title: 1α,25-dihydroxyvitamin D₃ rapidly modulates Ca(2+) influx in osteoblasts mediated by Ca(2+) channels.
abstract: The biologically active form of vitamin D, 1α,25-dihydroxy vitamin D₃ (VD), regulates the synthesis of the bone Ca-binding proteins osteocalcin and osteopontin. The actions of VD are mediated through the vitamin D receptor (VDR). Liganded VDR heterodimerizes with the retinoid X receptor and interacts with a vitamin D response element (VDRE). Recently, it has been demonstrated that vitamin D responses elicited in osteoblasts can be rapid as well as long-term. The purpose of this study was to elucidate the mechanism of Ca(2+) signaling of VD in osteoblasts using intracellular Ca(2+) ([Ca(2+)]i) measurements. A rapid VD (10 nM)-induced increase in [Ca(2+)]i was observed within 40 sec. This increase, however, was negated with application of Ca(2+)-free Krebs' solution. These results indicate that VD induces an increase in [Ca(2+)]i from extracellular Ca(2+) in osteoblasts.
authors.affiliation: Department of Orthodontics, Tokyo Dental College, Chiba, Japan.
authors.forename: Yushi
authors.initials: Y
authors.lastname: Uchida
authors.forename: Takayuki
authors.initials: T
authors.lastname: Endoh
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Shibukawa
authors.forename: Masakazu
authors.initials: M
authors.lastname: Tazaki
authors.forename: Kenji
authors.initials: K
authors.lastname: Sueishi
mesh_terms: D016475:3T3 Cells; D000818:Animals; D002117:Calcitriol / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism*; D020013:Calcium Signaling; D051379:Mice; D010006:Osteoblasts / Q000378:metabolism*; D018167:Receptors, Calcitriol / Q000378:metabolism*; D030181:Vitamin D Response Element / Q000502:physiology
chemical_list: D015220:Calcium Channels; D018167:Receptors, Calcitriol; D002117:Calcitriol; D002118:Calcium