title: Gingival epithelial cells support osteoclastogenesis by producing receptor activator of nuclear factor kappa B ligand via protein kinase A signaling.
abstract: OBJECTIVE
  Periodontal disease is dental plaque-induced inflammatory disease of the periodontal tissues that results in bone loss in the affected teeth. During bone resorption, receptor activator of nuclear factor kappa B ligand (RANKL) is an essential factor that regulates osteoclastogenesis. Recently, we found that gingival epithelial cells (GECs) in periodontal tissue produce RANKL, the expression of which is regulated by tumor necrosis factor-α and protein kinase A signaling. In this study, we asked whether RANKL-producing GECs induce bone marrow macrophages (BMMs) to form osteoclasts in a co-culture system.
  
  
  METHODS
  Ca9-22 GECs and osteoclast precursor BMMs were co-cultured with or without the protein kinase A signaling activator forskolin or inhibitor H89 to examine whether the RANKL-producing GECs could be induced to form osteoclasts, as determined using a pit formation assay.
  
  
  RESULTS
  Osteoclasts formed spontaneously in co-cultures of Ca9-22 cells and BMMs, even in the absence of RANKL. The cells were cultured on bone slices for 14 d, at which time resorption pits were observed. Forskolin treatment significantly increased osteoclast numbers in these co-cultures, but forskolin alone did not induce osteoclast formation by BMMs.
  
  
  CONCLUSIONS
  GECs producing RANKL are able to support osteoclastogenesis in an in vitro co-culture system using GECs and BMMs, in a process promoted by forskolin.
authors.affiliation: Department of Cardiology and Periodontology, Division of Periodontology, Kyushu Dental University, Kitakyushu City, Fukuoka, Japan.|Department of Periodontology, Showa University School of Dentistry, Ohta-ku, Tokyo, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Usui
authors.affiliation: Department of Oral and Maxillofacial Surgery, Saitama Medical University, Iruma-gun, Saitama, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Sato
authors.affiliation: Department of Oral Pathology and Diagnosis, Showa University School of Dentistry, Shinagawa-ku, Tokyo, Japan.
authors.forename: G
authors.initials: G
authors.lastname: Yamamoto
authors.affiliation: Dental Clinic, Showa University Medical Hospital, Shinagawa-ku, Tokyo, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Okamatsu
authors.affiliation: Department of Cardiology and Periodontology, Division of Periodontology, Kyushu Dental University, Kitakyushu City, Fukuoka, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Hanatani
authors.affiliation: Department of Cardiology and Periodontology, Division of Periodontology, Kyushu Dental University, Kitakyushu City, Fukuoka, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Moritani
authors.affiliation: Department of Cardiology and Periodontology, Division of Periodontology, Kyushu Dental University, Kitakyushu City, Fukuoka, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Sano
authors.affiliation: Department of Periodontology, Showa University School of Dentistry, Ohta-ku, Tokyo, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Yamamoto
authors.affiliation: Department of Cardiology and Periodontology, Division of Periodontology, Kyushu Dental University, Kitakyushu City, Fukuoka, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Nakashima
mesh_terms: D001854:Bone Marrow Cells / Q000378:metabolism*; D002478:Cells, Cultured; D018920:Coculture Techniques; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism*; D005881:Gingiva / Q000166:cytology* / Q000378:metabolism; D006801:Humans; D008264:Macrophages / Q000378:metabolism*; D010010:Osteoclasts / Q000502:physiology*; D010012:Osteogenesis / Q000502:physiology*; D053245:RANK Ligand / Q000096:biosynthesis*
chemical_list: D053245:RANK Ligand; C505688:TNFSF11 protein, human; D017868:Cyclic AMP-Dependent Protein Kinases
keywords: PKA signaling; RANKL; gingival epithelial cell; osteoclast