Osteopontin is indispensible for AP1-mediated angiotensin II-related miR-21 transcription during cardiac fibrosis.

Abstract

AIMS:

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.

METHODS AND 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.

CONCLUSION:

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: Johan M Lorenzen, Celina Schauerte, Anika Hübner, Malte Kölling, Filippo Martino, Kristian Scherf, Sandor Batkai, Karina Zimmer, Ariana Foinquinos, Tamas Kaucsar, Jan Fiedler, Regalla Kumarswamy, Claudia Bang, Dorothee Hartmann, Shashi K Gupta, Jan Kielstein, Andreas Jungmann, Hugo A Katus, Frank Weidemann, Oliver J Müller, Hermann Haller, Thomas Thum
• Journal: European heart journal (Eur Heart J) Vol. 36 Issue 32 Pg. 2184-96 (Aug 21 2015) ISSN: 1522-9645 [Electronic] England
• PMID: 25898844 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © The Author 2015. Published by Oxford University Press on behalf of the European Society of Cardiology.

Chemical References

• MIRN-21 microRNA, mouse
• MicroRNAs
• Recombinant Proteins
• Transcription Factors
• Osteopontin
• Angiotensin II
• Collagen
• Phosphatidylinositol 3-Kinases
• PTEN Phosphohydrolase
• PTEN protein, human
• Pten protein, mouse

Topics

• Adenoviridae
• Aged
• Angiotensin II (physiology)
• Animals
• Cell Survival
• Cells, Cultured
• Collagen (metabolism)
• Female
• Fibrosis (genetics)
• Gene Silencing
• Genetic Vectors (administration & dosage)
• Humans
• In Vitro Techniques
• Male
• Mice, Knockout
• MicroRNAs (genetics, metabolism)
• Myocardium (pathology)
• Myofibroblasts (physiology)
• Osteopontin (pharmacology, physiology)
• PTEN Phosphohydrolase (metabolism)
• Phosphatidylinositol 3-Kinases (metabolism)
• Recombinant Proteins (pharmacology)
• Transcription Factors