title: Reversal of MicroRNA Dysregulation in an Animal Model of Pulmonary Hypertension.
abstract: BACKGROUND
  Animals models have played an important role in enhancing our understanding of the pathogenesis of pulmonary arterial hypertension (PAH). Dysregulation of the profile of microRNAs (miRNAs) has been demonstrated in human tissues from PAH patients and in animal models. In this study, we measured miRNA levels in the monocrotaline (MCT) rat model of PAH and examined whether blocking a specific dysregulated miRNA not previously reported in this model, attenuated PAH. We also evaluated changes in miRNA expression in lung specimens from MCT PAH rats overexpressing human prostacyclin synthase, which has been shown to attenuate MCT PAH.
  
  
  METHODS
  Expression levels of a panel of miRNAs were measured in MCT-PAH rats as compared to naïve (saline) control rats. Subsequently, MCT PAH rats were injected with a specific inhibitor (antagomiR) for miR-223 (A223) or a nonspecific control oligonucleotide (A-control) 4 days after MCT administration, then weekly. Three weeks later, RV systolic pressure and RV mass were measured. Total RNA, isolated from the lungs, microdissected pulmonary arteries, and right ventricle, was reverse transcribed and real-time quantitative PCR was performed. MiRNA levels were also measured in RNA isolated from paraffin sections of MCT-PAH rats overexpressing prostacyclin synthase.
  
  
  RESULTS
  MiRs 17, 21, and 223 were consistently upregulated, whereas miRs 126, 145, 150, 204, 424, and 503 were downregulated in MCT PAH as compared to vehicle control. A223 significantly reduced levels of miR-223 in PA and lungs of MCT PAH rats as compared to levels measured in A-control or control MCT PAH rats, but A223 did not attenuate MCT PAH. Right ventricular mass and right ventricular systolic pressure in rats treated with A223 were not different from values in A-control or MCT PAH rats. In contrast, analysis of total RNA from lung specimens of MCT PAH rats overexpressing human prostacyclin synthase (hPGIS) demonstrated reversal of MCT-induced upregulation of miRs 17, 21, and 223 and an increase in levels of miR-424 and miR-503. Reduction in bone morphogenetic receptor 2 (BMPR2) messenger (m)RNA expression was not altered by A223, whereas human prostacyclin synthase overexpression restored BMPR2 mRNA to levels in MCT PAH to levels measured in naive controls.
  
  
  CONCLUSIONS
  Inhibition of miR-223 did not attenuate MCT PAH, whereas human prostacyclin synthase overexpression restored miRNA levels in MCT PAH to levels detected in naïve rats. These data may establish a paradigm linking attenuation of PAH to restoration of BMPR2 signaling.
authors.affiliation: Central Arkansas Veterans Healthcare System, Little Rock, Arkansas, United States of America.|Department of Internal Medicine, Division of Pulmonary and Critical Medicine, The University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America.
authors.forename: Igor B
authors.initials: IB
authors.lastname: Gubrij
authors.affiliation: Central Arkansas Veterans Healthcare System, Little Rock, Arkansas, United States of America.|Department of Internal Medicine, Division of Pulmonary and Critical Medicine, The University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America.
authors.forename: Amanda K
authors.initials: AK
authors.lastname: Pangle
authors.affiliation: Department of Pharmacology, The University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America.
authors.forename: Li
authors.initials: L
authors.lastname: Pang
authors.affiliation: Central Arkansas Veterans Healthcare System, Little Rock, Arkansas, United States of America.|Department of Internal Medicine, Division of Pulmonary and Critical Medicine, The University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America.
authors.forename: Larry G
authors.initials: LG
authors.lastname: Johnson
mesh_terms: D000818:Animals; D000070416:Antagomirs; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics; D004195:Disease Models, Animal; D005260:Female; D005786:Gene Expression Regulation; D015316:Genetic Therapy; D006801:Humans; D006976:Hypertension, Pulmonary / Q000139:chemically induced / Q000235:genetics* / Q000503:physiopathology / Q000628:therapy*; D019746:Intramolecular Oxidoreductases / Q000235:genetics; D008168:Lung / Q000378:metabolism / Q000503:physiopathology; D035683:MicroRNAs / Q000235:genetics*; D016686:Monocrotaline; D009841:Oligonucleotides / Q000627:therapeutic use*; D017207:Rats, Sprague-Dawley
chemical_list: D000070416:Antagomirs; C000609258:MIRN223 microRNA, rat; D035683:MicroRNAs; D009841:Oligonucleotides; C000603521:antagomir-223; D016686:Monocrotaline; D003577:Cytochrome P-450 Enzyme System; D019746:Intramolecular Oxidoreductases; C022461:prostacyclin synthetase
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