title: KLF4-dependent phenotypic modulation of smooth muscle cells has a key role in atherosclerotic plaque pathogenesis.
abstract: Previous studies investigating the role of smooth muscle cells (SMCs) and macrophages in the pathogenesis of atherosclerosis have provided controversial results owing to the use of unreliable methods for clearly identifying each of these cell types. Here, using Myh11-CreER(T2) ROSA floxed STOP eYFP Apoe(-/-) mice to perform SMC lineage tracing, we find that traditional methods for detecting SMCs based on immunostaining for SMC markers fail to detect >80% of SMC-derived cells within advanced atherosclerotic lesions. These unidentified SMC-derived cells exhibit phenotypes of other cell lineages, including macrophages and mesenchymal stem cells (MSCs). SMC-specific conditional knockout of Krüppel-like factor 4 (Klf4) resulted in reduced numbers of SMC-derived MSC- and macrophage-like cells, a marked reduction in lesion size, and increases in multiple indices of plaque stability, including an increase in fibrous cap thickness as compared to wild-type controls. On the basis of in vivo KLF4 chromatin immunoprecipitation-sequencing (ChIP-seq) analyses and studies of cholesterol-treated cultured SMCs, we identified >800 KLF4 target genes, including many that regulate pro-inflammatory responses of SMCs. Our findings indicate that the contribution of SMCs to atherosclerotic plaques has been greatly underestimated, and that KLF4-dependent transitions in SMC phenotype are critical in lesion pathogenesis.
authors.affiliation: 1] Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia, USA. [2] Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia, USA.
authors.forename: Laura S
authors.initials: LS
authors.lastname: Shankman
authors.affiliation: Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia, USA.
authors.forename: Delphine
authors.initials: D
authors.lastname: Gomez
authors.affiliation: Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia, USA.
authors.forename: Olga A
authors.initials: OA
authors.lastname: Cherepanova
authors.affiliation: Department of Surgery, University of Virginia, Charlottesville, Virginia, USA.
authors.forename: Morgan
authors.initials: M
authors.lastname: Salmon
authors.affiliation: 1] Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia, USA. [2] Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, Virginia, USA.
authors.forename: Gabriel F
authors.initials: GF
authors.lastname: Alencar
authors.affiliation: 1] Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia, USA. [2] Department of Pathology, University of Virginia, Charlottesville, Virginia, USA.
authors.forename: Ryan M
authors.initials: RM
authors.lastname: Haskins
authors.affiliation: 1] Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia, USA. [2] Intercollegiate Faculty of Biotechnology, University of Gdansk, Gdansk, Poland.
authors.forename: Pamela
authors.initials: P
authors.lastname: Swiatlowska
authors.affiliation: 1] Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia, USA. [2] Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, Virginia, USA.
authors.forename: Alexandra A C
authors.initials: AA
authors.lastname: Newman
authors.affiliation: Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia, USA.
authors.forename: Elizabeth S
authors.initials: ES
authors.lastname: Greene
authors.affiliation: Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors.forename: Adam C
authors.initials: AC
authors.lastname: Straub
authors.affiliation: 1] Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia, USA. [2] Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia, USA.
authors.forename: Brant
authors.initials: B
authors.lastname: Isakson
authors.affiliation: Division of Biology and Biomedical Sciences, Washington University, St. Louis, Missouri, USA.
authors.forename: Gwendalyn J
authors.initials: GJ
authors.lastname: Randolph
authors.affiliation: 1] Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia, USA. [2] Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia, USA.
authors.forename: Gary K
authors.initials: GK
authors.lastname: Owens
mesh_terms: D000818:Animals; D001057:Apolipoproteins E / Q000037:antagonists & inhibitors; D050197:Atherosclerosis / Q000235:genetics* / Q000473:pathology; D002454:Cell Differentiation / Q000235:genetics; D019070:Cell Lineage; D058948:Cell Tracking; D006801:Humans; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors / Q000235:genetics*; D008264:Macrophages / Q000473:pathology; D059630:Mesenchymal Stem Cells / Q000378:metabolism / Q000473:pathology; D051379:Mice; D032389:Myocytes, Smooth Muscle / Q000473:pathology*; D058226:Plaque, Atherosclerotic / Q000235:genetics* / Q000473:pathology; D011401:Promoter Regions, Genetic
chemical_list: D001057:Apolipoproteins E; C000715467:KLF4 protein, human; C000715468:Klf4 protein, mouse; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors