title: Estrogen regulates expression of osteoprotegerin and RANKL in human periodontal ligament cells through estrogen receptor beta.
abstract: BACKGROUND
  The function of periodontal ligament (PDL) cells may be affected by estrogen. PDL cells synthesize the receptor activator of nuclear factor-kappa B ligand (RANKL) and its decoy receptor, namely, osteoprotegerin (OPG), which directly controls osteoclastogenesis. The primary aim of this study was to investigate how estrogen affects the expression of OPG and RANKL in human PDL (hPDL) cells.
  
  
  METHODS
  We used a short interfering RNA technique to inhibit estrogen receptor beta (ERbeta) expression in hPDL cells; the cells were cultured with a saturating concentration of 17beta-estradiol (10(7) M) for 48 hours. Changes in the expression of OPG and RANKL were determined by reverse transcription-polymerase chain reaction and supported by Western blot analysis.
  
  
  RESULTS
  Estradiol caused an increase in OPG expression and decreased RANKL expression in hPDL cells. However, it had no effect on the expression of OPG and RANKL in hPDL-siERbeta (the short interfering RNA to block ER beta) cells.
  
  
  CONCLUSIONS
  Estrogen may play an important role in exerting antiresorptive effects on alveolar bone, at least in part, by increasing the expression level of OPG versus that of RANKL via ERbeta in hPDL cells.
authors.affiliation: Department of Stomatology, Second Hospital affiliated to General Hospital of the Chinese People's Liberation Army, Beijing, China.
authors.forename: Li
authors.initials: L
authors.lastname: Liang
authors.forename: Ji-feng
authors.initials: JF
authors.lastname: Yu
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.forename: Yin
authors.initials: Y
authors.lastname: Ding
mesh_terms: D000293:Adolescent; D015153:Blotting, Western; D002478:Cells, Cultured; D002648:Child; D004958:Estradiol / Q000494:pharmacology; D047629:Estrogen Receptor beta / Q000187:drug effects* / Q000235:genetics; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D005786:Gene Expression Regulation / Q000235:genetics; D020868:Gene Silencing; D006801:Humans; D008297:Male; D010010:Osteoclasts / Q000473:pathology; D053244:Osteoprotegerin / Q000187:drug effects*; D010513:Periodontal Ligament / Q000378:metabolism* / Q000473:pathology; D053245:RANK Ligand / Q000187:drug effects*; D034741:RNA, Small Interfering / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D047629:Estrogen Receptor beta; D004967:Estrogens; D053244:Osteoprotegerin; D053245:RANK Ligand; D034741:RNA, Small Interfering; D004958:Estradiol