title: Importance of CD44 in the proliferation and mineralization of periodontal ligament cells.
abstract: OBJECTIVE
  CD44 is a transmembrane glycoprotein that exhibits various biological functions. Histological studies have shown that CD44 is expressed in periodontal ligament (PDL). We investigated the role of CD44 in the in vitro biological functions of PDL cells.
  
  
  METHODS
  Immunohistochemistry and immunocytochemistry were used to examine CD44 protein expression in mouse molars and human PDL cells, respectively. PDL cells isolated from human third molars were assayed for their proliferation and mineralization after stably silencing their expression of CD44 using the small hairpin RNA technique. An osteogenesis-associated quantitative polymerase chain reaction array was used to identify downstream molecules of CD44 signaling in osteogenic medium. The PDL cells, transduced with control small hairpin RNA, were used as controls in all assays.
  
  
  RESULTS
  PDLs expressed CD44 in vitro and in vivo. When CD44 expression was stably suppressed in PDL cells, their proliferation and mineralization activities in both media were substantially decreased. The quantitative polymerase chain reaction array and Western blotting verified that bone morphogenetic protein-2 (BMP-2), fibroblast growth factor-1 (FGF-1) and intercellular adhesion molecule-1 (ICAM-1) were downregulated after CD44 was knocked down in PDL cells. Exogenous FGF-1 attenuated the proliferative suppression of CD44 knockdown cells. Exogenous BMP-2 rescued the suppressed mineralization of CD44 knockdown cells more than ICAM-1 did.
  
  
  CONCLUSIONS
  The in vitro assays demonstrated that CD44 is crucial for the proliferation and mineralization of PDL cells and is possibly mediated by BMP-2, FGF-1 and ICAM-1. Further studies are required to verify the mediators and identify the physiological ligands of CD44 for possible application in periodontal regeneration.
authors: Institute of Oral Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors: Y
authors: Y
authors: Yeh
authors: Y
authors: Y
authors: Yang
authors: K
authors: K
authors: Yuan
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000032:analysis / Q000494:pharmacology; D002113:Calcification, Physiologic / Q000187:drug effects / Q000502:physiology*; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D005260:Female; D016220:Fibroblast Growth Factor 1 / Q000032:analysis / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects / Q000502:physiology; D055785:Gene Knockdown Techniques; D020868:Gene Silencing; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000032:analysis; D006801:Humans; D018960:Hyaluronan Receptors / Q000235:genetics / Q000502:physiology*; D018799:Intercellular Adhesion Molecule-1 / Q000032:analysis / Q000494:pharmacology; D051379:Mice; D010012:Osteogenesis / Q000187:drug effects / Q000502:physiology; D010513:Periodontal Ligament / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D034741:RNA, Small Interfering; D015398:Signal Transduction / Q000502:physiology; D055815:Young Adult
chemical_list: C525718:BMP2 protein, human; C525719:Bmp2 protein, mouse; D055396:Bone Morphogenetic Protein 2; C497483:CD44 protein, human; C476399:Cd44 protein, mouse; D018960:Hyaluronan Receptors; D034741:RNA, Small Interfering; D016220:Fibroblast Growth Factor 1; D018799:Intercellular Adhesion Molecule-1; D016178:Granulocyte-Macrophage Colony-Stimulating Factor
keywords: CD44; RNA; antigens; fibroblasts; periodontal ligament; small interfering