Abstract
The initiation of atherosclerosis involves the subendothelial retention of lipoproteins by proteoglycans (PGs). Structural characteristics of glycosaminoglycan (GAG) chains on PGs influence lipoprotein binding and are altered adversely by platelet-derived growth factor (PDGF). The signaling pathway for PDGF-mediated GAG elongation via the PDGF receptor (PDGFR) was investigated. In human vascular smooth muscle cells, PDGF significantly increased (35)S-sulfate incorporation into PGs and GAG chain size. PGs from PDGF-stimulated cells showed increased binding low-density lipoprotein (P < 0.001) in gel mobility shift assays. Knockdown of PDGFRbeta using small interfering RNA demonstrated that PDGF mediated changes in PGs via PDGFRbeta. GAG synthesis and hyperelongation was blocked by inhibition of receptor tyrosine kinase autophosphorylation site Tyr857 activity using Ki11502 or imatinib. Downstream signaling to GAG hyperelongation was mediated through ERK MAPK and not phosphatidylinositol-3 kinase or phospholipase Cgamma. In high-fat-fed apolipoprotein E(-/-) mice, inhibition of PDGFRbeta activity by imatinib reduced aortic total lipid staining area by 35% (P < 0.05). Inhibition of PDGFRbeta tyrosine kinase activity leads to inhibition of GAG synthesis on vascular PGs and aortic lipid area in vivo. PDGFRbeta and its signaling pathways are potential targets for novel therapeutic agents to prevent the earliest stages atherosclerosis.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Aorta / drug effects
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Aorta / metabolism
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Apolipoproteins E / genetics
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Apolipoproteins E / metabolism
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Benzamides
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Biglycan
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Cells, Cultured
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Dietary Fats / administration & dosage
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Extracellular Matrix Proteins / metabolism*
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Extracellular Signal-Regulated MAP Kinases / metabolism*
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Glycosaminoglycans / metabolism*
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Humans
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Imatinib Mesylate
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Lipids / analysis
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Lipoproteins, LDL / metabolism*
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Male
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Mice
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Mice, Knockout
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Mitogen-Activated Protein Kinase 1 / metabolism
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Mitogen-Activated Protein Kinase 3 / metabolism
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Muscle, Smooth, Vascular / cytology
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Muscle, Smooth, Vascular / drug effects
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Muscle, Smooth, Vascular / metabolism
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Phosphorylation / drug effects
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Piperazines / pharmacology
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Platelet-Derived Growth Factor / pharmacology
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Protein Binding / drug effects
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Protein Kinase Inhibitors / pharmacology
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Protein-Tyrosine Kinases / antagonists & inhibitors
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Protein-Tyrosine Kinases / metabolism
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Proteoglycans / metabolism*
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Pyrimidines / pharmacology
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RNA Interference
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Receptor, Platelet-Derived Growth Factor beta / genetics
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Receptor, Platelet-Derived Growth Factor beta / metabolism*
Substances
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Apolipoproteins E
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BGN protein, human
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Benzamides
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Bgn protein, mouse
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Biglycan
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Dietary Fats
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Extracellular Matrix Proteins
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Glycosaminoglycans
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Lipids
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Lipoproteins, LDL
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Piperazines
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Platelet-Derived Growth Factor
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Protein Kinase Inhibitors
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Proteoglycans
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Pyrimidines
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Imatinib Mesylate
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Protein-Tyrosine Kinases
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Receptor, Platelet-Derived Growth Factor beta
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Extracellular Signal-Regulated MAP Kinases
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Mitogen-Activated Protein Kinase 1
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Mitogen-Activated Protein Kinase 3