title: Regulatory effects of bone morphogenetic protein-4 on tumour necrosis factor-α-suppressed Runx2 and osteoprotegerin expression in cementoblasts.
abstract: OBJECTIVE
  Root resorption is a common phenomenon presented in periodontitis and orthodontic treatment, both of which are accompanied by an elevated TNF-α expression level in the periodontal tissues. Previously, we proved that TNF-α showed an inhibitory effect on cementoblast differentiation, mineralization and proliferation. However, the effect of TNF-α on Runx2 and osteoprotegerin (OPG) expression remains undetermined. This study aimed to identify the influence of TNF-α on Runx2 and OPG expression in cementoblasts and to test whether BMP-2,-4,-6,-7 would affect TNF-α-regulated Runx2 and OPG.
  
  
  METHODS
  An immortalized murine cementoblast cell line OCCM-30 was used in this study. The expression of Runx2 and OPG were examined by qRT-PCR after stimulating cells with TNF-α. The role of signalling pathways, including MAPK, PI3K-Akt and NF-κB, were studied with the use of specific inhibitors. Cells were treated with TNF-α in combination with BMP-2,-4,-6 or -7, then the expression of Runx2 and OPG, the activity of MAPK and NF-κB pathways, and the proliferation ability were evaluated by qRT-PCR, Western blot and MTS assay respectively.
  
  
  RESULTS
  TNF-α inhibited Runx2 and OPG mRNAs in OCCM-30 cells, and the inhibitory effects were further aggravated by blocking p38 MAPK or NF-κB pathway. TNF-α-inhibited Runx2 and OPG were up-regulated by BMP-4. The p38 MAPK and Erk1/2 pathways were further activated by the combined treatment of BMP-4 and TNF-α compared with TNF-α alone. Finally, the TNF-α-suppressed proliferation was not obviously affected by BMP-2,-4,-6 or -7.
  
  
  CONCLUSIONS
  TNF-α inhibited Runx2 and OPG in cementoblasts, and the p38 MAPK and NF-κB pathways acted in a negative-feedback way to attenuate the inhibitory effects. TNF-α-inhibited Runx2 and OPG could be effectively up-regulated by BMP-4; however, further investigations are needed to fully elaborate the underlying mechanisms.
authors.affiliation: The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, 430079, PR, China.
authors.forename: Yunlong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, 430079, PR, China.
authors.forename: Hong
authors.initials: H
authors.lastname: He
authors.affiliation: The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, 430079, PR, China.
authors.forename: Zhengguo
authors.initials: Z
authors.lastname: Cao
authors.affiliation: The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, 430079, PR, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Fang
authors.affiliation: The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, 430079, PR, China.
authors.forename: Mingyuan
authors.initials: M
authors.lastname: Du
authors.affiliation: The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, 430079, PR, China.
authors.forename: Zhijian
authors.identifier: http://orcid.org/0000-0003-2849-6119
authors.initials: Z
authors.lastname: Liu
mesh_terms: D000818:Animals; D055415:Bone Morphogenetic Protein 4 / Q000494:pharmacology*; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D050659:Core Binding Factor Alpha 1 Subunit / Q000235:genetics / Q000378:metabolism*; D003739:Dental Cementum / Q000166:cytology / Q000378:metabolism; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D053244:Osteoprotegerin / Q000235:genetics / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D015854:Up-Regulation / Q000187:drug effects*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D055415:Bone Morphogenetic Protein 4; D050659:Core Binding Factor Alpha 1 Subunit; D016328:NF-kappa B; D053244:Osteoprotegerin; D012333:RNA, Messenger; C493716:Runx2 protein, mouse; D014409:Tumor Necrosis Factor-alpha; D019869:Phosphatidylinositol 3-Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases