title: Induction of microRNA-221 by platelet-derived growth factor signaling is critical for modulation of vascular smooth muscle phenotype.
abstract: The platelet-derived growth factor (PDGF) signaling pathway is a critical regulator of animal development and homeostasis. Activation of the PDGF pathway leads to neointimal proliferative responses to artery injury; it promotes a switch of vascular smooth muscle cells (vSMC) to a less contractile phenotype by inhibiting the SMC-specific gene expression and increasing the rate of proliferation and migration. The molecular mechanism for these pleiotropic effects of PDGFs has not been fully described. Here, we identify the microRNA-221 (miR-221), a small noncoding RNA, as a modulator of the phenotypic change of vSMCs in response to PDGF signaling. We demonstrate that miR-221 is transcriptionally induced upon PDGF treatment in primary vSMCs, leading to down-regulation of the targets c-Kit and p27Kip1. Down-regulation of p27Kip1 by miR-221 is critical for PDGF-mediated induction of cell proliferation. Additionally, decreased c-Kit causes inhibition of SMC-specific contractile gene transcription by reducing the expression of Myocardin (Myocd), a potent SMC-specific nuclear coactivator. Our study demonstrates that PDGF signaling, by modulating the expression of miR-221, regulates two critical determinants of the vSMC phenotype; they are SMC gene expression and cell proliferation.
authors.affiliation: Department of Biochemistry, Tufts University School of Medicine, Boston, Massachusetts, USA.
authors.forename: Brandi N
authors.initials: BN
authors.lastname: Davis
authors.forename: Aaron C
authors.initials: AC
authors.lastname: Hilyard
authors.forename: Peter H
authors.initials: PH
authors.lastname: Nguyen
authors.forename: Giorgio
authors.initials: G
authors.lastname: Lagna
authors.forename: Akiko
authors.initials: A
authors.lastname: Hata
mesh_terms: D001158:Arteries / Q000293:injuries / Q000378:metabolism; D002465:Cell Movement / Q000187:drug effects / Q000235:genetics; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D050760:Cyclin-Dependent Kinase Inhibitor p27; D005786:Gene Expression Regulation / Q000187:drug effects* / Q000235:genetics; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000378:metabolism*; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000235:genetics; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D019009:Proto-Oncogene Proteins c-kit / Q000096:biosynthesis / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects* / Q000235:genetics; D015534:Trans-Activators / Q000096:biosynthesis / Q000235:genetics; D000099251:Myocardin
chemical_list: D050760:Cyclin-Dependent Kinase Inhibitor p27; D047908:Intracellular Signaling Peptides and Proteins; D035683:MicroRNAs; D009687:Nuclear Proteins; D010982:Platelet-Derived Growth Factor; D019009:Proto-Oncogene Proteins c-kit; D015534:Trans-Activators; D000099251:Myocardin; C436291:CDKN1B protein, human; C525709:MIR221, human