating mutations locating in the extracellular (C129S) and transmembrane (A843E) domains, and generated two strains of CaSR knock-in mice to build an ADH mouse model. Both mutant mice mimicked almost all the clinical features of human ADH. JTT-305/MK-5442 treatment in vivo increased urinary cAMP excretion, improved serum and urinary calcium and phosphate levels by stimulating endogenous PTH secretion, and prevented renal calcification. In contrast, PTH(1-34) treatment normalized serum calcium and phosphate but could not reduce hypercalciuria or renal calcification. CaSR knock-in mice exhibited low bone turnover due to the deficiency of PTH, and JTT-305/MK-5442 as well as PTH(1-34) increased bone turnover and bone mineral density (BMD) in these mice. These results demonstrate that calcilytics can reverse almost all the phenotypes of ADH including hypercalciuria and renal calcification, and suggest that calcilytics can become a novel therapeutic agent for ADH.
authors.affiliation: Department of Medicine and Bioregulatory Sciences, University of Tokushima Graduate School of Medical Sciences, Tokushima, Japan.
authors.forename: Bingzi
authors.initials: B
authors.lastname: Dong
authors.affiliation: Department of Medicine and Bioregulatory Sciences, University of Tokushima Graduate School of Medical Sciences, Tokushima, Japan.
authors.forename: Itsuro
authors.initials: I
authors.lastname: Endo
authors.affiliation: Department of Medicine and Bioregulatory Sciences, University of Tokushima Graduate School of Medical Sciences, Tokushima, Japan.
authors.forename: Yukiyo
authors.initials: Y
authors.lastname: Ohnishi
authors.affiliation: Department of Medicine and Bioregulatory Sciences, University of Tokushima Graduate School of Medical Sciences, Tokushima, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kondo
authors.affiliation: Department of Developmental Biology of Hard Tissue, Hokkaido University Graduate School of Dental Medicine, Sapporo, Japan.
authors.forename: Tomoka
authors.initials: T
authors.lastname: Hasegawa
authors.affiliation: Department of Developmental Biology of Hard Tissue, Hokkaido University Graduate School of Dental Medicine, Sapporo, Japan.
authors.forename: Norio
authors.initials: N
authors.lastname: Amizuka
authors.affiliation: Animal Resource Development Unit, RIKEN Center for Life Science Technologies, Kobe, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kiyonari
authors.affiliation: Genetic Engineering Team, RIKEN Center for Life Science Technologies, Kobe, Japan.
authors.forename: Go
authors.initials: G
authors.lastname: Shioi
authors.affiliation: Department of Medicine and Bioregulatory Sciences, University of Tokushima Graduate School of Medical Sciences, Tokushima, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Abe
authors.affiliation: Fujii Memorial Institute of Medical Sciences, Tokushima University, Tokushima, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Fukumoto
authors.affiliation: Fujii Memorial Institute of Medical Sciences, Tokushima University, Tokushima, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Matsumoto
mesh_terms: D000818:Animals; D001483:Base Sequence; D001565:Benzoates / Q000494:pharmacology / Q000627:therapeutic use*; D016723:Bone Remodeling / Q000187:drug effects; D001842:Bone and Bones / Q000187:drug effects / Q000473:pathology; D002118:Calcium / Q000378:metabolism; D004195:Disease Models, Animal; D000089703:Fibroblast Growth Factor-23; D055879:Gene Knock-In Techniques; D057809:HEK293 Cells; D006801:Humans; D053565:Hypercalciuria / Q000188:drug therapy* / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology; D006996:Hypocalcemia / Q000188:drug therapy* / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology; D007011:Hypoparathyroidism / Q000151:congenital* / Q000188:drug therapy / Q000235:genetics / Q000473:pathology / Q000503:physiopathology; D051379:Mice; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics*; D009929:Organ Size / Q000187:drug effects; D010641:Phenotype; D011412:Propanolamines / Q000494:pharmacology / Q000627:therapeutic use*; D044169:Receptors, Calcium-Sensing / Q000235:genetics*
chemical_list: D001565:Benzoates; C000717427:FGF23 protein, human; C000717428:Fgf23 protein, mouse; C568849:JTT 305; D050505:Mutant Proteins; D011412:Propanolamines; D044169:Receptors, Calcium-Sensing; D000089703:Fibroblast Growth Factor-23; D002118:Calcium
keywords: BONE MODELING AND REMODELING; DISORDERS OF CALCIUM/PHOSPHATE METABOLISM; FGF23; GENETIC ANIMAL MODELS; HORMONE REPLACEMENT/RECEPTOR MODULATORS; PTH; VITAMIN D