title: Jagged1 inhibits osteoprotegerin expression by human periodontal ligament cells.
abstract: OBJECTIVE
  Notch signaling regulates bone homeostasis. The present study investigated the effect of Jagged1 on osteoprotegerin (OPG) and receptor activator of nuclear factor kappa-B ligand (RANKL) expression in human periodontal ligament stromal (hPDL) cells.
  
  
  METHODS
  hPDL cells were seeded on to indirect immobilized Jagged1 surfaces. OPG expression was determined using real-time polymerase chain reaction and enzyme-linked immunosorbent assay. Lentiviral small hairpin RNA particles against NOTCH2 were employed to inhibit NOTCH2 expression. Osteoclast formation was evaluated using RAW264.7 cells. An influence of exogenous OPG on osteogenic differentiation was determined by real-time polymerase chain reaction and Alizarin Red S staining.
  
  
  RESULTS
  Jagged1 significantly enhanced HES1 and HEY1mRNA expression in a dose-dependent manner. Furthermore, OPG mRNA and protein levels dramatically decreased upon exposing hPDL cells to Jagged1. However, RANKL mRNA levels were not significantly different. There was also no difference in M-CSF and MCP-1mRNA expression. A γ-secretase inhibitor and cycloheximide treatment rescued Jagged1-attenuated OPG expression. Furthermore, shNOTCH2 overexpressing hPDL cells did not exhibit a decrease in OPG expression upon exposure to Jagged1, implying the involvement of NOTCH2 in the regulatory mechanism. Culturing RAW264.7 cells with conditioned medium from Jagged1-treated hPDL cells enhanced osteoclast formation compared with those cultured with conditioned medium of the control group. Lastly, OPG treatment did not influence osteogenic differentiation by hPDL cells.
  
  
  CONCLUSIONS
  These results suggest that Jagged1 activates Notch signaling in hPDL cells, leading to decreased OPG expression. This may imply an indirect role of Jagged1 on the regulation of osteoclast differentiation via hPDL cells.
authors.affiliation: Mineralized Tissue Research Unit, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.|Department of Anatomy, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.
authors.forename: J
authors.initials: J
authors.lastname: Manokawinchoke
authors.affiliation: Mineralized Tissue Research Unit, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.|Department of Anatomy, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.
authors.forename: P
authors.initials: P
authors.lastname: Sumrejkanchanakij
authors.affiliation: Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.
authors.forename: K
authors.initials: K
authors.lastname: Subbalekha
authors.affiliation: Mineralized Tissue Research Unit, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.|Department of Anatomy, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.
authors.forename: P
authors.initials: P
authors.lastname: Pavasant
authors.affiliation: Mineralized Tissue Research Unit, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.|Department of Anatomy, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.
authors.forename: T
authors.initials: T
authors.lastname: Osathanon
mesh_terms: D015153:Blotting, Western; D002454:Cell Differentiation / Q000502:physiology; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D000072100:Jagged-1 Protein / Q000494:pharmacology / Q000502:physiology*; D053244:Osteoprotegerin / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010513:Periodontal Ligament / Q000166:cytology / Q000378:metabolism*; D053245:RANK Ligand / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology
chemical_list: D000072100:Jagged-1 Protein; D053244:Osteoprotegerin; D053245:RANK Ligand
keywords: 
  DAPT
  ; Jagged1; Notch2; osteoprotegerin; periodontal ligament; receptor activator of nuclear factor kappa-B ligand