title: Mitogen-activated protein kinase 14 is a novel negative regulatory switch for the vascular smooth muscle cell contractile gene program.
abstract: OBJECTIVE
  Several studies have shown through chemical inhibitors that p38 mitogen-activated protein kinase (MAPK) promotes vascular smooth muscle cell (VSMC) differentiation. Here, we evaluate the effects of knocking down a dominant p38MAPK isoform on VSMC differentiation.
  
  
  RESULTS
  Knockdown of p38MAPKα (MAPK14) in human coronary artery SMCs unexpectedly increases VSMC differentiation genes, such as miR145, ACTA2, CNN1, LMOD1, and TAGLN, with little change in the expression of serum response factor (SRF) and 2 SRF cofactors, myocardin (MYOCD) and myocardin-related transcription factor A (MKL1). A variety of chemical and biological inhibitors demonstrate a critical role for a RhoA-MKL1-SRF-dependent pathway in mediating these effects. MAPK14 knockdown promotes MKL1 nuclear localization and VSMC marker expression, an effect partially reversed with Y27632; in contrast, MAP2K6 (MKK6) blocks MKL1 nuclear import and VSMC marker expression. Immunostaining and Western blotting of injured mouse carotid arteries reveal elevated MAPK14 (both total and phosphorylated) and reduced VSMC marker expression.
  
  
  CONCLUSIONS
  Reduced MAPK14 expression evokes unanticipated increases in VSMC contractile genes, suggesting an unrecognized negative regulatory role for MAPK14 signaling in VSMC differentiation.
authors.affiliation: Department of Medicine, Aab Cardiovascular Research Institute, Box CVRI, University of Rochester School of Medicine and Dentistry, 601 Elmwood Ave, Rochester, NY 14642, USA. xiaochun_long@urmc.rochester.edu
authors.forename: Xiaochun
authors.initials: X
authors.lastname: Long
authors.forename: Sarah L
authors.initials: SL
authors.lastname: Cowan
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Miano
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D021581:Active Transport, Cell Nucleus; D000818:Animals; D015153:Blotting, Western; D020212:Carotid Artery Injuries / Q000201:enzymology / Q000235:genetics / Q000503:physiopathology; D017536:Carotid Artery, Common / Q000201:enzymology; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics; D003331:Coronary Vessels / Q000201:enzymology; D004268:DNA-Binding Proteins / Q000378:metabolism; D004195:Disease Models, Animal; D004789:Enzyme Activation; D005786:Gene Expression Regulation; D055785:Gene Knockdown Techniques; D005838:Genotype; D057809:HEK293 Cells; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D008810:Mice, Inbred C57BL; D048308:Mitogen-Activated Protein Kinase 14 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000201:enzymology* / Q000503:physiopathology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000201:enzymology*; D018995:Myosin Heavy Chains / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D015514:Oncogene Proteins, Fusion / Q000378:metabolism; D010641:Phenotype; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D034622:RNA Interference; D026362:Serum Response Factor / Q000378:metabolism; D015398:Signal Transduction; D013997:Time Factors; D015534:Trans-Activators / Q000378:metabolism; D014162:Transfection; D014661:Vasoconstriction / Q000235:genetics; D020742:rhoA GTP-Binding Protein / Q000378:metabolism; D000099251:Myocardin
chemical_list: D000199:Actins; D004268:DNA-Binding Proteins; D048308:Mitogen-Activated Protein Kinase 14; D018995:Myosin Heavy Chains; D009687:Nuclear Proteins; D015514:Oncogene Proteins, Fusion; D047428:Protein Kinase Inhibitors; D026362:Serum Response Factor; D015534:Trans-Activators; D020742:rhoA GTP-Binding Protein; D000099251:Myocardin; C541116:ACTA2 protein, human; C431575:MRTFA protein, human; C476858:SRF protein, human; C573943:myosin 11, mouse; C066737:RHOA protein, human