title: Aggregatibacter actinomycetemcomitans lipopolysaccharide regulates bone sialoprotein gene transcription.
abstract: Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) is believed to be associated with aggressive periodontitis characterized by a rapid bone loss. A. actinomycetemcomitans lipopolysaccharide (LPS) has a similar structure to Escherichia coli LPS, and they are Toll-like receptor 4 agonists. Bone sialoprotein (BSP) is an early marker of osteoblast differentiation. To investigate the effects of A. actinomycetemcomitans LPS on bone formation, we targeted BSP as a marker for osteogenic differentiation and bone formation. BSP mRNA levels were decreased by 0.1 µg/ml and increased by 0.01 µg/ml A. actinomycetemcomitans LPS at 6 h in osteoblast-like ROS17/2.8 cells. In transient transfection analyses, 0.1 µg/ml decreased and 0.01 µg/ml A. actinomycetemcomitans LPS increased luciferase activities of the construct (-116 to +60). Introduction of 2 bp mutations to the constructs showed that the effects of A. actinomycetemcomitans LPS were mediated by a cAMP response element (CRE), a FGF2 response element (FRE), and a homeodomain protein-binding site (HOX). Tyrosine kinase, ERK1/2, and PI3-kinase/Akt participated in the effects of both 0.1 and 0.01 µg/ml A. actinomycetemcomitans LPS. The results of gel shift showed that 0.1 µg/ml decreased while 0.01 µg/ml A. actinomycetemcomitans LPS increased CRE-, FRE-, and HOX-binding protein complexes formation at 6 h, and revealed that 0.01 µg/ml A. actinomycetemcomitans LPS induced BSP transcription through CREB1, JunD, Fra2, c-Fos, Runx2, Dlx5, and Smad1 targeting those response elements. These studies therefore indicated that 0.1 µg/ml suppressed and 0.01 µg/ml A. actinomycetemcomitans LPS increased BSP gene transcription mediated through CRE, FRE, and HOX elements in the rat BSP gene promoter.
authors.affiliation: Department of Periodontology, Nihon University School of Dentistry at Matsudo, Chiba 271-8587, Japan.
authors.forename: Xinyue
authors.initials: X
authors.lastname: Li
authors.forename: Liming
authors.initials: L
authors.lastname: Zhou
authors.forename: Hideki
authors.initials: H
authors.lastname: Takai
authors.forename: Yoko
authors.initials: Y
authors.lastname: Sasaki
authors.forename: Masaru
authors.initials: M
authors.lastname: Mezawa
authors.forename: Zhengyang
authors.initials: Z
authors.lastname: Li
authors.forename: Zhitao
authors.initials: Z
authors.lastname: Wang
authors.forename: Li
authors.initials: L
authors.lastname: Yang
authors.forename: Shuang
authors.initials: S
authors.lastname: Wang
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Matsumura
authors.forename: Takashi
authors.initials: T
authors.lastname: Kaneko
authors.forename: Atsutoshi
authors.initials: A
authors.lastname: Yoshimura
authors.forename: Yorimasa
authors.initials: Y
authors.lastname: Ogata
mesh_terms: D016976:Aggregatibacter actinomycetemcomitans / Q000737:chemistry*; D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D045744:Cell Line, Tumor; D047369:Chromatin Immunoprecipitation; D024202:Electrophoretic Mobility Shift Assay; D058574:Integrin-Binding Sialoprotein / Q000235:genetics / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D010006:Osteoblasts / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D060888:Real-Time Polymerase Chain Reaction; D014158:Transcription, Genetic / Q000187:drug effects / Q000235:genetics
chemical_list: D058574:Integrin-Binding Sialoprotein; D008070:Lipopolysaccharides