title: Effects of inorganic polyphosphate on bone sialoprotein gene expression.
abstract: Inorganic polyphosphate (poly(P)) is a biopolymer existing in almost all cells and tissues. The biological functions of poly(P) in micro-organisms have been extensively investigated in studies of poly(P) in eukaryotic cells, especially osteoblasts, and are increasing. Bone sialoprotein (BSP) is thought to function in bone mineralization, and is selectively expressed by differentiated osteoblasts. In this study, application of sodium phosphate glass type 25 (SPG25, 12.5 and 125 microM) increased BSP mRNA levels at 12 h in osteoblast-like ROS 17/2.8 cells. In transient transfection assay, 12.5 and 125 microM SPG25 increased luciferase activities of the constructs pLUC3 (-116 to +60), pLUC4 (-425 to +60), pLUC5 (-801 to +60) and pLUC6 (-938 to +60). Introduction of 2 bp mutations to the luciferase constructs showed that the effects of SPG25 were mediated by a FGF2 response element (FRE) and a homeodomain protein binding site (HOX). Luciferase activities induced by SPG25 were blocked by tyrosine kinase inhibitor herbimycine A, MAP kinase kinase inhibitor U0126, PI3-kinase/Akt inhibitor LY249002 and inorganic phosphate transport inhibitor foscarnet. Gel shift analyses showed that both 12.5 and 125 microM SPG25 increased nuclear protein binding to FRE and HOX elements. These studies demonstrate that SPG25 stimulates BSP transcription by targeting FRE and HOX elements in the proximal promoter of the rat BSP gene.
authors.affiliation: Department of Periodontology, Nihon University School of Dentistry at Matsudo, Chiba, 271-8587, Japan.
authors.forename: Zhitao
authors.initials: Z
authors.lastname: Wang
authors.forename: Xinyue
authors.initials: X
authors.lastname: Li
authors.forename: Zhengyang
authors.initials: Z
authors.lastname: Li
authors.forename: Li
authors.initials: L
authors.lastname: Yang
authors.forename: Yoko
authors.initials: Y
authors.lastname: Sasaki
authors.forename: Shuang
authors.initials: S
authors.lastname: Wang
authors.forename: Liming
authors.initials: L
authors.lastname: Zhou
authors.forename: Shouta
authors.initials: S
authors.lastname: Araki
authors.forename: Masaru
authors.initials: M
authors.lastname: Mezawa
authors.forename: Hideki
authors.initials: H
authors.lastname: Takai
authors.forename: Yorimasa
authors.initials: Y
authors.lastname: Ogata
mesh_terms: D000818:Animals; D002460:Cell Line; D005786:Gene Expression Regulation; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism; D010006:Osteoblasts / Q000378:metabolism*; D011122:Polyphosphates / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D051381:Rats; D012795:Sialoglycoproteins / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D009687:Nuclear Proteins; D011122:Polyphosphates; D012795:Sialoglycoproteins