title: Nuclear factor of activated T cells 5 regulates vascular smooth muscle cell phenotypic modulation.
abstract: OBJECTIVE
  The tonicity-responsive transcription factor, nuclear factor of activated T cells 5 (NFAT5/tonicity enhancer binding protein [TonEBP]), has been well characterized in numerous cell types; however, NFAT5 function in vascular smooth muscle cells (SMCs) is unknown. Our main objective was to determine the role of NFAT5 regulation in SMCs.
  
  
  RESULTS
  We showed that NFAT5 is regulated by hypertonicity in SMCs and is upregulated in atherosclerosis and neointimal hyperplasia. RNAi knockdown of NFAT5 inhibited basal expression of several SMC differentiation marker genes, including smooth muscle α actin (SMαA). Bioinformatic analysis of SMαA revealed 7 putative NFAT5 binding sites in the first intron, and chromatin immunoprecipitation analysis showed NFAT5 enrichment of intronic DNA. Overexpression of NFAT5 increased SMαA promoter-intron activity, which requires an NFAT5 cis element at +1012, whereas dominant-negative NFAT5 decreased SMαA promoter-intron activity. Because it is unlikely that SMCs experience extreme changes in tonicity, we investigated other stimuli and uncovered 2 novel NFAT5-inducing factors: angiotensin II, a contractile agonist, and platelet-derived growth factor-BB (PDGF-BB), a potent mitogen in vascular injury. Angiotensin II stimulated NFAT5 translocation and activity, and NFAT5 knockdown inhibited an angiotensin II-mediated upregulation of SMαA mRNA. PDGF-BB increased NFAT5 protein, and loss of NFAT5 inhibited PDGF-BB-induced SMC migration.
  
  
  CONCLUSIONS
  We have identified NFAT5 as a novel regulator of SMC phenotypic modulation and have uncovered the role of NFAT5 in angiotensin II-induced SMαA expression and PDGF-BB-stimulated SMC migration.
authors.affiliation: Department of Pharmacology, Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, USA.
authors.forename: Julia A
authors.initials: JA
authors.lastname: Halterman
authors.forename: H Moo
authors.initials: HM
authors.lastname: Kwon
authors.forename: Ramin
authors.initials: R
authors.lastname: Zargham
authors.forename: Pamela D Schoppee
authors.initials: PD
authors.lastname: Bortz
authors.forename: Brian R
authors.initials: BR
authors.lastname: Wamhoff
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism; D000804:Angiotensin II / Q000378:metabolism; D000818:Animals; D001057:Apolipoproteins E / Q000172:deficiency / Q000235:genetics; D050197:Atherosclerosis / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D000077214:Becaplermin; D001665:Binding Sites; D020212:Carotid Artery Injuries / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002465:Cell Movement; D049109:Cell Proliferation; D002478:Cells, Cultured; D047369:Chromatin Immunoprecipitation; D018920:Coculture Techniques; D019295:Computational Biology; D004195:Disease Models, Animal; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D006801:Humans; D006965:Hyperplasia; D007438:Introns; D051379:Mice; D018345:Mice, Knockout; D009131:Muscle, Smooth, Vascular / Q000378:metabolism* / Q000473:pathology; D032389:Myocytes, Smooth Muscle / Q000378:metabolism* / Q000473:pathology; D050778:NFATC Transcription Factors / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D010982:Platelet-Derived Growth Factor / Q000378:metabolism; D011401:Promoter Regions, Genetic; D021381:Protein Transport; D020574:Proto-Oncogene Proteins c-sis; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection; D017539:Tunica Intima / Q000378:metabolism* / Q000473:pathology
chemical_list: D000199:Actins; D000804:Angiotensin II; D001057:Apolipoproteins E; D000077214:Becaplermin; D050778:NFATC Transcription Factors; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D012333:RNA, Messenger; D014157:Transcription Factors; C118125:NFAT5 protein, human; C492200:Nfat5 protein, mouse; C492199:Nfat5 protein, rat; C498862:Acta2 protein, rat