title: MEF2B-Nox1 signaling is critical for stretch-induced phenotypic modulation of vascular smooth muscle cells.
abstract: OBJECTIVE
  Blood vessel hemodynamics have profound influences on function and structure of vascular cells. One of the main mechanical forces influencing vascular smooth muscle cells (VSMC) is cyclic stretch (CS). Increased CS stimulates reactive oxygen species (ROS) production in VSMC, leading to their dedifferentiation, yet the mechanisms involved are poorly understood. This study was designed to test the hypothesis that pathological CS stimulates NADPH oxidase isoform 1 (Nox1)-derived ROS via MEF2B, leading to VSMC dysfunction via a switch from a contractile to a synthetic phenotype.
  
  
  RESULTS
  Using a newly developed isoform-specific Nox1 inhibitor and gene silencing technology, we demonstrate that a novel pathway, including MEF2B-Nox1-ROS, is upregulated under pathological stretch conditions, and this pathway promotes a VSMC phenotypic switch from a contractile to a synthetic phenotype. We observed that CS (10% at 1 Hz) mimicking systemic hypertension in humans increased Nox1 mRNA, protein levels, and enzymatic activity in a time-dependent manner, and this upregulation was mediated by MEF2B. Furthermore, we show that stretch-induced Nox1-derived ROS upregulated a specific marker for synthetic phenotype (osteopontin), whereas it downregulated classical markers for contractile phenotype (calponin1 and smoothelin B). In addition, our data demonstrated that stretch-induced Nox1 activation decreases actin fiber density and augments matrix metalloproteinase 9 activity, VSMC migration, and vectorial alignment.
  
  
  CONCLUSIONS
  These results suggest that CS initiates a signal through MEF2B that potentiates Nox1-mediated ROS production and causes VSMC to switch to a synthetic phenotype. The data also characterize a new Nox1 inhibitor as a potential therapy for treatment of vascular dysfunction in hypertension.
authors.affiliation: From the Department of Pharmacology and Chemical Biology and Vascular Medicine Institute (A.I.R., G.C., D.J.R, D.M.F., L.A., P.J.P), and Departments of Bioengineering, Surgery, and Cardiothoracic Surgery and Center for Vascular Remodeling and Regeneration (K.J.B., D.A.V), University of Pittsburgh, PA; and Department of Basic Sciences, Faculty of Science, Universidad del Bío-Bío, Chillán, Chile (A.I.R).
authors.forename: Andrés I
authors.initials: AI
authors.lastname: Rodríguez
authors.affiliation: From the Department of Pharmacology and Chemical Biology and Vascular Medicine Institute (A.I.R., G.C., D.J.R, D.M.F., L.A., P.J.P), and Departments of Bioengineering, Surgery, and Cardiothoracic Surgery and Center for Vascular Remodeling and Regeneration (K.J.B., D.A.V), University of Pittsburgh, PA; and Department of Basic Sciences, Faculty of Science, Universidad del Bío-Bío, Chillán, Chile (A.I.R).
authors.forename: Gábor
authors.initials: G
authors.lastname: Csányi
authors.affiliation: From the Department of Pharmacology and Chemical Biology and Vascular Medicine Institute (A.I.R., G.C., D.J.R, D.M.F., L.A., P.J.P), and Departments of Bioengineering, Surgery, and Cardiothoracic Surgery and Center for Vascular Remodeling and Regeneration (K.J.B., D.A.V), University of Pittsburgh, PA; and Department of Basic Sciences, Faculty of Science, Universidad del Bío-Bío, Chillán, Chile (A.I.R).
