title: Decorin GAG synthesis and TGF-β signaling mediate Ox-LDL-induced mineralization of human vascular smooth muscle cells.
abstract: OBJECTIVE
  Decorin and oxidized low-density lipoprotein (Ox-LDL) independently induce osteogenic differentiation of vascular smooth muscle cells (VSMCs). We aimed to determine whether decorin glycosaminoglycan (GAG) chain synthesis contributes to Ox-LDL-induced differentiation and calcification of human VSMCs in vitro.
  
  
  RESULTS
  Human VSMCs treated with Ox-LDL to induce oxidative stress showed increased alkaline phosphatase (ALP) activity, accelerated mineralization, and a difference in both decorin GAG chain biosynthesis and CS/DS structure compared with untreated controls. Ox-LDL increased mRNA abundance of both xylosyltransferase (XT)-I, the key enzyme responsible for GAG chain biosynthesis and Msx2, a marker of osteogenic differentiation. Furthermore, downregulation of XT-I expression using small interfering RNA blocked Ox-LDL-induced VSMC mineralization. Adenoviral-mediated overexpression of decorin, but not a mutated unglycanated form, accelerated mineralization of VSMCs, suggesting GAG chain addition on decorin is crucial for the process of differentiation. The decorin-induced VSMC osteogenic differentiation involved activation of the transforming growth factor (TGF)-β pathway, because it was attenuated by blocking of TGF-β receptor signaling and because decorin overexpression potentiated phosphorylation of the downstream signaling molecule smad2.
  
  
  CONCLUSIONS
  These studies provide direct evidence that oxidative stress-mediated decorin GAG chain synthesis triggers TGF-β signaling and mineralization of VSMCs in vitro.
authors.affiliation: Cardiovascular Research Group, University of Manchester, United Kingdom.
authors.forename: Jianyun
authors.initials: J
authors.lastname: Yan
authors.forename: Sally E
authors.initials: SE
authors.lastname: Stringer
authors.forename: Andrew
authors.initials: A
authors.lastname: Hamilton
authors.forename: Valentine
authors.initials: V
authors.lastname: Charlton-Menys
authors.forename: Christian
authors.initials: C
authors.lastname: Götting
authors.forename: Benjamin
authors.initials: B
authors.lastname: Müller
authors.forename: Daniel
authors.initials: D
authors.lastname: Aeschlimann
authors.forename: M Yvonne
authors.initials: MY
authors.lastname: Alexander
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D002114:Calcinosis / Q000378:metabolism*; D002478:Cells, Cultured; D058575:Decorin / Q000096:biosynthesis* / Q000235:genetics; D005786:Gene Expression Regulation; D018398:Homeodomain Proteins / Q000378:metabolism; D006801:Humans; D008077:Lipoproteins, LDL / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000378:metabolism*; D010012:Osteogenesis; D018384:Oxidative Stress; D010430:Pentosyltransferases / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D034622:RNA Interference; D015398:Signal Transduction; D051899:Smad2 Protein / Q000378:metabolism; D013997:Time Factors; D053773:Transforming Growth Factor beta1 / Q000378:metabolism*; D000097608:UDP Xylose-Protein Xylosyltransferase
chemical_list: D000469:Alkaline Phosphatase; D058575:Decorin; D018398:Homeodomain Proteins; D008077:Lipoproteins, LDL; D010430:Pentosyltransferases; D051899:Smad2 Protein; D053773:Transforming Growth Factor beta1; D000097608:UDP Xylose-Protein Xylosyltransferase; C546878:DCN protein, human; C084119:MSX2 protein; C497782:SMAD2 protein, human; C508960:TGFB1 protein, human; C099252:oxidized low density lipoprotein