title: Gap-junction-mediated communication in human periodontal ligament cells.
abstract: Periodontal tissue homeostasis depends on a complex cellular network that conveys cell-cell communication. Gap junctions (GJs), one of the intercellular communication systems, are found between adjacent human periodontal ligament (hPDL) cells; however, the functional GJ coupling between hPDL cells has not yet been elucidated. In this study, we investigated functional gap-junction-mediated intercellular communication in isolated primary hPDL cells. SEM images indicated that the cells were in contact with each other via dendritic processes, and also showed high anti-connexin43 (Cx43) immunoreactivity on these processes. Gap-junctional intercellular communication (GJIC) among hPDL cells was assessed by fluorescence recovery after a photobleaching (FRAP) analysis, which exhibited dye coupling between hPDL cells, and was remarkably down-regulated when the cells were treated with a GJ blocker. Additionally, we examined GJs under hypoxic stress. The fluorescence recovery and expression levels of Cx43 decreased time-dependently under the hypoxic condition. Exposure to GJ inhibitor or hypoxia increased RANKL expression, and decreased OPG expression. This study shows that GJIC is responsible for hPDL cells and that its activity is reduced under hypoxia. This is consistent with the possible role of hPDL cells in regulating the biochemical reactions in response to changes in the hypoxic environment.
authors.affiliation: Division of Orthodontics and Dentofacial Orthopedics, Tohoku University Graduate School of Dentistry, Sendai, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Kato
authors.forename: Y
authors.initials: Y
authors.lastname: Ishihara
authors.forename: N
authors.initials: N
authors.lastname: Kawanabe
authors.forename: K
authors.initials: K
authors.lastname: Sumiyoshi
authors.forename: Y
authors.initials: Y
authors.lastname: Yoshikawa
authors.forename: M
authors.initials: M
authors.lastname: Nakamura
authors.forename: Y
authors.initials: Y
authors.lastname: Imai
authors.forename: T
authors.initials: T
authors.lastname: Yanagita
authors.forename: H
authors.initials: H
authors.lastname: Fukushima
authors.forename: H
authors.initials: H
authors.lastname: Kamioka
authors.forename: T
authors.initials: T
authors.lastname: Takano-Yamamoto
authors.forename: T
authors.initials: T
authors.lastname: Yamashiro
mesh_terms: D000293:Adolescent; D000328:Adult; D000073861:Apelin; D002450:Cell Communication / Q000502:physiology*; D018929:Cell Culture Techniques; D015687:Cell Hypoxia / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D018031:Connexin 43 / Q000032:analysis; D003676:Deferoxamine / Q000494:pharmacology; D003712:Dendrites / Q000648:ultrastructure; D015536:Down-Regulation; D005260:Female; D005452:Fluoresceins; D036681:Fluorescence Recovery After Photobleaching; D005456:Fluorescent Dyes; D017629:Gap Junctions / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D006034:Glycyrrhetinic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000032:analysis; D036341:Intercellular Signaling Peptides and Proteins / Q000032:analysis; D008297:Male; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D053244:Osteoprotegerin / Q000032:analysis; D010513:Periodontal Ligament / Q000166:cytology* / Q000648:ultrastructure; D053245:RANK Ligand / Q000032:analysis; D017262:Siderophores / Q000494:pharmacology; D013997:Time Factors; D055815:Young Adult
chemical_list: C115436:APLN protein, human; D000073861:Apelin; D018031:Connexin 43; D005452:Fluoresceins; D005456:Fluorescent Dyes; C500216:GJA1 protein, human; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D036341:Intercellular Signaling Peptides and Proteins; D053244:Osteoprotegerin; D053245:RANK Ligand; D017262:Siderophores; C505688:TNFSF11 protein, human; C119129:18alpha-glycyrrhetinic acid; C085925:calcein AM; D003676:Deferoxamine; D006034:Glycyrrhetinic Acid
keywords: Connexin43; cell communication; fluorescence recovery after photobleaching; gap junctions; hypoxia; periodontal ligament