title: 1 alpha,25-dihydroxyvitamin D3 increases IGF binding protein-5 expression in cultured osteoblasts.
abstract: Rat osteoblasts produce insulin-like growth factors (IGFs) and IGF binding proteins (IGFBPs). Expression of IGFBP-5, an IGFBP which stimulates DNA synthesis of osteoblasts, was studied in vitro under the influence of 1 alpha,25-dihydroxyvitamin D3 (1,25(OH)2D3) and parathyroid hormone (PTH). These two calcium-regulating hormones stimulated the expression of IGFBP-5 mRNA in cultured rat osteoblasts at low concentrations (10 pM) and in a dose- and time-dependent manner. Intact IGFBP-5 was not detected in the culture medium, but was found attached to the cell layer. IGFBP-5 may thus direct IGFs to the sites of bone remodeling.
authors.affiliation: Department of Internal Medicine, University Hospital, Zürich, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Schmid
authors.forename: I
authors.initials: I
authors.lastname: Schläpfer
authors.forename: M A
authors.initials: MA
authors.lastname: Gosteli-Peter
authors.forename: C
authors.initials: C
authors.lastname: Hauri
authors.forename: E R
authors.initials: ER
authors.lastname: Froesch
authors.forename: J
authors.initials: J
authors.lastname: Zapf
mesh_terms: D000818:Animals; D002117:Calcitriol / Q000494:pharmacology*; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D006801:Humans; D018975:Insulin-Like Growth Factor Binding Protein 5 / Q000096:biosynthesis* / Q000235:genetics; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D010006:Osteoblasts / Q000187:drug effects* / Q000378:metabolism; D010281:Parathyroid Hormone / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats
chemical_list: D018975:Insulin-Like Growth Factor Binding Protein 5; D010281:Parathyroid Hormone; D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I; D002117:Calcitriol