title: Expression of glutathione peroxidase 1 in the spheno-occipital synchondrosis and its role in ROS-induced apoptosis.
abstract: OBJECTIVE
  Chondrogenesis is an integral part of endochondral bone formation, by which the midline cranial base is developed. Reactive oxygen species (ROS) are required in chondrogenic differentiation and antioxidant enzymes regulate their levels. The aim of this study was to localize the antioxidant enzyme glutathione peroxidase 1 (Gpx1) at the spheno-occipital synchondrosis, as well as its effect on ROS challenge and its expression pattern in the course of differentiation.
  
  
  METHODS
  Gpx1 was semiquantified in immunohistochemically stained sections of spheno-occipital synchondroses of rats. The effect of Gpx1 on ROS-induced apoptosis was investigated by manipulating the expression of Gpx1 in ATDC5 cells. The temporal pattern of Gpx1 expression was determined during chondrocyte differentiation for 21 days in vitro.
  
  
  RESULTS
  Proliferating chondrocytes exhibited the greatest Gpx1 immunoreactivity and hypertrophic ones the lowest (P = 0.02). Cells transfected with Gpx1-siRNA had the highest apoptotic rate, while cells overexpressing Gpx1 the lowest one (P < 0.001). Gpx1 was significantly increased on days 10 (P = 0.02) and 14 (P = 0.01).
  
  
  CONCLUSIONS
  Hypertrophic chondrocytes have the lowest Gpx1 activity in the spheno-occipital synchondrosis. Gpx1 is implicated in the ROS-induced apoptosis in chondrocytes. Its expression was not constitutive during chondrogenic differentiation.
authors.affiliation: Department of Orthodontics, University Medical Centre Regensburg, Germany.
authors.forename: Vasiliki
authors.initials: V
authors.lastname: Koretsi
authors.affiliation: Department of Orthodontics, University Medical Centre Regensburg, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Kirschneck
authors.affiliation: Department of Orthodontics, University Medical Centre Regensburg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Proff
authors.affiliation: Department of Orthodontics, University Medical Centre Regensburg, Germany piero.roemer@ukr.de.
authors.forename: Piero
authors.initials: P
authors.lastname: Römer
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000502:physiology*; D018929:Cell Culture Techniques; D002454:Cell Differentiation / Q000502:physiology; D002460:Cell Line; D049109:Cell Proliferation; D019902:Chondrocytes / Q000201:enzymology / Q000502:physiology; D020219:Chondrogenesis / Q000502:physiology; D003393:Cranial Sutures / Q000166:cytology / Q000201:enzymology*; D055785:Gene Knockdown Techniques; D005979:Glutathione Peroxidase / Q000032:analysis* / Q000235:genetics / Q000502:physiology; D006984:Hypertrophy; D009777:Occipital Bone / Q000166:cytology / Q000201:enzymology*; D010012:Osteogenesis / Q000502:physiology; D034741:RNA, Small Interfering / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000032:analysis* / Q000494:pharmacology; D019291:Skull Base / Q000166:cytology; D013100:Sphenoid Bone / Q000166:cytology / Q000201:enzymology*; D013997:Time Factors; D000094765:Glutathione Peroxidase GPX1
chemical_list: D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D005979:Glutathione Peroxidase; D000094765:Glutathione Peroxidase GPX1; C000722069:Gpx1 protein, rat