Published online before print September 24, 2007, doi: 10.1161/CIRCULATIONAHA.107.708016
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(Circulation. 2007;116:1812-1820.)
© 2007 American Heart Association, Inc.
Vascular Medicine |
Y-Box Binding Protein-1 Controls CC Chemokine Ligand-5 (CCL5) Expression in Smooth Muscle Cells and Contributes to Neointima Formation in Atherosclerosis-Prone Mice
From the Institute for Molecular Cardiovascular Research (R.K., A.Z., E.S., E.A.L., C.W.) and Department of Nephrology and Clinical Immunology (U.R., P.R.M.), University Hospital Aachen, RWTH Aachen University, Aachen, Germany; Division of Biopharmaceutics (I.B., P.J.v.S., E.A.B.), Leiden Amsterdam Center for Drug Research, Leiden University, Leiden, The Netherlands; and Division of Clinical Biochemistry (P.J.N.), University Hospital, LMU Munich, Munich, Germany.
Correspondence to Dr Christian Weber, Institut für Kardiovaskuläre Molekularbiologie, Universitätsklinikum Aachen, RWTH Aachen, Pauwelsstrasse 30, 52074 Aachen, Germany. E-mail cweber{at}ukaachen.de
Received April 6, 2007; accepted August 8, 2007.
Background— The CC chemokine CCL5/Regulated on Activation, Normal T Cell Expressed and Secreted (RANTES) is upregulated in mononuclear cells or deposited by activated platelets during inflammation and has been implicated in atherosclerosis and neointimal hyperplasia. We investigated the influence of the transcriptional regulator Y-box binding protein (YB)-1 on CCL5 expression and wire-induced neointimal hyperplasia.
Methods and Results— Analysis of the CCL5 promoter revealed potential binding sites for YB-1, and interaction of YB-1 with a sequence at position –204/–173 was confirmed by DNA binding assays. Both YB-1 expression and CC chemokine ligand-5 (CCL5) mRNA expression were increased in neointimal versus medial smooth muscle cells, as analyzed by real-time polymerase chain reaction. Overexpression of YB-1 in smooth muscle cells (but not macrophages) enhanced CCL5 transcriptional activity in reporter assays, mRNA and protein expression, and CCL5-mediated monocyte arrest. Carotid arteries of hyperlipidemic apolipoprotein E–deficient mice were subjected to intraluminal transfection with a lentivirus encoding YB-1 short hairpin RNA or empty vector directly after wire injury. Double immunofluorescence revealed YB-1 expression in neointimal smooth muscle cells but not macrophages and colocalization with neointimal CCL5, which was downregulated by YB-1 short hairpin RNA. Neointima formation was decreased significantly after YB-1 knockdown compared with controls and was associated with a diminished content of lesional macrophages. A reduction of lesion formation by YB-1 knockdown was not observed in apolipoprotein E–deficient mice deficient in the CCL5 receptor CCR5 or after treatment with the CCL5 antagonist Met-RANTES, which indicates that YB-1 effects were dependent on CCL5.
Conclusions— The transcriptional regulator YB-1 mediates CCL5 expression in smooth muscle cells and thereby contributes to neointimal hyperplasia, thus representing a novel target with which to limit vascular remodeling.