title: [The expression of serine protease HtrA1 in human periodontal ligament tissue and the effect of HtrA1 on the proliferation of human periodontal ligament cells].
abstract: OBJECTIVE
  To observe the expression of serine protease HtrA1 in human periodontal ligament tissue and to explore the effect of HtrA1 on the proliferation of human periodontal ligament cells (hPDLC).
  
  
  METHODS
  Six human premolars and three human third molars(patient's ages ranging from 12 to 25, with intact root, without caries and/or periodontitis) were obtained in the Department of Maxillofacial Surgery of Wuhan University Hospital of Stomatology. Reverse transcription-PCR(RT-PCR) and immunohistochemistry analysis were applied to investigate the expression of HtrA1. Primary hPDLC were obtained by tissue-culture method in vitro. The proliferation of hPDLC was determined by methyl thiazolytetrazolium(MTT). Lentivirus-mediated over-expression and reduction of HtrA1 level was performed. An empty vector was used as negative control. On days 1, 3, 5, 7 and 9, the growth of hPDLC was characterized using cell counting kit-8(CCK-8) assay.
  
  
  RESULTS
  RT-PCR data indicated that HtrA1 mRNA was expressed in human periodontal ligament tissue. Immunohistochemistry analysis showed HtrA1 was expressed in human periodontal ligament, mainly in the cytoplasm of hPDLC and the extracellular matrix. The MTT result suggested that the growth curve was consistent with the growth characteristics of hPDLC. The stable over-expression and knockdown cell lines was successfully established by lentivirus with more than 90% transfection efficiency. CCK-8 assay showed that HtrA1 over-expression inhibited the proliferation of hPDLC(0.897±0.060, 0.890±0.083, 1.631±0.038, 1.111±0.041, 1.110±0.189), while cell proliferation increased after down-regulation of HtrA1(0.329±0.021, 0.529±0.044, 0.973±0.056, 1.626±0.102, 2.344±0.198)(P<0.05).
  
  
  CONCLUSIONS
  HtrA1 is expressed in human periodontal ligament tissue at both mRNA and protein levels, and may play an important role in regulating the proliferation of hPDLC.
authors.affiliation: Department of Endodontics, School of Stomatology, Tongji University, Shanghai Engineering Research Center of Tooth Restoration and Regeneration, Shanghai 200072, China.
authors.forename: Ran
authors.initials: R
authors.lastname: Li
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhang
mesh_terms: D000293:Adolescent; D000328:Adult; D002452:Cell Count; D049109:Cell Proliferation; D002478:Cells, Cultured; D002648:Child; D015536:Down-Regulation; D005822:Genetic Vectors; D000074289:High-Temperature Requirement A Serine Peptidase 1; D006801:Humans; D016086:Lentivirus / Q000502:physiology; D010513:Periodontal Ligament / Q000166:cytology* / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D055815:Young Adult
chemical_list: D012333:RNA, Messenger; D000074289:High-Temperature Requirement A Serine Peptidase 1; C474012:HTRA1 protein, human; D012697:Serine Endopeptidases