Abstract 13579: MiR-193-3p is Regulated by 4F via Retinoid X Receptor Alpha (RXR-α) and Its Gain Attenuates Proliferation of Pulmonary Artery Smooth Muscle Cells From Pulmonary Arterial Hypertension Patients
Background: Pulmonary hypertension (PH) is caused by increase in pulmonary arterial pressure leading to right ventricular(RV) hypertrophy and RV failure. We have shown that apolipoprotein A-I mimetic peptide 4F decreases circulating levels of oxidized fatty acids hydroxyeicosatetraenoic acids (HETEs) and hydroxyoctadecadienoic acids (HODEs) by inducing miR-193-3p (miR193) via regulation of lipoxygenases. Also, miR193 OE is sufficient to rescue PH in these models. Here, we explored the upstream mechanisms of miR193 regulation by 4F. We assessed changes in miR193 levels in the lung and buffy coat of samples from PH patients and the effect of miR193 manipulation on the proliferation of human pulmonary artery smooth muscle cells (HPASMCs) from idiopathic PH patients (IPAH). We also assessed the effect of 15HETE therapy on mice.
Methods and Results: Lung tissue and buffy coat were obtained from PAH patients and control subjects. HPASMCs were transfected with ctrl, mimic-193 and inhibitor-193 oligonucleotides (50nM). Cell proliferation was measured by Ki67 staining. ChIP was performed using Active Motif kit. MiR193 expression was assessed in HPASMCs treated with 5-, 12-, 15-HETEs and 9-, 13-HODEs (100ng/ml) alone or with 4F. HETEs and HODEs decreased miR193 expression compared to control cells, which was abrogated in the presence of 4F. HETEs and HODEs induce the transcription of RXRα in HPASMCs which was suppressed by 4F. ChIP validated the direct binding of RXRα to miR193 promoter. 15HETE treatment of HPASMCs enriched RXRα on miR193 promoter which is inhibited in the presence of 4F. MiR193-OE in HPASMCs from IPAH patients attenuated proliferation whereas miR193-KD stimulated proliferation in HPASMCs from CTRL subjects. MiR193 expression was downregulated in the lung and buffy coat of IPAH patients. Mice fed with 15HETE for 3 weeks developed significantly higher RV systolic pressure versus mice on regular chow (34.3±2.8mmHg in 15-HETE diet vs. 22.1±2.4mmHg in CTRL, p<0.05) Lastly, 15HETE diet significantly downregulated miR193 expression in the lungs of mice compared to controls.
Conclusion: 4F induces miR193 expression via RXRα. MiR193 is downregulated in the lung tissue and buffy coats of IPAH patients and its gain attenuates proliferation of HPASMCs.
Author Disclosures: S. Sharma: None. F. Potus: None. S. Umar: None. S. Breuils-Bonnet: None. S. Provencher: None. S.T. Reddy: None. S. Bonnet: Research Grant; Modest; Bayer. Other Research Support; Modest; actellion. Honoraria; Modest; Merck. M. Eghbali: None.
This research has received full or partial funding support from the American Heart Association
- © 2014 by American Heart Association, Inc.