title: Effect of hypoxia on the expression of RANKL/OPG in human periodontal ligament cells in vitro.
abstract: To investigate the impact of hypoxia on the expression of receptor activator of NF-kB ligand (RANKL) and osteoprotegerin (OPG) in human periodontal ligament cells (hPDLCs) in vitro. hPDLCs were incubated in a hypoxic atmosphere of 2% O2, 5% CO2, 94% N2 at 37°C for 6, 12, 24 and 48 h. After that, cell proliferation assay was determined using CCK-8 technique. SP immunocytochemistry method was performed to trace the expression of hypoxia-inducible factor 1 alpha (HIF-1α) in hPDLCs. The expression levels of RANKL and OPG were investigated using real-time PCR and ELISA. As a control, the cells were incubated at normoxic conditions of 20% O2, 5% CO2, 75% N2. All results were analyzed using one-way ANOVA at a significant level of P=0.05. OPG mRNA and protein levels were down-regulated meanwhile RANKL mRNA and soluble RANKL (sRANKL) protein levels were up-regulated after stimulated by hypoxia. The relative RANKL/OPG expression ratios were increased in both mRNA and protein levels. The expression of RANKL mRNA and sRANKL protein levels was enhanced significantly (P<0.05) under the hypoxia conditions at 12 h, 24 h and 48 h while OPG mRNA and protein were reduced significantly (P<0.05) at 12 h, 24 h and 48 h. Hypoxia can affect the expression of RANKL and OPG in hPDLCs, which constitute an important pathogenic event in the alveolar bone resorption. Lack of oxygen in periodontal tissue may accelerate the development of periodontitis.
authors.affiliation: Department of Periodontology, School and Hospital of Stomatology, Shandong Provincial Key Laboratory of Dental Tissue Regeneration, Shandong University Jinan, Shandong, People's Republic of China ; Department of Endodontics, Jinan Stomatological Hospital Jinan, Shandong, People's Republic of China.
authors.forename: Xi-Jiao
authors.initials: XJ
authors.lastname: Yu
authors.affiliation: Department of Periodontology, School and Hospital of Stomatology, Shandong Provincial Key Laboratory of Dental Tissue Regeneration, Shandong University Jinan, Shandong, People's Republic of China ; Department of Endodontics, Jinan Stomatological Hospital Jinan, Shandong, People's Republic of China.
authors.forename: Chang-Jie
authors.initials: CJ
authors.lastname: Xiao
authors.affiliation: Department of Endodontics, Jinan Stomatological Hospital Jinan, Shandong, People's Republic of China.
authors.forename: Yan-Mei
authors.initials: YM
authors.lastname: Du
authors.affiliation: Department of Periodontology, School and Hospital of Stomatology, Shandong Provincial Key Laboratory of Dental Tissue Regeneration, Shandong University Jinan, Shandong, People's Republic of China.
authors.forename: Shuang
authors.initials: S
authors.lastname: Liu
authors.affiliation: Department of Endodontics, Jinan Stomatological Hospital Jinan, Shandong, People's Republic of China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Du
authors.affiliation: Department of Periodontology, School and Hospital of Stomatology, Shandong Provincial Key Laboratory of Dental Tissue Regeneration, Shandong University Jinan, Shandong, People's Republic of China.
authors.forename: Shu
authors.initials: S
authors.lastname: Li
mesh_terms: D015687:Cell Hypoxia; D049109:Cell Proliferation / Q000502:physiology; D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007150:Immunohistochemistry; D010513:Periodontal Ligament / Q000378:metabolism*; D053245:RANK Ligand / Q000096:biosynthesis*; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D053245:RANK Ligand; C505688:TNFSF11 protein, human
keywords: Hypoxia; OPG; RANKL; hPDLCs