title: Effect of Oxidized Low Density Lipoprotein on the Expression of Runx2 and SPARC Genes in Vascular Smooth Muscle Cells.
abstract: Vascular calcification is an important stage in atherosclerosis. During this stage, vascular smooth muscle cells (VSMC) synthesize many osteogenic factors such as osteonectin (encoded by SPARC). Oxidative stress plays a critical role in atherosclerosis progression, and its accumulation in the vascular wall stimulates the development of atherosclerosis and vascular calcification. The osteonectin overexpression has been observed in the arterial wall during the course of atherosclerosis. However, the regulatory mechanism of oxidized low density lipoprotein (oxLDL)-mediated vascular calcification remains to be clarified. The aim of this study was to investigate the effect of oxLDL on the osteonectin gene expression through the Runx2 transcription factor.
  
  
  
  In this experimental study, VSMC were cultured in F-12K media and then treated with oxLDL. The expression of Runx2 and osteonectin genes was determined by real-time PCR method. Protein levels were investigated by the western blotting technique. The Runx2 gene was knocked down using siRNA in order to determine whether Runx2 regulates the osteonectin expression in VSMC induced by oxLDL. Then transfected cells were treated with oxLDL, and the expression levels of Runx2 and osteonectin were determined again.
  
  
  
  oxLDL was found to increase Runx2 and osteonectin gene expression (4.8±0.47- and 9.2±1.96-fold, respectively) after 48 h. Western blotting analysis confirmed the induced levels of Runx2 and osteonectin proteins. However, oxLDL-induced osteonectin expression was not observed to be blocked by Runx2 knockdown.
  
  
  
  The up-regulation of osteonectin by oxLDL is independent of Runx2, and it may be mediated by other transcription factors.
authors.affiliation: Cellular and Molecular Research Center, Shahrekord University of Medical Sciences, Shahrekord, Iran.
authors.forename: Effat
authors.initials: E
authors.lastname: Farrokhi
authors.affiliation: Clinical Biochemistry Research Center, Shahrekord University of Medical Sciences, Shahrekord, Iran.
authors.forename: Keihan
authors.initials: K
authors.lastname: GhatrehSamani
authors.affiliation: Cellular and Molecular Research Center, Shahrekord University of Medical Sciences, Shahrekord, Iran.
authors.forename: Morteza
authors.initials: M
authors.lastname: Hashemzadeh Chaleshtori
authors.affiliation: Dept. of Genetics and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Mohammad Amin
authors.initials: MA
authors.lastname: Tabatabaiefar
mesh_terms: D002478:Cells, Cultured; D050659:Core Binding Factor Alpha 1 Subunit / Q000235:genetics*; D006801:Humans; D008077:Lipoproteins, LDL / Q000502:physiology*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D015676:Osteonectin / Q000235:genetics*
chemical_list: D050659:Core Binding Factor Alpha 1 Subunit; D008077:Lipoproteins, LDL; D015676:Osteonectin; C493709:RUNX2 protein, human; C577241:SPARC protein, human; C099252:oxidized low density lipoprotein
keywords: Oxidized low density lipoprotein; Vascular calcification; Osteonectin; Runx2