title: Apoptotic gene expression by human periodontal ligament cells following cyclic stretch.
abstract: OBJECTIVE
  Periodontal ligament cells play an important role in maintaining homeostasis of periodontal tissue upon mechanical force loading caused by mastication or orthodontic force. Previous studies revealed force-driven periodontal ligament cell death via apoptosis, but the force-sensing genes assigned to the apoptotic pathway have not been fully characterized. The present study aimed to identify force-sensing genes implicated in the apoptotic pathway in periodontal ligament cells.
  
  
  METHODS
  Human periodontal ligament cells were exposed to 20% stretch strain for 6 or 24 h, and the differential expression of 84 genes implicated in the apoptotic pathway were quantified by real-time PCR array technology.
  
  
  RESULTS
  Ten and 11 genes showed upregulated expression after 6 and 24 h stretches, respectively, and there were two downregulated genes in response to both 6 and 24 h stretches. These genes included those encoding the tumor necrosis factor ligand family (TNFSF8), tumor necrosis factor receptor family (FAS, TNFRSF10B, TNFRSF11B, TNFRSF25 and CD27), the Bcl-2 family (BAG3, BAK1, BCL2L11 and BCLAF1), the caspase family (CASP5 and CASP7), the inhibitor of apoptosis proteins family (BIRC3, BIRC6 and NAIP), the caspase recruitment domain family (RIPK2 and PYCARD) and the death domain family (DAPK1), as well as an oncogene (BRAF).
  
  
  CONCLUSIONS
  This study identified several force-sensing genes implicated in the apoptotic pathway in periodontal ligament cells and should facilitate future studies on force-driven apoptosis by providing putative target genes.
authors.affiliation: Department of Prosthodontics, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China. imxuchun@163.com
authors.forename: C
authors.initials: C
authors.lastname: Xu
authors.forename: Y
authors.initials: Y
authors.lastname: Hao
authors.forename: B
authors.initials: B
authors.lastname: Wei
authors.forename: J
authors.initials: J
authors.lastname: Ma
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.forename: Q
authors.initials: Q
authors.lastname: Huang
authors.forename: F
authors.initials: F
authors.lastname: Zhang
mesh_terms: D017209:Apoptosis / Q000235:genetics*; D051017:Apoptosis Regulatory Proteins / Q000235:genetics; D020169:Caspases / Q000235:genetics; D002478:Cells, Cultured; D002648:Child; D003799:Dental Stress Analysis; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D008465:Mechanoreceptors; D005810:Multigene Family; D010513:Periodontal Ligament / Q000166:cytology*; D060888:Real-Time Polymerase Chain Reaction; D013314:Stress, Mechanical; D013718:Tensile Strength; D014087:Tooth Movement Techniques; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics
chemical_list: D051017:Apoptosis Regulatory Proteins; D014409:Tumor Necrosis Factor-alpha; D020169:Caspases