title: Regulation of vascular smooth muscle cell turnover by endothelial cell-secreted microRNA-126: role of shear stress.
abstract: BACKGROUND
  Endothelial microRNA-126 (miR-126) modulates vascular development and angiogenesis. However, its role in the regulation of smooth muscle cell (SMC) function is unknown.
  
  
  OBJECTIVE
  To elucidate the role of miR-126 secreted by endothelial cells (ECs) in regulating SMC turnover in vitro and in vivo, as well as the effects of shear stress on the regulation.
  
  
  RESULTS
  Coculture of SMCs with ECs or treatment of SMCs with conditioned media from static EC monoculture (EC-CM) increased SMC miR-126 level and SMC turnover; these effects were abolished by inhibition of endothelial miR-126 and by the application of laminar shear stress to ECs. SMC miR-126 did not increase when treated with EC-CM from ECs subjected to inhibition of miR biogenesis, or with CM from sheared ECs. Depletion of extracellular/secreted vesicles in EC-CM did not affect the increase of SMC miR-126 by EC-CM. Biotinylated miR-126 or FLAG (DYKDDDDK epitope)-tagged Argonaute2 transfected into ECs was detected in the cocultured or EC-CM-treated SMCs, indicating a direct EC-to-SMC transmission of miR-126 and Argonaute2. Endothelial miR-126 represses forkhead box O3, B-cell lymphoma 2, and insulin receptor substrate 1 mRNAs in the cocultured SMCs, suggesting the functional roles of the transmitted miR-126. Systemic depletion of miR-126 in mice inhibited neointimal lesion formation of carotid arteries induced by cessation of blood flow. Administration of EC-CM or miR-126 mitigated the inhibitory effect.
  
  
  CONCLUSIONS
  Endothelial miR-126 acts as a key intercellular mediator to increase SMC turnover, and its release is reduced by atheroprotective laminar shear stress.
authors.affiliation: Department of Bioengineering and Institute of Engineering in Medicine, University of California, San Diego, La Jolla, CA 92093, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhou
authors.forename: Yi-Shuan
authors.initials: YS
authors.lastname: Li
authors.forename: Phu
authors.initials: P
authors.lastname: Nguyen
authors.forename: Kuei-Chun
authors.initials: KC
authors.lastname: Wang
authors.forename: Anna
authors.initials: A
authors.lastname: Weiss
authors.forename: Yi-Chun
authors.initials: YC
authors.lastname: Kuo
authors.forename: Jeng-Jiann
authors.initials: JJ
authors.lastname: Chiu
authors.forename: John Y
authors.initials: JY
authors.lastname: Shyy
authors.forename: Shu
authors.initials: S
authors.lastname: Chien
mesh_terms: D000818:Animals; D060565:Argonaute Proteins / Q000235:genetics / Q000502:physiology; D017536:Carotid Artery, Common / Q000473:pathology; D018929:Cell Culture Techniques / Q000295:instrumentation; D002460:Cell Line; D018920:Coculture Techniques; D017077:Culture Media, Conditioned / Q000494:pharmacology; D042783:Endothelial Cells / Q000378:metabolism*; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors / Q000096:biosynthesis / Q000235:genetics; D005786:Gene Expression Regulation; D020868:Gene Silencing; D019254:Genes, bcl-2; D018056:Hemorheology; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D055504:Insulin Receptor Substrate Proteins / Q000096:biosynthesis / Q000235:genetics; D008026:Ligation; D051379:Mice; D035683:MicroRNAs / Q000235:genetics / Q000502:physiology* / Q000627:therapeutic use; D009131:Muscle, Smooth, Vascular / Q000166:cytology; D032389:Myocytes, Smooth Muscle / Q000166:cytology*; D058426:Neointima; D019899:Paracrine Communication; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis; D011993:Recombinant Fusion Proteins / Q000502:physiology; D014469:Umbilical Arteries / Q000166:cytology
chemical_list: C466422:AGO2 protein, human; D060565:Argonaute Proteins; D017077:Culture Media, Conditioned; C499517:FOXO3 protein, human; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; C526292:IRS1 protein, human; D055504:Insulin Receptor Substrate Proteins; C527111:MIRN126 microRNA, human; C545201:MIRN126 microRNA, mouse; D035683:MicroRNAs; D019253:Proto-Oncogene Proteins c-bcl-2; D011993:Recombinant Fusion Proteins
keywords: atherosclerosis; endothelial cell; extracellular miR-126; shear stress; smooth muscle cell