Decorin GAG synthesis and TGF-β signaling mediate Ox-LDL-induced mineralization of human vascular smooth muscle cells

Arterioscler Thromb Vasc Biol. 2011 Mar;31(3):608-15. doi: 10.1161/ATVBAHA.110.220749. Epub 2011 Jan 4.

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.

Methods and 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkaline Phosphatase / metabolism
  • Calcinosis / metabolism*
  • Cells, Cultured
  • Decorin / biosynthesis*
  • Decorin / genetics
  • Gene Expression Regulation
  • Homeodomain Proteins / metabolism
  • Humans
  • Lipoproteins, LDL / metabolism*
  • Muscle, Smooth, Vascular / metabolism*
  • Myocytes, Smooth Muscle / metabolism*
  • Osteogenesis*
  • Oxidative Stress
  • Pentosyltransferases / genetics
  • Pentosyltransferases / metabolism
  • Phosphorylation
  • RNA Interference
  • Signal Transduction*
  • Smad2 Protein / metabolism
  • Time Factors
  • Transforming Growth Factor beta1 / metabolism*
  • UDP Xylose-Protein Xylosyltransferase

Substances

  • DCN protein, human
  • Decorin
  • Homeodomain Proteins
  • Lipoproteins, LDL
  • MSX2 protein
  • SMAD2 protein, human
  • Smad2 Protein
  • TGFB1 protein, human
  • Transforming Growth Factor beta1
  • oxidized low density lipoprotein
  • Pentosyltransferases
  • Alkaline Phosphatase