title: Osteopontin is indispensible for AP1-mediated angiotensin II-related miR-21 transcription during cardiac fibrosis.
abstract: OBJECTIVE
  Osteopontin (OPN) is a multifunctional cytokine critically involved in cardiac fibrosis. However, the underlying mechanisms are unresolved. Non-coding RNAs are powerful regulators of gene expression and thus might mediate this process.
  
  
  RESULTS
  OPN and miR-21 were significantly increased in cardiac biopsies of patients with myocardial fibrosis. Ang II infusion via osmotic minipumps led to specific miRNA regulations with miR-21 being strongly induced in wild-type (WT) but not OPN knockout (KO) mice. This was associated with enhanced cardiac collagen content, myofibroblast activation, ERK-MAP kinase as well as AKT signalling pathway activation and a reduced expression of Phosphatase and Tensin Homologue (PTEN) as well as SMAD7 in WT but not OPN KO mice. In contrast, cardiotropic AAV9-mediated overexpression of OPN in vivo further enhanced cardiac fibrosis. In vitro, Ang II induced expression of miR-21 in WT cardiac fibroblasts, while miR-21 levels were unchanged in OPN KO fibroblasts. As pri-miR-21 was also increased by Ang II, we studied potential involved upstream regulators; Electrophoretic Mobility Shift and Chromatin Immunoprecipitation analyses confirmed activation of the miR-21 upstream-transcription factor AP-1 by Ang II. Recombinant OPN directly activated miR-21, enhanced fibrosis, and activated the phosphoinositide 3-kinase pathway. Locked nucleic acid-mediated miR-21 silencing ameliorated cardiac fibrosis development in vivo.
  
  
  CONCLUSIONS
  In cardiac fibrosis related to Ang II, miR-21 is transcriptionally activated and targets PTEN/SMAD7 resulting in increased fibroblast survival. OPN KO animals are protected from miR-21 increase and fibrosis development due to impaired AP-1 activation and fibroblast activation.
authors.affiliation: Institute of Molecular and Translational Therapeutic Strategies (IMTTS), Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany Department of Internal Medicine, Division of Nephrology and Hypertension, Hannover Medical School, Hannover, Germany lorenzen.johan@mh-hannover.de thum.thomas@mh-hannover.de.
authors.forename: Johan M
authors.initials: JM
authors.lastname: Lorenzen
authors.affiliation: Institute of Molecular and Translational Therapeutic Strategies (IMTTS), Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
authors.forename: Celina
authors.initials: C
authors.lastname: Schauerte
authors.affiliation: Institute of Molecular and Translational Therapeutic Strategies (IMTTS), Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
authors.forename: Anika
authors.initials: A
authors.lastname: Hübner
authors.affiliation: Institute of Molecular and Translational Therapeutic Strategies (IMTTS), Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
authors.forename: Malte
authors.initials: M
authors.lastname: Kölling
authors.affiliation: Institute of Molecular and Translational Therapeutic Strategies (IMTTS), Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
authors.forename: Filippo
authors.initials: F
authors.lastname: Martino
authors.affiliation: Institute of Molecular and Translational Therapeutic Strategies (IMTTS), Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
authors.forename: Kristian
authors.initials: K
authors.lastname: Scherf
authors.affiliation: Institute of Molecular and Translational Therapeutic Strategies (IMTTS), Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
authors.forename: Sandor
authors.initials: S
authors.lastname: Batkai
authors.affiliation: Institute of Molecular and Translational Therapeutic Strategies (IMTTS), Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
authors.forename: Karina
authors.initials: K
authors.lastname: Zimmer
authors.affiliation: Institute of Molecular and Translational Therapeutic Strategies (IMTTS), Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
authors.forename: Ariana
authors.initials: A
authors.lastname: Foinquinos
authors.affiliation: Institute of Molecular and Translational Therapeutic Strategies (IMTTS), Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
authors.forename: Tamas
authors.initials: T
authors.lastname: Kaucsar
authors.affiliation: Institute of Molecular and Translational Therapeutic Strategies (IMTTS), Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Fiedler
authors.affiliation: Institute of Molecular and Translational Therapeutic Strategies (IMTTS), Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
authors.forename: Regalla
authors.initials: R
authors.lastname: Kumarswamy
authors.affiliation: Institute of Molecular and Translational Therapeutic Strategies (IMTTS), Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Bang
authors.affiliation: Institute of Molecular and Translational Therapeutic Strategies (IMTTS), Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
authors.forename: Dorothee
authors.initials: D
authors.lastname: Hartmann
authors.affiliation: Institute of Molecular and Translational Therapeutic Strategies (IMTTS), Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
authors.forename: Shashi K
authors.initials: SK
authors.lastname: Gupta
authors.affiliation: Department of Internal Medicine, Division of Nephrology and Hypertension, Hannover Medical School, Hannover, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Kielstein
authors.affiliation: University Hospital Heidelberg, Internal Medicine III, Heidelberg, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Jungmann
authors.affiliation: University Hospital Heidelberg, Internal Medicine III, Heidelberg, Germany DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg/Mannheim, Germany.
authors.forename: Hugo A
authors.initials: HA
authors.lastname: Katus
authors.affiliation: Department of Cardiology and Angiology, Würzburg University, Würzburg, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Weidemann
authors.affiliation: University Hospital Heidelberg, Internal Medicine III, Heidelberg, Germany DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg/Mannheim, Germany.
authors.forename: Oliver J
authors.initials: OJ
authors.lastname: Müller
authors.affiliation: Department of Internal Medicine, Division of Nephrology and Hypertension, Hannover Medical School, Hannover, Germany.
authors.forename: Hermann
authors.initials: H
authors.lastname: Haller
authors.affiliation: Institute of Molecular and Translational Therapeutic Strategies (IMTTS), Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany National Heart and Lung Institute, Imperial College London, London, UK lorenzen.johan@mh-hannover.de thum.thomas@mh-hannover.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Thum
mesh_terms: D000256:Adenoviridae; D000368:Aged; D000804:Angiotensin II / Q000502:physiology*; D000818:Animals; D002470:Cell Survival; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism; D005260:Female; D005355:Fibrosis / Q000235:genetics; D020868:Gene Silencing; D005822:Genetic Vectors / Q000008:administration & dosage; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D018345:Mice, Knockout; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D009206:Myocardium / Q000473:pathology*; D058628:Myofibroblasts / Q000502:physiology; D053495:Osteopontin / Q000494:pharmacology / Q000502:physiology*; D051059:PTEN Phosphohydrolase / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D014157:Transcription Factors
chemical_list: D000804:Angiotensin II; D003094:Collagen; D035683:MicroRNAs; D053495:Osteopontin; D051059:PTEN Phosphohydrolase; D019869:Phosphatidylinositol 3-Kinases; D011994:Recombinant Proteins; D014157:Transcription Factors; C494929:PTEN protein, human; C487757:Pten protein, mouse; C531950:MIRN21 microRNA, mouse
keywords: Angiotensin II; Cardiac fibrosis; Osteopontin; miR-21; microRNA