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Ranayhossaini
authors.affiliation: From the Department of Pharmacology and Chemical Biology and Vascular Medicine Institute (A.I.R., G.C., D.J.R, D.M.F., L.A., P.J.P), and Departments of Bioengineering, Surgery, and Cardiothoracic Surgery and Center for Vascular Remodeling and Regeneration (K.J.B., D.A.V), University of Pittsburgh, PA; and Department of Basic Sciences, Faculty of Science, Universidad del Bío-Bío, Chillán, Chile (A.I.R).
authors.forename: Douglas M
authors.initials: DM
authors.lastname: Feck
authors.affiliation: From the Department of Pharmacology and Chemical Biology and Vascular Medicine Institute (A.I.R., G.C., D.J.R, D.M.F., L.A., P.J.P), and Departments of Bioengineering, Surgery, and Cardiothoracic Surgery and Center for Vascular Remodeling and Regeneration (K.J.B., D.A.V), University of Pittsburgh, PA; and Department of Basic Sciences, Faculty of Science, Universidad del Bío-Bío, Chillán, Chile (A.I.R).
authors.forename: Kory J
authors.initials: KJ
authors.lastname: Blose
authors.affiliation: From the Department of Pharmacology and Chemical Biology and Vascular Medicine Institute (A.I.R., G.C., D.J.R, D.M.F., L.A., P.J.P), and Departments of Bioengineering, Surgery, and Cardiothoracic Surgery and Center for Vascular Remodeling and Regeneration (K.J.B., D.A.V), University of Pittsburgh, PA; and Department of Basic Sciences, Faculty of Science, Universidad del Bío-Bío, Chillán, Chile (A.I.R).
authors.forename: Lillian
authors.initials: L
authors.lastname: Assatourian
authors.affiliation: From the Department of Pharmacology and Chemical Biology and Vascular Medicine Institute (A.I.R., G.C., D.J.R, D.M.F., L.A., P.J.P), and Departments of Bioengineering, Surgery, and Cardiothoracic Surgery and Center for Vascular Remodeling and Regeneration (K.J.B., D.A.V), University of Pittsburgh, PA; and Department of Basic Sciences, Faculty of Science, Universidad del Bío-Bío, Chillán, Chile (A.I.R).
authors.forename: David A
authors.initials: DA
authors.lastname: Vorp
authors.affiliation: From the Department of Pharmacology and Chemical Biology and Vascular Medicine Institute (A.I.R., G.C., D.J.R, D.M.F., L.A., P.J.P), and Departments of Bioengineering, Surgery, and Cardiothoracic Surgery and Center for Vascular Remodeling and Regeneration (K.J.B., D.A.V), University of Pittsburgh, PA; and Department of Basic Sciences, Faculty of Science, Universidad del Bío-Bío, Chillán, Chile (A.I.R). pagano@pitt.edu.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Pagano
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000378:metabolism; D002465:Cell Movement; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D064326:MEF2 Transcription Factors / Q000235:genetics / Q000378:metabolism*; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D040542:Mechanotransduction, Cellular / Q000187:drug effects; D008840:Microfilament Proteins / Q000378:metabolism; D009124:Muscle Proteins / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism*; D009247:NADH, NADPH Oxidoreductases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000074624:NADPH Oxidase 1; D053495:Osteopontin / Q000378:metabolism; D010641:Phenotype; D011311:Pressoreceptors / Q000378:metabolism*; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D013997:Time Factors; D014162:Transfection; D066253:Vascular Remodeling / Q000187:drug effects; D000096985:Calponins
chemical_list: D015415:Biomarkers; D002135:Calcium-Binding Proteins; D003598:Cytoskeletal Proteins; D004791:Enzyme Inhibitors; D064326:MEF2 Transcription Factors; D020780:Matrix Metalloproteinase 9; D008840:Microfilament Proteins; D009124:Muscle Proteins; D009247:NADH, NADPH Oxidoreductases; D000074624:NADPH Oxidase 1; D053495:Osteopontin; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D000096985:Calponins; C491051:Smtn protein, rat; C506897:Spp1 protein, rat; C000614712:NOX1 protein, rat; C572337:Mmp9 protein, rat
keywords: MEF2B; Nox1; oxidative stress; vascular remodeling