Phenotypic Modulation of Smooth Muscle Cells in Atherosclerosis Is Associated With Downregulation of LMOD1, SYNPO2, PDLIM7, PLN, and SYNM

Arterioscler Thromb Vasc Biol. 2016 Sep;36(9):1947-61. doi: 10.1161/ATVBAHA.116.307893. Epub 2016 Jul 28.


Objective: Key augmented processes in atherosclerosis have been identified, whereas less is known about downregulated pathways. Here, we applied a systems biology approach to examine suppressed molecular signatures, with the hypothesis that they may provide insight into mechanisms contributing to plaque stability.

Approach and results: Muscle contraction, muscle development, and actin cytoskeleton were the most downregulated pathways (false discovery rate=6.99e-21, 1.66e-6, 2.54e-10, respectively) in microarrays from human carotid plaques (n=177) versus healthy arteries (n=15). In addition to typical smooth muscle cell (SMC) markers, these pathways also encompassed cytoskeleton-related genes previously not associated with atherosclerosis. SYNPO2, SYNM, LMOD1, PDLIM7, and PLN expression positively correlated to typical SMC markers in plaques (Pearson r>0.6, P<0.0001) and in rat intimal hyperplasia (r>0.8, P<0.0001). By immunohistochemistry, the proteins were expressed in SMCs in normal vessels, but largely absent in human plaques and intimal hyperplasia. Subcellularly, most proteins localized to the cytoskeleton in cultured SMCs and were regulated by active enhancer histone modification H3K27ac by chromatin immunoprecipitation-sequencing. Functionally, the genes were downregulated by PDGFB (platelet-derived growth factor beta) and IFNg (interferron gamma), exposure to shear flow stress, and oxLDL (oxidized low-density lipoprotein) loading. Genetic variants in PDLIM7, PLN, and SYNPO2 loci associated with progression of carotid intima-media thickness in high-risk subjects without symptoms of cardiovascular disease (n=3378). By eQTL (expression quantitative trait locus), rs11746443 also associated with PDLIM7 expression in plaques. Mechanistically, silencing of PDLIM7 in vitro led to downregulation of SMC markers and disruption of the actin cytoskeleton, decreased cell spreading, and increased proliferation.

Conclusions: We identified a panel of genes that reflect the altered phenotype of SMCs in vascular disease and could be early sensitive markers of SMC dedifferentiation.

Keywords: actin cytoskeleton; atherosclerosis; downregulation; hyperplasia; smooth muscle cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actin Cytoskeleton / metabolism
  • Adaptor Proteins, Signal Transducing / genetics
  • Adaptor Proteins, Signal Transducing / metabolism*
  • Animals
  • Apolipoproteins E / deficiency
  • Apolipoproteins E / genetics
  • Atherosclerosis / genetics
  • Atherosclerosis / metabolism
  • Atherosclerosis / pathology
  • Autoantigens / genetics
  • Autoantigens / metabolism*
  • Calcium-Binding Proteins / genetics
  • Calcium-Binding Proteins / metabolism*
  • Carotid Arteries / metabolism
  • Carotid Arteries / pathology
  • Carotid Arteries / physiopathology
  • Carotid Artery Diseases / genetics
  • Carotid Artery Diseases / metabolism*
  • Carotid Artery Diseases / pathology
  • Carotid Artery Diseases / physiopathology
  • Carotid Artery Injuries / genetics
  • Carotid Artery Injuries / metabolism
  • Case-Control Studies
  • Cell Dedifferentiation
  • Cells, Cultured
  • Cytoskeletal Proteins / genetics
  • Cytoskeletal Proteins / metabolism*
  • Disease Models, Animal
  • Down-Regulation
  • Genetic Association Studies
  • Humans
  • Intermediate Filament Proteins / genetics
  • Intermediate Filament Proteins / metabolism*
  • LIM Domain Proteins / genetics
  • LIM Domain Proteins / metabolism*
  • Male
  • Mice, Knockout
  • Microfilament Proteins / genetics
  • Microfilament Proteins / metabolism*
  • Middle Aged
  • Muscle, Smooth, Vascular / metabolism*
  • Muscle, Smooth, Vascular / pathology
  • Muscle, Smooth, Vascular / physiopathology
  • Myocytes, Smooth Muscle / metabolism*
  • Myocytes, Smooth Muscle / pathology
  • Neointima
  • Phenotype
  • Plaque, Atherosclerotic*
  • RNA Interference
  • Rats, Sprague-Dawley
  • Signal Transduction
  • Time Factors
  • Transfection
  • Vasoconstriction


  • Adaptor Proteins, Signal Transducing
  • Apolipoproteins E
  • Autoantigens
  • Calcium-Binding Proteins
  • Cytoskeletal Proteins
  • Intermediate Filament Proteins
  • LIM Domain Proteins
  • LMOD1 protein, human
  • Microfilament Proteins
  • PDLIM7 protein, human
  • SYNPO2 protein, human
  • desmuslin
  • phospholamban