Abstract 11498: MicroRNA 140 Regulates Disease Phenotype in Experimental Pulmonary Arterial Hypertension And Identifies Smurf1 as a Novel Therapeutic Target
Rationale: Clinical therapies for the treatment of pulmonary arterial hypertension (PAH) target vasoconstriction. However, the proliferative pulmonary vascular remodelling that drives disease persists contributing to significant patient morbidity and mortality. MicroRNA (miR) are short non-coding RNA that mediate post-transcriptional regulation of mRNA targets. We hypothesise that dysregulation of miR leads to de-repression of cellular targets central to disease pathogenesis.
Objective: To identify dysregulated circulating miR in patients with PAH, determine their phenotypic effect using in vitro and in vivo models and identify key mechanistic regulators that may represent novel therapeutic targets.
Methods and Results: Expression of miR-140 was reduced in whole blood samples from patients with PAH and the monocrotaline (Mct) and Sugen5416 plus Hypoxia (SuHx) rat models of PAH. Reduced expression of miR-140 at the time of diagnosis identified patients with adverse clinical outcome. Network and pathway analysis identified key regulators of TGFß and PDGF signalling as miR-140 targets. Transfection with miR-140 inhibitor resulted in increased proliferation and migration of PASMC and de-repression of key targets. Nebulised delivery of miR-140 mimic prevented the development of PAH in the Mct rat model and attenuated progression of established PAH in the Mct and SuHx rat models. SMAD Specific E3 Ubiquitin Protein Ligase 1 (SMURF1) mRNA and protein was decreased in the lungs of miR-140 mimic treated animals. Levels of SMURF1 protein correlated inversely with miR-140. Direct regulation of SMURF1 by miR-140 was demonstrated in vitro by 3’UTR luciferase activity. Both miR-140 mimic and SMURF1 siRNA increased BMP response element activity identifying SMURF1 as a key negative regulator of BMP signalling in PASMC. Genetic ablation of SMURF1 in C57BL6 mice conferred allele dependent protection from SuHx induced PAH. Finally, whole blood mRNA and pulmonary vascular immunoreactivity of SMURF1 was increased in patients with PAH.
Conclusions: These studies suggest that miR-140 and SMURF1 are key regulators of BMP signaling and disease pathology in PAH and highlight SMURF1 as a potential novel therapeutic target.
Author Disclosures: A.M. Rothman: None. N.D. Arnold: None. J.A. Pickworth: None. J. Iremonger: None. L. Ciuclan: Employment; Significant; Novartis Institutes for BioMedical Research. R. Allen: Employment; Significant; Novartis Institutes for BioMedical Research. S. Guth-Gundel: Employment; Significant; Novartis Institutes for BioMedical Research. M. Southwood: None. N.W. Morrell: None. S.E. Francis: None. D. Rowlands: Employment; Significant; Novartis Institutes for BioMedical Research. A. Lawrie: None.
- © 2015 by American Heart Association, Inc.