title: Angiotensin II suppresses osteoblastic differentiation and mineralized nodule formation via AT1 receptor in ROS17/2.8 cells.
abstract: BACKGROUND
  Angiotensin II (Ang II) not only regulates systemic blood pressure through a vasoconstrictive effect, but also promotes bone resorption. We recently reported that Ang II (10(-6) M) stimulated the production of matrix metalloproteinases via the AT1 receptor in osteoblastic ROS17/2.8 cells, but suppressed alkaline phosphatase activity. However, the roles of Ang II in osteoblastic differentiation and the function of osteogenesis in osteoblasts are unclear. Therefore, we examined the effect of Ang II on the expression of osteogenesis-related transcription factors and extracellular matrix (ECM) proteins, as well as mineralized nodule formation in ROS17/2.8 cells.
  
  
  METHODS
  ROS17/2.8 cells were cultured with 0 (control) or 10(-6) M Ang II in the presence or absence of the AT1 receptor blocker losartan. Mineralized nodule formation was detected by Alizarin Red staining. Gene and protein expression levels of transcription factors and ECM proteins were determined using real-time PCR and Western blotting, respectively.
  
  
  RESULTS
  Runx2, Msx2, and osteocalcin expression significantly decreased with Ang II compared to the control, whereas AJ18 expression significantly increased. Osterix, Dlx5, type I collagen, bone sialoprotein, and osteopontin expression was unaffected. Mineralized nodule formation and calcium content in mineralized nodules decreased with Ang II. Losartan blocked suppressive or stimulatory effects of Ang II on Runx2, Msx2, osteocalcin, and AJ18 expression.
  
  
  CONCLUSIONS
  These results suggest that Ang II suppresses osteoblastic differentiation by altering the expression of osteogenesis-related transcription factors via the AT1 receptor and the function of osteogenesis in ROS17/2.8 cells.
authors.affiliation: Division of Oral Health Sciences, Nihon University Graduate School of Dentistry, Tokyo, Japan.
authors.forename: Kumiko
authors.initials: K
authors.lastname: Nakai
authors.affiliation: Department of Oral Health Sciences, Nihon University School of Dentistry, Tokyo, Japan ; Division of Functional Morphology, Dental Research Center, Nihon University School of Dentistry, Tokyo, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Kawato
authors.affiliation: Department of Oral Health Sciences, Nihon University School of Dentistry, Tokyo, Japan ; The Lion Foundation for Dental Health, Tokyo, Japan.
authors.forename: Toyoko
authors.initials: T
authors.lastname: Morita
authors.affiliation: The Lion Foundation for Dental Health, Tokyo, Japan.
authors.forename: Yoji
authors.initials: Y
authors.lastname: Yamazaki
authors.affiliation: Department of Oral Health Sciences, Nihon University School of Dentistry, Tokyo, Japan ; Division of Functional Morphology, Dental Research Center, Nihon University School of Dentistry, Tokyo, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Tanaka
authors.affiliation: Department of Oral and Maxillofacial Surgery, Nihon University School of Dentistry, Tokyo, Japan.
authors.forename: Morio
authors.initials: M
authors.lastname: Tonogi
authors.affiliation: Department of Oral and Maxillofacial Surgery, Nihon University School of Dentistry, Tokyo, Japan ; Division of Immunology and Pathobiology, Dental Research Center, Nihon University School of Dentistry, Tokyo, Japan.
authors.forename: Hidero
authors.initials: H
authors.lastname: Oki
authors.affiliation: Department of Oral Health Sciences, Nihon University School of Dentistry, Tokyo, Japan ; Division of Functional Morphology, Dental Research Center, Nihon University School of Dentistry, Tokyo, Japan.
authors.forename: Masao
authors.initials: M
authors.lastname: Maeno
keywords: angiotensin; extracellular matrix proteins; osteoblast; transcription factors